Download Investigating Infectious Diseases

Investigating
Infectious Diseases
Common Core & Essential
Standards

Common Core Literacy Standards
 RST.6-8.1 Cite specific textual evidence to support analysis of
science and technical texts.
 RST.6-8.2 Determine the central ideas or conclusions of a text;
provide an accurate summary of the text distinct from prior knowledge
or opinions.
 SL.8.1c Follow rules for collegial discussions and decision-making,
track progress toward specific goals and deadlines, and define
individual roles as needed.
 SL.8.4 Present claims and findings, emphasizing salient points in a focused,
coherent manner with relevant evidence, sound valid reasoning, and wellchosen details; use appropriate eye contact, adequate volume, and clear
pronunciation.

Essential Standards
 8.L.1.1
Summarize the basic characteristics of viruses, bacteria,
fungi and parasites relating to the spread, treatment and prevention of
disease.
 8.L.1.2
Explain the difference between epidemic and pandemic as
it relates to the spread, treatment and prevention of disease.
Learning Targets
 I can explain the characteristics of bacteria, viruses,
protists, and fungi.
 I can explain how diseases are treated and prevented.
 I can explain the differences in pandemics and
epidemics related to how they are spread, treated, and
prevented.
 I can summarize a scientific text.
 I can use text evidence to support conclusions drawn
from the text.
 I can present key ideas about diseases to others in a
clear voice.
 I can self-direct my learning.
Mystery Piece
Gallery Walk
 Have microscopes, computers, and photographs
set up around the room so that students can view
examples of fungi, bacteria, viruses, and protists.
 Do not label them.
 Have students make notes in their notebooks about
what the NOTICE and WONDER.
Note-Catcher
 Have students work in groups to add
their notices and wonders to the following
note-catcher frame (see next slide).
 Use chart paper or poster board.
 Students should write their notices and
wonders in RED in the outside frame.
Diseases
Notices and Wonders in RED here…
Notices and Wonders in RED here…
Notices and Wonders in RED here…
Notices and Wonders in RED here…
Common Article
 Have students read this article.
 Students should use the following codes
as they read to annotate the text.
“I knew this!”
“This is new information.”
?
“This is confusing!”
“This is important.”
Infectious Diseases
Article
Infectious Diseases. (2013). The New Book of Knowledge.
Retrieved November 7, 2013, from Grolier Online
http://nbk.grolier.com/ncpage?tn=/encyc/article.html&id=010000
97&type=0ta
Note-Catcher
 Have students work in groups to add
what they learned to the following notecatcher frame (see next slide) AS THEY
READ.
 Use chart paper or poster board.
 Students should write what they learned
from the article in BLUE in the inside
frame.
Add notes from
common article
here in BLUE.
Diseases
Add notes from common
article here in BLUE.
Notices and Wonders in RED here…
Notices and Wonders in RED here…
Notices and Wonders in RED here…
Notices and Wonders in RED here…
Expert Folder Stations
 Assign each group an expert folder: bacteria, viruses,
fungi, protists, non-infectious diseases, and
pandemic/epidemic.
 Give students 20-30 minutes to read and take notes
using the contents of the folder. Students will need 2030 per folder.
 Rotate folders until everyone has had a chance to
collect information from each folder (this may take more than one
class period).
Note-Catcher
 Have students work in groups to add
what they learned to the following notecatcher frame (see next slide) AS THEY
READ.
 Use chart paper or poster board.
 Students should write what they learned
from the article in PURPLE in the inside
frame.
Add notes from
common article
here in BLUE.
Severe
Weather
Add notes from common
article here in BLUE.
Notices and Wonders in RED here…
Notices and Wonders in RED here…
Notices and Wonders in RED here…
Notices and Wonders in RED here…
B
A
C
T
E
R
I
A
http://nbk.grolier.com/encycmedia/a000050-nbk/0ma/10599278
http://www.microbeworld.org/types-of-microbes/bacteria
http://www.microbeworld.org/types-of-microbes/bacteria/where-they-re-found
http://www.microbeworld.org/types-of-microbes/bacteria/what-they-eat
http://www.microbeworld.org/types-of-microbes/bacteria/how-they-move
Scan this QR code to visit the
MetroHealth website to learn more
about infectious diseases.
Scan this QR code and watch one of the
two videos about infectious diseases.
Scan this QR code to visit the
MetroHealth website to learn
more about infectious diseases.
Scan this QR code and watch one of the
two videos about infectious diseases.
http://www.sparknotes.com/biology/microorganisms/monera/section1.rhtml
http://www.mayoclinic.com/health/infectious-disease/AN00652
What’s Living on You
(article in separate file)
V
I
R
U
S
Why Do We Catch Colds?
Many common beliefs about colds are just myths.
Why Do We Catch Colds?
Many common beliefs about colds are just myths.
By Elaine Pascoe
By Elaine Pascoe
Aaa-choo! You sneeze. Your nose is runny, and your throat is scratchy. Uh-oh--those are signs
of the common cold. As illnesses go, most colds aren't very serious. But for as long as a cold
lasts, it makes you feel miserable.
The common cold really is common. At any one time, at least 12 million people worldwide have
colds! Adults average two to three colds every year. Children average six to ten. Younger
children usually get more colds than older children. Over the age of 4, girls get more colds than
boys.
What causes all these millions of colds? Viruses. There are more than 200 different cold viruses.
Like all viruses, they can multiply only inside living cells. The cold starts when a virus gets into
your nose. The virus invades the cells of the mucous membrane, which lines the nose. It begins
to multiply right away. In just a day, a few viruses can multiply to 100 million!
Your body fights back. Your nose streams mucus, washing out cells killed by the viruses.
Meanwhile, white blood cells and other parts of your body's immune system rush to battle the
viruses.
Your body's reaction, as much as the viruses, produces cold symptoms such as a sore throat,
headaches, and chills and fever. Most colds are over within a week. But it's important to rest
when you have a cold, to give your body a chance to fight the infection.
Many common beliefs about colds are just myths. For example, it's not true that you're more
likely to catch a cold if you become chilled. Nor will central heating cause you to catch cold by
drying out your nose. And there's no evidence that "feeding a cold"--eating a lot--will help you
recover. Chicken soup does seem to help clear stuffy noses, though.
Scientists haven't found a cure for the common cold yet. But they have figured out how colds
are passed from person to person. The viruses can spread through the air when a cold sufferer
sneezes. More often, they're spread through touch.
Suppose you have a cold, and you touch your nose. Now there are cold viruses on your hand.
Your hand leaves a trail of viruses on anything you touch, from dishes to doorknobs. If your
sister touches those things after you, or touches you directly, she picks up some viruses. If she
touches her nose or eyes, the viruses invade. And she catches your cold.
To lessen your chances of getting colds this winter, take these steps:
(1)Avoid people with colds, especially during the first three days of the illness. That's when
colds are most contagious.
(2)Wash your hands if you've come in contact with a person with a cold or with anything that
person may have touched or sneezed on.
(3) Keep your fingers away from your eyes and nose.
(4) Try not to let a person with a cold cough or sneeze in your direction.
Aaa-choo! You sneeze. Your nose is runny, and your throat is scratchy. Uh-oh--those are
signs of the common cold. As illnesses go, most colds aren't very serious. But for as long as
a cold lasts, it makes you feel miserable.
The common cold really is common. At any one time, at least 12 million people worldwide
have colds! Adults average two to three colds every year. Children average six to ten.
Younger children usually get more colds than older children. Over the age of 4, girls get
more colds than boys.
What causes all these millions of colds? Viruses. There are more than 200 different cold
viruses. Like all viruses, they can multiply only inside living cells. The cold starts when a
virus gets into your nose. The virus invades the cells of the mucous membrane, which lines
the nose. It begins to multiply right away. In just a day, a few viruses can multiply to 100
million!
Your body fights back. Your nose streams mucus, washing out cells killed by the viruses.
Meanwhile, white blood cells and other parts of your body's immune system rush to
battle the viruses.
Your body's reaction, as much as the viruses, produces cold symptoms such as a sore
throat, headaches, and chills and fever. Most colds are over within a week. But it's
important to rest when you have a cold, to give your body a chance to fight the infection.
Many common beliefs about colds are just myths. For example, it's not true that you're
more likely to catch a cold if you become chilled. Nor will central heating cause you to
catch cold by drying out your nose. And there's no evidence that "feeding a cold"--eating a
lot--will help you recover. Chicken soup does seem to help clear stuffy noses, though.
Scientists haven't found a cure for the common cold yet. But they have figured out how
colds are passed from person to person. The viruses can spread through the air when a
cold sufferer sneezes. More often, they're spread through touch.
Suppose you have a cold, and you touch your nose. Now there are cold viruses on your
hand. Your hand leaves a trail of viruses on anything you touch, from dishes to doorknobs.
If your sister touches those things after you, or touches you directly, she picks up some
viruses. If she touches her nose or eyes, the viruses invade. And she catches your cold.
To lessen your chances of getting colds this winter, take these steps:
(1)Avoid people with colds, especially during the first three days of the illness. That's when
colds are most contagious.
(2)Wash your hands if you've come in contact with a person with a cold or with anything
that person may have touched or sneezed on.
(3) Keep your fingers away from your eyes and nose.
(4) Try not to let a person with a cold cough or sneeze in your direction.
™ & © 2013 Scholastic Inc. All rights reserved.
™ & © 2013 Scholastic Inc. All rights reserved.
Virus
Table of Contents
How to Cite This Article
Viruses are the smallest creatures known. We are aware of them because of the diseases they cause in humans, such as the common cold, chicken pox, and AIDS. Viruses can infect not only humans but every
living thing—plants and animals, as well as microscopic organisms. Even the name "virus," which means "poison," tells of a deadly nature. Yet viruses can also be beneficial. They can add the special color
patterns found in fancy tulips, provide the tools for new vaccines, and help cure serious diseases.
Viruses are fascinating creatures. Scientists are not even sure whether they are really alive or whether viruses are just organized packages of chemicals that take over cells. Their existence prompts many
questions: How can such small and simple creatures survive and reproduce? How can they cause diseases and even cancer? What role do they play in our world of living organisms?
What Is a Virus?
Viruses do not carry enough information in their genes, or "instructional" molecules, to live by themselves. They can only live and reproduce within the cells of other organisms. Because viruses usually give
nothing useful to the cell they infect and often damage it, we call them parasites. The skin sores in chicken pox are an example of this cell damage.
Viruses lack the basic machinery of life. They cannot make their own essential molecules, such as proteins and carbohydrates. They also cannot produce ATP, the basic energy carrier of a cell. These tiny
creatures act like cell pirates, taking over and using the chemical factories of the host cell and most of its production molecules, which are called enzymes, to survive.
Characteristics of Viruses
Scientists realized that, like viruses, there are some bacteria that need living host cells to multiply. To identify a virus, scientists searched for features that were truly unique to viruses. The size, shape, simple
chemical composition, and structure of viruses make them distinct from all other creatures.
Size.
Viruses are very small and compact. Most can only be seen with an electron microscope. The size of these tiny organisms is measured in nanometers. A nanometer is about 1/25 millionth of an inch. The smallest
viruses, such as the common cold viruses, are 20 to 30 nanometers in diameter, while the largest viruses, such as the smallpox viruses, are 200 to 300 nanometers in diameter. To get an idea of the size of
viruses in relation to cells, think of a large ocean liner, a tugboat, and a rowboat. The tugboat next to the large ocean liner would be about the size of a large virus compared to a cell. The small rowboat next to
the ocean liner would be about the size of a small virus compared to a cell.
Shape.
Viewing viruses with the electron microscope, scientists were also able to examine their shapes. Viruses come in several shapes: helical,polyhedral, and complex. The tobacco mosaic virus, a helical virus, looks
like a long rod with a hollow core. Polyhedral viruses look like soccer balls. They look almost spherical, but they are actually made up of many triangular sides, or faces.
Viruses with very complicated structures are called complex viruses. For example, viruses that infect bacteria have both a polyhedral and a helical part. A bacterial virus looks like a tadpole with its polyhedral
head and its helical tail. In addition, this virus has special tail fibers and plates attached to its tail that help it to bind to the cells it infects.
Chemical Composition.
The cells of living organisms carry instructions for all their characteristics in a chemical code. This chemical code is found in the hereditary units called genes. These genetic messages are found in the nucleic
acid molecule called DNA (deoxyribonucleic acid). The genetic information in the DNA passes from generation to generation as the cell divides. Cells also contain a second type of nucleic acid, called RNA
(ribonucleic acid). This molecule carries the information from the DNA to the chemical factories in the cell. The RNA messages tell the cell to make various molecules needed for life, such as types of proteins
called enzymes.
Viruses also contain their genetic information in nucleic acid. But viruses are unique. They only have one type of nucleic acid, either DNA or RNA and so are called DNA viruses and RNA viruses. They never carry
both types of nucleic acid. Some viruses have only one copy, or strand, of their particular nucleic acid. Other viruses have two strands of DNA or RNA. Still other viruses have their nucleic acid in pieces or
segments.
Because viruses have only one type of nucleic acid, they have had to find special ways to live in cells and to reproduce. Viruses are often classified by the type of nucleic acid and the number of strands they
have.
Structure.
The genetic material of viruses, whether it is DNA or RNA, is wrapped inside a protein coat called a capsid. The capsid gives the virus its characteristic shape. Identical building blocks called capsomeres make up
this coat. The capsomeres join together spontaneously in such a uniform manner that viruses of any one type are always the same size and shape. The ability to reproduce in this way is called self-assembly. It is
an ability that only viruses have.
In some types of viruses, a protective membrane called an envelope covers the protein coat. The virus gets this membrane, which is made of fatty acids and proteins, from the cell it infects. Viruses that acquire
this membrane are called enveloped viruses. Viruses that do not acquire an envelope are called naked or non-enveloped viruses.
Not all envelopes are the same. Some viruses put their own identifying marks, in the form of molecules, into the envelope. These molecules, called spikes, stick out from the envelope like stiff hairs. Spikes are
important to the virus because they help it attach to other cells and enter them. For example, the virus that causes AIDS has spikes in its envelope. The spikes help the AIDS virus attach to molecules on the
surface of T-lymphocytes, a type of white blood cell.
Multiplication of Viruses
Each virus needs a certain type of cell in which to multiply: Plant viruses multiply only in plant cells; animal viruses multiply only in animal cells. Some viruses are even more particular, such as the animal viruses
that only infect certain types of cells in animals.
After infecting a host cell, a single virus can produce hundreds or even thousands of similar viruses. The virus carries the essential information for its life cycle in its genes, while the host cell supplies the energy,
machinery, building blocks, and production enzymes necessary for the virus to live and multiply. The new viruses are made in an orderly, step-by- step process. The steps used by all viruses are 1) attachment, 2)
entry, 3) synthesis of virus parts, 4) assembly, and 5) release.
Attachment
In order to multiply, the virus must first attach itself to the surface of a cell. The virus and the host cell must bind together tightly and fit each other exactly. Bacteriophages, viruses that attack bacteria, use their tail
fibers to bind to molecules called receptors on the outside surface of bacteria. Other viruses identify their host-cell receptors using molecules in the protein coat of the virus. Other chemicals on the virus also help it to
enter the host cell.
Entry
Once attached, viruses must free their genetic material inside the host cell so that new virus parts can be made. Sometimes the whole virus will enter the cell before gaining access to the host cell's protein-making
processes. Other times just the nucleic acid will enter the host cell.
The method a virus uses to enter a cell depends on the type of virus. Some viruses are engulfed and taken in by the host cell. Other viruses, such as bacteriophages, inject their nucleic acid into the host. The tail of the
bacteriophage contracts like a syringe and shoots the nucleic acid into the bacterium. The old protein coat of the virus is no longer needed and stays on the outside of the bacterium. The virus, with its genetic material
free and open within the host cell, can now make new viruses.
Synthesis and Assembly
Once freed inside the cell, the viral genes get to work and take over the cell machinery. The host cell becomes a factory, with all of its processes dedicated to turning out new viruses. Copies of the viral nucleic acid are
made instead of the cellular nucleic acid. Then viral proteins that will make up the outside of the virus—head, tail, and tail fibers—are made. Soon each copy of viral nucleic acid is surrounded by many capsomeres.
The capsomeres assemble to form the capsid, and a complete, mature virus is produced.
Release
The final step of the virus life cycle is the release of the viruses from the host cell. Some viruses destroy the cell when they are released. Bacteriophages make molecules that weaken the walls of the host cells. The
large numbers of new bacterial viruses cause the weakened cells to burst. Because these viruses break down, or lyse, their host cells, they are called lytic viruses. Other viruses may not destroy the cell as they are
released, but they may signal a cell to start reproducing rapidly, which may lead to cancer.
Variations in Multiplication
Although the basic way viruses multiply is similar for most bacterial, animal, and plant viruses, there are some variations in the way each type of virus enters and exits a host cell and in when a virus multiplies.
Bacterial Viruses.
Some bacterial viruses have the choice of several lifestyles. That is, they can work hard and make new viruses, or they can stay quietly in the host bacteria without multiplying. These quiet viruses attach to the bacteria
and inject their genes in the same manner as the lytic bacteriophages. However, these virus genes do not make new viruses and lyse the cell, even though they could. Their viral DNA becomes a part of the bacterial
DNA and travels along with the bacterial genes.
Because no heads or tails are seen, the virus seems to disappear within the host cell. Even the bacteria do not notice the viral genes. But when the bacteria divide, they make a copy of the viral genes along with the
bacterial genes. The bacteria with the extra viral genes remain healthy and continue to multiply. Special conditions trigger the virus genes to pop out of the bacterial DNA. When this happens, the virus acts like a lytic
virus. It makes new viral nucleic acid and protein coats, assembles, and upon release, bursts open the cell.
There are rare times when these quiet bacterial viruses make a mistake. They will package some bacterial genes into their protein coats along with their own genes. Then the bacteriophages become unsuspecting
carriers of new genetic information. These carriers will inject into other bacteria both their viral nucleic acid and the nucleic acid from the first bacterium. The second bacterium may use these new genes and get traits
from the first bacterium. The ability of a bacteriophage to carry traits from one bacterium to another is called transduction. Transduction has allowed bacteria to change and evolve very quickly because of the new
genes they acquire.
Animal Viruses.
Animal viruses use almost the same pattern to multiply as bacteriophages. Animal viruses do differ, however, in how they enter and exit the host cell. Like bacteriophages, animal viruses attach to specific receptors on
the cell membranes of host cells. The capsids or the spikes in enveloped viruses help the virus to find the right cell and bind to it.
Following attachment, animal viruses can then sneak into cells in two ways. Some viruses, such as the human immuno-deficiency virus (HIV) that causes AIDS, can enter by joining the viral envelope with the host cell
membrane. Other viruses trick the cell into engulfing them. Once inside, the viral cell removes its protective layers—the envelope and capsid. This separation of the viral nucleic acid from the protein coat is called
uncoating. The uncoating process is only seen in animal viruses.
The exposed viral nucleic acid is then copied to make new viral genes. In addition, viral proteins need to be made. To make new proteins, the virus uses messenger RNA (mRNA). Many viruses cause the host cell to
make viral mRNA, while some RNA viruses use their own genes as mRNA. The mRNA decodes the genetic information and directs the manufacturing processes of the cell to make new virus proteins—capsomeres, virus
enzymes, and spikes for the envelope. Then, like the bacteriophage, the viral nucleic acid and protein will join to form new viruses.
Animal viruses have found two ways to get out of the cell. Some viruses rupture the cell, like the bacteriophages, and leave as naked viruses. Other viruses leave the cell by budding. These viruses push through and
steal a little of the host cell membrane to make its envelope. Budding is the way enveloped viruses leave the cell. Budding viruses do not immediately kill the host cell, but they can change and damage it.
Certain animal viruses have a process that is similar to the lysogeny of bacteriophages. The nucleic acid of the virus can be inserted into the host DNA. The viruses stay inactive, or latent, for a long time. The DNA virus
that causes chicken pox is one example. In some people, it hides in nerve cells for many years. Special conditions cause the virus to reappear, multiply, and produce the disease called shingles. The DNA of the virus is
no longer carried quietly in the host DNA. It becomes active and produces lytic viruses that damage the cell.
RNA viruses can become latent also. Animal viruses that have RNA as their nucleic acid must first copy the RNA into viral DNA before it can be put into the host DNA. These special RNA viruses work backward from the
way most cells transfer genetic information and are called retroviruses, retro meaning reverse. The viruses use a viral enzyme called reverse transcriptase to change their RNA into viral DNA. The viral DNA in these
latent viruses then becomes part of the host cell DNA. New traits show that the host cell contains the viral DNA. Some of these characteristics are beneficial and help animals and plants to evolve faster. Other changes
are harmful. Latent DNA viruses and retroviruses are believed to cause cancer and other diseases.
Plant Viruses.
Plant viruses have shapes and sizes similar to animal viruses. Most plant viruses have RNA as their genetic material, but small DNA-containing plant viruses also exist. Latent DNA viruses and RNA viruses that make
reverse transcriptase enzymes can be found in plants. These latent, or quiet, viruses have allowed scientists to transfer genes from one plant to another and develop plants with properties such as resistance to insects.
The multiplication of plant viruses is also similar to animal viruses. However, plant viruses need more help to get from a diseased plant to a healthy plant. A virus may be carried from one plant to another by insects or
air currents. Plant viruses also need more help once they get to a healthy plant. Healthy plants have strong cell walls that are difficult to penetrate. Various types of insects, such as aphids, help viruses get into plant
cells. As the aphids feed, they bore into the plant, clearing the way for viruses to enter. Sometimes a virus can enter if the plant is damaged. A few viruses can be transferred through the seeds or structures of a plant.
Once inside the cell, most plant viruses immediately take over the cell machinery and make new viruses. Damage to the cells occurs during release of the virus and results in the spots, lesions, and curling and drying of
leaves seen in diseased plants.
Growing Viruses
For scientists to be able to study viruses, their structures, how they assemble themselves, and how they multiply, they must have a reliable supply of viruses. That is, they must be able to grow viruses. Many organisms
grown in the laboratory have simple requirements—once they are isolated, they will multiply given the proper nutrients. However, it is harder to study viruses than most creatures because they need to grow in living
cells instead of chemical nutrients.
Bacterial viruses are easier to grow than plant and animal viruses. That is why many studies on the multiplication and effects of viruses are done with bacterial viruses. Bacteria, which are the host for bacteriophages,
will reproduce quickly in liquid or solid foods, called media. Bacteriophages can quickly form hundreds of new viruses inside the bacterial cell. When these new viruses form, the cell bursts open and the viruses are
released.
During the release of the viruses, the bacterial cell is destroyed. The destroyed bacteria are easy to see. Killed bacteria on solid media appear as clear areas, as if the virus has eaten the bacteria. That is why these
viruses are called bacteriophages, which means "bacteria that eat." It is also possible to tell which bacteria have not been infected and destroyed by the virus. Bacteria that are not infected grow and form a cloudy
surface on the solid media.
When scientists examine the media, along with being able to tell which bacteria were infected and which were not, they are able to tell how many bacteriophages were present at the start. They do this by counting
the clear areas, called plaques. Each plaque comes from one of the original bacteriophages.
Growing animal and plant viruses in living organisms is more difficult and also more expensive. At one time, scientists could see the damage viruses caused in animals, but they could not study how the viruses
multiplied. Then in the 1950's, a new method, which became known as tissue or cell culture, was developed. The new technique made it possible for scientists to study viruses in living tissue, but without causing
disease in live animals.
To create a tissue culture, cells from the tissues of living organisms are separated and placed in plastic dishes. The cells are then fed liquid nutrients on a regular basis to allow them to grow. When a virus is added to
the culture, it can enter and multiply in the cells. The action of the virus on the living cells can then be observed. Sometimes the cells are killed by the virus. If the virus destroys the cells, a plaque, similar to that caused
by the bacteriophages, will be seen. However, viruses do not always destroy the cells they infect. Viruses also can change the appearance of the cells in a culture. For example, some viruses can join or fuse several cells
into one abnormal giant cell. The alteration of cells caused by viruses is called a cytopathic effect. These changes show that the virus is present and multiplying in the cells.
Viruses and Disease
Viruses can cause many diseases in humans, other animals, and plants. Some common diseases in humans are the cold, chicken pox, measles, warts, and cold sores. More serious diseases include hepatitis, rabies,
polio, and AIDS. In other animals viruses cause, among other ailments, distemper, rabies, and foot-and-mouth disease. Plants can have such virus diseases as peanut stunt, blueberry leaf mottle, beet curly top, and
cauliflower mosaic.
Types of Virus Infections
The kind of disease and the way it progresses in living organisms depends on the virus, the host cell, and the effects of the virus on the host cell. There are three basic ways that a virus infection can progress. The
infection can be acute, chronic, or latent.
Acute Infection. Influenza, or flu, is a familiar example of an acute infection, which starts soon after exposure to the virus. We are soon aware of these viruses that multiply quickly and damage or lyse our cells. The
cough, muscle ache, and fever that are common to the flu indicate the presence of the influenza virus. The virus is altering the cells in the respiratory tract and signaling the body's defenses to fight the invasion.
Another characteristic of influenza viruses is that they continually change. That is why each year there are a number of different acute influenza infections in humans. Influenza epidemics —outbreaks of the disease in
which large numbers of people get sick—also occur some years.
Chronic Infection. In a chronic infection, viruses multiply in small numbers and slowly damage the tissues. We do not always know that the virus is present. But disease can eventually occur when the damage builds
up. Chronic infections continue over a long time. These diseases are harder to detect and identify than acute infections.
Some viruses, such as the hepatitis-B virus, can cause both acute and chronic infections. Symptoms of this virus, which causes an infection of the liver in humans, include yellowing of the skin, loss of appetite, and a
low fever. Most people with an acute hepatitis infection recover with proper care. The virus, however, continues to multiply slowly in some people. These people carry the virus and can infect others. Eventually the
virus will cause permanent damage to the liver. Of more concern is the finding that liver cancer is more common in people with chronic hepatitis.
Latent Infection. Viruses classified as latent seem to produce little or no effects on the host cells. A complete virus may not be detected for a long time. An example of a latent infection is the cold sore, or fever blister.
A sore may occur near the lips, disappear for many months or longer, and then reappear. The virus remains dormant within long nerve cells, which extend from a region near the temple to the lips. Stresses caused by a
cold, fever, or sunburn stimulate the virus to start reproducing. Soon afterward, another painful infection of the cells near the lips occurs.
Viruses and Cancer
As pirates of the cell, viruses can take over important activities of the host cell. Sometimes viruses can cause the cell to divide in an uncontrollable way. Viruses can also change a healthy cell into an abnormal form that
will reproduce in an uncontrollable way. Cancer results when large numbers of the abnormal cells are produced.
The way viruses cause cancer is not completely understood. Scientists know that changes in host DNA can sometimes produce cancer. Altered genes that cause cancer are called oncogenes. Surprisingly, scientists
found that normal cells had genes that looked like oncogenes. These normal genes are called proto-oncogenes. The proto-oncogenes make proteins that are essential to the cell. These proteins are bosses of the cell.
They direct the cell to start important work and make molecules necessary to the cell's survival.
When viruses infect a cell, they can alter the proto-oncogenes, causing them to become oncogenes. For example, the job of one proto- oncogene is to make a protein that tells the cell to stop dividing. The body
normally turns on cell division when it needs new cells and turns it off when enough new cells have been made. If the virus changes the gene to an oncogene, an abnormal protein can be made. Then the cell divides
continuously because the abnormal protein cannot work properly to stop the cell from dividing. The result is cancerous cell growth.
The viral genes also may change the host genes so that the amount of protein made by the cell is altered. In addition, the viruses can transfer and insert the deadly oncogenes into the next cell they infect. Once again
new cancer cells are produced.
New Developments with Viruses
The study of viruses has provided insights into how they cause disease. It has also shown how viruses can be used to help us rather than harm us. We know that viruses can carry extra genes. Some viruses can also
permanently add genes to the cells they infect. New vaccines to prevent disease, gene therapy to cure hereditary diseases and cancer, and biological control of plant diseases are just some of the scientific advances
possible using the special abilities of viruses.
Viral vaccines are preparations that train our immune system to recognize and combat viral invaders. Smallpox, a serious viral disease, is the only disease ever eliminated from the entire planet by a vaccine. New virus
vaccines are being tested to protect against hepatitis, malaria, and even the deadly AIDS virus.
Viruses may someday help us to treat cancer and certain genetic diseases. Retroviruses, which are very efficient at transferring genes, are being tried for these roles. Scientists first weaken the retrovirus so that it
cannot cause cancer or other diseases. The virus is then used to slip a new gene into the cells they infect. The cell will then permanently make the protein from the new gene. For example, they can insert a gene into
white blood cells that will make a cancer toxin, or poison. The newly equipped defense cells can then go about the task of killing cancer cells.
Viruses also may help us to cure serious genetic diseases. A normal gene transferred by a virus may correct a defective gene in the patient. Scientists have begun studies to correct diseases affecting the immune
system and blood-cell production using such gene therapy.
Plant diseases destroy many important crops we need for food. Methods using viruses to control plant disease and improve agricultural crops are being developed. To protect plants from disease, genes that make coat
proteins for harmless viruses are inserted into plants. The presence of these coat proteins can stop infections by similar destructive viruses. The harmless virus protects the plant against the disease virus. Scientists
have successfully used the technique to protect the tomato from infection by the tomato mosaic virus. A tomato resists infection because it carries the viral gene for a chemically similar, harmless coat protein. Many
other plant diseases are being tested using this new approach.
We often think of viruses as agents of disease and death. However, by understanding how viruses function, scientists have learned how to control and use some viruses for the benefit of humans.
Cynthia V. Sommer Department of Biological Sciences University of Wisconsin at Milwaukee
How to cite this article:
Sommer, Cynthia V. "Virus." The New Book of Knowledge. Grolier Online, 2013. Web. 8 Nov. 2013.
™ & © 2013 Scholastic Inc. All rights reserved.
Ten cool facts about viruses
19 OCTOBER 2009
1. Some parasitic wasps lay eggs in caterpillars, where they mature into adult wasps. The wasp eggs contain a virus, encoded in the wasp genome, which prevents the caterpillar from rejecting
the eggs.
2. There are a million virus particles per milliliter of seawater – for a global total of 1030 virions! Lined up end to end, they would stretch 200 million light years into space.
3. The genetic information of viruses can be DNA or RNA; single or double stranded; one molecule or in pieces.
4. The name virus was coined from the Latin word meaning slimy liquid or poison.
5. Walter Reed discovered the first human virus, yellow fever virus, in 1901.
6. Viruses are not alive – they are inanimate complex organic matter. They lack any form of energy, carbon metabolism, and cannot replicate or evolve. Viruses are reproduced and evolve only
within cells.
7. Over 1016 human immunodeficiency virus genomes are produced daily on the entire planet. As a consequence, thousands of viral mutants arise by chance every day that are resistant to
every combination of antiviral compounds in use or in development.
8. The first human influenza virus was isolated in 1933. In 2005, the 1918 pandemic influenza virus strain was constructed from nucleic acid sequence obtained from victims of the disease.
9. The biggest known viruses are mimiviruses, which are 400 nanometers (0.0004 millimeters) in diameter. The viral genome is 1,200,000 nucleotides in length and codes for over 900 proteins.
10. The smallest known viruses are circoviruses, which are 20 nanometers (0.00002 millimeters) in diameter. The viral genome is 1,700 nucleotides in length and codes for two proteins.
Bonus fact: The HIV-1 genome, which is about 10,000 nucleotides long, can exist as 106020 different sequences. To put this number in perspective, there are 1011 stars in the Milky Way galaxy
and 1080 protons in the universe.
Source: http://www.virology.ws/2009/10/19/ten-cool-facts-about-viruses/
Ten cool facts about viruses
19 OCTOBER 2009
1. Some parasitic wasps lay eggs in caterpillars, where they mature into adult wasps. The wasp eggs contain a virus, encoded in the wasp genome, which prevents the caterpillar from rejecting
the eggs.
2. There are a million virus particles per milliliter of seawater – for a global total of 1030 virions! Lined up end to end, they would stretch 200 million light years into space.
3. The genetic information of viruses can be DNA or RNA; single or double stranded; one molecule or in pieces.
4. The name virus was coined from the Latin word meaning slimy liquid or poison.
5. Walter Reed discovered the first human virus, yellow fever virus, in 1901.
6. Viruses are not alive – they are inanimate complex organic matter. They lack any form of energy, carbon metabolism, and cannot replicate or evolve. Viruses are reproduced and evolve only
within cells.
7. Over 1016 human immunodeficiency virus genomes are produced daily on the entire planet. As a consequence, thousands of viral mutants arise by chance every day that are resistant to
every combination of antiviral compounds in use or in development.
8. The first human influenza virus was isolated in 1933. In 2005, the 1918 pandemic influenza virus strain was constructed from nucleic acid sequence obtained from victims of the disease.
9. The biggest known viruses are mimiviruses, which are 400 nanometers (0.0004 millimeters) in diameter. The viral genome is 1,200,000 nucleotides in length and codes for over 900 proteins.
10. The smallest known viruses are circoviruses, which are 20 nanometers (0.00002 millimeters) in diameter. The viral genome is 1,700 nucleotides in length and codes for two proteins.
Bonus fact: The HIV-1 genome, which is about 10,000 nucleotides long, can exist as 106020 different sequences. To put this number in perspective, there are 1011 stars in the Milky Way galaxy
and 1080 protons in the universe.
Source: http://www.virology.ws/2009/10/19/ten-cool-facts-about-viruses/
Ten Cool Facts About Viruses
http://bigbrainscience.com/ten-cool-facts-about-viruses
Posted on February 25, 2012
1.Because viruses are such simple organisms made up of just genetic code (DNA or RNA) and a protein shell, some scientist feel that they should not be classified as living. They may be an intermediate step between
organic chemicals and more complex living cells like bacteria. 2. Viruses are extremely small, only 20 to 250 nanometres in size so thousands of them could fit into one cell, but don’t let them in they will just wreck
the place and leave a mess. 3. Viruses can’t reproduce by themselves they always take over living cells in plants, and animals. 4.Just because they are always parasitic doesn’t mean that they are all bad for humans
sometimes they attack bacteria that is harmful to us. So it is a classic ‘the enemy of my enemy is my friend’ situation. 5. Many viruses cause disease, viruses cause colds, flu, chickenpox, measles, mumps, rubella, and
even HIV, which causes AIDS, is a virus. They are nasty and unlike bacterial infection it is very hard to treat viral infections. 6.There are two types of viruses depending on the type of genetic material forms their
method of replication. DNA Viruses are fairly stable because it make good copies of itself which means doctors can take a dead or weakened version and put it in your body and your body will learn to defend itself
from that type of infection. RNA Viruses are less stable populations because they make frequent mistakes in making copies of itself that means that diseases caused by RNA type viruses are hard to vaccinate against
and change very quickly. That is why a new flu vaccine is needed every year. 7 . Vaccinations for some diseases were so effective the disease is no longer present in the population, small pox, which is a very deadly
disease, was eliminated this way, People who get vaccinated even protect those who are not vaccinated because they don’t provide a place for the disease to multiply and spread from. Depending on the virus and
how it is spread if 85-95% of the population get vaccinated everyone will benefit from ‘herd immunity’, that is really what it is called so don’t laugh. 8.Colds are caused by viruses but there is no vaccine because
there are literally thousands of viruses that cause colds, so it looks like chicken soup for you and some nice bed rest. 9.Viruses are usually adapted to live in a certain type of host animal of plant but if a mutation
allows it to jump species the results can be devastating because non of the new host population has any immunity to the new virus and so the initial infection can spread very quickly and be very dangerous until
people start to develop immunity. 10. Viruses can not reproduce without a host so they are most often spread by sneezing, coughing, or by touching someone who is infected – That is why it is important to wash your
hands regularly and sneeze or cough into a tissue or your hand. It is also vital to avoid people who are not following these basic rules because one person can infect thousands.
Ten Cool Facts About Viruses
http://bigbrainscience.com/ten-cool-facts-about-viruses
Posted on February 25, 2012
1.Because viruses are such simple organisms made up of just genetic code (DNA or RNA) and a protein shell, some scientist feel that they should not be classified as living. They may be an intermediate step between
organic chemicals and more complex living cells like bacteria. 2. Viruses are extremely small, only 20 to 250 nanometres in size so thousands of them could fit into one cell, but don’t let them in they will just wreck
the place and leave a mess. 3. Viruses can’t reproduce by themselves they always take over living cells in plants, and animals. 4.Just because they are always parasitic doesn’t mean that they are all bad for humans
sometimes they attack bacteria that is harmful to us. So it is a classic ‘the enemy of my enemy is my friend’ situation. 5. Many viruses cause disease, viruses cause colds, flu, chickenpox, measles, mumps, rubella, and
even HIV, which causes AIDS, is a virus. They are nasty and unlike bacterial infection it is very hard to treat viral infections. 6.There are two types of viruses depending on the type of genetic material forms their
method of replication. DNA Viruses are fairly stable because it make good copies of itself which means doctors can take a dead or weakened version and put it in your body and your body will learn to defend itself
from that type of infection. RNA Viruses are less stable populations because they make frequent mistakes in making copies of itself that means that diseases caused by RNA type viruses are hard to vaccinate against
and change very quickly. That is why a new flu vaccine is needed every year. 7 . Vaccinations for some diseases were so effective the disease is no longer present in the population, small pox, which is a very deadly
disease, was eliminated this way, People who get vaccinated even protect those who are not vaccinated because they don’t provide a place for the disease to multiply and spread from. Depending on the virus and
how it is spread if 85-95% of the population get vaccinated everyone will benefit from ‘herd immunity’, that is really what it is called so don’t laugh. 8.Colds are caused by viruses but there is no vaccine because
there are literally thousands of viruses that cause colds, so it looks like chicken soup for you and some nice bed rest. 9.Viruses are usually adapted to live in a certain type of host animal of plant but if a mutation
allows it to jump species the results can be devastating because non of the new host population has any immunity to the new virus and so the initial infection can spread very quickly and be very dangerous until
people start to develop immunity. 10. Viruses can not reproduce without a host so they are most often spread by sneezing, coughing, or by touching someone who is infected – That is why it is important to wash your
hands regularly and sneeze or cough into a tissue or your hand. It is also vital to avoid people who are not following these basic rules because one person can infect thousands.
INFECTIOUS DISEASES
Coughing, a stuffy nose, diarrhea, a fever--many of those icky symptoms are preventable by
avoiding the germs that cause them. The two main ways of prevention are personal hygiene
and vaccines. Colds, influenza, and mononucleosis are all preventable infections, mostly via
hygiene. Infectious bacteria and viruses hitch rides on surfaces, including your skin.
Did You Know?
* Viruses (such as those that cause colds and flus) do not respond to antibiotics, but many
bacterial infections (such as strep throat) do.
* Whooping cough (also known as pertussis) is hard to shake. It's much more severe in young
kids. Preventing it in yourself also protects younger siblings.
* Reptiles often have diarrhea-causing bacteria on their skin. Wash your hands after handling
reptilian pets.
Prevention Tips
* Wash your hands. Frequent hand washing removes viruses and bacteria sticking to surfaces
you've touched. Always wash your hands after using the bathroom, before and after handling
food, and before eating. You can use any kind of soap, but be sure to scrub well for at least
20seconds. Babysitting? Wash your hands after changing diapers to avoid catching a baby's
diarrhea.
* Get vaccinated. Ask your doctor for the flu vaccine in the fall, before flu season starts. And
make sure you get other vaccines as scheduled; they protect you from several serious
diseases, such as tetanus, meningitis (an often fatal disease that affects the brain),
chickenpox, and human papilloma virus (a virus that can cause cancer in women). Ask your
doctor or school nurse.
* Sharing isn't always caring. Avoid sharing a beverage, swapping lip gloss, or using the same
fork, suggests Dr. Christopher Rizzo, an infectious diseases specialist from Cleveland.
* Cook food well. Heat hamburger and chicken thoroughly to kill off the diarrhea-causing
salmonella bacteria.
* If you're sick, cover your nose and mouth when you cough or sneeze. Then wash your
hands. And stay home when you're sick. These actions can prevent the spread of illness to
others.
Watch this video about viruses.
Watch this video about viruses.
Watch this video about viruses.
Watch this video about viruses.
What is a virus? How does it affect
plants, animals, and people?
Visit this website to find out.
What is a virus? How does it affect
plants, animals, and people?
Visit this website to find out.
What is a virus? How does it affect
plants, animals, and people?
Visit this website to find out.
What is a virus? How does it affect
plants, animals, and people?
Visit this website to find out.
How Do Vaccines Work?
June 06, 2010
How Do Vaccines Work?
June 06, 2010
http://www.kitsforkids.com/blog/2010/06/how-do-vaccines-work/
http://www.kitsforkids.com/blog/2010/06/how-do-vaccines-work/
What exactly are vaccines, and how do they work? Let’s start with some
background about how our bodies fight off diseases. Most of us have had
chicken pox before, but we only get it once. Why don’t we get it again? Well,
when we get sick, our immune systems identify the harmful virus or bacteria
(also known as an antigen) causing the disease, and create antibodies to kill
the antigens.
What exactly are vaccines, and how do they work? Let’s start with some
background about how our bodies fight off diseases. Most of us have had
chicken pox before, but we only get it once. Why don’t we get it again?
Well, when we get sick, our immune systems identify the harmful virus or
bacteria (also known as an antigen) causing the disease, and create
antibodies to kill the antigens.
Once the infection goes away, the antibodies required to fight off the disease
stay in our bodies so if we ever catch the disease again, our immune systems
are prepared. Unfortunately, antibodies are antigen-specific. That means we
need a different sets of antibodies for each different virus or bacterial
infection.
Once the infection goes away, the antibodies required to fight off the
disease stay in our bodies so if we ever catch the disease again, our
immune systems are prepared. Unfortunately, antibodies are antigenspecific. That means we need a different sets of antibodies for each
different virus or bacterial infection.
This is where vaccines come in handy. When you get a vaccine, a very small
amount of a specific antigen is introduced to your body – enough for your
immune system to recognize the virus and develop antibodies to fight it off,
but not enough to get you sick. That way, when you get the virus or infection
for real, your body already has antibodies to fight it off, and you don’t get
sick. Neat, huh?
This is where vaccines come in handy. When you get a vaccine, a very
small amount of a specific antigen is introduced to your body – enough for
your immune system to recognize the virus and develop antibodies to fight
it off, but not enough to get you sick. That way, when you get the virus or
infection for real, your body already has antibodies to fight it off, and you
don’t get sick. Neat, huh
Vaccination and Immunization
Table of Contents
How to Cite This Article
You probably give very little thought to becoming ill with a life-threatening disease. For your great-grandparents, serious illnesses—especially during
childhood—were constant concerns. Today that is no longer true, thanks to vaccinations.
Vaccination, also called inoculation or immunization, is a medical procedure that protects a person against certain diseases. It has eliminated the disease
smallpox from the world and has helped control many other diseases. Diphtheria, tetanus, yellow fever, pertussis (whooping cough), polio, measles, mumps,
and rubella all can be prevented with vaccinations.
Vaccinations are usually given as injections (often called shots). A shot injects the vaccine through the skin with a needle. Other vaccines are given orally (by
mouth). You may remember receiving vaccinations in both forms when you were a young child.
Today the terms vaccination, inoculation, and immunization are used interchangeably; this was not always the case. The first vaccination was given in 1796
during a time when many people suffered and died of smallpox. An English doctor, Edward Jenner, wanted to help fight this dreaded disease. He injected a
young boy with a substance from a cow with cowpox disease. Cowpox is caused by the vaccinia virus, which is similar to smallpox virus. The injection of the
vaccinia virus did what Dr. Jenner had hoped—it prevented the boy from getting smallpox. Dr. Jenner called the new procedure "vaccination," which
specifically meant injection with the vaccinia virus. Today "vaccination" usually means protection from any type of disease.
Defenses Against Diseases
Vaccinations work because they stimulate the body to build defenses against infection. These defenses are part of the body's immune system. The immune
system's job is to protect and defend the body from infections and illnesses.
When disease-causing organisms (germs), such as bacteria and viruses, enter the body, certain cells in the immune system begin to make antibodies.
Antibodies are chemical substances that can stop disease organisms from causing a massive infection. The immune-system cells make a special antibody for
each type of disease organism. Other cells directly attack the organisms and work to remove them from the body.
After a person recovers from an infectious disease, some of the antibodies and defensive cells for that particular disease remain in the body. If the same
disease organisms enter the body again, the defenses are ready to help prevent the illness. This is why we rarely experience two episodes of certain infectious
diseases, such as measles or rubella. When the body's defenses prevent an infection of a disease, a person is said to have an immunity to that disease.
.
Types of Vaccinations
Vaccination is a way to provide immunity to a disease without illness. The way vaccines do this is by causing the immune system to build up antibodies.
Vaccines are formed in three different ways. Each contains all or part of the disease-causing organism. One type of vaccine contains disease-causing viruses or
bacteria that have been killed by heat or chemicals. For example, the whooping cough vaccine and the Salk injected polio vaccine contain "killed" organisms.
When injected into the body, these killed organisms cannot cause disease. However, they do stimulate the cells to form antibodies, thereby creating
immunity.
Another type of vaccine contains weakened living viruses. Because these viruses are weakened, they do not cause disease, but, like the killed organisms, they
cause antibodies to form. The vaccines to prevent measles, mumps, rubella, and the oral polio vaccine all contain weakened viruses.
The third type of vaccine consists of certain parts of the disease organisms. For example, the disease tetanus is caused by a toxin (poison) made by one type of
bacteria. This toxin can be purified, then altered by chemicals so that it is not dangerous. The altered toxin is called a toxoid and is injected into the body as a
toxoid vaccine. The cells then make antibodies against the toxoid, thereby preventing a tetanus infection.
A similar procedure is used for the Haemophilus influenzae vaccine. This vaccine contains the purified surface covering of the Haemophilus influenzae
bacteria. When the surface covering is injected into the human body, antibodies are formed that will prevent Haemophilus influenzae disease. The diphtheria
and hepatitis B vaccines also contain parts of the disease-causing organisms.
Vaccination Schedules
All children should receive routine childhood vaccinations in order to prevent common childhood infectious illnesses. Some vaccines are given in more than
one dose. With each dose, more antibodies are produced against the disease. After the initial series of doses, "booster" doses are given to raise the quantities
of antibodies again. In this way, long-lasting protection is achieved. As new vaccines are developed, the schedule for recommended vaccinations changes.
For people traveling or living in nonindustrialized nations, additional vaccines are recommended to prevent diseases that occur in certain parts of the world.
For example, the vaccine against yellow fever is recommended for people living in or traveling to South America and parts of Africa, where yellow fever is a
problem. Likewise, vaccines against cholera, typhoid, and meningococcal disease are recommended only for people living in regions where these diseases are
a threat.
Some vaccines are recommended only for people who are at special risk from certain diseases. For example, a vaccine to prevent influenza virus disease (not
the same as Haemophilus influenzae bacterial disease) is recommended for all adults aged 50 or older. It is also recommended for children and adults with
certain medical problems, such as heart or lung disease. Such people are likely to develop very severe influenza when exposed to the virus—unless they are
protected by the vaccine. The influenza vaccine is only effective for about one year, so people in high-risk groups should be revaccinated each year.
In some cases, vaccines are given only after exposure to the disease. Rabies vaccine is an example of this. When a person has been exposed to the rabies
virus, usually from the bite of a rabid animal, he or she receives a series of injections to provide quick, short-term protection against rabies.
New Vaccines
Doctors and scientists are continually working to develop new vaccines for many serious illnesses. One of the most serious diseases for which there is no
vaccine is malaria. Malaria is a killer of children and adults in many parts of the world. It affects the liver, spleen, and red blood cells, causing fever, chills,
headache, and weakness. A vaccine to prevent malaria would improve the health of millions of people.
In addition, a vaccine to prevent AIDS, the disease caused by the human immuno-deficiency virus, or HIV, is becoming very much needed. As HIV becomes
more widespread, a great many people could be helped by an HIV vaccine.
Universal Immunization
The World Health Organization (WHO) is an agency within the United Nations whose goal is to promote good health. The agency is working to immunize every
child in the world against six preventable diseases: diptheria, whooping cough, tetanus, measles, polio, and tuberculosis. WHO's Immunization Program has
reached approximately 80 percent of all the children in the world, so its goal is very much in sight.
Mark C. Steinhoff, M.D.
Johns Hopkins University School of Medicine
How to cite this article:
MLA (Modern Language Association) style:
Steinhoff, Mark C. "Vaccination and Immunization." The New Book of Knowledge. Grolier Online, 2013. Web. 8 Nov. 2013.
™ & © 2013 Scholastic Inc. All rights reserved
Information for
The Center for
Disease Control
and Prevention
Information for
The Center for
Disease Control
and Prevention
Fungi & Protists
http://www.cdc.gov/meningitis/index.html
http://www.cdc.gov/meningitis/index.html
3
3
Practice
mosquito vector. The mosquito can live year-round only in the red-shaded areas.
Concept 1. Protists and Human Disease
Worldwide Distribution of Malaria. This map shows where malaria is found. The area is determined by the
FIGURE 1.2
3. Terri lost her water bottle while hiking in Canada. It was a hot day, so she drank water from a stream to stay
hydrated. A few days later, Terri became ill with abdominal pain, fever, and diarrhea. Her doctor thinks she has a
protozoan infection. Which type of protozoa do you think is most likely responsible for Terri’s illness? How do you
think Terri became infected?
2. State why malaria is commonly found only in tropical and subtropical regions of the world.
1. Describe how the protozoa that cause Chagas disease are spread to human hosts.
Review
1. Can protozoans cause deadly disease in humans?
2. What is Giardia? How does it spread and what are the manifestations of a Giardia infection?
3. What protist causes malaria?
• http://www.hippocampus.org/Biology ! Non-Majors Biology ! Search: Protozoa
Practice
www.ck12.org
Use this resource to answer the questions that follow.
mosquito vector. The mosquito can live year-round only in the red-shaded areas.
Worldwide Distribution of Malaria. This map shows where malaria is found. The area is determined by the
FIGURE 1.2
www.ck12.org
Non-Infectious Diseases
Disease
Table of Contents
How to Cite This Article
A disease is a disturbance of a body structure or function. It may make a person physically or mentally ill. It may limit his or her activities. Or it may even lead to death.
Sometimes disease brings obvious changes in body structures, such as swelling of the jaw in mumps or the open sores in certain types of cancer. Sometimes no changes in
body structures can be found, even under a microscope. But the person loses some normal capabilities. For example, the person cannot see clearly, or is unable to become
pregnant.
A sick person may feel pain or weakness. These are subjective changes. They are called symptoms of disease. Objective changes are changes other people can observe, These
are referred to as signs of disease. For example, people can observe unusual redness or a spotty rash on the skin, a higher than normal body temperature, or an increase in
the number of white blood cells. Various other changes that can be seen or discovered through tests can all be signs of disease.
Kinds of Diseases
An illness that comes on suddenly, such as an attack of vomiting after eating spoiled food, is referred to as acute. In a chronic condition, symptoms either continue or return
from time to time for a period of months or years. Some diseases can be chronic but then become acute. For example, diabetes is a chronic disease in which the body does
not use and store sugars properly. Diabetics (people who have diabetes) can usually keep their symptoms under control and lead a relatively normal life. They need to
exercise, eat a special diet, and take certain drugs or injections of the hormone insulin. But a diabetic who takes in too much sugar or injects too much insulin may have a
sudden acute attack that can result in unconsciousness.
Diseases can have many causes. Infectious diseases are the result of invasions of tiny microbes such as bacteria and viruses. The microbes get into the body and multiply to
huge numbers. Some of the symptoms of microbe-caused diseases are actually the effects of toxins. These are poisons produced by the germs. Some signs, such as fever and
swelling, are actually a part of the body's defenses against infection.
Not all diseases are the result of infection. Noninfectious diseases are usually the result of something going wrong with organs or functions of the body. In immunological
diseases, for example, the body's immune defenses do not work properly. They may turn against the body's own cells. That is, the defenses may damage cells instead of
protecting them. Some noninfectious diseases are congenital, meaning they are present at birth. Others are hereditary, passed on from parents to children. In hormonal
diseases, the body's chemistry can be disrupted by endocrine system disorders. In degenerative diseases, various parts of the body break down and lose their ability to work
normally. In neoplastic diseases, the processes of cell growth and reproduction run wild and form tumors. Neoplastic diseases include many forms of cancer.
Failure to eat a balanced diet or conditions in which the body is unable to use certain foods properly may result in nutritional diseases. Chemicals in the air, water, and food
as well as radiation, noise, and other influences that can affect people at home or at work may have damaging effects on the body. They can produce various occupational
and environmental diseases. Mental and emotional diseases, such as depression, may be the result of disorders in the body or influences in the environment. The mind can
also have positive and negative effects on the health of the body. You can read more about mental and emotional diseases in the article Mental Illness.
Congenital and Hereditary Diseases
Both congenital and hereditary diseases are present at birth. But their causes are very different. Congenital conditions arise during the period of development before birth or
during the birth process. Hereditary diseases are those that were determined at the moment of conception, programmed into the genes inherited from the parents.
Congenital birth defects may result if a pregnant woman becomes infected with the rubella (German measles) virus or certain other microbes. These pathogens can interfere
with her child's development. A baby's development before birth may also be harmed if the mother smokes, drinks alcoholic beverages, or takes certain drugs.
Hereditary diseases may be dominant or recessive. A dominant condition appears in the parent and is passed on to the children. Recessive conditions must be inherited from
both parents, who may have no signs or symptoms but carry the genes for the disease. (You can read more about how this works in the article Genetics.) Some hereditary
diseases are sex-linked. That is, they affect mainly members of one sex. Hemophilia, the "bleeders' disease," occurs mostly in males. But it can be carried by females.
Hereditary diseases may affect many systems of the body. Down syndrome, for example, produces characteristic changes in the face and body, mental retardation, and
usually a shortened lifetime. Many hereditary diseases are metabolic diseases. They result from a change in some important chemical reaction in the body. Children born
with phenylketonuria (PKU), for instance, cannot use one of the amino acids that are normal building blocks of proteins. If the condition is not treated, the child becomes
mentally retarded. Fortunately, phenylketonuria can be detected by a simple test of a baby's urine. And its harmful effects can be prevented with a special diet.
People who know or suspect that a hereditary disease runs in their family can undergo genetic counseling to determine their chances of having a child with the disease.
When a woman is pregnant, tests such as amniocentesis or chorionic villi sampling can be used to check for various hereditary diseases. Women in their late thirties or
forties, who have a higher than average chance of giving birth to a child with Down syndrome, may also choose to have such a test. (See the article Down Syndrome.)
Hormonal Diseases
Hormones are chemical messengers produced in structures called endocrine glands. Hormones help control growth, reproduction, and many other body functions.
Endocrine disorders resulting in the production of too much or too little of a hormone can cause serious diseases.
Disorders of the pituitary gland can increase or decrease the gland's production of growth hormone. Too little growth hormone can result in dwarfism. Too much can result in
gigantism. Thyroid hormones help determine how fast the body's chemical reactions take place. Too little of these hormones makes a person sluggish and fat. Too much
makes a person "hyper." The person may feel nervous, lose weight, or be unable to sleep.
Endocrine hormones act on each other in many ways. Normal sexual development, for example, is influenced by hormones that are released by different glands. These
include the reproductive organs (ovaries in females and testes in males) and the pituitary and adrenal glands.
Hormonal disorders may be treated by giving replacements of the lacking hormones. If a gland is producing too much of a hormone, the condition may be treated with
surgery or radiation.
Degenerative Diseases
Body cells are constantly being destroyed and replaced. But as a person grows older, the systems that repair damage to body structures become less effective. Some kinds of
cells are not replaced. Once they are lost, they are gone forever. (Such cells include brain cells.)
Some degenerative disease are part of the natural aging process. The constant wear and tear of daily living gradually makes various body organs less able to do their jobs.
Also, the general breakdown of different body structures leads to various degenerative diseases. Common degenerative diseases include certain types of arthritis and
cardiovascular diseases (diseases of the heart and blood vessels). Other examples are cirrhosis of the liver, osteoporosis of the bones, and emphysema of the lungs.
The development of effective drugs and vaccines to control infectious diseases has helped people live longer. But the result of longer life spans is that larger numbers of
people now develop degenerative diseases. These diseases have become the greatest causes of disablement and death in the developed countries of the world.
Neoplastic Diseases
Neoplastic diseases are the result of changes in the body's own cells. Ordinarily, cells have an ability called contact inhibition. They recognize when they are in contact with
other cells, and they stop dividing. But cells may lose contact inhibition and begin to divide uncontrollably. These are neoplastic cells. They continue to multiply, piling up and
spreading out into surrounding tissues. Neoplastic cells also tend to lose their differentiation. That is, they lose the specific characteristics of the tissue in which they develop.
The result of unregulated cell division is a neoplasm. The word means "new growth." Neoplasms are also called tumors. When a tumor is cancerous, cells from it may break
away and travel through the body by way of the blood or lymph circulation. They may settle in other places and form new tumors. This process of migration is called
metastasis. When this happens, the cancer is said to have metastasized. Cancer is the leading cause of death in some age groups.
Recent research suggests that cancer may be caused by oncogenes. These are special cancer-causing genes that act by controlling cell multiplication. Normally the oncogenes
are in a harmless, "turned-off" form. But the oncogenes in a cell can be turned on by exposures to radiation, cancer-causing chemicals (carcinogens), or virus infections. As a
result, the cell becomes neoplastic. Tobacco contains many carcinogens. It is the leading cause of lung cancer and emphysema.
The body's immune defenses normally guard against cancer. White blood cells recognize new neoplastic cells by their chemical changes. If the immune defenses are
adequate, the white blood cells destroy the neoplastic cells before they can spread. If these immune defenses are weakened, cancer can develop. (You can read more about
this in the article Cancer and the article Immune System.)
Nutritional Diseases
In many parts of the world, malnutrition is one of the most serious health problems. When children do not get enough to eat, they cannot grow and develop properly. Adults
suffer from starvation, too. They lose weight and have little energy for doing things. And they have poor defenses against infectious diseases. Worldwide, over 800 million
people are undernourished.
In the United States and other industrial countries, eating too much is often a problem. Overeating leads to obesity (excessive fatness). And it contributes to cardiovascular
disease, diabetes, and other harmful conditions. Obesity rates have increased over the last several decades. In 2000, nearly one in three American adults was obese.
Good nutrition means more than just eating the right amount of food. People also need to eat the right kinds of food. Proteins, carbohydrates, and fats are needed to fuel
growth, repair, and other body functions. Also, these nutrients yield essential chemical building blocks. Water is vital, too.
Vitamins and minerals are important in the body's chemical reactions. A failure to eat enough of a particular vitamin or mineral can result in a deficiency disease. For
example, a lack of calcium or a lack of vitamin D can result in bone diseases such as rickets and osteoporosis. Vitamin deficiencies can result in such diseases as scurvy,
beriberi, and pellagra.
Doctors prescribe vitamin or mineral supplements for deficiency diseases. Some people take vitamin pills on their own. But many medical experts say that eating a balanced
diet is the best way to avoid nutritional diseases.
Occupational and Environmental Diseases
Certain jobs are well known for being dangerous. Mine workers may develop a disabling lung disease called silicosis from breathing in rock dust. Workers in asbestosmanufacturing plants may suffer from a lung disease called asbestosis. Also, they may develop an unusual type of lung cancer. Pesticides used to protect food crops from
insects may be poisonous to manufacturing and agricultural workers. These toxins may also harem the public if proper safety measures are not taken.
More ordinary jobs and even daily living have their own, less obvious dangers. Repetitive motions, such as those needed to operate power tools or type at a keyboard, may
cause carpal tunnel syndrome. Tendons become irritated and thickened. They press against nerves, causing pain in the hand and wrist.
Automobiles, factories, and home furnaces all burn fuels and send soot particles and various gases into the air. (These gases include carbon monoxide, hydrocarbons, and
oxides of sulfur and nitrogen.) This air pollution can contribute to emphysema, allergies, and lung cancer. Factories may also produce solid or liquid toxic wastes. These are
sometimes discharged into rivers and oceans or buried underground. Heavy metals such as mercury, lead, and cadmium are dangerous pollutants. They can damage the
muscles and nerves if they are breathed in or get into the food we eat. These pollutants may exist in very, very tiny amounts in the soil or in water. But they can be
concentrated many times by food chains. The pollutants are first taken in by plants or micro-organisms. These organisms are then eaten by animals. And these animals are
then eaten by other animals or humans. Each creature in the chain keeps more of the pollutant in its body tissues.
Noise is a type of pollution that can contribute to disease. People may be subjected to high noise levels by listening to loud music, working in factories, or living near a busy
airport. The consequences of noise pollution are not limited to hearing losses. Other possibilities include hypertension (high blood pressure) and heart disease. Constant
stress from noise may also lower their resistance to infectious diseases and cancer.
Many people are worried about exposure to radiation. Radiation is the transmission of energy through space. Some forms of radiation are strong enough to damage the
body's tissues. In general, these forms of radiation are referred to as ionizing radiation. A substance that is ionized undergoes a change at the chemical level. A formerly
neutral chemical becomes electrically charged or is even broken into electrically charged fragments. If the chemicals that form the body’s genetic materials become ionized,
the consequences can be severe.
Some forms of ionizing radiation consist of particles. These particles include high-energy electrons and fragments of atomic nuclei. Other forms of ionizing radiation consist of
electromagnetic waves. These waves include gamma rays, X-rays, and high-energy ultraviolet rays.
Sources of ionizing radiation include nuclear reactions. Such reactions are associated with nuclear power plants and the detonation of nuclear weapons. Ionizing radiation
also comes from the spontaneous decay of unstable atomic nuclei such as radon nuclei. In some areas radon gas is given off by rocks in the ground. It accumulates inside
buildings. It can be a serious health hazard.
Gamma rays, X-rays, and high-energy ultraviolet waves are all powerful forms of light. They occur naturally in the environment. They are also emitted by devices such as
particle accelerators and special lamps. High doses of these powerful forms of light can be dangerous. They contribute to the risk of cancer and other diseases.
Too much exposure to sunlight can be very dangerous. Ultraviolet radiation from sunlight can burn the skin and make it dry and leathery. It can also lead to skin cancer.
People who lie in the sun or under ultraviolet lamps to get a suntan are taking a serious risk.
Although they can be dangerous, powerful forms radiation have medical uses. For example, X-rays may be used to produce useful images. (X-ray imaging uses very small
amounts of radiation, below the danger level.) Focused gamma rays may be used to destroy tumors.
How to cite this article:
MLA (Modern Language Association) style:
Silverstein, Alvin, Glenn Austin, and Virginia Silverstein. "Disease." Reviewed by Margaret O. Hyde. The New Book of Knowledge. Grolier Online, 2013. Web. 12 Nov. 2013.
Chicago Manual of Style:
Silverstein, Alvin, Glenn Austin, and Virginia Silverstein. "Disease." Reviewed by Margaret O. Hyde. The New Book of Knowledge. Grolier Online
http://nbk.grolier.com/ncpage?tn=/encyc/article.html&id=a2007930- h&type=0ta (accessed November 12, 2013).
APA (American Psychological Association) style:
Silverstein, A., Austin, G., & Silverstein, V. (2013). Disease. (M. O. Hyde, Rev.). The New Book of Knowledge. Retrieved November 12, 2013, from Grolier Online
http://nbk.grolier.com/ncpage?tn=/encyc/article.html&id=a2007930- h&type=0ta
™ & © 2013 Scholastic Inc. All rights reserved.
Discovery Channel
http://curiosity.discovery.com/question/what-is-noninfectious-disease
Noninfectious diseases can't be passed from one person to another. Instead, these types of diseases are caused by
factors such as the environment, genetics and lifestyle. The term comes from a distinction health experts like to make
between infectious diseases -- which are caused by organisms and can be passed from one person to another (also
known as contagious) -- and those that can't. Examples of these infectious diseases are colds, flu, herpes, measles and
even AIDS, which is caused by infection with HIV. Many infectious diseases are bigger problems in underdeveloped
countries, where there is less control of sanitation, fewer vaccinations and other problems that contribute to higher
levels of infectious diseases [source: EHNRI].
Noninfectious diseases are not caused by specific organisms and are studied and cared for more in developed
countries, where many infectious diseases are under control. Examples of inherited noninfectious conditions include
cystic fibrosis and Down syndrome, and examples of conditions caused by environmental or lifestyle factors include
heart disease and skin cancer. We can't change our genetic codes, but there are plenty of ways to prevent other
noninfectious diseases. For example, cutting down on exposure to cigarette smoke and the sun's rays will prevent
certain types of cancer.
In fact, most chronic noninfectious diseases can be prevented. The chronic noninfectious diseases that cause the most
deaths in the United States -- heart disease, stroke, diabetes and cancer -- are largely preventable [source: Minnesota
Department of Health]. For example, some cancers have genetic risks, but people at high risk for cancers can have
screening examinations to catch them early or sometimes can take other steps to prevent the cancers. Heart disease,
stroke and diabetes are mostly linked to lifestyle choices, even when family history puts a person at higher risk for the
diseases.
Overall, people in the United States are contributing to higher rates of noninfectious diseases by taking advantage of
technology and social environments that encourage sedentary lifestyles and faster and cheaper, but less healthy, meals.
People also are living longer, but can choose to live more healthily by adopting regular exercise routines and healthy
eating habits.
Noncommunicable diseases
Fact sheet
Updated March 2013
Key facts
•Noncommunicable diseases (NCDs) kill more than 36 million people each year.
•Nearly 80% of NCD deaths - 29 million - occur in low- and middle- income countries.
•More than nine million of all deaths attributed to NCDs occur before the age of 60; 90% of these "premature" deaths occurred in low- and middle-income countries.
•Cardiovascular diseases account for most NCD deaths, or 17.3 million people annually, followed by cancers (7.6 million), respiratory diseases (4.2 million), and diabetes (1.3 million1).
•These four groups of diseases account for around 80% of all NCD deaths.
•They share four risk factors: tobacco use, physical inactivity, the harmful use of alcohol and unhealthy diets.
Overview
Noncommunicable diseases (NCDs), also known as chronic diseases, are not passed from person to person. They are of long duration and generally slow progression. The four main types of noncommunicable diseases
are cardiovascular diseases (like heart attacks and stroke), cancers, chronic respiratory diseases (such as chronic obstructed pulmonary disease and asthma) and diabetes.
NCDs already disproportionately affect low- and middle-income countries where nearly 80% of NCD deaths – 29 million – occur. They are the leading causes of death in all regions except Africa, but current projections
indicate that by 2020 the largest increases in NCD deaths will occur in Africa. In African nations deaths from, NCDs are projected to exceed the combined deaths of communicable and nutritional diseases and maternal
and perinatal deaths as the most common causes of death by 2030.
Who is at risk of such diseases?
All age groups and all regions are affected by NCDs. NCDs are often associated with older age groups, but evidence shows that more than 9 million of all deaths attributed to noncommunicable diseases (NCDs) occur
before the age of 60. Of these "premature" deaths, 90% occurred in low- and middle-income countries. Children, adults and the elderly are all vulnerable to the risk factors that contribute to noncommunicable
diseases, whether from unhealthy diets, physical inactivity, exposure to tobacco smoke or the effects of the harmful use of alcohol.
These diseases are driven by forces that include ageing, rapid unplanned urbanization, and the globalization of unhealthy lifestyles. For example, globalization of unhealthy lifestyles like unhealthy diets may show up
in individuals as raised blood pressure, increased blood glucose, elevated blood lipids, overweight and obesity. These are called 'intermediate risk factors' which can lead to cardiovascular disease, a NCD.
Risk factors
Modifiable behavioural risk factors
Tobacco use, physical inactivity, unhealthy diet and the harmful use of alcohol increase the risk of or cause most NCDs.
•Tobacco accounts for almost 6 million deaths every year (including over 600 000 deaths from exposure to second-hand smoke), and is projected to increase to 8 million by 2030.
•About 3.2 million deaths annually can be attributed to insufficient physical activity.
•Approximately 1.7 million deaths are attributable to low fruit and vegetable consumption.
•Half of the 2.32 million annual deaths from harmful drinking are from NCDs.
Metabolic/physiological risk factors
These behaviours lead to four key metabolic/physiological changes that increase the risk of NCDs: raised blood pressure, overweight/obesity, hyperglycemia (high blood glucose levels) and hyperlipidemia (high levels
of fat in the blood).
In terms of attributable deaths, the leading NCD risk factor globally is elevated blood pressure (to which 16.5% of global deaths are attributed) (1) followed by tobacco use (9%), raised blood glucose (6%), physical
inactivity (6%) and overweight and obesity (5%). Low- and middle-income countries are witnessing the fastest rise in overweight young children.
What are the socioeconomic impacts of NCDs?
NCDs threaten progress towards the UN Millennium Development Goals. Poverty is closely linked with NCDs. The rapid rise in NCDs is predicted to impede poverty reduction initiatives in low-income countries,
particularly by forcing up household costs associated with health care. Vulnerable and socially disadvantaged people get sicker and die sooner than people of higher social positions, especially because they are at
greater risk of being exposed to harmful products, such as tobacco or unhealthy food, and have limited access to health services.
In low-resource settings, health-care costs for cardiovascular diseases, cancers, diabetes or chronic lung diseases can quickly drain household resources, driving families into poverty. The exorbitant costs of NCDs,
including often lengthy and expensive treatment and loss of breadwinners, are forcing millions of people into poverty annually, stifling development.
In many countries, harmful drinking and unhealthy diet and lifestyles occur both in higher and lower income groups. However, high-income groups can access services and products that protect them from the greatest
risks while lower-income groups can often not afford such products and services.
Prevention and control of NCDs
To lessen the impact of NCDs on individuals and society, a comprehensive approach is needed that requires all sectors, including health, finance, foreign affairs, education,
agriculture, planning and others, to work together to reduce the risks associated with NCDs, as well as promote the interventions to prevent and control them.
An important way to reduce NCDs is to focus on lessening the risk factors associated with these diseases. Low-cost solutions exist to reduce the common modifiable risk
factors (mainly tobacco use, unhealthy diet and physical inactivity, and the harmful use of alcohol) and map the epidemic of NCDs and their risk factors (1).
Other ways to reduce NCDs are high impact essential NCD interventions that can be delivered through a primary health-care approach to strengthen early detection and
timely treatment. Evidence shows that such interventions are excellent economic investments because, if applied to patients early, can reduce the need for more expensive
treatment. These measures can be implemented in various resource levels. The greatest impact can be achieved by creating healthy public policies that promote NCD
prevention and control and reorienting health systems to address the needs of people with such diseases.
Lower-income countries generally have lower capacity for the prevention and control of noncommunicable diseases.
High-income countries are nearly four times more likely to have NCD services covered by health insurance than low-income countries. Countries with inadequate health
insurance coverage are unlikely to provide universal access to essential NCD interventions.
WHO response
The 2008-2013 Action plan of the global strategy for the prevention and control of noncommunicable diseases provides Member States, WHO and international partners with
steps on how to address NCDs in countries.
WHO is also responding with measures that lessen the risk factors that are associated with NCDs.
•Implementation by countries of the anti-tobacco measures laid out in the WHO Framework Convention on Tobacco Control can greatly reduce public exposure to tobacco.
•The WHO Global strategy on diet, physical activity and health aims to promote and protect health by enabling communities to reduce disease and death rates related to
unhealthy diet and physical inactivity.
•The WHO Global strategy to reduce the harmful use of alcohol offers measures and identifies priority areas of action to protect people from harmful alcohol use.
•As requested by the UN Political Declaration on NCDs, WHO is developing a comprehensive global monitoring framework for the prevention and control of NCDs, including a
set of indicators and a set of voluntary global targets.
•In response to a resolution (WHA 64.11) of the World Health Assembly, WHO is developing the Global NCD Action Plan 2013-20 to provide a roadmap for the
implementation of the political commitments of the UN High-level Meeting. The draft action plan will be up for adoption by the World Health Assembly in May 2013.
Footnotes
1Based on data from death certificates.
2This figure takes into account the estimated beneficial impact of low levels of alcohol use on some diseases in some population groups.
References
(1)Lim SS, Vos T, Flaxman AD, Danaei G, Shibuya K, Adair-Rohani H et al. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk
factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet, 2012; 380(9859):2224-2260.
http://www.who.int/mediacentre/factsheets/fs355/en/#
LUNG DISEASE
Why should teens care? Mostly because people usually start smoking between the
ages of 12 and 17 and keep smoking as adults. Smoking, according to the American
Lung Association, is the culprit in 90 percent of deaths from lung cancer and at
least 80 percent of deaths from other diseases, such as emphysema and bronchitis.
Did You Know?
* Each day in the United States, about 4,000 youths ages 12 to 17 try their first
cigarettes.
* With current smoking patterns, about 6.4 million of today's young people are
expected to die prematurely--from smoking-related diseases.
* While a person smokes, the heart rate increases and certain blood vessels in the
body constrict. It takes about 30 minutes for the vessels to go back to normal.
* Smoking can also cause cancers of the mouth, pharynx, esophagus, and bladder.
Prevention Tips
* Don't start smoking. It's that simple! You will dramatically reduce your chances of
developing lung disease.
* If you already use tobacco, quit now. Ask your school guidance counselor or a
doctor about programs for quitting smoking. Encourage friends to forgo smoking.
Make smoking uncool.
VASCULAR DISEASE
The disease process that leads to future heart disease and stroke launches early in life.
Your lifestyle choices as a teen will affect your health as an adult. A high-fat diet and
a lack of exercise can lead to "fatty streaks"--fat deposits that stick to the inside walls
of blood vessels, according to Dr. Stephen Daniels from the University of Colorado.
Over time, the streaks turn into fatty blobs that block vessels, causing heart attacks
and strokes. You could develop these diseases far earlier than people in your parents'
generation.
Did You Know?
* Heart disease and stroke are largely preventable through two lifestyle choices--healthy
diet and regular exercise.
* Being overweight alters aspects of your metabolism, leading to unhealthy levels of
cholesterol, increased blood pressure, and other changes that can bring on diabetes.
* Cholesterol levels are related directly to the types of fats you eat, as well as to genetics.
Eating fatty meats and eggs can contribute to your body's levels of unhealthy
cholesterol. Vegetables contain zero cholesterol and mostly healthy fats.
Prevention Tips
* Be active. Replace some of those online chat hours with walking, dancing, or other
physical activities. For general fitness, you should be active for about 60 minutes
daily, according to the
* Aim for a balanced diet. Include plenty of fiber-rich foods (beans, fruits, vegetables,
and whole grains), and cut back on fats. Increase foods that have complex
carbohydrates, such as whole grains and brown rice. Decrease simple carbohydrate
foods and sugar.
SKIN CANCER
Fun in the sun won't be fun anymore if you develop skin cancer. You're not likely to get skin
cancer as a teen, but what you do now affects your risk later in life. Melanoma, the most
dangerous form of the disease, is also the number-one cancer in people ages 25 to 29. Skin
cancer is preventable by using sunscreen or sunblock, wearing protective clothing, and staying
in the shade.
Did You Know?
* Skin cancer is the most common cancer in the United States. More than 1 million new cases
are diagnosed each year.
* Burns and tans are signs of skin damage caused by exposure to ultraviolet (UV) radiation
from the sun.
* UV rays from tanning beds in tanning salons are just as dangerous as UV rays from the sun.
* Sunburn damages the genetic material in your skin cells. Normally, your body replaces this
material. Repeat sunburns, though, increase the likelihood of damage--and the cancer it can
cause.
Prevention Tips
* Wear protective clothing. Long sleeves and a hat with a brim will help.
* Use a product that has a high sun protection factor (SPF). The higher the SPF number,
the more protection you get. Get into the habit of wearing sunscreen every day, not just at the
beach or on the ski slopes.
* Wear sunglasses with UV protection. That prevents the formation of cataracts--UV-induced
damage to the lenses of your eyes.
Image of a leukemia cell taken by an
electron microscope. The cancerous
leukemia cell is shown next to a normal cell,
which is much smaller. Cancer cells are
usually larger than normal cells.
(© Oliver Meckes/Nicole Ottawa/Photo
Researchers)
™ & © 2013 Scholastic Inc. All Rights
Reserved.
Image of a leukemia cell taken by an
electron microscope. The cancerous
leukemia cell is shown next to a normal cell,
which is much smaller. Cancer cells are
usually larger than normal cells.
(© Oliver Meckes/Nicole Ottawa/Photo
Researchers)
™ & © 2013 Scholastic Inc. All Rights
Reserved.
High Blood
Pressure
Stress
Obesity
Raised
Cholesterol
Unhealthy Diet
Alcohol
Raised Blood
Glucose
Physical
Activity
Tobacco
Use
Non – Communicable Diseases
Non-communicable diseases are chronic diseases that occur due to urbanization.
They include:
1. Cardiovascular
Diseases
2. Diabetes
3. Chronic
Respiratory
Disorder
4. Cancer
Go to this website to learn more about
specific non communicable (non infectious)
diseases.
Go to this website to learn more about
specific non communicable (non infectious)
diseases.
Go to this website to learn more about
specific non communicable (non infectious)
diseases.
Go to this website to learn more about
specific non communicable (non infectious)
diseases.
Watch this video that explains
Why non infectious disease is
On the rise and how it could also
Relate to the U.S.
Watch this video that explains
Why non infectious disease is
On the rise and how it could also
Relate to the U.S.
Watch this video that explains
Why non infectious disease is
On the rise and how it could also
Relate to the U.S.
Watch this video that explains
Why non infectious disease is
On the rise and how it could also
Relate to the U.S.
*Colorectum including anus ICD-10 C18-C21
Prepared by Cancer Research UK
Original data sources:
Ferlay J, Shin HR, Bray F, Forman D, Mathers C, Parkin DM. GLOBOCAN 2008 v1.2, Cancer Incidence and Mortality
Worldwide: IARC CancerBase No. 10 [Internet]. Lyon, France: International Agency for Research on Cancer, 2010.
Available from: http://globocan.iarc.fr
*Colorectum including anus ICD-10 C18-C21
Prepared by Cancer Research UK
Original data sources:
Ferlay J, Shin HR, Bray F, Forman D, Mathers C, Parkin DM. GLOBOCAN 2008 v1.2, Cancer Incidence and Mortality
Worldwide: IARC CancerBase No. 10 [Internet]. Lyon, France: International Agency for Research on Cancer, 2010.
Available from: http://globocan.iarc.fr
Pandemic vs. Epidemic
What is a pandemic?
•
The word pandemic comes from the Greek pandemos meaning "pertaining to all people". The Greek word pan means "all"
and the Greek word demos means "people." According to the Medilexicon´s medical dictionary a pandemic is "Denoting a
disease affecting or attacking the population of an extensive region, country, continent, global; extensively epidemic."
A pandemic is an outbreak of global proportions. It happens when a novel virus emerges among humans - it causes serious
illness and is easily human transmissible (spreads easily from person-to-person). What is the difference between a pandemic
and an epidemic?
What is the difference in a pandemic and an epidemic?
•
•
•
•
•
•
A pandemic is different from an epidemic or seasonal outbreak.
Put simply, a pandemic covers a much wider geographical area, often worldwide. A pandemic also infects many more people
than an epidemic. An epidemic is specific to one city, region or country, while a pandemic goes much further than national
borders.
An epidemic is when the number of people who become infected rises well beyond what is expected within a country or a
part of a country. When the infection takes place in several countries at the same time it then starts turning into a pandemic.
A pandemic is usually caused by a new virus strain or subtype - a virus humans either have no immunity against, or very little
immunity. If immunity is low or non-existent the virus is much more likely to spread around the world if it becomes easily
human transmissible.
In the case of influenza, seasonal outbreaks (epidemics) are generally caused by subtypes of a virus that is already circulating
among people. Pandemics, on the other hand, are generally caused by novel subtypes - these subtypes have not circulated
among people before. Pandemics can also be caused by viruses, in the case of influenza, that perhaps have not circulated
among people for a very long time.
Pandemics generally cause much higher numbers of deaths than epidemics. The social disruption, economic loss, and
general hardship caused by a pandemic are much higher than what an epidemic can cause.
How do influenza pandemics emerge?
•
•
•
A pandemic can emerge when the influenza A virus changes suddenly - what experts call an antigenic shift. The HA and/or
NA proteins, which are on the surface of the virus, have new combinations; resulting in a new influenza A virus subtype.
This new influenza subtype needs one characteristic to cause a pandemic - it must be easily human transmissible (it can
easily spread from one person to another).
After the pandemic has emerged and spread, the virus subtype circulates among humans for several years, causing
occasional flu epidemics. These will not usually become more than epidemics because humans have developed some
immunity over time. Various bodies around the world, such as the Health Protection Agency (UK), the World Health
Organization (WHO), and the Centers for Disease Control and Prevention (USA) monitor the behavior and movements of the
virus.
http://www.medicalnewstoday.com/articles/148945.php
Examples of pandemics throughout history
•
Below you can see the dates of the most famous pandemics throughout history. Some may have been
epidemics which crossed borders but did not go right round the world:
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
Antonine Plague (possibly smallpox) 165-180 A.D.
Plague of Cyprian 251-266 A.D.
Plague of Justinian 541 A.D.
Black Death 1300s A.D.
Typhus 1501-1587 A.D.
Influenza 1732-1733 A.D.
Influenza 1775-1776 A.D.
Cholera 1816-1826 A.D.
Cholera 1829-1851 A.D.
Influenza 1847-1848 A.D.
Cholera 1852-1860 A.D.
Bubonic Plague 1855 A.D.
Influenza 1857-1859 A.D.
Cholera 1863-1875 A.D.
Influenza 1889-1892 A.D.
Cholera 1899-1923 A.D.
Spanish Flu (avian flu) 1918-1920 A.D.
El Tor (Vibrio cholerae - cholera) 1960s A.D.
HIV/AIDS 1980s-to date
Swine Influenza - 2009 (experts say not likely to cause many deaths)
http://www.health.ny.gov/publications/9534.pdf
What are the Six Stages of a pandemic?
•
The World Health Organization has a Six Stage influenza program, plus two Periods:
– Stage 1
No animal influenza virus circulating among animals have been reported to cause infection in humans.
–
Stage 2
An animal influenza virus circulating in domesticated or wild animals is known to have caused infection in
humans and is therefore considered a specific potential pandemic threat.
–
Stage 3
An animal or human-animal influenza reassortant virus has caused sporadic cases or small clusters of
disease in people, but has not resulted in human-to-human transmission sufficient to sustain communitylevel outbreaks.
–
Stage 4
Human-to-human transmission of an animal or human-animal influenza reassortant virus able to sustain
community-level outbreaks has been verified.
–
Stage 5
The same identified virus has caused sustained community level outbreaks in two or more countries in
one WHO region.
–
Phase 6
In addition to the criteria defined in Phase 5, the same virus has caused sustained community level
outbreaks in at least one other country in another WHO region.
–
LOST PEAK PERIOD
Levels of pandemic influenza in most countries with adequate surveillance have dropped below peak
levels.
–
POST PANDEMIC PERIOD
Levels of influenza activity have returned to the levels seen for seasonal influenza in most countries with
adequate surveillance.
http://www.health.ny.gov/publications/9534.pdf
http://www.summitcountyhealth.org/adults/emergency-preparedness/public-health-planning-response/pandemic-influenza/
ROLE OF PUBLIC
HEALTH OFFICIALS
EXPOSURE TO PLAGUE
Plague is a highly infectious bacterial
disease which affects primarily rodents.
Humans and other animals can get plague if
they visit or live in areas where wild rodents are
naturally infected. People can get plague in
several ways.The most important routes
of transmission are:
State and local health agencies
monitor plague activity throughout the state.
Public health officials:
Work with doctors and veterinarians to
identify suspect cases of plague, confirm the
diagnosis, and ensure that patients receive
necessary treatment.
Conduct investigations of confirmed plague
cases to determine how the person was
exposed and to identify others who may
be at risk of plague.
Work with rangers, park personnel, and
others to watch for sick or dead rodents
or other evidence that plague may be
active in a particular area.
If signs of plague are identified, health
authorities institute preventive measures
including notification of residents and
visitors, posting of warning signs, and, if
deemed necessary, closing off the area so
that flea control measures can be conducted.
BITES FROM FLEAS OF INFECTED RODENTS
FACTS ABOUT
PLAGUE
IN
CALIFORNIA
Hungry fleas will
leave a sick or dead
rodent to bite another
animal, including humans.
DIRECT CONTACT WITH SICK RODENTS
Plague bacteria in the
blood or tissues of an
infected animal can
enter through cuts and
scrapes in the skin or
through the eyes, nose,
and mouth.
You can minimize your exposure
to plague by carefully following
the precautions listed in this
pamphlet.
Additional information on plague can be
obtained from your local health department
and the CDPH website, www.cdph.ca.gov.
Arnold Schwarzenegger, Governor
S. Kimberly Belshé, Secretary
Health and Human Services Agency
Mark Horton, MD, MSPH, Director
Department of Public Health
PLAGUE AREAS IN CALIFORNIA
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Plague is endemic (naturally occuring) in
many parts of California. Plague in California
occurs in the mountains and foothills shown
in shaded areas on the map.
Plague is absent from the southeast ern
desert and the central valleys.
Plague is most common in the rural and
undeveloped mountain regions, as well as the
suburban foothills of some larger cities.
PET INVOLVEMENT
Cats with plague pneumonia
can spread plague bacteria
when they cough or sneeze.
Plague has not occured in urban and
developed areas of California for nearly
100 years.
Field Work / Expert
Interview
 Teachers will:
 Arrange for the local Health Department to speak to
students about infectious disease prevention and
treatment.
 Contact the local hospital or medical research
facility to donate culture dishes so that students can
swab the school: toilet seats, faucet handles, door
knobs, water fountains, etc.
 Have Health Department rep help student interpret
the culture results.
Documentation Panels
 Students will create tri-side panels to
share what they have learned about
bacteria, viruses, fungi, and protists.
 Students will present what they have
learned to invited school visitors such as
teachers, parents, Board members,
administrators, etc.