Download Combating Infections

Infectious Diseases
General Principles
Slide Index
Click on a Subject to Go Directly to That Topic
• Overview of Microbes
– Bacteria
— Prions
— Fungi
– Viruses
— Protozoa
• Overview of Infectious Agents and Disease
– Food Poisoning
— Respiratory Disease
– Liver Disease
— STD’s
• Break the Transmission Cycle
• Kill the Infectious Agent
• Increase Host Resistance
– Active and Passive Immunization
– Vaccines
• Case Studies: More Information on Specific Diseases
What is a Microbe?
• Microbes are microscopic
organisms that can live almost
anywhere. Different microbes
have different habitat
preferences, ranging from
extreme heat to extreme cold.
Some microbes need oxygen and
some do not.
• Most microbes can live in a large
variety of habitats, but they can
only thrive in a few habitats.
• We even have microbes in our
bodies--some help us out and
some hurt us.
You have to have a microscope
to see microbes!
Where can microbes live?
A
In plants
B
In animals
C
In the dirt
D
All of these
Microbes and Disease
• Most microbes belong to
one of five categories:
bacteria, viruses, prions,
protozoa, or fungi.
• Some microbes cause
disease and some don’t.
Infectious agents are microbes that
can cause disease.
• Microbes that cause
disease are called
infectious agents,
commonly called “germs”
or “bugs.”
What Do They Look Like?
Infectious agents look different, depending on what class of
agent they are
E. coli
Source: NASA
HIV Virus
Source: NLM.gov
Dutch Elm Fungus Campylobacter jejuni
Source: AGRIC.gov
Hepatitis C Virus
Source: Amgen, Inc; NIH.gov
Source: cfsan.fda.gov
Ciliated Protozoa
Source: blm.gov; Wilhelm Foissner
Bacteria
Bacteria can
look like balls,
rods, or spirals.
Source: NSF.gov
• Bacteria are prokaryotic,
unicellular microbes.
• They have their own
metabolism.
• There are countless
numbers of bacteria on the
Earth but less than 1% of
them cause disease in
humans.
• Bacteria can live in a vast
range of places, but need
energy sources to thrive.
• Some bacteria produce
toxins that can harm us.
Viruses
• A virus is a microbe that
consists of a nucleic acid
housed within a
protective coat.
• The virus reproduces by
hijacking the host cell’s
metabolic machinery to
replicate its own DNA or
RNA.
• Most viruses cause
disease and are specific as
to which type of cell they
will attack.
Source: niaid.nih.gov
Prions
• A prion is an infectious particle
made from an abnormally
folded protein found on the
surfaces of neurons.
• Prions are highly resistant to
heat, UV radiation, and
disinfectants.
• The best known prion forms
holes in brain tissue, making
the brain look like Swiss
cheese. The prion causes mad
cow disease.
Protozoa
• One celled microbes
that can be parasites or
predators.
• Can live in a variety of
places, but prefer moist
habitats.
• Usually cause disease in
humans.
• Protozoa are sometimes
helpful to other
animals. They are a
food source for whales
and help cows as well as
termites digest their
food!
Protozoa found in human stool
samples
Source: CDC.gov
Fungi
• A multi-cellular
microbe that is much
larger than the other
microbes.
• Only about 1/2 of all
fungi causes disease in
humans.
• A fungal disease is
called a mycose.
• Yeast is a fungus that is
used to make bread and
cheese for us!
What Am I?
Click on the Buttons to quiz
yourself on the various microbes!
Word Bank
Protozoa
Virus
Fungi
Bacteria
Prion
How Can an Infectious Agent
Attack Me?
• Infectious agents can
enter through air, food,
water, sexual
interactions, skin
contact, blood
transfusions, etc.
• The body’s reaction to
an infection can vary
from a mild discomfort
to death.
Infectious
Agent
Species Specificity
I can transmit
Brucellosis and
Tapeworm
We can transmit lots
of infectious agents
including arenaviruses
and hantavirus.
I can transmit
Ebola virus!
• Some infectious
diseases of animals
can be transferred to
humans.
• These are called
zoonotic diseases.
• All mammals can
transmit rabies but
raccoons and skunks
are the most common
carriers.
Where Else Are Infectious Agents?
• Bacteria, protozoa,
and fungi all reside in
the soil.
• Other infectious
agents can live on
surfaces for hours or
even days, like the
cold virus.
Life Cycle of Infectious Agents
• Once a few microbes enter the body, it
may take a few hours or days for the agent
to reproduce enough to become infectious
for others or to cause disease.
Can a person transmit an infectious
agent before the disease affects him?
Yes
No
Infectious Agents are Deadly
• Infectious diseases cause
more deaths worldwide
than any other single
cause.
• Infectious diseases
account for over 56% of
deaths in developing
countries.
• However, these diseases
account for only 8% of
deaths in rich countries.
Why do more people die from infectious
diseases in undeveloped, poor countries
than in developed, rich countries?
A Poorer countries do not have good
vaccination programs.
B Poorer countries are mostly located in the
southern hemisphere where warm
temperatures are perfect for infectious agents.
C None of these.
What are the Main Types of
Infectious Disease?
Food Poisoning
Respiratory Diseases
Liver Diseases
Sexually Transmitted Diseases
Food Poisoning is a Disease
Caused by Infectious Agents
• Classical food poisoning is
poisoning from foods
contaminated with
enterotoxins.
• Bacterial food poisoning is
caused by the bacteria itself,
not the toxin it produces.
• Both bacterial and classical
food poisoning have similar
symptoms.
Why do you think there was a
picture of a hamburger on the
previous slide?
A
Because hamburgers are unhealthy and
have lots of fat which poisons us.
B
Because hamburgers are a common
place for food poisoning to occur.
C
Because we are talking about food safety
so there is a picture of some food.
Food Poisoning
Symptoms
• nausea
• vomiting
• abdominal cramps
• fever
• diarrhea
•Botulism-neurologic
collapse, respiratory failure,
and death. (Caused by
improper canning methods)
• Classical food poisoning
can be prevented by
better food storage and
handling techniques.
• Outbreaks usually occur
at picnics, school
cafeterias, or anywhere
where the food is not
handled properly or
stored unrefrigerated for
a long period of time.
Which Foods are Problem Foods?
• Almost all foods can
carry infectious
agents.
• Hamburgers, potato
salad, cold cuts, hot
dogs, soft cheeses,
eggs, and any raw
meat are favorite
places where
microbes can grow
and become likely to
infect.
Respiratory Diseases
• Many infectious
agents attack the
respiratory tract.
• The most common
respiratory disease is
the cold, but others
include bronchitis,
influenza, SARS, and
pneumonia.
Liver Diseases
• Most liver diseases are
caused by a variety of
viruses collectively
known as hepacivirus.
• These viruses cause
hepatitis (inflammation
of the liver)
• You were probably
vaccinated for Hepatitis
A virus when you were
young.
Source: consensus.nih.gov
A liver with varying stages of
hepatitis. The cells on the left
are normal liver cells.
In the previous slide you learned that
many viruses cause hepatitis (aka:
inflammation of the liver). What does
the “itis” mean?
Move your mouse around if an input box
does not appear.
Sexually Transmitted Diseases
• STD’s are a result of various viral and bacterial
infections that are transmitted through sexual
interaction or blood/serum exchange.
• There are more than 20 STD’s identified.
• The most common are:
Microbe
Disease
Chlamydia
Chlamydia trachomatis
Syphilis
Treponema pallidum
AIDS
HIV
Herpes
Herpes Simplex Virus
Acne is an Infectious Disease!
• The pimples are dead white
blood cells that were
attacking bacteria in the
skin’s pores.
• The sebaceous glands in
your skin make an oily
substance called sebum.
Too much sebum can clog
up the hair follicle. This
Acne is not contagious allows bacteria to grow and
or transferable
multiply.
• White blood cells rush to the
rescue to fight the infection.
Different infectious diseases
require different approaches for
prevention and control.
Here are some ideas that apply to
most infectious diseases.
Three Key Steps
reak the cycle of transmission
ill the infectious agent
ncrease host resistance
reak the Cycle of Transmission
• Control animals and other biological disease carriers
(e.g. insects, rats).
• Control air, dust, or dirt that may harbor infectious
agents.
• Use sanitary practices.
–
–
–
–
Good personal hygiene
Proper food-handling procedures
Use of protective clothing
Avoid water, foods, animals, and insects likely to transmit
disease
• Detect disease early and start treatment.
• Isolate or limit exposure to infected people.
• Use aseptic technique in the management of patients and
their excretions and secretions.
Controlling Disease Carriers
Source: www.lbl.gov
Source: USDA
• Sterile males can be
used to control insect
populations.
• Cleaning regularly and
picking up trash can
keep rodents away.
• Sometimes the only
way to stop a disease
transmission is to kill
the carriers.
Why does introducing sterile males
into a population of insects reduce the
transmission of infectious agents?
A
It prevents non-sterile males from
surviving and reproducing.
B
It indirectly reduces carrier
population numbers.
C
Sterile males cannot carry diseases.
Contamination
Infection
versus
• Contamination occurs
when you have the
infectious agent in or
on you but it is not
injuring you.
However, it does have
the potential to injure
others.
• Infection occurs when
you have the
infectious agent in or
on you and it is
injuring you in some
way.
Are the natural bacteria in your large
intestine contaminating you or
infecting you?
Contaminating
Infecting
Which is an example of a contaminated
person that is not infected?
A
A nauseated doctor (who had her flu vaccine) that had previously
helped a man with the flu.
B
A healthy nurse (who had her flu vaccine) that had previously helped a
man with the flu.
Good Sanitary Practices Prevent
the Spread of Infection
• Wash your hands
regularly!
• Always keep your area
clean and neat!
• Be careful around people
with infections
Why does keeping your area clean and
neat help prevent the spread of
infection?
A It helps keep potential disease
carriers, like rodents and flies,
away.
B A neat and clean environment is not
the best habitat for germs.
C It helps keep germs from multiplying
and creating large populations.
D All of the Above
Cleanliness = Healthiness
• Scrubbing with soap
and water eliminates
dirt and kills most
germs.
• Using disinfectant
provides an extra
margin of safety.
• The biggest place for
germs to reside in
your house is in the
kitchen.
Click on a button to see the best places
for infectious agents to reside!
Cafeteria
Playground
Teacher’s Desk
Classroom
Bathrooms
What are the Best Disinfectants
Disinfectant
Strength
Enveloped
Viruses
Non-Enveloped
Viruses
Bacteria
Fungi
Chlorox Bleach
Low
Good
Good
Good
Good
Iodine
Low
Good
Fair
Good
Good
Alcohol
Low
Good
Good
Fair
Good
Chlorhexidine
Low
Poor
Good
Fair
Good
Quaternary
Ammonia
Low
Poor
Good
Fair
Fair
All of these are low level in strength but anything higher is
not necessary for everyday use.
Based upon the previous slide, which
disinfectant is the best one to use?
Chlorox Bleach
Chlorhexidine
Iodine
Alcohol
Quaternary
Ammonia
Washing Your Hands
Fun Statistics About Washing
Your Hands:
1. A study of 305 Detroit students
found that washing their hands
4 times a day reduced their
sick days due to respiratory
illnesses by 24% and stomach
flues by 51%.
2. 1 out of every 3 people do not
wash their hands after using
the bathroom.
Source: foodsafety.gov
• Washing your hands is
the most important thing
you can do to keep from
getting sick!
• You pick up germs and
infect yourself by
touching your nose, eyes,
and mouth.
• The spread of the cold,
hepatitis A, meningitis,
and diarrhea can all be
prevented by washing
your hands.
How long should you scrub
your hands when washing
them?
A
0-10 seconds
B
15-30 seconds
C
1-2 minutes
Why does touching your nose,
eyes, and mouth get you sick if
you haven’t washed your
hands?
A
B
Because your nose, eyes, and mouth
have mucous membranes that easily
transfer infectious agents from your
hands to the rest of your body.
Because your nose, eyes, and mouth
have no resistance to infectious agents
so infection is a sure thing.
Food Preparation
• Many deadly infectious
agents live in our food.
• Always clean your area
before and after
cooking, especially
when cooking raw
meat.
• Always cook food well
and keep foods
refrigerated.
The All Important Refrigerator
• Keeping foods cold is
even more important
than cooking them.
• Cold temperatures keep
infectious agents from
multiplying and growing.
• Always refrigerate foods
within two hours of
cooking.
• Keep foods at or below
40°F.
Why does cooking food help
prevent infectious disease?
A
Cooking food prevents infectious agents
from growing and multiplying
B
Cooking food kills infectious agents
Isolate the Disease
This card was posted outside the house of a
person who had scarlet fever. The
authorities quarantined him to prevent the
spread of infection.
Source: National Library of Medicine
• The key to blocking the
transmission of infection
is to isolate the disease.
• Volunteer isolation and
quarantine are the best
ways to prevent the
spread of disease.
• Public authorities must
act quickly to prevent
outbreaks from becoming
epidemics.
Problems with Isolation
• Most people do not
want to voluntarily
quarantine
themselves.
• Mass transit allows an
easy route for an
infectious disease to
spread.
Kill the Infectious Agent
• Heat
– Usually 150°F or above
– Cook chicken/turkey to 165 °F
• Cold
– Foods should be refrigerated at or below 40 °F.
– Cooling may only slow infectious organisms’ growth,
not kill the organism.
• Chemical sterilization (e.g. chlorinate water
supplies and sewage)
Organisms that form spores may survive heat, cold, and chemical
sterilization. Prions are unaffected by these methods.
Increase Host Resistance
• Use vaccines and toxoids for active
immunization and immunoglobulins for
passive immunization.
• Improve general health - proper nutrition,
exercise, healthy lifestyle, etc.
Active vs. Passive Immunization
Active
Passive
- Occurs when a person is
exposed to an infectious
agent, contracts the
disease, and develops
antibodies against that
infectious agent.
- Vaccines are artificial
active immunization
because they cause the
immune response without
causing the disease
(usually!)
- Occurs when a person is
injected with antibodies,
such as immunoglobulins.
- This is a short term
immunity since it does not
stimulate the immune
system to make it’s own
antibodies.
- Unlike active
immunization, passive
immunization will never
cause the disease.
If a person is infected by an
infectious agent, contracts a
disease, and lives through it,
has he acquired passive or
active immunization?
Passive
Active
Vaccines
• Vaccines are very important
preventative medicine.
• Vaccines consist of killed or weakened
microbes that stimulate the immune
system against that microbe.
• Some infectious agents can change
their genetic makeup making it
difficult to produce a vaccine.
• Texas’ required immunizations
include: Polio, Haemophilus Influenza
B, Diphtheria, Tetanus, Pertussis,
Hepatitis A, Chickenpox, Measles,
Mumps, Rubella, and Hepatitis B.
Types of Vaccines
• Inactivated Vaccines
• Live, Weakened
Vaccines
• Toxoids
• Conjugate Vaccines
• Subunit Vaccines
• Recombinant Vector
Vaccines
Click Me to Visit the PEER web site and review
your knowledge of the Immune System!
Inactivated Vaccines
• These vaccines are produced by killing the
infectious agent.
Pros
Cons
- They do not have to be
refrigerated.
- They usually require
booster shots because they
only weakly stimulate the
immune system to make
antibodies.
- They will never come
back to life and cause the
disease.
Weakened Vaccines
• These vaccines are produced by weakening
a live vaccine or removing it’s disease
causing ability.
Pros
- They emit a large
immune system response
so you only have to
receive the vaccine once
or twice.
Cons
- They have to be kept in
special conditions, like
refrigeration.
- They can mutate and
cause the disease.
Toxoids
• Toxoids are produced by inactivating the
toxin that some infectious agents create.
• Toxoids are used against Tetanus and
Diphtheria.
Pros
- You only have to have
the vaccine once or twice.
- They will never be
reactivated and cause the
disease.
Cons
- They have to be
refrigerated.
Conjugate Vaccines
• Immature immune systems, like those
found in children, cannot recognize some
infectious agents.
• Conjugate vaccines are produced by
attaching a protein or toxin from a
microbe that young immune systems can
recognize to an infectious microbe that
these immune systems can’t recognize.
• The Hib vaccine is a conjugate vaccine.
Subunit Vaccines
• These vaccines are produced by taking apart an
infectious agent and only using the antigen part
(the part that stimulates an immune response).
• The vaccines for Hepatitis B and Streptococcus
pneumoniae are subunit vaccines.
Pros
- They cannot cause the
disease.
Cons
- They are more difficult to
make and require new,
expensive technology.
Recombinant Vector Vaccines
• These vaccines are produced by inserting
the harmless genetic material of an
infectious agent into a different, weakened
or killed, infectious agent.
• Scientists have not been able to make
vaccines for all infectious agents. They are
hoping that inserting the genetic material
from these infectious agents into another
vaccine will evoke an immune system
response against these infectious agents.
Test Your Knowledge!!
Word Bank
Conjugate Vaccine
Inactivated Vaccine
Subunit Vaccine
Toxoid
Weakened Vaccine
Recombinant Vector
Vaccine
The questions will keep repeating until you get them
all correct!! Each word is used only once.
How Vaccines are Made
• The microbes grow on an
agar or tissue graft such as
calf fetal serum, chick
serum/egg, or monkey
serum/egg.
• The microbes are purified
and the vaccine is produced.
• Allergic reactions to a
vaccine can occur when the
purification process does not
eliminate all of the serum.
When a person has an allergic
reaction to the vaccine, what is
that person really allergic to?
A
He is allergic to the weakened or dead
microbe.
B
He is allergic to the serum used to grow
the microbes.
Genetic Recombination and
Bacterial Resistance
• Many infectious agents can
change their genetic makeup to
become stronger, more virulent
microbes.
• These microbes are unaffected
by vaccines or antibiotics that
previously killed that species of
microbe.
• Genome sequencing of these
microbes helps scientists
identify drug targets for the
microbes and understand their
resistance abilities.
Healthy Lifestyle--The Best
Preventative Maintenance
• Eating healthy food,
taking vitamins, and
regular exercise
stimulates the immune
system.
• Good sanitation
practices also limits an
infectious agent’s
ability to spread to you
and others.
Case Studies:
Infectious Agents Attack!
Influenza Virus
See the PEER Influenza
Supplement for more
information.
• Infects the nose, throat,
and lungs causing the
flu.
• Symptoms: fever,
muscle ache, chills,
sweating, sore throat.
• This virus rapidly
changes its RNA to
produce more virulent
strains and new
vaccines have to be
made each season.
Severe Acute Respiratory
Syndrome
• First identified in February, 2003.
• The virus or viruses cause a form of atypical
pneumonia which results in acute respiratory
distress and can lead to death.
• It is unknown what this virus is or how it works.
Researchers think it is a type of cornavirus (the same
category of the common cold virus).
• It can be spread from person to person through
respiratory droplets, just like the common cold.
• Symptoms include a fever greater than 100.4°F,
cough, and difficulty breathing. Sometimes the
person will also feel the same symptoms as those
caused by the influenza virus.
Clostridium tetani
• Causes Tetanus or Lockjaw
• Symptoms: muscle spasms and
tetanic seizures that can lead to
bone fractures and muscle tears.
• The bacteria produces a toxin
called tetanospasmin which
blocks inhibitory nerve
transmission from spinal cord to
muscles. This causes an overexcitation of the muscles.
• Without treatment, 1 out of 3
people die.
Escherichia coli
• Causes E. coli enteritis,
a disease caused by the
bacteria itself and/or the
toxin it produces.
• Symptoms: diarrhea,
cramps, vomiting
• Can lead to Hemolytic
Uremic Syndrome which
is life threatening.
Source: CDC