Download infectious diseases

Myth There isn’t much a person can do to avoid spreading or
catching a cold or the flu.
Fact About 80% of infectious diseases are spread by hand
contact. Washing your hands with soap and water is a simple and
effective way to prevent the spread of colds and the flu.
Do you think most teens wash their hands as much as
they should? What do you think are some ways to encourage
more frequent hand washing?
Causes of Communicable Diseases
•Communicable diseases, also know as infectious
diseases are caused by organisms or viruses that enter
and multiply within the human body.
•Microorganisms are organisms that can be seen only
through a microscope.
•Microorganisms and viruses that cause disease are called
pathogens.
•Pathogens can cause an infectious disease when they
enter your body and multiply.
Bacteria
•Bacteria (bak TEER ee uh) are simple,
single-celled microorganisms. Bacteria
live in air, soil, food, and in and on the
bodies of plants and animals, including
you.
•Some bacteria injure cells by giving off
poisons called toxins (TAHK sinz).
Viruses
•The smallest pathogens are viruses.
•A virus can multiply only after entering
a living cell.
•The virus then takes over the cell’s
reproductive mechanisms, resulting in
cell damage or death.
Fungi
•Organisms such as yeasts,
molds, and mushrooms are
known as fungi (FUN jy).
•Fungi grow best in warm, dark,
moist areas.
Protozoans
•Single-celled organisms that are
much larger and more complex
than bacteria are known as
protozoans (proh tuh ZOH unz).
•Protozoans have the ability to
move through fluids in search of
food.
How Pathogens Are Spread
Pathogens can spread through contact with
•an infected person
•an infected animal
•contaminated objects
•contaminated food
•contaminated soil
•contaminated water
The pathogens can then enter the body through breaks in
the skin or through the moist linings of the eyes, ears,
nose, mouth, or other openings.
Infected People
•Many infectious diseases are spread through some form
of contact with a person who has the disease.
•The contact may be direct physical contact.
•Infectious diseases can
also spread through
indirect contact.
Infected Animals
Some infectious diseases are
transmitted to humans through
the bites of animals.
Contaminated Objects
•Some pathogens can survive for a period of time outside
a person’s body.
•These pathogens can be spread from person to person on
objects such as
•doorknobs
•eating utensils
•towels
•needles used for
body piercings and
tattoos
Contaminated Food, Soil, or Water
•Some pathogens are naturally
present in food and soil.
•Sometimes water and food become
contaminated with pathogens from
infected people.
Your Body’s Physical and Chemical Defenses
5)
1)
2)
3)
4)
Stomach
Saliva andacid
tears
When
certain
Saliva you
and swallow
tears can
wash pathogens
with
water,
or mucus, acids in your
awayfood,
some
pathogens.
stomach can kill those pathogens.
1
Mucous membranes
Mucus traps some pathogens,
preventing them from entering
your body.
Cilia
Cilia help move mucus
and pathogens out of
your body when you
cough or sneeze.
2
3
4
Skin
Your skin is an effective barrier
against many pathogens.
5
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Health Stats Note the difference between the leading causes of death in
the United States in 1900 and in 2000.
Were any of the leading causes of death in 2000 infectious
diseases? Explain why you think this is the case.
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Bacterial Diseases
• There are thousands of infectious diseases, and over
40 kinds commonly occur in the United States.
• Four infectious diseases caused by bacteria are
• strep throat
• Lyme disease
• meningitis
• tuberculosis
Strep Throat
• “Strep” is short for Streptococcus, the bacterium that
causes the disease.
• Strep bacteria, which are usually found in the nose
and throat, can be spread by contact with mucus
from an infected person.
• Symptoms include
• sore throat
• swollen lymph nodes on the sides of the neck
• headache
• fever
Lyme Disease
• Humans can become infected with the bacteria that
cause Lyme disease when they are bitten by an
infected tick.
• Symptoms of Lyme disease include
• a red rash at the site of the tick bite
• fever
• chills
• body aches
• The best way to protect yourself from Lyme disease
is by avoiding tick bites.
Bacterial Meningitis
• An infection of the fluid in the spinal cord and the
fluid that surrounds the brain is called meningitis.
• Symptoms of meningitis include high fever,
headache, vomiting, and a stiff neck.
• There are two types of meningitis—one is caused by
bacteria, the other by a virus.
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Tuberculosis
• A highly contagious bacterial infection of the lungs is
tuberculosis (too bur kyuh LOH sis), or TB.
• It is transmitted when droplets from an infected
person’s cough or sneeze are inhaled.
• Symptoms, which include fatigue, weight loss, a mild
fever, and a constant cough, may not show up for
many years after the initial infection.
Treating Bacterial Diseases
• An antibiotic (an tih by AHT ik) is a drug that inhibits
or kills bacteria.
• Using antibiotics exactly as they are prescribed is
very important to prevent bacteria from developing
resistance to the medicine.
• Antibiotic resistance can result if you don’t finish your
prescription and some of the bacterial pathogens in
your body survive.
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Viral Diseases
Viral diseases include
• the common cold
• influenza
• pneumonia
• hepatitis
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The Common Cold
• The common cold is really a group of symptoms that is caused by a
number of different viruses.
• One or two days after exposure to a cold virus, people develop
• sneezing
• sore throats
• runny noses
• coughing
• chest congestion
• fever
• headaches
• muscle aches
• Colds spread when a person touches a contaminated object or inhales
droplets from a sneeze or a cough.
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Influenza
• The flu, or influenza, is a common viral infection of
the upper respiratory system.
• Influenza is spread by airborne droplets and contact
with contaminated objects.
• High fever, sore throat, headache, and a cough are
typical symptoms of the flu.
The Stages of the Flu
Pneumonia
• In people who are elderly, or who have heart disease
or breathing problems, flu may develop into
pneumonia (noo MOHN yuh), a serious infection of
the lungs.
• Many people die each year from pneumonia, which
can be caused by viruses, bacteria, or even fungi.
Hepatitis
• A group of viruses that infect the liver can cause hepatitis
(hep uh TY tis), or inflammation of the liver.
• Symptoms of hepatitis include
• fever
• nausea
• pain in the abdomen
• jaundice (JAWN dis), or yellowing of the skin.
• Hepatitis A is transmitted in human wastes and in
contaminated water and food.
• Hepatitis B can be transmitted in blood, during sexual
contact, or during tattooing or body piercing.
• Hepatitis C can be transmitted in blood, during sexual
contact, or during tattooing or body piercing.
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Treating Viral Diseases
• In most cases, there is no particular medicine that
can cure a viral infection.
• The best treatments for viral infections are rest, a
well-balanced diet, and plenty of fluids.
• Many over-the-counter medicines can treat the
symptoms of viral infections.
When to Seek Medical Care
• If you are worried about your health for any reason, see a
doctor and discuss your concerns with him
or her.
• Seek professional medical care if you have
• an extremely sore throat, earache, vomiting, diarrhea,
or a temperature of 101°F that lasts more than two
days
• mucus from your nose or throat that is thick and
yellowish green
• difficulty breathing, or severe pain anywhere
• a cut, scrape, or sore that does not seem to be
healing as it should
• an illness that lasts longer than usual
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Preventing Infectious Diseases
Here are some healthful behaviors you should
practice to help you avoid disease.
• Wash your hands several times a day, especially
before eating and after using the bathroom.
• Do not share items that can transfer pathogens,
such as towels, eating utensils, cups,
or hairbrushes.
• Cook and store foods properly. Meats should be
cooked thoroughly. Hot foods should be kept hot,
and cold foods should be kept cold.
• Avoid close contact with people who are ill.
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Preventing Infectious Diseases
Here are some healthful behaviors you should
practice to help you avoid disease.
• Stay home when you are not feeling well.
• Learn to manage stress in healthful ways, and
get at least eight hours of sleep each night.
• Eat well-balanced meals, and do not skip meals.
Exercise regularly, at least three or more times a
week.
• Avoid unhealthful substances, such as tobacco,
alcohol, and illegal drugs.
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Using Medicines Correctly
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Using Medicines Correctly
Read all the information on the label and follow
the directions.
Only take medicines prescribed for you.
Call your doctor if a medicine causes
serious side effects.
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Using Medicines Correctly
Never combine medicines without checking
with your doctor.
Never drink alcohol while taking medicines.
Store medicines according to the
label’s instructions. (expiration, original
container)
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