Chapter 28:
Infectious Diseases
p. 619
Lesson 1:
What Causes Infectious Diseases?
P. 620
Health Terms p. 620
 Infectious diseases
 Parasites
 Virus
 Transmission
 Immunity
 Mucous membranes
 Phagocytosis
 Neutrophils
 antibodies
Causes of Infectious Diseases
 Every infectious disease is caused by a pathogen.
 Pathogens invade the body and attack it’s cells and
tissues.
 Most pathogens are parasites.
Bacteria
 Single-celled
microorganism
 Can live almost
anywhere
 Some produce poisons
that are harmful to
human cells
 Abundant in the air, soil
and water
 Upon entering the body,
they multiply rapidly
through cell-division
 Division can take place
every 20min.
 1 bacterium can be 4
billion in just 15 and 1/2
hours
 Usually body’s immune
system does not allow
this
Viruses
 Smallest infectious agent
 HIV is one of the deadliest
known viruses; it causes
AIDS
 Are not living cells
 Invade all known forms of life
 Viruses very specific in
the cells it invades
 Upon entering the body,
it attaches to a cell and
injects its genetic
material in that cell.
The virus then makes
copies that repeat the
process
 Usually killed by
immune system
Rickettsias
 Organisms that resemble
small bacteria
 Act like viruses in that they
need to invade the cells of
another life form
 Most are found in the
intestinal tract of insects
 Rickettsias are passes to
human or animal by bites or
feces deposits on the skin
 Typhus
 Rocky Mountain Spotted
Fever
Protozoans
Fungi
 Single-celled
 Simple organisms
 Larger than bacteria
 Prefer dark, damp
 Most are harmless
 About 30 types causes
disease in humans
 Most common in tropical
areas that have poor
sanitation
environments
 Most invade deep tissues
of hair, nails and skin
causing infections of the
scalp and feet
 Examples are ringworm
and athletes’s foot
How Infectious Diseases
Spread
I.
People

Direct contact - when an uninfected person comes in
to physical contact with an infected person.


Sexually Transmitted Diseases (STD’s) are spread this
way
Pregnant women may transmit infection to an unborn
child
How Infectious Diseases
Spread cont’d
People cont’d
I.

Indirect contact- Pathogens spread through the air
or other means of transmission other than direct
contact.
 Pathogens can be spread through touching

contaminated objects.(Desk, utensils, glasses or
needles)
Pathogens can be spread through the environment.
(Food, water, soil, and even the air)
How Infectious Diseases
Spread cont’d
II.
Animals

may spread infectious diseases such as Malaria or
Rabies.
How Your Body Defends
Against Infectious Disease
How does your body remain health?
Immunity
 Your immune system fights millions of pathogens
each day
 thus keeping your body mostly free of infection.
 Nonspecific Resistance- Inborn, or general,
defenses against infection
 When nonspecific, the body responds the same way to
every foreign substance
 4 types:
The Immune Response
Nonspecific Resistance
1. Physical barriers
-
-
Skin first line of defense against invading pathogens,
the main barrier
Mucous membrane/mucous
Cil
The Immune Response cont’d
Nonspecific Resistance cont’d
2. Chemical Barriers
•
•
Enzymes in tears
Acidic digestive juices
3. Body Cells
•
White Blood Cells (WBC)


Phagocytes
Neutrophils - chief phagocytes
The Immune Response cont’d
Nonspecific Resistance cont’d
4. Inflammatory response



“Red Alert” stage, increased blood flow.
Symptoms include heat, redness and swelling
Once pathogens are destroyed, tissues return to
normal.
Specific Resistance

Immune system mounts specific attacks against
particular types of pathogens.

Lymphocytes- Type of white blood cell that fights
pathogens.

Two main types of lymphocytes are B cells and T
cells.
Specific Resistance cont’d
1. B cells- Enlarge and multiply, eventually turning into
antibodies. If you encounter the same specific
pathogen again, the antibodies are still there to fight.
2. T Cells- Two main types.
 Killer T cells - multiply by the presence of abnormal
body cells; they then fight to kills the abnormal cells
 Helper T cells - aid the activity of the B and Killer T
cells.
Specific Resistance cont’d
When you fail to take in adequate nutrients, you can
jeopardize the immune system. This is why those with
poor eating habits tend to get more sick.
Chapter 28:
Infectious Diseases
p. 619
Lesson 2:
Common Infectious Diseases
p. 627
Health Terms
 Pneumonia
 Tuberculosis (TB)
 Strep throat
 Vaccine
 Immunization
 Rubella
Respiratory Infections
Infections of the breathing passages, most of these
are caused by a virus or a bacteria.
1. Common Cold - viral infection, inflammation of
the mucous membranes lining the nose and
throat.
 Mostly contracted by breathing in virus
 sneezed or coughed by an infected person,
 or rubbing the eyes or nose with fingers that picked

up the virus
 by direct contact or indirect contact
There is no cure, but most clear up in a week or so.
The best treatment is rest, proper nutrition, and
drinking plenty of fluids.
Respiratory Infections cont’d
2. Influenza (The Flu)- viral infection, spread and
treated the same way as cold.
 Major breakouts generally occur in the winter.
 Secondary bacterial infection may accompany the flu


which can develop in to pneumonia (A serious
inflammation of the lungs)
Secondary infections need antibiotic treatment
Respiratory Infections cont’d
3. Tuberculosis (TB)- Highly contagious bacterial
infection that most often affects the lungs.
 Spread by airborne droplets produced by coughing or

sneezing.
Main symptoms include coughing, chest pains,
shortness of breath, fever, sweating, and weight loss.
Respiratory Infections cont’d
4. Strep Throat - A bacterial infection of the throat.




Spread through droplets coughed or sneezed in the
air.
Symptoms include sore throat, fever, general feeling
of sickness and enlarged lymph nodes in the neck.
If left untreated can lead to serious complications.
Strep can be cured with antibiotics.
Infectious Diseases of the
Nervous System
1. Encephalitis




Inflammation of the brain
Often caused by a virus carried by a mosquito
No known cure
Can be caused by herpes simplex virus
 If can be cures with an antiviral
Infectious Diseases of the
Nervous System cont’d
2. Meningitis



An inflammation of the membranes that cover the brain
and spinal cord
Viral illness is mild
Bacterial is life-threatening
3. Poliomyelitis (Polio)


Viral
1950 to scientists developed a vaccine
Measles
 viral
 Fever
 Total body rash
 Can cause encephalitis
 Vaccine - part of the MMR series
Mononucleosis
 “Mono”
 “Kissing Disease”
 Usually spread through direct contact
 3-6 weeks for recovery
Hepatitis
 Inflammation of the liver
 Can result in permanent damage
 Common symptom is yellowing skin and eyes
 Appear 3 - 4 weeks after exposure
 Lasts 2 - 6 weeks
Hepatitis cont’d
3 Types of Hepatitis:
1. Hepatitis A

The virus is contracted by eating or drinking foods
contaminated with the virus; food in contact with
feses
2. Hepatitis B



Found in body fluids
Spread via blood and sexual contact
Can cause liver damage
Hepatitis cont’d
3. Hepatitis C


Found in blood
Can cause liver cancer
NO CURE
VACCINE FOR HEPATITIS B
Chapter 28:
Infectious Diseases
p. 619
Lesson 3:
Preventing Infectious Diseases
p. 632
Health Terms
 Active immunity
 Passive immunity
IMMUNITY
The body’s natural resistance to
many pathogens
2 Types:
IMMUNITY cont’d
1. Active immunity - the body develops specific, long
term antibodies to fight pathogens.
 ie Chicken Pox virus enters and your body produces
antibodies to kill that virus
2. Passive Immunity - infant acquires immunity through
its mother while in womb and shortly after birth
Immunization
Additional help to establish immunity against specific
pathogens
Immunization cont’d
1. Passive immunization


Blood is taken from an infected person who has
developed antibodies
An extract of that blood is injected into the person
needing immunity help
2. Active Immunization


Also know as a vaccine
3 types:
Immunization cont’d
3 Types of Active Immunization:
1. Live-virus vaccine



Made from weakened viruses
Help the person to produce antibodies and not get sick
Measles, rubella, & oral polio
Immunization cont’d
2. Killed-virus vaccine



Made from killed viruses
Helps a person to produce antibodies and not get
sick
Less powerful than Live-Virus vaccine


Thus boosters are needed
Cholera, typhoid fever, rabies and injected polio
Immunization cont’d
3. Toxoid

Made with chemically treated bacteria toxins
 These toxoids stimulate production of antibodies
Immunization for All
Why do you think immunizations are important in the
school setting?
Common Sense Measures
Keep your body healthy
 Good nutrition
 Adequate slee
 Exercise
Bathe or shower every day
Avoid sharing eating & drinking utensils
Wash your hands after using the restroom or
changing diapers
Common Sense Measures
cont’d
 Wash your hands before handling food
 Avoid giving your illness to others
 Cover your mouth & nose when sneezing/coughing
 Use tissues only once and dispose
 Avoid contact with those who are sick
Test Review
 Rickettsias resemble bacteria and are able to
reproduce only by invading the cells of another life
form.
 Chief type of white blood cells involved in
phagocytosis are neutrophils
 TB is caused by a bacteria
 B cells produce antibodies against pathogens
 When they encounter a pathogen, B cells turn into
plasma cells.
 Meningitis is an inflammation of the membranes that
cover the brain and spinal cord.
 A live-virus vaccine is a type of vaccine made
from a weakened virus.
 Hepatitis is an inflammation of the liver usually
caused by a viral infection in which the skin and
the whites of the eyes turn yellow.
 Know ALL of your vocabulary!!!
 Page 638- 1-17
 Directions- Write the answer, then take the
answer and use it in a sentence that you either
made up or found in the book. Sentences should
show knowledge of the def.