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Communicable/Infectious
Diseases
Unit 8
Page 484
Immune System P. 485
Lymphocytes- white blood cells that help the
body fight pathogens
Two Types:
B Cells- produce antibodies
T Cells- signal B-cells to produce
antibodies
Immunity P.485
- the body’s resistance to disease-causing agents.
Active- resistance to disease due to the presence of
antibodies
Passive- introducing antibodies into a persons blood
stream
Vaccine- weakened disease that is introduced into the
body to give immunity (make antibodies)
Communicable/Infectious
Diseases p. 487
- An illness caused by pathogens that can be
spread from one living thing to another.
Pathogens- microbes which can cause
infectious diseases.
Contagious- having the ability to be
transmitted.
Epidemiology- the study of the source & the
spread of diseases.
What to know about types of
pathogens P. 487
Bacteria- microscopic, single celled org. that cause
disease.
Fungi(yeast & mold)- simple org., can’t make own
food (ex: Athlete’s foot, ringworm)
Viruses
Protozoa- single celled org., can produce toxins that
cause disease.
Helminith(worms)- not micro org., cause disease in
human body by infecting intestines, muscles,
rectum (ex: Round worms or Trichinosis)
Microbes- tiny organisms that can not be seen
by the naked eye.
Bacteria
- multiplies in moist, dark, warm, nutrient-rich body
tissue.
(can also live and multiply outside the body)
- microscopic, single celled organisms that can
cause disease.
Tetanus, Tuberculosis(492) & Lyme disease,
Strep Throat, Syphilis and Gonorrhea are all
caused by bacteria.
Viruses
Viruses are not cells! Viruses cause diseases by
invading cells forcing them to reproduce viruses.
Some remain in the body for life. Can live outside
the body for a short time but must multiply inside.
* Smallest disease causing pathogen
Examples: rabies, polio, common cold, hepatitis,
mumps, chicken pox, shingles and warts.
How Pathogens are Spread
P.488
Possible Causative Factors
1.
2.
3.
4.
Host- person who is ill, & is carrying the virus.
Environment- where the host lives.
Time- season of the year.
Agent- germ which caused the illness.
Susceptible: having a high chance of getting disease.
Relapse: recurrence of symptoms of disease after a
period of improvement.
Defense Against Infection
P.485
First Line of Defense- Structural
1. Skin (unbroken)
2. Mucous Membranes in the mouth, nose and
bronchial tubes.
3.Cilia
4. Digestive Juices (stomach acids)
5. Tears
Second Line of Defense- Cellular
1. White Blood Cells
Phagocytes- eat up invaders
2. Lymph Nodes- gland like structures that serve as
filters to screen out bacteria.
Immunity- Last Line of Defense
T-cells: lymphocytes recognize invaders and
activate B-cells
B-cells: responsible for producing antibodies
that destroy invading germs.
Inborn Immunity- temporary immunity that an infant
has. (acquired from mothers antibodies)
Bacterial STD’s
P.499
ChlamydiaPID- Pelvic Inflammatory Disease
Syphilis- chancre appears, if it goes away doesn't
mean STD is gone, its dormant.
Spirochete- bacteria that causes syphilis
GonorrheaGonococcus- bacteria that causes gonorrhea
* Bacterial STD’s are curable with antibiotic
Viral STD’s
P.502
Herpes I- blisters or sores appear on or around the mouth
Herpes II- causes blisters to appear in genital region.
HPV- wart in genital area
(can cause cervical cancer in females)
Hepatitis (A,B,C,D,E)- viral infection of the liver
Parasites
Pubic LiceTrichomoniasis-
HIV P. 504
Transmissible virus that attacks T-cells of the
immune system and causes immune deficiency.
- the virus that causes AIDS. Some people who
become infected with HIV, become ill & die
within six months. Others may remain in good
health and show no signs for six to ten years.
Opportunistic Infections- infections like pneumonia
or cancer, that actually kill the person because
immune system is so low due to HIV.
Ways of Transmission
P. 506
List the 7 ways-Contact with infected blood, semen, or vaginal
secretions.
-Injection of infected blood or blood products
-Infected mother to baby (breast milk)
High Risk Behaviors: Anal intercourse, injecting
needles with multiple users, vaginal intercourse.
Other Risky Behaviors: oral sex, receiving blood
(not too probable in this day and age)
** Ways HIV is not transmitted
How HIV Takes Over the Body
P.505
The virus destroys the T cells& disables their
function of signaling the B cells to produce
antibodies. With the immune system so low,
the T cells are not able to fight off other
microorganisms & cancer cells. The HIV
cells multiply.
Early Signs of HIV
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Tiredness
Skin rashes
Night sweats
Loss of weight
Diarrhea
Sore throat & fever
Incubation Period
Word given for the time period when you turn from
HIV- to HIV+
It may take 6 weeks to 6 months before HIV
antibodies will show up in the blood. Most people
develop antibodies in 6-12 weeks.
Treatment Drugs- slows down the germs ability to
reproduce. P. 510
Cure- none
Tests
P. 512
ELISA- blood test that identifies whether a
person has HIV antibodies.
If negative- retest in 6 months, if positiveanother ELISA is done to confirm.
Western Blot Test- this is also an antibody test
done to confirm the results of the ELISA
test.
AIDS
Acquired Immune Deficiency Syndrome
- the last and deadly stage of HIV is AIDS.
When a person has 200 T cells or less they
are considered to have AIDS. After
symptoms marking the beginning of AIDS
development, most people die within two
years & the rest within five years.
Avoiding STD’s & HIV
P. 508