Download Unit 8 Communicable Diseases

Diseases and
Disorders
Unit 8
Chapters 23-24-25
Causes of Infectious
Diseases
Pathogens-invade the body and attack its
cells and tissues.
Most pathogens are parasites.
Parasites live in or on another organism and
derive nourishment from it.
EX: BACTERIA, VIRUSES, RICKETTSIAS,
PROTOZOANS, AND FUNGI
BACTERIA
Single cell organism
Classified in 3 categories: spherical, rod-shaped, and
spiral-shaped
EX: Streptococcus, Staphylococcus, and E. coli
Streptococcus
Strep throat - a sore, red throat, sometimes
with white spots on the tonsils
Scarlet fever - red rash on the body
Impetigo - a skin infection
Cellulitis and necrotizing fasciitis (flesh-eating
disease)
Staphylococcus
Skin infections
Pneumonia
Food poisoning
Toxic shock syndrome
Blood poisoning (bacteremia)
E. Coli
Intestinal bacteria
Symptoms: diarrhea, food poisoning
Goes away untreated in 5-10 days.
Treatment for Bacterial
Infections
Antibiotics-kill bacteria or stop it from
reproducing
Antibiotics DO NOT kill viruses:
Colds
Flu
Most coughs and bronchitis
Sore throats, unless caused by strep
Viruses
Smallest known type of infectious agent
1/2 to 1/100 the size of the very smallest bacterium
Consist of an inner core of genetic material
surrounded by a protective protein shell and are
entirely dependent on living cells for survival and
reproduction.
HOW
A
VIRUS
WORKS
Examples of Viruses?
Human Immunodeficiency Virus (HIV), which is the
virus that causes AIDS.
herpes simplex virus, which causes cold sores,
smallpox, and the human papilloma virus, now
believed to be a leading cause of cervical cancer in
adult women.
Rickettsias
Resemble small bacteria but work like a
virus, they must invade the cell of another life
form.
Usually invade the intestinal tracts of fleas,
mice, ticks, and mites
When humans are bitten they can contract
the rickettsias and contract typhus and Rocky
Mountain spotted fever.
What is Typhus/Rocky
Mountain Spotted
Fever
Typhus occurs throughout the world where
people and rats occupy the same living area
or building.
Infection occurs when rat fleas bite humans
Rocky Mountain spotted fever occurs most
commonly in the mountains of the US and
Mexico
It is spread by ticks, carrying rickettsias
Protozoans
Single-Cell Organisms, larger than bacteria
with a more complex cell structure.
Most are harmless
Most common in tropical areas with poor
sanitation
Water supplies and contaminated animals
Fungi
Simple organisms that cannot make their own food
Most are saprophytes or organisms that feed off
dead animals, insects, and leaves.
The most common are athlete’s foot and ringworm
Athlete’s Foot
Ringworm
How Infectious Diseases
are Spread
Direct Contact-Human to Human
Indirect Contact-bacteria and viruses can both enter
the body through the lungs if droplets are exhaled,
coughed, or sneezed out.
Animals Spread
Infectious Diseases
Mad cow disease
Malaria
Rabies
West Nile
Typhus
The Immune System
It’s a network of cells, tissues, organs, and chemicals
that fight off pathogens.
Inflammatory Response
A reaction to tissue damage caused by injury or
infection.
What Happens?
Tissue damaged, blood vessels near injury expand
Fluid and cells from bloodstream cause swelling
Phagocytes attack invading pathogens
Pathogens killed, tissue damage under control, body
begins to repair
Specific Defenses
The inflammatory response is different than the
immune response.
How the “Immune
System” Responds
An antigen enters the body and causes the immune
system to respond.
Lymphocytes are specialized white blood cells that
coordinate and perform many specific functions of
immunity.
T cells and B cells
Immune System
Memory
Your immune system has a memory of every antigen
it has encountered.
Active Immunity develops naturally and artificially.
Vaccinations are prepared dead or weakened
pathogens that are introduced into the body to
stimulate an immune response.
Passive Immunity
You acquire passive immunity when your body
receives antibodies from another person or animal.
This immunity is temporary.
Emerging Diseases and
Pandemics
These are emerging diseases whose occurrence in
humans has increased within the past two decades or
threatens to increase in the near future.
Avian Influenza
H1N1 Virus
Salmonella and E. Coli
Recreational Water Illness
HIV/AIDS
How Diseases Affect
the World
Pandemic-global outbreak of an infectious disease.
5 Deadliest Pandemics
in History
The Peloponnesian War Pestilence (430 BC)
The Antonine Plague (165 AD)
The Plague of Justinian (541-542 AD)
The Black Death (14th Century)
The Spanish Flu (1918)