1. INFECTIOUS DISEASE

2. What is a disease?
A disease is any change, other than an injury, that disrupts the normal functions of the body.
What can cause this change?
Genetics
Materials in the environment
Pathogens

3. What is a pathogen?
Disease-causing organisms are called pathogens, which literally means “sickness makers.”
Diseases caused by pathogens are generally called infectious disease because they enter, or infect, the body of the organism that gets sick.

4. What causes infectious diseases?
People used to believe curses, evil spirits, or night vapors caused diseases.
In mid 1800s Louis Pasteur and Robert Koch provided another explanation – THE GERM THEORY OF DISEASE
This theory concluded that infectious diseases were caused by microorganisms, more commonly known as germs.

5. How are infectious diseases different?
Diseases are change in the normal functions of the body.
They may or may not be infectious diseases.
Infectious diseases are diseases that are caused by the invasion of a host by an agent whose activities harm the host’s tissues (that is it causes the disease) and can be transmitted to other individuals (that is they are infectious).

6. How were diseases identified?
Once it was believed that pathogens (germs) were causing diseases, Koch developed a series of guidelines still used today to identify the microorganisms that cause specific diseases.
These rules are known as Koch’s postulates.

7. Koch’s Postulate Find pathogen in sick hosts, but not healthy ones
Isolate and grow pathogen
When pathogen is placed in new host, it should cause same disease as original host
Very same pathogen should be isolated

9. What are pathogens? Pathogens are also known as infectious agents.
Infectious Agents include:
Bacteria
Viruses
Protozoa
Helminth (Worms)
Fungi
Prion

10. Bacteria
Very small unicellular prokaryotes (remember what this means?) that have cell walls containing peptidoglycans (peptide = protein, gylcan = carbohydrate)
Example Diseases:
Anthrax
Botulism
Tuberculosis
Typhoid
Treatment for bacterial diseases:
Vaccines
Antibiotics

11. Bacteria Reproduce through Binary fission – one cells splits into
two cells
2 cells

12. Bacteria Classified into three types based on their shape Bacillus –
Rod Shaped
Coccus –
Sphere Shaped
Spirillum –
Spiral Shaped

13. Viruses Viral Diseases: Treatment:
AIDS
Measles
Hepatitis
Ebola
Treatment:
Vaccines
Antiviral
Viruses
Small particle composed of nucleic acid enclosed in a protein
Can only reproduce by infecting living cells
CANNOT BE TREATED WITH ANTIBIOTICS

14. Fungus Multicellular microorganism
They live on your hair, nails and outer skin layers
Fungal Diseases:
Athlete’s Foot
Ringworm
Treatment:
Antibiotics
Antifungals

15. Protozoa Simple, unicellular eukaryote (remember what this means?)
Protozoan Diseases:
Chagas
Amoebic Dysentery
Malaria
Treatment:
Antibiotics

16. Helminth (Worm) Multicellular worms Examples: Treatment: Pinworm
Roundworm
Tapeworm
Hookworm
Treatment:
Antihelminths

17. Prion Treatment: Small particle composed only of protein
NO KNOWN TREATMENT
Small particle composed only of protein
Only passed through food
Example Diseases:
CJD (mad cow disease)
Scrapie

18. How do diseases spread? Direct Contact
Coming into contact with someone that has the disease
Person to Person: most common; direct transfer of pathogen from one person to another
Animal to Person: animal waste; being bitten or scratched
Vector = Animals that carry disease-causing organisms
Doesn’t cause the disease, just carries it
Examples: Mosquitoes, Ticks, Flea, Mouse
Mother to unborn Child: through the placenta mothers can pass germs to her unborn baby

19. How do diseases spread? Airborne Indirect Contact
Some germs can travel as
small particles or through
water vapor droplets
Indirect Contact
Many germs can linger on inanimate
objects (table top, doorknobs,
sink handles)

20. How do diseases spread? Vehicles Vectors Through food or water
Allows the disease to spread to many people through a single source
Vectors
Through animals that carry the disease
Mosquitos, Ticks, Fleas

21. How can you prevent diseases from spreading?
Wash your hands often.
Get vaccinated.
Use antibiotics sensibly.
Don’t eat foods with antibiotics in them.
Don’t take antibiotics when you don’t need them.
Don’t use antibacterial soap.
Stay at home if you have signs
and symptoms of an infection.
Be smart about food preparation.
Disinfect the 'hot zones' in your home.
Kitchens, bathrooms
Practice safe sex.
Don't share personal items.
Toothbrushes, dining utensils
Keep your pets healthy.

22. How do you categorize diseases? (This should sound familiar!)
Infectious Agent
bacteria, virus, protists, helminth, fungi, prion
Treatment
Prevention
History of Disease
Transmission
Airborne, direct/indirect contact, vehicles, vectors

23. Categorizing Diseases, History
Endemic
Disease has been around for a while and the rate of incidence (number of people with the disease) is consistent

24. Categorizing Diseases, History
Emerging
Diseases that have developed in recent history
Draw Graph
Re-Emerging
Diseases whose incidence (number of people with disease) had remained relatively stable, but then increased in the past 20 years