1. Bacterial & viral Disease
Biology 20.3

2. Pathogen defined
Yellow fever virus
“A bacterium, virus, or other micro organism that can cause disease.”
Bacteria & viruses are some of the most common
Clostridium botulinum bacteria

3. Bacteria cause disease!
Pasteur’s “swan-neck flask” experiment
(7’)

4. Bacteria cause disease by…
Damaging host tissue
Ex: TB (tuberculosis – caused by Mycobacterium tuberculosis)
Releasing toxic chemicals that disrupt homeostasis
Ex: Botulism (Clostridium botulinum)
Hypotonia due to botulism

5. FYI – how people use botulism for “good”

6. Bacteria:
Most bacteria are harmless …beneficial, actually, as you know!
Bacterial infections are NOT fun & control measures are needed:
Physical removal: ex- washing hands; dislodges pathogens
Disinfectants: ex- chemicals that kill used in hospitals, bathrooms, kitchens, etc.
Food storage: ex- refrigerator with low temps helps slow growth
Food processing: ex- boiling, frying, steaming with high temps kill many bacteria
Sterilization by heat: ex- autoclaving medical instruments at temperatures over 100◦C prevents growth

7. Preventing disease with vaccines
In SIMPLE terms, how do they work?
(1.59’)
Why should we care?
(3.51’)
Herd immunity?
Is it enough?
Is it socially responsible?
We’ll come back to this…

8. 1. Interfere with bacterial cell wall synthesis 2
1. Interfere with bacterial cell wall synthesis 2. Disrupt bacterial protein synthesis at the ribosome  3. Inhibit function of enzymes involved in DNA synthesis by masquerading as a natural component of the synthetic machinery
Antibiotic action

9. How do viruses cause disease? …review;)
Poliomyelitis virus
Disrupting body’s normal homeostasis
Attack & destroy body’s cells (ex: polio & nerve cells=paralysis)
Force cells to change growth & development and potentially lead to cancers (ex: HPV & cervical epithelial cells= cervical cancer)
Human Paplilomavirus

10. Prevention w/ protection is the
Simple forms of protection can go a LOOONG way!
BREAK THE CYCLE!!

11. Vaccine controversy? NPR’s “All Things Considered” 7/14/11
(8.23’)

12. When prevention fails…
Antibiotics do NOT work for viral infections
AND taking an antibiotic for a virus can lead to antibiotic resistance (i.e. SUPERBUGS – yikes!)
Bacterial Infections
Viral Infections
Bladder infections
Bronchitis
Many wound and skin infections, such as staph
Colds
Severe sinus infections that last longer than 2 weeks
Flu (influenza)
Some ear infections
Most coughs
Strep throat
Most ear infections
Most sore throats
Source: Mayo Clinic, Antibiotics: Misuse puts you and others at risk. 2/4/12
Stomach flu (viral gastroenteritis)

13. Emerging Disease
Defined: “An unknown disease that appears in a population for the first time or a well-known disease that suddenly becomes harder to control”
Why such a threat?
Changes in lifestyle – isolation not as likely
High-speed travel – remember “Hot Zone”??
Commerce – increase shipping worldwide
Little to no resistance against them
Methods of control not developed yet

14. Evolution of disease
Replication/“gene shuffling” happens sooooooooo quickly (e.g. SUPERBUGS)
Viruses can switch host species (ex: AIDS)
Prions (ex: mad cow and other brain wasting diseases)

15. No matter what…best to stay educated;)