Bacterial & viral Disease Biology 20.3

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

Bacteria cause disease! Pasteur’s “swan-neck flask” experiment http://education-portal.com/academy/lesson/the-germ-theory-of-disease-definition-louis-pasteur.html#lesson (7’)

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

FYI – how people use botulism for “good”

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

Preventing disease with vaccines In SIMPLE terms, how do they work? https://www.youtube.com/watch?v=SduMbjW2V9A (1.59’) Why should we care? https://www.youtube.com/watch?v=JZvpF6gaGH4 (3.51’) Herd immunity? Is it enough? Is it socially responsible? We’ll come back to this…

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

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

Prevention w/ protection is the Simple forms of protection can go a LOOONG way! http://abcnews.go.com/WNT/video/best-sneeze-22258478 BREAK THE CYCLE!!

Vaccine controversy? NPR’s “All Things Considered” 7/14/11 http://www.npr.org/2011/01/09/132735944/as-the-facts-win-out-vaccinations-may-too (8.23’)

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)

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

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)

No matter what…best to stay educated;)