1. Unit 6--Microbiology Chapter 19 continued

2. Viruses Hard to classify as living, because: Contain only a protein coat (capsid) and a nucleic acid core (DNA or RNA) –May also contain a protein envelope that protects virus from host organism recognition Reproduces only by infecting a host cell

3. Virologists consider viruses to be acellular organisms. Bacteriophages: viruses that infect bacterial cells Viroids: naked RNA Prions: naked protein (protein infectious particles)

4. Viral Morphology (structural shape)

5. Lytic cycle

6. Lysogenic cycle: may produce latent (recurring) infections

8. Viruses leaving cell

9. Lytic vs lysogenic Viral infections that are lytic, destroy host cells quickly (& move on…) –Ex: Ebola, Chicken Pox Lysogenic infections destroy host cells slowly or not at all. Lysogenic viruses undergo lytic cycle when host cell becomes stressed (may be recurring) –Ex: HIV, herpes

10. Lytic or Lysogenic?

12. Proportional size of bacterium to virus

14. Epidemiology The study of diseases within a population Center for Disease Control Headquarters: Atlanta, Georgia (US) World Health Organization Headquarters: London, England

15. Pandemic A global infection Ex: 1918 flu pandemic killed 25 million+ Bubonic plague (black death) killed 24 million in 1300s Tuberculosis (white death) killed 2 billion in last 2 centuries

16. Outbreak A sudden & unexpected increase in numbers of infected individuals Ex: West Nile Virus, Ebola, etc

17. Epidemic A sudden increase in the occurrence of disease above what was expected Ex: Swine flu (’76), Polio (’50s), Legionnaires disease(’76)

18. Endemic A steady, low-level frequency that happens at regular intervals Ex: Common Cold, chicken pox, etc

19. Morbidity rate # of new disease in a population # of individuals in the population Mortality rate Mortality rate # of deaths caused by disease in a population # of individuals in the population How might these numbers be useful? How might these numbers be useful?

20. Emerging infectious diseases Medical students today are concerned that people misuse antibiotics and that Doctors over-prescribe antibiotics. How can these 2 factors contribute to infectious disease emerging once again? Ex: Tuberculosis, Smallpox, etc

21. Epidemiological Study Materials: –numbered containers for each student (test tubes or small containers) –2-3 drop of dilute sodium hydroxide in one –Distilled water in all the others –Paper numbered 1-5 to keep record of “contacts” –Penolpthalein (1 drop in each beaker to test after all contacts are complete)

22. Epidemiological study Procedure: –Only one container is contaminated with the fluids from an infected individual –Select one container to represent your fluids –You need to exchange fluids with 5 individuals. Keep track of these people, in order of sharing –Wait to be tested

23. Epidemiological study Challenge: –The entire class must work together in a cooperative group… –You have to tell me who the original carrier was. –You have only 2 guesses (asking me privately counts as a guess) –If you guess correctly, you win!! –(if you do not take part in the problem-solving, you will receive a zero for today)