a. Basic Chemistry
A. Viral molecules
B. Drug intervention processes
b. Cells---viruses work in cells
A. Cell biology
B. Virus replication
C. Requires knowledge of molecular genetics
c. Immunology
A. HIV virus attacks the immune system
B. Immune response
d. Ways of fighting infections beyond the immune system
A. Anti-viral drugs
B. Vaccines
e. Pathogenesis
A. How viruses make you sick
B. Epidemiology

a. Some definitions
A. An epidemic is an infectious disease that spreads widely through a population at a given point in time.
B. Epidemiology is the study of the spread and patterns of spread of diseases within populations along with the study of how diseases can be combated in lifestyle and community patterns.
C. A pandemic is a new infection (like flu) that spreads to affect the whole world.
b. Epidemics have had a huge impact on the course of human history.
A. New populations exposed to unfamiliar viruses get sick in huge numbers.
B. Examples:
1. Cortez and the Aztecs
2. Black Death in Europe where 1/3 of the world's population died between 1346 and 1350
3. Malaria
4. 1918 influenza epidemic
5. Decimation of Roman and Athenian populations at various points in time
6. AIDS

a. Microorganisms cause infections; types of microorganisms:
A. Viruses---mononucleosis (EBV, CMV viruses), Ebola, West Nile virus (mosquito borne), foot and mouth disease, chicken pox
B. Bacteria (TB)
C. Parasites (malaria)
1. unicellular
2. multicellular
D. Fungi
E. Some diseases like hepatitis and meningitis are really symptomatic conditions in which different versions of the disease are caused by different infectious agents
F. We want to be mindful of the "vectors" by which infectious agents are conveyed to new hosts.
b. Spread of viral disease
A. Some viruses (like chicken pox) develop lifelong relationships with your body---shingles is the return of the chicken pox virus to active status.
B. Most viruses (like cold and flu) are eliminated from your body once the infection is resolved. Thereafter you're immune to THAT virus, although there often are many versions (as with cold and flu).
C. Viral diseases spread of there are available new susceptible individuals.
1. Viruses can only spread if they are not too deadly; if they are, they kill off the population of susceptibles before the disease can be widely spread.
2. Although AIDS is very deadly, it acts slowly and hence can be widely spread.
3. Even when a virus is very deadly, a population may build up immunity over the course of generations
a. few resistant individuals usually exist, they survive, and as they reproduce their immunity is spread through the population.
b. This was the case with myxomatosis, a rabbit plague introduced in Australia
D. Methods of virus transmission
1. airborne---settles into the respiratory tract
2. animal/insect vector---bites break the skin and transmit the virus (skin usually must be broken for one to be susceptible to infection); urine and feces of animals spread virus
3. blood product sharing (needles, insect bites)
4. sexual transmission (via the urogenital tract)
5. oral/fecal transmission (food; poor hand washing)
6. skin to skin contact (normally requires a break in skin to happen)

a. Example: Bolivian hemorrhagic fever in 1963 which wiped out some villages and infected scientists sent to investigate
A. As often happens, there was social change that upset the traditional protections against disease spread
B. As population expanded, traditional grasslands were cleared and farmed.
C. The local field mouse population expanded and was put in contact with people.
D. They carried the virus which got into the food chain and affected people in the villages.
b. In general, the "new" viral diseases have always been there, but they have become available to susceptible populations because social changes have occurred: lands are opened, people travel, etc.
c. In the 1960s through the 1980s, we pretty much thought we had infectious diseases licked. AIDS is an emerging virus and its appearance caused scientists to realize that new viruses were a real threat.
d. Emerging infections appear because of:
A. Farming practices (like having ducks and pigs clear rice fields in China which has a role in the emergence of new strains of flu)
B. Deforestation
C. Travel
D. Importing animals for research or other purposes
E. Global warming (spreads the range of insects; changes the syncronicity of reproductive patterns of animals and their predators)
F. Mutation (seems to be a minor factor)
G. Research errors
H. Urbanization
I. Medical techniques (like immunosuppression or viruses resident in transplanted tissues.)