#epidemiology notes

19th Century Theories -- contagion theory -- supernatural theory -- personal behavior theory -- miasma theory

20th Century Theories -- germ theory -- lifestyle theory -- environmental theory -- multi-causal theory

-- 15% of infected people have recurring symptoms in a 6 to 9 month period

-- occurs in epidemics

-- during epidemics, number of US cases reached 35,000

-- case number decreased in the early 1990s when a vaccine began to be used

-- 1/3 of Americans have hepatitis A at some point in their life