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Putting It Together

Take another look at our epidemic curve. Note that the number of cases rises very quickly, peaks, and then begins to fall off. Also bear in mind that the average incubation period is about 28 days, with a range of 15 to 50 days. So far all of the cases are contained within a single incubation period.

Then, put this together with a) what you already know about the biology and the epidemiology of hepatitis A and b) the ages of the cases on the line listing. We know that hepatitis A is transmitted via the fecal-oral route , that is, virus particles in the stool of an infected person somehow get ingested. This can occur as a result of travel to a developing country with suboptimal sanitation, sexual contact (especially MSM), in a child day-care setting where fecal contamination and children putting things into their mouths are common elements, or when food is contaminated by an infected food handler.