While the sexy aspect of the field is being a "virus hunter," like Dustin Hoffman's role in the 1995 film Outbreak, epidemiology in general is the study of health and illness within populations, says Dr. Michael Bell, chief of the special pathogens branch of the Center for Disease Control's epidemiology unit.
"If you talk about the number of sick people in a town versus in that town's nursing home, you're talking about hugely different things," says Bell, 40. "If you've got the same rate of pneumonia in both, you've got something seriously wrong in that town."
Epidemiologists range from people who never leave the sanctity of their offices, spending their time writing books on how best to design studies and calculations, to people living out of a suitcase and collecting data from the field. Bell falls into the latter category.
"This year two-thirds of my time has been spent on the road," he says. "I'd prefer that to be a little less, quite frankly. My suitcase is getting old."
While Bell has been sent around the world working to contain and prevent outbreaks like Severe Acute Respiratory Syndrome and monkey pox, epidemiologists also work with endemic viruses, such as measles and polio.
When faced with an outbreak, Bell's first job is to locate the populations involved. He tries to zero in on a subgroup and identify the risk factors involved that allowed that group to get sick in the first place. Those reasons can range anywhere from exposure to increased susceptibility because of immune deficiencies. After that, he hopes to answer the question, "What are we going to do about it?"
"Sometimes it's important to just describe a problem," he says. "But at the end of the day, it's more helpful to have an answer."
Epidemiology has an important future as populations expand rapidly and increased travel creates fewer barriers to disease transmission. More sudden outbreaks of severe illness are likely.
But understanding the demographics of populations has non-medical applications, too. Understanding a customer base for the purpose of product development might be as much in the future of an epidemiologist as SARS.
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