MELISSA BLOCK, HOST:
In New York City, special investigators are trying to track down people who have been in contact with Craig Spencer. He is the doctor who was hospitalized with Ebola last week. These investigators are known as disease detectives. Fred Mogul of member station WNYC spoke with some former detectives to find out what that job is like.
FRED MOGUL, BYLINE: When epidemiologists try to figure out how a disease is spreading, they work in teams. There are clinicians taking medical histories and parsing symptoms. There are number crunchers looking at data. And there are street detectives who go looking for contacts who might be infected.
DENIS NASH: They're just really good at finding people.
MOGUL: Denis Nash worked for the Centers for Disease Control and Prevention in the New York City Health Department on HIV and West Nile virus. He says these detectives can find almost anybody.
NASH: The person can say, you know, he's the light-skinned guy that hangs out on this corner with a freckle. And these disease intervention specialists will go out and find them and let them know that they may have been exposed, and that they need to be tested.
MOGUL: Nash is now with the City of New York School of Public Health with Dr. Lorna Thorpe, a tuberculosis specialist who also worked for the same federal and local agencies. Neither of them has any inside knowledge of the current investigation. But Thorpe says you can bet there's one strategy that trumps almost all others.
LORNA THORPE: You need to prioritize.
MOGUL: In TB investigations, Thorpe began by focusing on households, work and other contacts. She and her colleagues would start with the first or index patient and work their way out.
THORPE: We would literally draw concentric circles and prioritize accordingly because you can't expend all your human resources chasing everybody.
MOGUL: This happens every day for sexually transmitted diseases, tuberculosis, measles and other contagious illnesses. The searchers don't just swing into action when a headline-grabbing, super bug emerges. And Nash points out those other searches are still going on.
NASH: They can't stop doing TB surveillance and TB contact tracing because there's an Ebola outbreak going on. So it's all about trying to manage the whole, big picture which is really hard.
MOGUL: That being said this Ebola outbreak, at least in its current form, has some things going for it that make it easier to deal with than other outbreaks. First of all, Ebola is transmitted only by direct contact with bodily fluids. Nash says that's different than a lot of illnesses. Take the measles -
NASH: There have been examples of people - that not even being in the same room as a measles case - contracting the infection because it is so infectious and airborne. This is- this is so worlds away from that.
MOGUL: Secondly, you know who the index case is. That's often very difficult to figure out. And thirdly, Thorpe says Dr. Craig Spencer is pretty much the ideal index patient - an emergency physician knowledgeable about the disease he's been infected with who has been closely monitoring his own health.
THORPE: He came in early. The channel of communication between him, his employers, the health department and the medical facility seemed to be very efficient. And by evening time, we had people in quarantine, and the public had a deep knowledge about where he has been.
MOGUL: City officials say for now their focus is Spencer and his three close contacts. But it's not clear how many other people they're reaching out to - if only to gather phone numbers and e-mail. Thorpe says that would depend on available manpower, but typically it would be useful to know who are the people in the next concentric circle or two out from patient zero - just in case. For NPR News, I'm Fred Mogul in New York.
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