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Disease Forecasting

Disease Forecasting by Jim Duffy, Page 2

Wolfe and University of Yaoundé doctoral student Cyrille Djoko are now combing the samples for the lentiviruses that include the simian immunodeficiency viruses (SIV), the source in humans of HIV-1 and HIV-2. Wolfe sees no reason to expect anything different in this class, so look for him to report soon that some of his hunters are carrying SIVs.

"And all of these discoveries have come out of those first 1,000 samples," Wolfe says. "We've only looked at 20 or 30 percent of our existing collection."

Wolfe is now aiming to develop a longitudinal portrait of the workings of zoonosis in the Central African jungle. In addition to donating their own blood, hunters are gathering filter-paper samples from animals they kill.

One of Wolfe and Burke's doctoral students, David Sintasath, is analyzing these for prevalence data on retro-viruses among nonhuman primates. (Another, Amy Peterson, is screening for similar numbers on primate malarias.)

Wolfe is well-positioned, then, to boost basic knowledge about primate viruses and their movement into humans. He's hopeful that his work will shed light on lingering mysteries surrounding the precise origins of the AIDS epidemic. And he has a chance, too, at an exciting scientific first: capturing the "actual moment" of a virus transmission via samples from both hunted and hunter.

"That's not going to be easy," he says, "but it's something we have the potential to do."

Smallpox's Lethal Cousin

But Wolfe is not waiting until all this basic science is sorted out before pursuing a future in which science can see the next AIDS coming in enough time to make a monumental difference. It's the driving force behind a just-off-the-ground collaboration with Anne Rimoin, an assistant professor of Epidemiology at the UCLA School of Public Health and adjunct assistant professor in International Health at the Bloomberg School.

Rimoin, too, studies African hunters. Her hunters are even more isolated than Wolfe's, as she spends half of each year in a stretch of the Democratic Republic of Congo (DRC, formerly Zaire) accessible only by cargo plane.

"Basically, I'm the only person crazy enough to go out there," says Rimoin, PhD '03. Her research centers on monkeypox. The relative of smallpox was discovered in 1958 in laboratory monkeys, though its real animal reservoir remains unknown. It was first observed in humans in 1970, at the tail end of the smallpox eradication campaign. While rarely fatal in the developed world, according to the Centers for Disease Control (CDC), monkeypox can kill as many as 10 percent of its victims in less developed countries.

Most experts who looked at monkeypox early on in places like DRC weren't overly concerned. They saw a rural disease in countries that were urbanizing. They saw a hunter's disease in countries increasingly using domesticated livestock.

But neither trend survived the onset in the late 1990s of the Second Congo War, which claimed millions of lives and is considered the world's deadliest conflict since World War II. The military forces that occupied the area where Rimoin now works slaughtered livestock, burned fields and brutalized the local populace, driving them into the rainforest. "People are now exclusively reliant on bushmeat," reports Rimoin.

Big picture, eye-in-the-sky technology now chases epidemiological mysteries: Satellite imagery of the southwestern U.S. uncovered a chain of natural events that culminated in a 1993 hantavirus outbreak.

When reports of monkeypox cases began filtering out of the jungle, Rimoin got in touch with DRC's public health officials and volunteered to investigate. The disease had always been regarded as one that appeared only in brief, sporadic outbreaks, but what Rimoin found was something else: endemic monkeypox.

Her research is an attempt to sort through the biological, ecological, epidemiological and sociological factors behind this surprise. How much of the monkeypox that she is finding can be attributed to increased exposures? Is its resurgence related to the disappearance of smallpox, an ecological competitor? Why does the disease predominantly strike young adolescents?

"There are lots of reasons why this is a very, very interesting disease," Rimoin says.

In her collaboration with Wolfe, Rimoin will gather information on Wolfe's retroviruses from her hunters, while Wolfe will bring Rimoin's acute disease surveillance techniques to Cameroon.

But their goal is bigger than this simple swap of information and techniques. They're out to create a pair of pilot "hunter networks" to serve as sentinel stations that could warn of the emergence of new viral disease.

Key to the project will be building a strong relationship with hunting communities. "In the past, they've been considered the enemy of conservation," Rimoin says. "But we're looking at them as an untapped resource. We're not just going to engage them as study participants. We'll also work with them as active collaborators."

Hunters will monitor the jungle for animal die-offs, often a precursor to human disease. They will alert researchers to new and virulent human disease events. In addition, researchers and hunters will look together at hunting behaviors such as butchering, with an eye toward developing techniques that protect hunters' health.

These networks are prototypes for the sort of sentinel disease surveillance stations that may someday operate in disease hotspots around the world, sounding alerts to the appearance of new pathogens. To Wolfe, this is a critical next step for public health.

"In a hundred years," he says, "I [don't want] people to look back at the way we do things today and say, 'They went chasing after diseases too late. They didn't pay attention until the diseases were global.' That's not doing it the right way."

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