Nipah replicates fast in pigs. Passage to the lungs brings on a "terrible rasping cough," hemorrhaging and raging pneumonia, Field says. When the virus hits the brain, it kills quickly.
Environmental Change, Reservoirs of Disease
Humans get the virus from contact with the infected pigs. Flu-like symptoms can lead to encephalitis and catatonia. In 40 percent of cases the disease is fatal.
Nipah's emergence in 1998 may have derived from the interaction of man and nature, according to Daszak and researcher Jonathan Patz, director of the Program on Health Effects Of Global Environmental Change at Johns Hopkins University in Baltimore.
The researchers envisioned a scenario where an El Niño caused severe dry conditions. Fires that people had set to clear land burned out of control.
The smoke and haze stunted fruit development in the shrinking forests and forced the bats to migrate to places outside their usual habitat—like the forest outskirts, near neighboring pig farms.
On many farms, animal pens mingle with orchards. The researchers believe that fruit bats may have contaminated fruit that then fell into the pigpens.
"It's a really unnatural set of circumstances that has brought pigs in close contact with fruit bats," says Daszak. "The real tragedy is that Pteropus vampyrus is already endangered. Now these viruses make it even more unwanted."
"It's an extremely complex situation," says Patz. "These environmental landscape changes like logging and burning are global in scale, and have the potential to bring together people, wildlife and reservoirs of diseases in ways we couldn't anticipate."
Researchers understand little about the link between ecological disruption and disease. The field requires a multidisciplinary approach. The Consortium, for example, draws on information from ecologists, epidemiologists, physicians, public-health specialists, veterinarians, virologists and wildlife specialists.
"With increasing globalization there are more opportunities to spread an otherwise geographically contained disease," Morse says. "A good surveillance system is required to prevent such outbreaks."
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