Mysterious disease kills indigenous tribe members in Venezuela

A mysterious illness has killed at least thirty-eight remote area of the South American rain forest in recent months. Most, if not all, of the dead are Warao, an indigenous tribe native to north-eastern Venezuela. The nation’s health authorities are just beginning to tackle the disease, while early indications may point to bat-transmitted rabies, according to The New York Times. Without epidemiological studies and confirmatory lab work, however, that conclusion remains speculative, says Charles Rupprecht, a tropical disease expert at the U.S. Centers for Disease Control and Prevention in Atlanta. “One would hope that at least there is a proper field investigation going on,” he told Ewen Callaway of New Scientist. Rabies outbreaks, often spread by infected vampire bats, are not unheard of in South America, says Hervé Bourhy, a virologist at the Pasteur Institute in Paris, France. Yet they account for a fraction of the 50,000 to 60,000 rabies deaths worldwide each year, most of them in Asia and Africa and spread by dogs, he says.

Vampire bats prefer to lunch on cattle and other livestock, but protective nets often keep the bats away from these animals. In search of a blood meal, many turn to humans sleeping out of doors or in open-air houses. “It’s probably a problem of poverty in the sense that, in fact, most of the people that are dying are those that are living outside and bitten during their sleep,” Hervé says. For those unfortunate enough to contract rabies in a remote area, “it is a death sentence”, says virologist Charles Calisher of Colorado State University in Fort Collins. Vaccines offer some hope after exposure, but are often unavailable. “People out in the middle of nowhere are not going to be vaccinated with an expensive vaccine. It’s 150 bucks a shot and there’s not much around,” he says.

Rupprecht, who has previously trapped vampire bats in South American jungles, still is not sure that the disease affecting the Warao is indeed rabies. Many of the victims have lived longer than is typical for rabies, and previous vampire bat infections have often involved ecological changes brought on by logging, mining and damming. Another emerging disease could underlie the outbreak, he says. “There’s a whole suite of things that can be found in the American tropics.” Moreover, the current outbreak may represent a baseline level of infection and nothing extraordinary, he says. “The vast majority or people who die of rabies in these situations are never counted.”

Two American researchers living among the Warao, anthropologist Charles Briggs of the University of California, Berkeley, and his wife medical researcher Clara Mantini-Briggs, have called on Venezuela’s government to tackle the disease. “The authorities must investigate this outbreak with extreme urgency,” Mantini-Briggs told The New York Times.