Fatal Elephant Virus Uncovered
At least 10 elephants living in U.S. zoos have died after being infected with a previously unknown form of the herpes virus, researchers say.
In a study published Friday in the journal Science, scientists at Johns Hopkins in Baltimore and at the National Zoo in Washington report that they have isolated and identified a lethal virus that apparently can jump from African elephants to Asian elephants.
"This is very troubling because these are endangered species and also because there may still be carrier African elephants in the zoos," Johns Hopkins researcher and study co-author Gary Hayward said in a statement.
The study found that seven of the 34 elephants born in U.S. and Canadian zoos between 1983 and 1996 died from the virus. Study of stored tissue shows that three animals earlier died of the virus, and two others may have died of the disease, researchers report.
Of the dead animals, all but two were Asian elephants.
There is some good news though. One elephant in Florida was cured of the infection when it was treated with Famciclovir, an antiviral drug developed to treat herpes in humans. "It's a great feeling," Dr. Laura Richman, a Johns Hopkins veterinary researcher, said of the discovery.
The medication also saved an Asian elephant at the Ringling Brothers Conservation Park in Sarasota, Fla.
Although they closely resemble each other, Asian and African elephants are distinctly different. The Asian elephant is the one most frequently bred in captivity and used as a working animal.
The elephant herpes is similar to a virus that causes cold sores and painful genital sores in humans.
The virus is commonly found in both wild and captive African elephants, in which it causes only minor problems. But it turns deadly when it jumps species to Asian elephants. The problem may have resulted from human meddling: Asian elephants never encounter African elephants in the wild but are frequently housed together in captivity.
The researchers said the herpes virus attacks the blood vessels of the heart, liver and other organs in Asian elephants and can kill in only a few days.
Hayward said it was hard to believe at first, as this herpes virus was so different from any others he had ever studied. "I said 'herpes viruses don't kill by hemorrhaging and they don't kill in five days'," he said. "It's actually a very different type of virus, but not related to any other kind of herpes virus that we know about," he added.
The National Zoo began looking for answers in 1995 when Kumari, a beloved 16-month-old female, became lethargic and stopped eating. Her neck and trunk swelled, and her tongue turned purple. She died five days after becoming sick.
Hayward thinks it makes sense that a virus would be deadly in one species of elephant but not the other. "Asian and African elephants are separated by three million years of evolution and their viruses are separated as well," he said.
No the team is checking to see how the virus is transmitted, and to if perhaps separating Asian and African elephants in zoos and circuses will help prevent infection. But that may no be easy. Like people, elephants develop friendships. "It's a big thing to do," said Richard Montali, senior pathologist at the National Zoo in Washington, who also took part in the investigation. "Once they are socialized it is hard to de-socialize them."