Cause of young elephants' deaths identified as herpes

Elephants spread the infection when housed together in zoos

WASHINGTON (CNN) -- The cause of a mysterious disease that has been killing young elephants in zoos and breeding centers across North America has been identified as a herpes virus.

Two slightly different versions of the virus -- a distant relative of the viruses that cause chickenpox and cold sores in humans -- are believed responsible. One virus is found among African elephants, the other among Asian elephants.

Researchers now think the viruses turn fatal when African elephants transmit the virus to Asian elephants and vice versa.

"The herpes virus that I found in the Asian elephants that have died is the same virus that is in African elephants. But it doesn't cause any disease in them," says Laura Richman of the Johns Hopkins University School of Medicine.

Researchers from Johns Hopkins and the National Zoo in Washington reported their findings in the latest issue of the journal Science.

Dr. Bill Lindsay examines Benjamin's tongue for signs of herpes

The herpes infections have affected about a third of the elephants born in captivity since 1983 at zoos and breeding centers in North America. Ten elephants have died.

Unlike common herpes simplex viruses, which attack the skin and lie latent in nerve cells, the herpes strains affecting elephants attack endothelial cells, which line blood vessels, the heart and other organs.

Some of the baby elephants died of heart attacks when their blood vessels collapsed. The elephants' tongues swelled and turned purple, signs of internal bleeding and heart failure.

In the wild, African elephants live far away from their Asian counterparts. Researchers surmise that they started infecting each other when housed together in zoos. Similar infections have been found in elephants in Switzerland and Germany.

Two young elephants were saved when they were given famciclovir, used to treat genital herpes and shingles in people.

Researchers are trying to figure out how the elephants transmit the virus to each other. Richman believes that until the path of transmission is understood, African and Asian elephant mothers and babies should be housed apart.

Correspondent Ann Kellan and Reuters contributed to this report.

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