Cause of Hansa's death: newly discovered herpes virus

Hansa, a 6 ½-year-old Asian elephant, the first born in captivity in Washington state, died from a previously undiscovered herpes virus, according to officials at the Woodland Park Zoo in Seattle.

The young elephant died June 8.

Zoo officials said today that the herpes virus that killed Hansa had never been seen before, even though two other herpes viruses were known to attack elephants. They were ruled out in Hansa's death.

Bruce Bohmke, the zoo's deputy director, said animal specialists from six institutions around the country were called in to try to diagnose what killed Hansa, and the answer came from Dr. Laura Richman, the world's leading expert on herpes viruses from the Smithsonian National Zoo.

Richman found the other two known elephant herpes viruses that have been documented to cause disease and death in wild and captive elephants.

The most closely related viruses to the one that infected Hansa are the Asian and African elephant endotheliotropic herpes viruses, known as EEHV. But that is not what killed Hansa, said Bohmke. For one thing, he said, she didn't have a swollen purple tongue, a herpes sign.

The virus that attacked Hansa attacked the lining of her blood vessels, but zoo officials don't know how she contracted it — nor whether any of the zoo's other elephants are at risk. But Bohmke said the other elephants appear healthy.

"Our effort is unraveling this puzzle and helping preserve the species," he said.

Kelly Helmick, lead veterinarian at the zoo, said studies of Hansa's body found lesions that were strongly suggestive of a herpes virus but didn't match the known herpes viruses.

Helmick said the known viruses are very deadly to elephants: Out of 18 cases in North American elephants reported since 1983, only three survived. Sometimes, she said, the elephants can die within a day, which made the case of Hansa so unusual because she showed only mild symptoms of reduced activity and appetite and seemed to be getting better before she died.

Zoo officials don't know how long Hansa had the virus, but said elephants under age 10 seem to be at a higher risk. Officials also don't know how the virus is passed but hope a test will become available.

Helmick said as soon as a test becomes available, the zoo will test the other elephants.

"It gratifies us to find out the cause," said Bohmke.

Curator Nancy Hawkes said finding the cause of Hansa's death gives the zoo some closure. "We're still deeply saddened by her death," she said, adding that the other elephants did acknowledge the loss of Hansa, but over the last three weeks have returned to their normal routines. "They do have a sense of her death," she said.

The zoo is now alerting the nation's elephant community to let them know about the new, still-unnamed herpes virus. The virus will eventually be named by viral taxonomists based on its genetic composition. It could take months to years to characterize and understand the disease.

After Hansa died, a necropsy ruled out numerous causes, such as sand colic — caused when an animal eats sand — obstruction from a foreign body, cancer and other Dozens of blood, tissue and organ samples were sent to labs across the state and country, including to the Washington Animal Disease Diagnostic Laboratory in Pullman and a lab at Michigan State University, as well as the Smithsonian.

As the zoo awaited news of what caused Hansa's death, zoo officials were disappointed to learn that an attempt to artificially inseminate Hansa's mother, Chai, was unsuccessful. Zoo officials said there was no plans to try again.

Susan Gilmore: 206-464-2054 or sgilmore@seattletimes.com