Veterinarians at Springfield's Dickerson Park Zoo are studying the death of Nisha, she’s the 16-month old elephant that died yesterday morning at the zoo.

Officials say she was treated for a herpes virus that usually kills elephants in just five days. Zoo officials say Nisha received aggressive treatment and good care, but now one California-based animal group called In Defense of Animals, is calling for the zoo to stop breeding. The group claims that the facility is contaminated.

“It is unconscionable for the zoo to subject another young elephant to this fatal disease and to put its mother through the anguish of watching their baby die a terrible death,” said Suzanne Roy from IDA during a phone interview.

The Dickerson Park Zoo stands behind its treatment of the animals and says it follows national guidelines to breed elephants. “The herpes virus is not something that is completely to zoos,” says Mike Crocker, Director of Dickerson Park Zoo. “I think we see a little bit more of it in zoos because we intensively manage the animals. They make observations on them all day but long, but it has been documented in recent years in the wild elephants.”

Dickerson Park Zoo officials also say the animal group is extreme, saying it has no credible credentials to comment on elephant care.

In Defense of Animals spokespeople say the zoo may have helped spread the fatal infection that killed Nisha to at least 10 other zoos.