Elephant Herpesvirus Q and A

What is the elephant herpesvirus (EEHV)?

The elephant endotheliotropic herpesvirus was first documented in 1995 by researchers at Smithsonian National Zoo and Johns Hopkins School of Medicine.

What is known about EEHV?

EEHV is believed to be an ancient virus that has co-evolved with elephants over tens of millions of years, just as human herpesviruses have co-evolved with humans. Herpesviruses are species-specific but share common features. Once inside a host, whether human or animal, the virus can go into a latent or hidden phase after causing only mild symptoms or no signs of disease at all.

Both Asian and African elephants carry the herpesvirus, but it is lethal for a much larger proportion of the Asian elephant population than for African elephants. African elephants may have developed a natural resistance to the virus.

Researchers do not know where EEHV hides in its latent phase or how the virus is transmitted from one animal to another, which is the current belief. Neither is it known why some animals develop immunity to the virus while other animals die from EEHV infection.

Does EEHV affect elephants in zoos only?

No, every elephant worldwide – in the wild, in zoos and in private hands – potentially has one or more herpesvirus. EEHV has been identified as the cause of death in wild elephants in Asia.

Are some elephants more susceptible to EEHV? Are there "hotspots" for the virus?

A: Many animals and humans carry herpesviruses throughout their lives and never become ill. It is not known why some animals become ill and others don't. It is not about who has the virus, but who gets ill and when. There are a number of mature Asian elephants who have high levels of antibodies, as measured by titers, which researchers believe indicates that they have survived a past incidence of herpesvirus and developed an immunity to it.

Why is it important to continue breeding elephants in zoos?

Elephants in zoos are ambassadors for their wild cousins. A Harris Interactive poll found that 94 % of the people surveyed believe that seeing elephants in zoos fosters a greater appreciation of these majestic and intelligent animals and encourages people to learn more about them.

Elephant breeding at zoos accredited by the AZA, such as the Houston Zoo, provides critical support for elephant conservation. Many research questions can be answered through scientific inquiry utilizing elephants in the care of humans.

The Asian elephant in the wild is currently classified by the International Union for Conservation of Nature as endangered because 50 percent of the population is currently lost each generation in the wild. It is estimated that only 35,000 Asian elephants remain in the wild.

Given an uncertain future in the wild, zoo-based management programs are becoming increasingly important to the survival of Asian elephants. Zoos play an important role in the conservation and study of elephants, expanding the body of scientific knowledge that is almost impossible to collect from wild populations.