Elephant Endotheliotropic Herpes Virus (EEHV)
Herpes viruses are thought to occur in all species, and there are at least 19 different herpes viruses that affect elephants. All adult Asian and African elephants in zoos and in the wild are infected with endotheliotropic-type herpes viruses. Since herpes viruses cause life-long infection, this means every adult elephant has been exposed, infected, and developed protective immunity to the effects of the virus. In contrast, juvenile elephants need to develop immunity and may become compromised by EEHV strains throughout their early lives.
EEHV-Hemorrhagic Disease (EEHV-HD) can occur when EEHV loads overcome immunity, resulting in destruction of blood vessels. With EEHV-HD, shock, organ failure, and death can occur in 12-72 hours. Young elephants are most sensitive to EEHV-HD as antibodies passed from mom are decreasing and they are developing their own immunity. Without early detection and aggressive treatment, mortality rates are near 85% for those that develop EEHV-HD, thus making EEHV-HD the leading cause of death in Asian elephants.
At the Cincinnati Zoo & Botanical Garden, we will be managing a multi-generational breeding herd of Asian elephants similar to groups found in nature. This is necessary for exceptional animal welfare and allows elephants to participate in natural behaviors. This also means that the Zoo will house young animals at risk for EEHV-HD. To provide early detection of disease and to look for shedding from adult animals, the Cincinnati Zoo developed an EEHV PCR lab to screen blood and trunk wash samples for the presence of EEHV. Virus can be detected in blood up to 10 days before symptoms, allowing for earlier treatment and better outcomes. Trunk washes can show which strains are being shed and cue veterinary and keeper staff to which elephants are at greatest risk. Advances in diagnosis and treatment have improved survival rates but once a young elephant is sick with EEHV-HD, mortality rates are still high at about 65% with treatment.
A comprehensive monitoring and treatment protocol has been developed by zoo veterinarians. Combined with effective training and sample collection by animal husbandry and veterinary staff, this monitoring should allow for early detection and treatment of elephants, and hopefully result in better survival if/when EEHV-HD occurs at the Cincinnati Zoo.
Furthermore, through the Elephant Behind-the-scenes tours, the Zoo is contributing funds for development of a vaccine to help with EEHV infections. The Elephant and Behind-the-Scenes teams are directly contributing to elephant conservation through these efforts.
For more information, please visit EEHVinfo.org.