The Cincinnati Zoo will retest its elephants for a potentially deadly virus following the deaths of two African elephants at the Indianapolis Zoo in March.
The elephants, a 6-year-old named "Nyah" and an 8-year-old named "Kalina," died on March 19 and March 26 from hemorrhagic disease caused by elephant endotheliotropic herpesvirus (EEHV).
The Cincinnati Zoo says its four Asian elephants "are not in a high-risk category because they're adults" and "EEHV most commonly affects younger elephants."
Cincinnati's elephants have been tested in the past and showed very low levels, says Christina Gorsuch, the zoo's curator of mammals. "We recently spoke about testing them again as well as 'Sabu' (the zoo's male elephant) in order to get updated baseline information in case they get sick or we have a calf. The test will let us know what strain they have and their levels."
A spokeswoman confirms the zoo plans to retest the animals in the next few months.
EEHV was discovered in 1995 by researchers at the Smithsonian's National Zoo in Washington, D.C. They are part of the herpesvirus family and there are 14 known strains affecting elephants. Like herpesvirus in humans, elephants can carry the dormant disease and never have a problem.
"Most animal species on this planet - everything from fish and frogs to mammals, bears, people, monkeys - we all have several herpesvirus that are endemic or infect us. Sometimes there are multiple varieties," says Paul Ling, Ph.D., associate professor at Baylor College of Medicine in Houston, Texas, who studies EEHV.
"EEHV is the most significant cause of death among captive juvenile Asian elephants," Ling says. The National Zoo reports it is "responsible for about half of the deaths of young elephants in zoos."
EEHV affects captive and wild populations.
"Current research indicates that the elephant-specific herpesvirus may have been in elephant populations for tens of millions of years, just as human herpesviruses have been in human populations," according to the National Elephant Herpesvirus Laboratory at the National Zoo. "Since this is a naturally occurring disease, every elephant in the wild and in human care probably carries one or more forms of elephant herpesvirus within them."
Some of the most well-known herpesviruses in humans are the strains that cause chickenpox in children or shingles in adults and the Epstein-Barr virus which causes mononucleosis. Elephant strains cannot be passed to humans.
"The fact that elephants have herpesviruses that naturally infect them and the fact that herpesviruses are known sometimes to cause diseases in animals they naturally effect, none of that is surprising," according to Ling. "The fact that it's killing these young, juvenile Asian elephants - and in the case of Indianapolis juvenile African elephants - seems a little bit unusual to us and we don't really understand why."
Researchers are studying the disease to find those answers and Ling's lab is trying to develop a vaccine as there currently is none nor a cure.
They also want to know more about how and why it's becoming a problem in African elephants. It's been a known issue for Asian elephants.
The Cincinnati Zoo in June 2018 announced plans to build a new elephant yard as part of a capital campaign to expand the facility and give animals "more home to roam." The intent is to expand the zoo's elephants to8-10, a full herd.