What is the virus that has killed two Dublin Zoo elephants, with a third testing positive?

Q&A: An explainer on how and why a herpes virus can be lethal for elephants

Asha, Dublin Zoo's 17-year-old Asian elephant, has tested positive for EEHV. Photograph: Dublin Zoo
These are dark days at Dublin Zoo?

They are indeed. Two elephants in Dublin Zoo’s small herd have already died after contracting a lethal virus, and a third member of the herd has now tested positive although she has not yet manifested any symptoms.

And what exactly is the virus?

It is basically a herpes virus although one that causes internal bleeding in elephants and is fatal in 85 per cent of cases. It is called Elephant Endotheliotropic Herpesvirus (EEHV) and it has been circulating among elephant communities both in the wild and in captivity for decades. It only really came to public attention in this part of the world in recent days when elephants in Dublin Zoo started getting sick.

How sick?

Very sick. First there was eight-year-old Avani who died at the end of June and then there was seven-year-old Zinda who succumbed to the illness last weekend.

How many elephants are in the Dublin Zoo herd?

At the start of June the herd in the elephant habitat at the Kaziranga Forest Trail featured the five-tonne bull elephant Aung Bo, who moved to Ireland from Chester Zoo last month. He joined an all-female herd that was, at the time, made up of Dina (40 years), Asha (17), Samiya (10), Zinda (7) and Avani (8). The youngest two have now died.

How did the virus enter the herd in Dublin?

It has most likely been dormant for some time. Like the human herpes virus, it can stay in systems for decades and cause no harm.

So why the current outbreak?

There is not much knowledge about how the virus is transmitted and research is ongoing, including into why it manifests in some elephants but not others.

Third elephant at Dublin Zoo tests positive for deadly virusOpens in new window ]

What is being done to help the elephants in Dublin Zoo?

Asha, the 17-year-old who has tested positive, is being treated by the vets in Dublin Zoo and has access to special antiviral medication. Other than that, there is not much that can be done.

Are the elephants being isolated?

No. “We’re not isolating them – that wouldn’t work,” Dublin Zoo director Christoph Schwitzer said. “Elephants are a very social species and live in these matriarchal herds, and if we isolated one of the females that wouldn’t be very good for them.”

What is EEHV?

It is an unpredictable, fatal virus found in young Asian elephants. By the time there is a positive diagnosis or symptoms, it is often too late to do anything. According to Chester Zoo, which refers to the virus as a “global crisis”, EEHV is known to have caused deaths in at least eight countries. In fact, it is reported to be the most common cause of mortality in young Asian elephants in Europe and North America. The virus causes an acute haemorrhagic disease and can cause death within 24 hours.

Are outbreaks of it common?

The first case was reported in a Swiss elephant in 1990, and multiple case reports in captive and wild elephants have popped up in peer-reviewed literature since then, according to the journal Nature. The Smithsonian’s National Zoo and Conservation Biology Institute has said EEHV has been responsible for about half of the deaths of young elephants in zoos.

Does this pose a risk to humans?

No, EEHV only affects elephants, and in the aftermath of the recent Irish cases, Dublin Zoo was quick to point out there is no health risk to people.

And are there treatments?

According to the Smithsonian, existing antiviral treatments can suppress EEHV and elephants can recover if diagnosed and treated quickly – the success rate with antiviral therapy is about 40 per cent. Antiviral drugs have been used successfully in North America. There is no true cure for herpesviruses, generally, in animals or humans. According to the Smithsonian, the “treatment protocols continue to improve, and detection and treatment recommendations continue to evolve”. For more than a decade, co-operative research has been conducted to make improvements. But there is no vaccination because scientists have, so far, been unable to culture the virus to create one.

Are Asian elephants under significant threat in the wild?

They are. They are classified as endangered, with the main threats being habitat loss, human-elephant conflict over crops and poaching for their ivory tusks. It is estimated there are some 40,000 to 50,000 Asian elephants left in the wild.

In practical terms what happens if an elephant dies as a result of this virus?

The herd is given time to grieve in the first instance after which a postmortem is carried out and then the body is incinerated.

Will this outbreak cost Dublin Zoo a lot of money?

Dr Schwitzer says the zoo does not worry about the financial implications. “That is something that we don’t worry at all about, not only at the moment but not at all because these breeding programmes are designed in such a way that money doesn’t change hands when elephants change hands. It is expensive to bring animals in but we don’t worry about that at all – that is not on our minds at the moment.”