Case study – Advances in elephant conservation

After five years of dedicated research with our partners at the University of Surrey, in 2021 we began a pilot study of a new vaccine for Elephant Endotheliotropic Herpes Virus (EEHV). The vaccine aims to ‘educate’ the immune system of the Asian elephant to fight this deadly virus – it has previously affected our herd and is posing a threat to this endangered species globally, both in zoos and the wild. It is the first vaccine of its kind to enter a pilot study phase anywhere in the world.

The initial study is being carried out on our elephant herd here at Chester Zoo, but we are also supported by other major conservation zoos that hold Asian elephants in the UK and Ireland.

EEHV is a major threat to the long-term survival of the Asian elephant, of which just 40,000 now remain. Reports of wild elephant fatalities at the hands of the disease are on the rise in India, Nepal, Myanmar and Thailand, while cases have been recorded in five further countries across its native range, as well as in zoo conservation breeding programmes worldwide. Controlling this disease is becoming an important part of efforts to reverse the decline of Asian elephants (target 2 of our Conservation Masterplan).

Vaccines work by giving the immune system a practice run at fighting a disease in a safe environment, equipping its ‘long-term memory’ with the knowledge of how to fight the real infection. Part of our approach includes inserting a small piece of the DNA (the genetic code) from the EEHV into a benign virus that doesn’t harm the elephant. This tiny slice of DNA relates to the external markers that viruses carry, and that animal cells use to identify the viruses and signal to their immune system. After years of painstaking research, we have identified candidate parts of EEHV DNA to use safely for this process. When injected into an elephant, the immune system mounts a response and, in the process, forms a ‘memory’ of what EEHV looks like – setting up an advanced alert system for when real EEHV arrives.

Although we still have some way to go, this is an important milestone for elephant conservation. The initial results from the pilot study are encouraging, not least because the vaccine appears to stimulate an immune response. These are still early days, however, and we are yet to prove the vaccine will prevent young elephants from dying of EEHV. It will be several months until the first stage of our work to select the best candidate vaccine and determine optimal dosages and frequencies is complete. Then, if successful, trials in zoos and in the field will need to take place to fully ascertain its efficacy at preventing disease.

Our EEHV work is part of our wider programme designed to reverse the decline of Asian elephants by reducing the threats they face (target 2). As well as EEHV, elephants in the wild face increased habitat degradation and attacks from people whose lives and livelihoods are affected when they come into contact with them.

Our longstanding work on this in Assam – where we are in partnership with the Wildlife Trust of India to support communities living alongside elephants in the Manas forest landscape – forms one of our conservation landscape programmes aimed at achieving target 3 of our Conservation Masterplan. In 2021, work with 20 villages in this landscape resulted in a 100% reduction in human deaths due to human–elephant conflict and almost no elephant mortalities due to retaliation, a 95% reduction in crop loss, and 80% reduction in commercial fuelwood extraction in the forest habitat bordering the villages. We now aim to scale this successful approach up across the whole 9,600ha landscape.

Sustainable Development Goals:

The EEHV and fieldwork both support SDG 15 (Life on Land) and our landscape work in Assam also supports SDGs 1 (No Poverty), 2 (Zero Hunger) and 8 (Decent Work and Economic Growth) through support for sustainable livelihoods.

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