Improving elephant health and welfare
Elephants face a raft of threats including a deadly virus. We have made huge strides toward a solution while enriching the lives of the elephants we care for
Asian elephants face a host of threats, from human-elephant conflict, habitat loss and elephant endotheliotropic herpesvirus (EEHV), a deadly virus carried by much of the species' population.
Conservation breeding programs afford an opportunity to boost elephant population numbers and to develop a better understanding of the needs of these complex and intelligent animals. Our science and keeper teams frequently collaborate on ways to improve the survival and welfare of elephants in human care and the wild.
Case study: pioneering diagnostic, treatment and vaccine science to combat EEHV
EEHV is a devastating disease which is latent in a large proportion of elephants, leading adult elephants to periodically shed the virus. Unlike their mature relatives, younger elephants have not built up an immunity to EEHV, and they can succumb quickly to the fast-acting virus, which causes death through hemorrhaging.
Once suspected to be an issue for elephants in human care, it is now known the disease is present in in situ populations.
EEHV deaths pose an existential risk to Endangered wild Asian elephants and insurance populations of elephants held in human care.
In response to these losses, we launched our fundraising campaign ‘Never Forget‘ to help educate our supporters on the effects of EEHV, and encourage them to support our scientific mission for an effective vaccine.
The Problem:
A decade ago, very little was known about EEHV. Time is of the essence when treating EEHV, but the virus was difficult to detect and diagnose until the onset of symptoms. Once symptoms develop, it is sometimes too late to treat the affected elephant.
In addition, unlike viruses like those that cause smallpox, flu and measels in humans, EEHV cannot be cultured in a lab. This means that it is not possible to introduce live-attenuated (weakened) or inactive (dead) versions of the virus to help elephants develop a swift and effective immune response.
The Solution:
In an incredible breakthrough, we have developed a vaccine in partnership with with University of Surrey (UoS) researchers and the Animal and Plant Health Agency (APHA). The vaccine induces an immune response to EEHV by targeting specific protein markers only produced when the virus replicates within a host animal's cells.
The vaccine allows us to educate an elephants’ immune system before they come into contact with the virus for the first time. This vaccine is the first of its kind and brings hope in the fight against EEHV globally. We announced the conclusions of a groundbreaking trial in autumn 2025.
This follows the pioneering development of an early warning system for EEHV. Our scientists work with UoS and APHA to test our elephants to detect EEHV using blood samples before clinical signs appear. Early detection enabled us to successfully treat Indali Hi-Way, who survived the onset of EEHV symptoms in 2019 through swift intervention.
While it is early days for the vaccine, and researchers are clear this is not a complete cure, this is a major step forward for the fight against EEHV.
Beyond our EEHV research, we work on multiple fronts to protect Asian elephants and enrich their lives. As part of the European Asian elephant conservation breeding programme, we constantly develop new and innovative ways to monitor the health, wellbeing and safety of both the elephants in our care and their wild cousins. Beyond the zoo, we support in situ elephant conservation.
At the zoo, we routinely collect faecal samples to assess the reproductive health of our herd, of which the samples can be used to detect a number of important health indicators, from pregnancy to predicting birth due dates, and regularly devise new ways to enrich the lives of the elephants in our care by encouraging natural foraging behaviours and adapting their habitat to encourage exploration and play.
Our researchers and keepers have developed a night-time behaviour monitoring routine which is used to detect changes in sleep patterns and social interactions. Interestingly, our data suggested herd members sleep for longer periods of time, when the social relationships between individuals are more positive.
Our scientists also developed social network analysis methods to assess herd compatibility and calculated daily activity levels and distance travelled by individual elephants, using two novel methods: a customised computerised app and a specially designed tracking device. They have also used heat maps (pictured) to monitor how elephants make use of their habitat.
Much of our research has been published and presented at worldwide conferences, to share the breadth of knowledge we’ve gained with our peers. This work includes studies of male elephant breeding cycles, stress hormone levels in female elephants, and identifying ways to detect biomarkers to help monitor health and facilitate diagnoses.
We’re incredibly proud to run the annual Resource Management and Husbandry Workshop, which is organised and hosted at Chester Zoo and is attended by leading zoo professionals from across the globe.
