The Oklahoma City Zoo and Botanical Garden’s Zoo’s Commitment to EEHV Research and Prevention

In honor of August being Asian Elephant Awareness Month, the Oklahoma City Zoo and Botanical Garden is sharing about its commitment to elephant conservation through the story of Malee, the first Asian elephant born at the Zoo, who passed away unexpectedly on 1 October 2015, at the age of four years old after succumbing to the deadly elephant endotheliotropic herpesvirus (EEHV).

Following the loss of Malee, the Zoo’s Director of Veterinary Services, Dr. Jennifer D’Agostino, led an initiative to prevent future losses of the Zoo’s growing, multi-generational Asian elephant herd to EEHV. This is Malee’s story:

April 15, 2011 marked the culmination of years of planning and hard work with the birth of Malee, the first elephant calf born in the Zoo’s history. It will always be remembered as one of the best days of my career. October 1, 2015, was the worst day of my career. That is the day Malee succumbed to EEHV.

EEHV is a type of herpesvirus that can cause fatal hemorrhagic disease in young elephants. All elephants carry some form of the virus both in human care and in the wild, however, it remains latent. EEHV is a fast-moving virus with a 60 percent fatality rate. Thus, it is a major problem for establishing a self-sustaining population of elephants in human care. Additionally, it is a major concern for range countries, many of which do not have access to equipment and training needed to test for EEHV and treat affected elephants.

Prior to the birth of Malee, and throughout her short life, the Zoo’s veterinary and pachyderm teams had planned and prepared for EEHV. Blood samples were collected from the calf weekly for surveillance. The Zoo also had a detailed response plan and ran regular EEHV drills to stay prepared. Despite the extensive prevention measures taken to ensure a successful medical response should Malee be affected, Malee succumbed to the virus.

After Malee’s passing, the Zoo re-assessed its EEHV action plan and worked to determine areas for improvement for surveillance and response. The main objective became reducing the amount of time it took to receive surveillance test results.

Testing blood samples for EEHV is fairly specialized, and at the time, the Zoo utilized the services of the National Elephant Herpesvirus Laboratory at the Smithsonian National Zoo. This required shipping samples overnight to the lab, and results could take up to 48 hours to receive.

The EEHV disease is known to progress very quickly, and in Malee’s case, she passed within 12 hours of becoming ill. Because of this fast-moving virus, receiving test results as quickly as possible is crucial. With this important realization in mind, it was determined that the only way the Zoo could reduce test time was to begin initiating testing in-house at the Zoo’s Joan Kirkpatrick Animal Hospital.

EEHV testing is completed by polymerase chain reaction (PCR), which requires specialized equipment and staff training. Therefore, developing and running an EEHV PCR lab requires a significant organizational commitment. With the assistance of the National Elephant Herpesvirus Laboratory, EEHV Advisory Group and other experts in the field, we were able to develop a proposal and pitched the idea of developing an in-house EEHV lab to Zoo leadership.

When presented with the data collected surrounding the time of Malee’s death, it was evident that in-house EEHV PCR testing would be extremely beneficial when monitoring the activity of this virus within the Zoo’s Asian elephant herd.

Developing the lab and learning to run PCR was a steep learning curve for all staff involved. The Zoo’s registered veterinary technicians are responsible for processing samples and running tests. This isn’t a technique that is part of the standard veterinary technician training, which required Zoo veterinary technicians to learn a new skill.

One of the additional benefits to running in-house PCR is that we are able to run, not only blood samples on the calves, but also regular trunk wash samples from each member of our herd to monitor for intermittent, viral shedding. This means that if any of the adults are shedding the virus, we can increase our level of surveillance in the calves due to the increased potential for viral exposure. The Zoo is also able to run samples at any time, no matter the time of day, or whether it is a weekend or holiday, and avoid delays due to shipping constraints.

Having the ability to perform EEHV surveillance in-house has enabled the Zoo to study and learn about the epidemiology of the virus within its Asian elephant herd and advanced its efforts to continue to gain scientific knowledge about the disease.

More recently, Malee’s half-sister, two-year-old Kairavi, tested positive for EEHV1A. Thanks to the Zoo’s in-house testing and preparedness efforts, the elephant care team and veterinary teams were able to detect the presence of the virus early and start treatments immediately, which helped to save her life.

Because this was the first time Kai tested positive for EEHV, the animal and veterinary care teams took no risks and began administering antiviral treatments on July 29. Treatments and 24/7 monitoring continued for two weeks until her blood values improved and virus levels started to decline. The early detection of EEHV1A virus in Kai’s blood and aggressive medical treatment are the best-known way to help elephants overcome this naturally occurring virus.

For over two weeks, treatment ranged from antiviral medicines and fluids to stem cell treatments and whole blood/plasma transfusions. Kai received blood and plasma from her herd members, Asha, Chandra, Kandula, and Bamboo, who voluntarily participated in the process as a result of our elephant care team’s successful training program.

The veterinary and elephant care teams also worked with other Association of Zoos and Aquariums (AZA)-accredited elephant care facilities around the country to receive donations of plasma for Kai from compatible elephants, which were vital to her treatment.

Today, Kai is in the recovery phase. Because there isn’t a cure for EEHV, the virus continues to circulate in Kai’s blood but is decreasing. However, Kai’s treatments have helped her to build the antibodies needed to eliminate the virus from her blood and resist future recurrence of disease. Kai will continue to be observed and receive supportive treatment as she recovers.

The devastating loss of Malee inspired a whole-hearted mission to prevent any future losses of life due to EEHV at the Zoo. Reaching the recovery phase of Kai’s fight against EEHV after two difficult weeks of round-the-clock treatment is a testament to that mission. Malee’s memory will forever live on as part of this successful endeavor.

Increased surveillance and testing for EEHV has further enhanced the Zoo’s exceptional care and welfare program for its Asian elephants. The dedication of our vet team at the Zoo to the EEHV PCR lab is unwavering, and everyone is extremely proud of their efforts, as well as the commitment the Zoo has made to elephant conservation. To learn more about what the Zoo is doing for EEHV research and prevention, click here

The Zoo is home to a seven-member multi-generational breeding herd of Asian elephants with individuals ranging from 2 years old to 55 years old. The Zoo is anticipating the arrival of its fourth Asian elephant calf to mom Asha, 26, in February 2022.

Photo Credit: ©Oklahoma City Zoo and Botanical Garden

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