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The Cincinnati Zoo & Botanical Garden is taking proactive measures to keep its Asian elephant herd healthy. Vets and elephant keepers are working hard to protect the elephants from contracting  Elephant Endotheliotropic Herpesvirus – EEHV, or at least mitigating the severity if they do.  The zoological community have been working together with researchers to understand what can be done to combat this deadly virus.

In June of 2024, Sanjay and Kabir, the two young males who live at Elephant Trek, received plasma transfusions from one of the Zoo’s long-time elephant residents. The hope is that the plasma transfusions will boost the young elephants’ antibody response against the EEHV virus. In October 2024, the boys received a dose of an mRNA vaccine created by virologists at Baylor College of Medicine (BCM) to prevent EEHV. The Cincinnati Zoo is the third Zoo to vaccinate elephants against EEHV. The Houston Zoo and the Rosamond Gifford Zoo elephants also received this ground breaking vaccine.

The elephant keepers worked closely with Kabir and Sanjay to prepare them to receive the vaccination. Injection training is accomplished using positive reinforcement operant conditioning -just like training your dog to sit with treats!

The keepers start by teaching the boys a “target” behavior which is them leaning assorted body parts into the end of a pole.

• They moved this behavior to their hip and in small increments reinforce  the elephant every time their hip touches the pole
• Eventually the elephant knows to lean into the pole and even press their hip against it
• The pole is switched out with a paper clip and then eventually a blunt needle – all the while the elephant is reinforced to lean into the sharper objects and hold still. The elephant can choose to walk away from the training at any time!

The final step is training with a real needle with veterinary technicians until everyone feels comfortable with giving the vaccine!

Kabir and Sanjay are doing well post-vaccination. The mRNA vaccine’s development has involved extensive preclinical trials, with positive preliminary results indicating that it can induce antibodies against the virus with no adverse side effects. The vaccine is too new to have data back on success rates, but vets are cautiously optimistic that it will provide the elephants with the protection they need. The Cincinnati Zoo is collaborating by providing some of the first samples to further understanding of the immune response to the vaccine.

Plans also include making this vaccine available to other elephants, both in human care and then in the wild. This vaccine is anticipated to have a significant impact on the global Asian elephant population and lay the foundational work for a similar vaccine for African elephants as well.