Zoo hippo dies: Found with COVID-19 in Vietnam

Zoo hippo dies: Found with COVID-19 in Vietnam

Scientists now say that a 20-year-old female hippopotamus in Hanoi, Vietnam, who passed away after a mysterious 17-day illness in 2021, may have died of COVID-19. She had shown signs of lethargy, depression and reduced appetite at her death, baffling veterinary staff.

On her death, tissue samples from the liver, spleen, lung, intestine and blood were collected by the National Institute of Veterinary Research (NIVR) in Hanoi for further diagnosis. Scientists from NIVR, the International Livestock Research Institute (ILRI) and Chungnam National University College of Veterinary Medicine successfully identified the cause of death to be the virus SARS-CoV-2.

SARS-CoV-2 infections in humans have spilt over into non-human hosts such as dogs, cats, zoo animals and farmed mink before. This is, however, the first study indicating a spillover transmission from humans to a hippopotamus.

The recent study, published in Emerging Infectious Diseases, highlights the urgent need to establish comprehensive monitoring systems for coronavirus in animals. The findings underscore hippos’ susceptibility to COVID-19 and further contribute to our knowledge of the epidemiology of coronavirus lineages to help track transmission pathways.

ILRI scientists currently work on several research activities linked to wildlife and their role as reservoirs for pathogens causing emerging infectious diseases and zoonoses. ILRI’s One Health strategy enables four thematic research areas, one of which addresses the early detection of pandemics and epidemics. In Vietnam, ILRI has worked closely with key partners, including NIVR and the Hanoi University of Public Health, since 2007.

Bui Nghia Vuong, a scientist at NIVR who led the study, said, ‘The source of the hippopotamus’ infection could not be determined’. But, he added, ‘the zoo was open to the public, and it may be that a visitor or staff member could have transmitted the virus to the hippo’.

While COVID-19 precautions have been put into place, the biosecurity measures were not sufficient to prevent the airborne transmission of the virus from humans to animals.

Hung Nguyen-Viet, co-leader of ILRI's Animal Human Health program and leader of the CGIAR Initiative on One Health said, ‘The COVID-19 pandemic has demonstrated that a global public health challenge also affected the lives of wildlife across the world who have been infected through human spillover transmission, whether it be in zoos, mink farms or forests.

'For this reason, it is important to safeguard the health and well-being of humans, animals and ecosystems by using a holistic approach to tackle infectious disease challenges.'

The study was funded by the CGIAR COVID-19 Hub and the CGIAR Initiative on One Health.

Learn more about ILRI's One Health activities

Photo credit: Hippos at the Mara River (ILRI/Ekta Patel)