SARS-CoV-2 in a Hanoi Hippopotamus

By: Austin Weynand, MHS

SARS-CoV-2, the culprit behind a years-long pandemic that infected millions, is often overlooked for its cross-species potential. A flexible agent in human-to-animal transmission, the coronavirus has caused disease in pets such as dogs and ferrets, in captive animals such as big cats and primates, in mink, and in wildlife.² Recently, hippopotamuses have been added to the growing list of wildlife species. Instances of hippo infection with SARS-CoV-2 have been found in both in Antwerp, Belgium³ and Hanoi, Vietnam. The latter discovery was described in Emerging Infectious Diseases by UTMB One Health collaborators Drs. Bui Nghia Vuong and Tung Duy Dao of Vietnam’s National Institute of Veterinary Research.

As scientists in the Virology Department, Drs. Bui and Dao work on multiple diverse research projects. Their work blends the fields of epidemiology and veterinary medicine, an important nexus for One Health. One partnership of theirs is with Hong Kong University, with whom they conduct surveillance for swine influenza, an ongoing project that requires performing PCR on suspect samples and subtyping those that come back positive. With Dr. Gray’s One Health research group at UTMB, they’re surveilling live bird markets for avian flu in 3 Vietnamese provinces along the border with China. Vietnam’s capital city, Hanoi, is also appraised for virus; Dr. Dao shares that 10 to 20,000 poultry are sold in a day. After collection of avian samples in Vietnam, sequencing and characterization of the influenza A viruses they identify are being performed at UTMB’s One Health laboratory.

Vuong and Tung are also on-call for specific zoonotic concerns. According to Tung, their team sampled some 3,000 wildlife and conservation animals in 2022, which included examining bat feces from caves, a known reservoir for SARS-CoV-2. They also, when the need arises, lend their expertise to zoos. “[The Hanoi] Zoo had one hippo that died; they called the Virology Department and we investigated,” Vuong explains. “Initially we thought it was H5 influenza … but upon autopsy, tissue samples from the liver, lung, and intestines were influenza negative.” Further analysis of the tissue samples (including one from the spleen) revealed SARS-CoV-2 instead. Phylogenetically, the virus was linked to three human cases. They cannot determine who infected the hippopotamus, but they know it’s certainly biologically plausible.

Catching viral spillover as it is happening may be a fair way to characterize their mission. The discovery that COVID-19 can kill an enormous mammal such as a hippo raises concern for other protected animals, as well as the risk of establishment of a new animal reservoir. Surveillance for novel respiratory virus among Vietnamese poultry is particularly important to Southeast Asia because of the international trade of these animals, which, under the right circumstances, can cause novel strains to spread to new regions, threatening both poultry and humans. Vuong and Tung, along with their colleagues, are performing cutting-edge surveillance work that could provide early warning of new viral threats to livestock, wildlife, and humans.

Dr. Bui’s interests include molecular epidemiology and viral pathogenesis; his research profile can be found here. Dr. Dao’s interests also include molecular epidemiology, as well as bioinformatics and a variety of viruses; his research profile can be found here.

1. Bui, V. N., Dao, T. D., Tran, L. H., Vu, T. T., Nguyen, T. H., Nguyen, G. H., Tran, K. V. D., Nguyen, H. X., Bui, A. N., Unger, F., Nguyen-Viet, H., & Lee, H. S. (n.d.). SARS-CoV-2 Infection in a Hippopotamus, Hanoi, Vietnam—Volume 29, Number 3—March 2023—Emerging Infectious Diseases journal—CDC. https://doi.org/10.3201/eid2903.220915
2. Animals and COVID-19. (2020, February 11). Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/daily-life-coping/animals.html
3. Vercammen, F., Cay, B., Gryseels, S., Balmelle, N., Joffrin, L., Van Hoorde, K., Verhaegen, B., Mathijs, E., Van Vredendaal, R., Dharmadhikari, T., Chiers, K., Van Olmen, T. J. S., Agliani, G., Van den Brand, J. M. A., & Leirs, H. (2023). SARS-CoV-2 Infection in Captive Hippos (Hippopotamus amphibius), Belgium. Animals : An Open Access Journal from MDPI, 13(2), 316. https://doi.org/10.3390/ani13020316