By: Gregory C. Gray, MD, MPH
It now seems to be public knowledge that animal pathogens may occasionally spillover to cause illness in humans. We often consider these as zoonotic or anthroponosis disease events. The 2009 influenza A pandemic and the recent COVID-19 pandemic are two
recent well-known examples where animal viruses have caused respiratory epidemics in humans. What is not often understood is that human pathogens may sometimes spillover to cause illness in animals. Such “reverse zoonotic” events or zooanthroponosis
events are increasingly being detected. Examples of such zooanthroponosis events include epidemics of the 2009 influenza A (H1N1) pandemic virus in swine and epidemics of SARS-CoV-2 in mink and white tail deer. In fact, as of September 26, 2023 the
SARS-ANI VIS database (https://vis.csh.ac.at/sars-ani/) has now documented more [SDB1] 900 SARS-CoV-2 animal events in 39 countries
involving 34 non-human animal species.
We are becoming increasingly aware that viruses thought to be specific for a human or non-human animal host may occasionally spillover to a new host causing serious illness. We are also now aware that these spillover pathogens may take a long
time to fully adapt to their new host before becoming efficient in transmitting within the new species. These observations underscore the need to detect such spillover events soon after they first occur, before they have time to adapt. We
argue that such detections can best be made when surveillance for spillover is conducted using a One Health approach. Often this involves viral surveillance among humans with close contact with large populations of animals, the animals they
have contact with, and the environment where the close contact occurs. Hence, the USDA-funded novel virus surveillance study mentioned elsewhere in this monthly newsletter is an important approach to follow.
Further reading:
Keenliside J. Pandemic Influenza A H1N1 in Swine and Other Animals. Curr Top Microbial Immunol 2013;370:259-71. https://pubmed.ncbi.nlm.nih.gov/23254339/
Nerpel, A., Yang, L., Sorger, J. et al. SARS-ANI: a global open access dataset of reported SARS-CoV-2 events in animals. Sci Data 9, 438 (2022). https://doi.org/10.1038/s41597-022-01543-8
Messenger AM, Barnes AN, Gray GC. Reverse Zoonotic Disease Transmission (Zooanthroponosis): A Systematic Review of Seldom-Documented Human Biological Threats to Animals. PLoS One. 2014 Feb 28;9(2):e89055. doi: 10.1371/journal.pone.0089055. eCollection
2014. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0089055
Anderson BD, Barnes AN, Umar S, Guo X, Thongthum T, Gray GC. Reverse Zoonotic Transmission (Zooanthroponosis): An Increasing Threat to Animal Health. In: Zoonoses: Infections Affecting Humans and Animals. Springer, Cham. Edited by Andreas Sing.
2023. Pgs 1-63.
https://doi.org/10.1007/978-3-030-85877-3_59-1.