Influenza A viruses remain infectious for more than seven months in northern wetlands of North America

Authors: RAMEY, ANDREW - Us Geological Survey (USGS); REEVES, ANDREW - Us Geological Survey (USGS); DREXLER, JUDITH - Us Geological Survey (USGS); ACKERMAN, JOSHUA - Us Geological Survey (USGS); DE LA CRUS, SUSAN - Us Geological Survey (USGS); LANG, ANDREW - Memorial University Of Newfounland; LEYSON, CHRISTINA - Orise Fellow; LINK, PAUL - Louisiana Department Of Wildlife; PROSSER, DIANN - Us Geological Survey (USGS); ROBERTSON, GREGORY - Environment And Climate Change Canada; WRIGHT, JORDAN - Memorial University Of Newfounland; YOUK, SUNGSU - Orise Fellow; Spackman, Erica; Pantin Jackwood, Mary; POULSON, REBECCA - Southeastern Cooperative Wildlife Disease Study; STALLKNECHT, DAVID - Southeastern Cooperative Wildlife Disease Study

Submitted to: Proceedings of the Royal Society. B. Biological Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2020
Publication Date: 9/9/2020
Citation: Ramey, A.M., Reeves, A.B., Drexler, J., Ackerman, J., De La Crus, S., Lang, A., Leyson, C., Link, P., Prosser, D., Robertson, G., Wright, J., Youk, S., Spackman, E., Pantin Jackwood, M.J., Poulson, R.L., Stallknecht, D.E. 2020. Influenza A viruses remain infectious for more than seven months in northern wetlands of North America. Proceedings of the Royal Society B. 287(1934). Article 20200655. https://doi.org/10.1098/rspb.2020.1680.
DOI: https://doi.org/10.1098/rspb.2020.1680

Interpretive Summary: Wild waterfowl are natural reservoirs of influenza A viruses (IAVs). The maintenance and spread of IAVs in avian hosts have been well studied, but it’s not clear how long the viruses can survive in the environment. In this study, we examined if IAVs shed by ducks could remain viable for extended periods in surface water when maintained under naturally occurring temperatures in wetlands in North America. We found that IAVs could be isolated from filtered surface waters from Alaska and Minnesota after being maintained at wetland field sites for 181–229 days. In a comparative laboratory experiment, we found a monthly decline in the viability of IAVs in filtered surface water, generally concordant with the decline in infectivity of viruses observed for the field samples. Through an experimental challenge study, we found that IAVs that had been maintained in filtered surface water at wetlands in Alaska and Minnesota for 214–226 days were able to infect mallards. In conclusion, results from this study support the premise that northern North American environmental surface waters represent a biologically important medium in which IAVs can be maintained and suggest that surface waters of wetlands may serve as an abiotic reservoir for infectious IAVs during the overwintering period of migratory birds.

Technical Abstract: The maintenance and spread of influenza A viruses (IAVs) in avian hosts have been the focus of extensive global research and surveillance efforts; however, far-less research has been focused on the viability of viruses in the environment. In this investigation, we used a combination of field-based and laboratory approaches to assess if IAVs shed by ducks could remain viable for extended periods in surface water when maintained under naturally occurring temperatures in three wetland complexes across a latitudinal gradient in North America. Through a field experiment in which replicate samples were tested both upon initial collection and again after a defined period of up to seven months, we found evidence that IAVs could be molecularly detected and isolated from filtered surface waters from Alaska and Minnesota after being maintained at wetland field sites for 181–229 days. In a comparative laboratory experiment, we found evidence for monthly declines in the viability of IAVs in filtered surface water from Minnesota during September 2018–April 2019, generally concordant with the decline in infectivity of viruses observed for samples maintained in Minnesota wetlands through our field experiment. Through an experimental challenge study, we found that IAVs that had been maintained in filtered surface water at wetlands in Alaska and Minnesota for 214–226 days were able to infect mallards. Collectively, results from this investigation support the premise that northern North American environmental surface waters represent a biologically important medium in which IAVs are both transmitted and maintained. Furthermore, our results suggest that surface waters of northern wetlands may serve as an abiotic reservoir for infectious IAVs during the overwintering period of migratory birds.