Birds within the orders Charadriiformes (shorebirds, gulls) and Anseriformes (waterfowl) are reservoir hosts for avian influenza (AI) viruses, but their role in the transmission dynamics of AI viruses is unclear. To date, waterfowl have been the predominant focal species for most surveillance and epidemiological studies, yet gulls, in particular, have been shown to harbor reassortant AI viruses of both North American and Eurasian lineages and are underrepresented in North American surveillance efforts. To address this gap in surveillance, 1346 ring-billed gulls (Larus delawarensis) were sampled during spring and fall migrations and at three breeding sites in 2017 across Minnesota. Results indicate noticeable age-cohort dynamics in AI virus prevalence within ring-billed gulls in Minnesota. Immunologically naïve juveniles represented the cohort with the highest prevalence rate (57.8%). Regardless of age, more gulls had AI virus detected in oropharyngeal (OP) than in cloacal (CL) swabs. The high AI virus prevalence within ring-billed gulls, particularly in immunologically naïve birds, warrants further targeted surveillance efforts of ring-billed gulls and other closely related species.
Bibliographical noteFunding Information:
The authors acknowledge the invaluable help and advice from the following people: Dr. Tom Cooper and Mr. Dave Fronzak (U.S. Fish and Wildlife Service); Timothy White (U.S. Department of Agriculture Animal Plant Health Inspection Service); Beth Rasmussen (University of Minnesota); Fred Strand (Wisconsin Department of Natural Resources, retired); Steve Mortensen and Ben Benoit (Leech Lake Division of Resource Management); and Kelsie LaSharr and John Wollenberg (Minnesota Department of Natural Resources). Cristian Flores Figueroa and Jeannette Munoz Aguayo of the Mid-Central Research and Outreach Center of the University of Minnesota performed the AI virus rRT-PCR assays. This work was funded by the Environment and Natural Resources Trust Fund from the Legislative–Citizen Commission on Minnesota Resources.
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- Larus delawarensis
- avian influenza virus
- ring-billed gull