Herd immunity drives the epidemic fadeout of avian cholera in Arctic-nesting seabirds

• Published in: Scientific Reports
• Main Authors: van Dijk, Jacintha G. B., Iverson, Samuel A., Gilchrist, H. Grant, Harms, N. Jane, Hennin, Holly L., Love, Oliver P., Buttler, E. Isabel, Lesceu, Stephanie, Foster, Jeffrey T., Forbes, Mark R., Soos, Catherine
• Other Authors: British Ornithologists’ Union, Environment and Climate Change Canada, Arctic Institute of North America, ArcticNet, Natural Sciences and Engineering Research Council of Canada, STAGE, Institute for Wetland and Waterfowl Research, Ducks Unlimited Canada, University of Saskatchewan’s Wildlife Health Research Fund, Nunavut Wildlife Management Board, University of Saskatchewan’s Interprovincial Graduate Fellowship, W. Garfield Weston Foundation, Northern Scientific Training Program, Baffinland Inc, Oceans North, Polar Continental Shelf Program, Polar Knowledge Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: Multidisciplinary; Arctic; Nunavut; Somateria mollissima
• Online Access: http://dx.doi.org/10.1038/s41598-020-79888-6; http://www.nature.com/articles/s41598-020-79888-6.pdf; http://www.nature.com/articles/s41598-020-79888-6

Abstract Avian cholera, caused by the bacterium Pasteurella multocida , is a common and important infectious disease of wild birds in North America. Between 2005 and 2012, avian cholera caused annual mortality of widely varying magnitudes in Northern common eiders ( Somateria mollissima borealis ) breeding at the largest colony in the Canadian Arctic, Mitivik Island, Nunavut. Although herd immunity, in which a large proportion of the population acquires immunity to the disease, has been suggested to play a role in epidemic fadeout, immunological studies exploring this hypothesis have been missing. We investigated the role of three potential drivers of fadeout of avian cholera in eiders, including immunity, prevalence of infection, and colony size. Each potential driver was examined in relation to the annual real-time reproductive number (R t ) of P. multocida , previously calculated for eiders at Mitivik Island. Each year, colony size was estimated and eiders were closely monitored, and evaluated for infection and serological status. We demonstrate that acquired immunity approximated using antibody titers to P. multocida in both sexes was likely a key driver for the epidemic fadeout. This study exemplifies the importance of herd immunity in influencing the dynamics and fadeout of epidemics in a wildlife population.