Submitted to: Avian Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2002
Publication Date: 8/1/2003
Citation: Hanson, B.A., Stallknecht, D.E., Swayne, D.E., Lewis, L.A., Senne, D.A. 2003. Avian Influenza Viruses In Minnesota Ducks 1998 - 2000. 2003,Avian Diseases, 47:867-871. Interpretive Summary: Wild ducks have been shown to have infections by avian influenza (AI) viruses, but understanding the role they play as reservoirs over multiple year is unclear. Ducks in Mississippi flyway were sampled from 1998-2000. The most frequent subtypes of AI viruses were the H3, H4 and H6 subtypes, but H5, H7 and H9 subtypes were also present. These latter subtypes have been associated with mild infections in humans and deadly infections of poultry. Wild ducks are a reservoir of multiple subtypes of AI viruses which persist over multiple years
Technical Abstract: Although wild ducks are known to be a major reservoir for avian influenza viruses (AIV), there are few recent published reports of surveillance directed at this group. Predominant AIV hemagglutinin (HA) subtypes reported in previous studies of ducks in North America include H3, H4, and H6, with the H5, H7, and H9 subtypes not well-represented in these host populations. The objective of this study was to determine if these subtype patterns have persisted. Each September from 1998 to 2000, cloacal swabs were collected from wild ducks banded in Roseau and Marshall counties, Minnesota. Mallards (Anas platyrhynchos) were sampled all years and northern pintails (A. acuta) were sampled only in 1999. Influenza viruses were isolated from 11%, 14%, and 8% of birds during 1998, 1999, and 2000 respectively. Prevalence, as expected, was highest in juveniles, ranging 11-23% in mallards. Viruses representative of the HA subtypes 2, 3, 4, 5, 6, 7, 9, 10, 11, and 12 were isolated. Viruses in the H5, H7, and H9 subtypes, which are associated with highly pathogenic influenza in poultry or recent infections in humans, were not uncommon and each of these subtypes was isolated in 2 out of the 3 years of surveillance.