Avian influenza viruses and avian paramyxoviruses in wintering and breeding waterfowl populations in North Carolina, USA.

Although wild ducks are recognized reservoirs for avian influenza viruses (AIVs) and avian paramyxoviruses (APMVs), information related to the prevalence of these viruses in breeding and migratory duck populations on North American wintering grounds is limited. Wintering (n=2,889) and resident breeding (n=524) ducks were sampled in North Carolina during winter 2004-2006 and summer 2005-2006, respectively. Overall prevalence of AIV was 0.8% and restricted to the winter sample; however, prevalence in species within the genus Anas was 1.3% and was highest in Black Ducks (7%; Anas rubripes) and Northern Shovelers (8%; Anas clypeata). Of the 24 AIVs, 16 subtypes were detected, representing nine hemagglutinin and seven neuraminidase subtypes. Avian paramyxoviruses detected in wintering birds included 18 APMV-1s, 15 APMV-4s, and one APMV-6. During summers 2005 and 2006, a high prevalence of APMV-1 infection was observed in resident breeding Wood Ducks (Aix sponsa) and Mallards (Anas platyrhynchos).