Type A influenza viruses in waterfowl in Ohio and implications for domestic turkeys.

Because ducks are considered an important reservoir for type A influenza virus, and type A influenza viruses had not been recovered from ducks in Ohio, a 3-year virus surveillance study was conducted in Ohio waterfowl and waterfowl passing through Ohio to determine if domestic turkeys were at risk of exposure to avian influenza (AI) viruses from the waterfowl reservoir. The prevalence of AI infections in ducks during the fall migration averaged about 5.9%. The 55 waterfowl-origin type A influenza viruses recovered from ducks during fall 1986, 1987, and 1988 represented 23 different hemagglutinin-neuraminidase sub-type combinations of type A influenza viruses. Virus recovery frequencies ranged from 3.6% to 7.8% between years, from 2.0% to 8.2% between study sites, from 0.0% to 16.7% for sampling days, and from 0.0% to 14.3% among species of ducks sampled.