Influenza A Outbreaks in Minnesota Turkeys Due to Subtype H10N7 and Possible Transmission by Waterfowl

Abstract
Avian influenza outbreaks in Minnesota involving the H10N7 subtype occurred on 2 turkey farms in 1979 and on a 3rd in 1980. The H10N7 (Hav2 Neq1) subtype had not previously been detected in turkeys in Minnesota or reported in the USA. The clinical signs ranged from severe, with a mortality rate as high as 31%, to subclinical. Antigenically indistinguishable viruses were isolated from healthy mallards on a pond adjacent to the turkey farms, suggesting that the virus responsible for the outbreak may have been introduced by feral ducks.