[Incidence of influenza virus infection in black-headed gulls]

Two strains of influenza A viruses were isolated in 1978 from tracheal washings of 18 nestlings of black-headed gulls examined for influenza. Three strains of influenza A viruses were isolated in 1979 from 55 gull embryos collected in the same colony, the isolates being similar in their antigenic characteristics with the influenza virus isolated from a gull nestling in 1978. This confirms the possibility of simultaneous circulation of antigenically different variants of influenza A virus among birds in the same colony and transoviral transmission of virus to the offsprings.