Occurrence of Hsw 1 N 1 subtype influenza A viruses in wild ducks in Europe.

Two identical strains of influenza A viruses antigenically related to swine influenza (Hsw 1 N 1) have been isolated from adult mallard ducks (Anas platyrhynchos) in Southern Germany. They were designated A/Duck/Bavaria/1/77 and A/Duck/Bavaria/2/77. Serologic tests revealed a close antigenic relationship to the strain A/Duck/Alberta/35/76. Experimental infections of piglets with strain A/Duck/Bavaria/1/77 demonstrated the susceptibility of swine to this virus strain. The virus was isolated from nasal swabs of infected piglets up to 8 days p. inf. and from contact animals up to 9 days. No seroconversion was detected during an observation period of 30 days.