Serological evidence of inter-epidemic infection of feral pigs in New South Wales with Murray Valley encephalitis virus.

The sera of 617 feral pigs, collected from three widely separated areas of northern and central New South Wales, were examined for antibody to Murray Valley encephalitis (MVE) virus and to Ross River virus. Haemagglutination-inhibition (HI) antibody was detected to MVE in 58% of sera and to Ross River virus in 15% of sera. Neutralization tests suggested that the MVE HI antibody resulted from infection with MVE virus in the summers of 1971-1972 and 1972-1973 when the virus was not known to be active in New South Wales. These same tests suggested that more than one flavivirus infected the feral pigs in the summer of 1973-1974 and that Kunjin virus was active in the summer of 1975-1976.