ANNUAL EXAMINATION OF INFLUENZA-VIRUS INFECTION AMONG PIGS IN MIYAGI PREFECTURE, JAPAN - APPEARANCE OF HSW1N1 VIRUS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 23  (3) , 240-248
Abstract
Annual dissemination of swine and Hong Kong influenza viruses among hogs in Miyagi Prefecture, Japan, was examined by virus recovery and serological tests. The serological examination revealed that 2 distinct influenza A viruses, H3N2 and Hsw1N1, had caused dual epidemics in pigs since mid-1977. Some individual sera contained antibodies against both strains. Although positive sera against Hong Kong or swine influenza viruses appeared in the serosurvey throughout the year, positive ratios indicated a peak in the early spring of 1978. During this high prevalence period, positive sera against the H3N2 strain were found throughout the prefecture, but high incidences of Hsw1N1 virus were found only in limited areas northeast of Sendai City [Japan]. Four influenza A virus strains were isolated from bronchial swabs collected from hogs in April, 1978. These strains were identified as Hsw1N1 viruses and were closely related to the A/New Jersey/8/76 strain.