Seroprevalence survey of Aino virus infection in dairy cattle of Fukuoka, Japan in 1990.

The seroprevalence and seroconversion to Aino virus infection were epidemiologically analyzed in Fukuoka Prefecture, by a cohort study, in 1990. Serum samples (872) were taken from 436 cattle of 128 farms in five different districts at twice sampling with four month-intervals and were tested by a serum neutralizing test with Aino virus. In the first sampling (May-July), 38.3% of sera and 40.6% of farms tested were positive and 33.3% of cattle and 40.6% of farms were sero-converted during the period of September-November in 1990. Significant differences were found in seroprevalence of farms and seroconversion of cattle/farms among five districts; there was, however, a highly significant correlation between seroprevalence and seroconversion of farm. Consequently, five districts of Fukuoka Prefecture were classified into four epidemic areas according to seroprevalence and seroconversion factors of a principal component analysis.