[Spread of acute haemorrhagic conjunctivitis virus in virgin soil (Hokkaido, Japan): observation with serological surveys (author's transl)].

Acute haemorrhagic conjunctivitis (AHC), a novel disease caused with a new type of enterovirus, occurred for the first time in Sapporo City and other areas of Hokkaido in October of 1971. During first 4 months, 1,000 or more cases of AHC were reported in Sapporo and 2,300 cases in other areas. Thereafter, there are no epidemic of AHC in any areas, though there are sporadic cases up to date. To know the spread of exogenous agent, AHC virus, in Hokkaido, the neutralizing antibody was measured with sera of healthy adults resident in 12 separated districts of Hokkaido in 1973 and 1974. It was revealed that the positive reactors to AHC virus were found in 5 to 35% in all districts but one in 1974, and AHC virus was distributed in almost all the areas of Hokkaido within a period of two and half years after invasion. In addition, a sequential sero-survey to detect the spread of AHC virus has been carried out in Sapporo. A rate of neutralizing antibody positives in healthy adults did not show a clear increase on sera withdrawn one year after epidemic of AHC in comparison with those before epidemic, but show a remarkable increase on sera withdrawn later in spite of non-epidemic. An increase of antibody positive rate in non-epidemic period was also obtained from sera of healthy adults resident in districts other than Sapporo. These findings made doubt the changes in transmission on mode and/or in clinical pictures, and the viral mutation in biological character, such as temperature for propagation, may be supposed.