[Differences in influenza epidemics in Osaka City--epidemiological surveillance of infectious disease].

Influenza viruses in outpatients with influenza symptoms in Osaka City were analyzed in an epidemiological surveillance of infectious disease between 1989 and 1993. During influenza epidemics a mixed prevalence of several types of influenza viruses existed. Three types of influenza viruses, AH1, AH3 and B, were isolated during the 1990/1991 season.

Agglutination of human O erythrocytes by influenza A(H1N1) viruses freshly isolated from patients.

The hemagglutinin titers of 10 influenza A (H1N1) viruses were examined using the erythrocytes of several species. Human O erythrocytes showed the highest agglutination titer to the viruses, whereas chicken erythrocytes showed a low titer. These findings were noted for at least 10 passages by serial dilutions of the viruses in Madin-Darby canine kidney (MDCK) cells.