Abstract
Seroepidemiological studies were carried out on the outbreaks of swine type influenza in swine and human beings. The studies consisted of two surveys one was conducted on the employees of a slaughterhouse in Asahi City, Chiba Prefecture for the period from Jan. 1979 to Mar. 1982, and the other was on the swine and workers in a breeding stock farm in Saitama Prefecture for the period from Jan. 1982 to Mar. 1982.
The following results were obtained :
1) The positive rate of HI antibody against the swine type virus strain among the workers in the slaughterhouse was 10.7% in 1979, 13.0% in 1980, 20.6% in 1981 and 25.3% in 1982, thus showing a yearly increase.
2) An outbreak of a respiratory disease was observed clinically in the swine of the breeding stock farm in the middle of Jan. 1982. From 5 of the swine, serum samples were collected in the acute and convalescent stage and was examined for changes in HI antibody against the swine type influenza virus strain. As a result, 4 of them were found infected by the strain, and it was demonstrated that an epizootic of swine type influenza had broken out.
3) Seven to ten days after the onset of the epizootic among swine, several workers in the breeding stock farm began to complain of pyrexia with a temperature of 38-39°C, coughing, sputum, rhinorrhea, encephalagia and anorexia. Serological examination on 10 samples revealed swine type influenza virus strains in five.
It was concluded that the swine type influenza prevailing in swine had been transmitted to human beings on the breeding stock farm.
