An outbreak of influenza in the swine with Hong Kong influenza virus (author's transl)

Abstract

Early in the winter of 1968, an outbreak of acute respiratory disease was seen in a herd of swine in Osaka, Japan. The isolation of virus from diseased swine, the identification of the virus and serological investigation were tried.Clinical symptoms: The onset of disease was sudden. Anorexia and extreme weakness were first to appear and followed by fever and prostration. Diseased animal were crowded together to lie down and coughed when they were moved and handled. The first onset was found in pigs in a pen. Some of pigs kept in the other 13 pens of the same herd showed the same symptoms three days after the first onset. After all, 245 of 535 pigs of the herd were involved, in spite of the very short period of illness varying from 5 to 10 days.Isolation of virus: Viruses agglutinating chick erythrocytes were isolated from throat or nasal swab specimens of three pigs which had been inoculated into the allantoic cavity of 10 day-old chick embryos. They were identified as those of Hong Kong influenza virus by the cross hemagglutination inhibition (HI) test.Serological survey: Thirty convalescent serum samples were tested for HI antibody against swine influenza virus (A/Swine/S15/31) and five strains of human influenza virus. No antibody against swine influenza virus (A/Swine/S15/31) was detected. All the sera, however, inhibited he hemagglutination of Hong Kong influenza virus (A/Aichi, 2/68) and the isolated virus, A/Swine/Wadayama/69. Therefore, the isolated virus was considered to be the same as, antigenically similar to, A/Aichi, 2/68 virus.Many kinds of bacteria were also isolated from throat and nasal swabs of five pigs inspected for virus. Hemophilus, Staphylococcus, Corynebacterium and Klebeiella were isolated from all the pigs.