Epizootics of Equine Influenza in Czechoslovakia Caused by the Type A/Equi 2(H3N8), and the Effects of Vaccination

An acute respiratory illness of horses was reported from many parts of Czechoslovakia in the summer of 1989. Equine influenza virus, identified as the subtype A/equi 2(H3N8) was isolated from nasal swabs or secrets of affected animals. This is the first report of the occurrence of this subtype in our country. The disease usually passed without subsequent complications and the virus induced formation of specific antibodies in the affected horses. During the epizootics the protective effect of a vaccine prepared in our laboratory was confirmed. Almost none of the vaccinated horses showed any signs of respiratory illness and only mild symptoms developed in the rest.