Horsesickness : immunization of horses and mules in the field during the season 1934-1935 with a description of the technique of preparation of polyvalent mouse neurotropic vaccine

Abstract

1. Details of the method adopted for the preparation of the vaccine are given. 2. The results obtained in the field during the season 1934-35 with the immunization of 1,815 police remounts and 28,659 other horses and mules are discussed. Of the police horses there was no mortality as a direct result of immunization, no adverse after effects were noted, and the immunity of 12 was broken down on exposure to natural infection. Of those 10 died and 2 recovered. Of the other horses and mules there were 3 deaths for which the vaccine may have been responsible or to which it may have contributed. On the whole the reactions were exceedingly mild and there were no adverse after effects. The immunity of 247 (0.87 per cent.) was broken down on exposure to natural infection. Of these 165 (0.58 per cent.) died and 82 (0.29 per cent.) recovered. 3. From the police breakdowns 3 strains of virus were isolated and have been fixed neurotropically in mice. Their antigenic inter-relationship is being worked out. 4. In mules 5 cases of blindness following immunization have been reported. 5. The problem of immunization by the neurotropic virus method is discussed.