Field experiment with BCG vaccine in Malawi

A field trial to determine the value of BCG vaccine as a means of reducing the incidence and spread of bovine tuberculosis was carried out over a period of five years with Malawi Zebu cattle kept under village conditions. 204 cattle were vaccinated twice as young calves; 210 cattle acted as controls. The cattle were physically checked and tuberculin tested at regular intervals throughout the experimental period. The cattle were slaughtered and examined post mortem. Bacteriological samples were taken from all animals. The results of the tuberculin testing and of the post-mortem and bacteriological examinations showed no significant differences between the vaccinated and control cattle. The possibility of the vaccine having a beneficial effect in preventing the progression of the disease was also investigated, but there was no significant difference between the two groups. Previous experiments on the use of BCG vaccine in cattle are discussed and it is concluded that the vaccine has no preventive effect against infection with Mycobacterium bovis, Afro-Asian strain.