Detection of Dermatophilus congolensis antibody in the milk of streptothricosis infected cows.

Passive haemagglutination and agar gel diffusion tests were used to detect specific antibody to Dermatophilus congolensis antigens in serum and milk of eight streptothricosis infected Friesian milking cows. All the sera and milk samples showed the presence of antibody but titres were higher in sera. Precipitating antibodies were detected only in three sera. A possible implication of this finding is discussed with respect to passive immunity in the young calves from infected dams.