Bovine paratuberculosis II. A comparison of fecal culture and the antibody response.

Fecal culture for Mycobacterium paratuberculosis and a complement fixing serological test using a carbohydrate antigen were compared for diagnostic efficiency in cattle naturally infected with M. paratuberculosis. Serological reactivity was associated with the persistent fecal shedding of large numbers of bacteria and in the absence of false positives in the population studied, was considered an efficient method for the identification of this segment of infected cattle. Minimally infected cattle, which inconsistently shed small numbers of bacteria, were generally serologically negative. One persistent fecal shedder demonstrated a fluctuating serological response to the carbohydrate antigen following abortion. The advantages and disadvantages of this serological diagnostic procedure in relationship to fecal culture are discussed.