[Intestinal Chlamydia psittaci infection of cattle: frequency and technical aspects of the cultural detection of the agent].

With the purpose to evaluate the prevalence of latent chlamydial infections in cattle, 190 animals were examined for fecal shedding of chlamydiae. From the feces of 42 animals (22.1%) Chlamydia (C.) psittaci was grown either in the yolk sac of chicken embryos and/or in coverslip cultures of BGM-cells. The cell culture proved to be of lower susceptibility to chlamydial infections. In comparison with the chicken egg technique a sixfold quantity of chlamydial particles was required to initiate detectable intracellular growth. With the chicken embryo technique as a standard cell culture with a sensitivity range of 31.6% was not satisfactory for isolating chlamydiae from bovine feces. Attempts to recover chlamydiae from feces of two experimentally infected heifers in embryonated chicken eggs provided evidence that at least four randomly subsequent isolation trials are required to detect asymptomatic chlamydial infections of the bovine gut with a 95% confident level. Based on this fact, the positivity rate of 22.1% obtained by single fecal specimen examination indicates a wide spread occurrence of chlamydial infections in cattle.