Prevalence of zoonotic chlamydiae in dairy cattle and contact persons
Chlamydial infections are a known problem in cattle farming. We want to find out whether they are related to chronic respiratory illness in farmers. We selected 48 dairy farms with a history or suspicion of chlamydial infections. Nasal and vaginal swabs, milk and fecal samples and paired sera were obtained from 5 cows of each farm. The presence of chlamydiae was analysed by rtPCR, by the ArrayTube DNA microarray test and paired sera were examined using an ELISA. The farmers were clinically examined by lung function testing, serology, allergy skin test, and their induced sputum was rtPCR tested. The analysis of 48 farms showed that in 31 (64.6%) farms at least 1 sample from at least 1 cow was positive in rtPCR and 12 (25%) farms were positive only by ELISA. Chlamydophila (C.) psittaci and C. pecorum were the most frequently identified species. At one farm, Chlamydia trachomatis was identified in cattle. So, far 39 individuals have been examined, 12 had respiratory symptoms and 33 were positive in serology. C. pneumoniae IgA occurred in 15 (38.5%) subjects and IgG in 26 (66.7%). Only 2 persons were positive for C. psittaci IgG. In 5 (12.8%) human sputum samples Chlamydia trachomatis was identified. We found a prevalence of 64.6% (rtPCR), which is a wide dissemination of chlamydial infections in cattle herds. In humans, we found signs of an immune reaction against zoonotic C. psittaci in 2 subjects, which had regular contact to birds. The cattle of these farms were tested negative. The presence of Chlamydia trachomatis in 5 sputum samples is remarkable and interesting and needs further investigation, as well as the detection of Chlamydia trachomatis of 4 cows. The farmers of this farm have not yet been examined.