Chlamydia pecorum is the endemic intestinal species in cattle while C. gallinacea, C. psittaci and C. pneumoniae associate with sporadic systemic infection.

To investigate the prevalence and diversity of bovine Chlamydia spp. in cattle, whole blood from dairy and beef cattle in 11 provinces of China (n=2003) and vaginal swabs, whole blood samples, feces, milk samples from cows in a Yangzhou dairy farm (n=108) were examined using genus- and species-specific PCRs. In cattle from 11 provinces, 2.4% (48/2003) of whole-blood samples were positive for Chlamydia spp., and four Chlamydia species (C. pneumoniae, 41.7%, 20/48; C. psittaci, 22.9%, 11/48; C. gallinacea, 20.8%, 10/48; C. pecorum, 6.3%, 3/48) were identified. In a further study on a Yangzhou dairy farm, 64.8% (70/108) of the cows were positive for Chlamydia spp. C. pecorum was the intestinal endemic species (51/51, 100%), and C. gallinacea was the most frequent species in vaginal swabs (24/27, 88.9%), whole blood buffy coats (5/8, 62.5%) and milk (4/6, 66.7%). C. psittaci and C. pneumoniae were infrequently detected. DNA sequencing of the ompA gene demonstrated the presence of multiple in-herd C. pecorum serovars and single C. gallinacea and C. psittaci serovars which were identical with those of poultry from Yangzhou. This is the first report of C. gallinacea and C. pneumoniae in cattle. Further study is required to address the transmission of Chlamydia spp., in particular of C. gallinacea and C. pneumoniae from their natural hosts, and their potential pathogenic effect on health and production of cattle.