Prevalence of Coxiella burnetii in bulk milk samples from dairy bovine, ovine, caprine, and camel herds in Iran as determined by polymerase chain reaction.

Q fever is a widespread zoonosis caused by the obligate intracellular micro-organism Coxiella burnetii. The objective of this study was to determine the prevalence rate of C. burnetii in bulk milk samples from dairy bovine, ovine, caprine, and camel herds in Isfahan province, Iran. In the present study, 567 bulk milk samples from 186 dairy bovine, ovine, caprine, and camel herds were tested for C. burnetii using a nested polymerase chain reaction assay. The animals whose milk samples collected for this study were clinically healthy. In total, 8 of 247 (3.2%) bovine milk samples were positive; the positive samples originated from 6 of 90 (6.7%) dairy herds. Eight of 140 (5.7%) ovine bulk milk samples from 42 sheep breeding farms and 5 of 110 (4.5%) caprine bulk milk samples from 32 goat breeding farms were positive for C. burnetii. One of 70 (1.4%) camel bulk milk samples from 22 camel breeding farms was also positive for C. burnetii. Although no extensive prevalence study was undertaken, the results of this study indicate that clinically healthy dairy animals are important sources of C. burnetii infection in Iran. To the authors' knowledge, this study is the first report of direct identification of C. burnetii using polymerase chain reaction in bulk milk samples from dairy ovine herds in Iran and the first report of direct identification of C. burnetii in bulk milk samples from dairy camel herds. Further intensive prevalence studies on Coxiella infection and on possible risks of dairy products will be needed to elucidate the epidemiology of Q fever in Iran.