Molecular detection of Coxiella burnetii in vaginal swabs from aborted cattle in Mexico

Background: Coxiella burnetii is an obligate intracellular bacterium that causes Q fever, a worldwide contagious and zoonotic disease. Q fever is primarily transmitted to humans by infected cattle, sheep, and goats. Ruminants do not always develop clinical signs, except for pregnant females, which can present reproductive failure such as abortions and stillbirths. Regardless of its worldwide distribution, in Mexico this is considered an exotic disease, although serological evidence of C. burnetii has been demonstrated and at least six confirmed human cases have been reported. Objective: To assess the presence of C. burnetii in cattle in Mexico. Methods: Genomic DNA was extracted from 153 vaginal swabs obtained from cattle dwelling in 12 Mexican states and analyzed by PCR. Results: The C. burnetii IS1111 insertion sequence was identified by endpoint PCR in 33.33% (51/153) of the vaginal swabs. We obtained two nucleotide sequences that confirmed the genetic material of C. burnetii. Conclusion: Our results constitute a first step to elucidate the current epidemiology of Q fever in our country, and they indicate that cattle may be a reservoir of C. burnetii. To the best of our knowledge, this report provides the first molecular proof that this pathogen exists among cattle in Mexico.