Molecular and serological herd-level prevalence of Coxiella burnetii in bovine dairy herds in Montenegro

Abstract

Introduction: Shedding of Coxiella burnetii through milk is significant, particularly in dairy cattle, making milk a potential source of infection for humans. The aims of this study were to estimate the individual and herd-level prevalence of C. burnetii on dairy cattle, and to assess potential public health risk.

Methodology: The study was conducted as a screening study in 95 randomly selected dairy herds from Montenegro from March to May 2019. No abortions, reproductive disorders, or human diseases were reported in these farms. In order to identify positive farms, anti-C. burnetii antibodies and C. burnetii DNA were detected in bulk tank milk (BTM) using enzyme-linked immunosorbent assay (ELISA) and quantitative polymerase chain reaction (qPCR), respectively. All animals from the positive farms were sampled twice, 2 months apart; the presence of C. burnetii DNA in individual milk samples and the presence of anti-C. burnetii antibodies in milk and blood serum was detected using qPCR and ELISA.

Results: The overall herd-level prevalence of C. burnetii was 9.47% (9/95). Analysis of individual milk samples in the positive farms revealed anti-C. burnetii antibodies and C. burnetii DNA in 13.48% and 4.49% of the cows, respectively. Antibodies were also detected in 15.73% of the blood samples. No significant differences were observed between the results obtained through serological and molecular examination on the same farm two months later.

Conclusions: Although a low presence was detected in the farms, public health risk cannot be excluded. Further research is needed for unravelling the current epidemiological situation in the country.