Serological and molecular prevalences and phylogenetic analysis of Coxiella burnetii in dogs in Al-Qadisiyah and Baghdad Provinces, Iraq.

Abstract

Background and aim: Coxiella burnetii is a highly contagious zoonotic bacterial micro-organism. This study aimed to estimate the prevalence of C. burnetii in dogs using serological and molecular methods. Furthermore, a sequencing analysis of C. burnetii dog isolates was conducted.

Materials and methods: A total of 172 dogs, including 93 pet dogs, 21 police dogs, 38 guardian dogs, and 20 stray dogs, were selected. Venous blood was drained from the dogs and examined serologically by indirect enzyme-linked immunosorbent assay (ELISA) and molecularly by polymerase chain reaction (PCR) for C. burnetii. A sequencing analysis of C. burnetii dog isolates was conducted.

Results: The overall prevalence of C. burnetii was 16.86%, accounting for 55% in stray dogs, 9.68% in pet dogs, 19.05% in police dogs, and 13.16% in guardian dogs. Strong positive sera were observed in stray dogs (4.84 ± 0.29), whereas weak sera were observed in pet dogs (3.22 ± 0.18). PCR analysis revealed 6.4% positive dogs, accounting for 1.08%, 4.76%, 2.63%, and 40% in pet, police, guardian, and stray dogs, respectively. Phylogenetic tree analysis of local C. burnetii isolates revealed a total rate of similarity and mutations/changes between 95.47% and 100% and 0.059%, respectively. Subsequently, the local isolates were significantly similar to Chinese hedgehog, Iraqi camel, and Colombian human C. burnetii National Center for Biotechnology Information-GenBank isolates.

Conclusion: This is the first study on prevalence of C. burnetii in dogs in Iraq. To prevent transmission of C. burnetii to humans, the role of dogs or other domestic and wild animals as sources of infection must be investigated extensively. In addition, the prevalence of C. burnetii in other Iraqi regions should be surveyed using the most sensitive and specific diagnostic assays, such as ELISA and PCR.