Molecular detection of Brucella abortus and Brucella melitensis in domestic ruminants and their ticks in selected areas of western Iran

Background: Brucellosis is one of the most important zoonotic diseases caused by Gram-negative bacteria belonging to the genus Brucella. Detection of Brucella species in different countries is of utmost importance. Aims: This study aimed to detect Brucella abortus and Brucella melitensis in domestic ruminant blood samples and their ticks in western Iran. Methods: Sampling was conducted on ruminants from August to September 2020 in four different counties of Kurdistan Province, including Divandareh, Marivan, Baneh, and Sanandaj. Totally, 250 blood samples were collected from 250 small ruminants. There were no ticks on the skin of six (2.4%) ruminants, and 244 ticks were isolated from 244 animals. After genomic DNA extraction from all the collected samples, quantitative polymerase chain reaction (qPCR) was performed to detect IS711 gene. Results: Based on qPCR results, Brucella genus was detected in two blood samples (0.8%) from female sheep and four ticks (1.6%) from male sheep, including three Dermacentor marginatus (1.22%) and one Rhipicephalus turanicus (0.4%). Although B. melitensis was not detected in any tick or blood sample, one tick sample (D. marginatus) was positive for B. abortus. Conclusion: Considering the positivity of ticks for brucellosis in this study, there is a possibility of Brucella transmission from infected ticks to humans and animals through tick bites, nevertheless, in order to identify the Brucella transmission relationship between ticks and animals, serological tests should be used in future studies.