Brucella abortus contamination of camel milk in two Iranian regions

Brucella spp. commonly infect humans in various regions worldwide. Human brucellosis mainly spreads through the consumption of contaminated raw dairy products and meat from domestic livestock (water buffalo, goats, sheep, cattle, pigs and camels). In this regard, the origin and routes of transmission of this bacterium should be carefully determined in order to control the source of infection. This study aimed to evaluate the rate of Brucella spp. contamination of camel milk samples sent for analysis to the national brucellosis laboratory during 2018 in Iran. For this purpose, 96 milk samples from 96 dairy camel herds were randomly collected from two provinces and investigated for the presence of Brucella spp contaminations by both bacterial culture method and polymerase chain reaction (PCR). No clinical manifestation of brucellosis was reported in camels from which milk samples were collected. Using the culture method, three milk samples (3%) originating from two camels of Isfahan province (4%) and one camel from the Semnan province (2%), were contaminated with Brucella abortus. According to PCR analyses, B. abortus gene was detected in 14 (14.5%) milk samples, including 9 and 5 samples from Isfahan (18%) and Semnan (11%) province, respectively. PCR method revealed significant differences (p = 0.02) in the level of contamination with B. abortus between milk samples collected from two regions. These results represent the first report regarding the isolation of B. abortus from raw camel milk in Iran and highlight the importance to screen apparent healthy camels. Therefore, the consumption of raw camel milk may contribute to the spread of human brucellosis in endemic regions.