Q fever is an important zoonotic disease caused by Coxiella burnetii. Domestic ruminants are the main reservoirs, and bacterial shedding through milk poses a risk of transmission to humans. This study aimed to determine the molecular prevalence of Coxiella burnetii in milk of cattle and goats in the Sistan region and to investigate the risk factors of age and species.
In this cross-sectional study, 100 milk sampleswere collected by cluster sampling from herds in Zabol, Hamoon, Zahak, Hirmand, and Nimroz cities during spring 2025. After DNA extraction using the Sinaclon kit, the com1 gene was amplified by Nested PCR . The 438-bp products were electrophoresed on 1.5% agarose gel. Statistical analysis was performed using SPSS with chi-square and Fisher's exact tests (significance level: 0.05).
Out of 100 samples, 4 samples were positive. Prevalence was 4.3% in cattle and 3.3% in goats. There was a significant association between age and infection (P=0.031), with all positive cases observed in animals older than 4 years. No significant association was found between species and infection (P=0.843).
Although the 4% prevalence is lower than some studies in Iran, detection of bacterial DNA in raw milk indicates the possible presence of the agent in the region and highlights the need for continuous monitoring and observance of hygienic principles in milk consumption. However, for definitive proof of bacterial presence and transmission risk, sequencing confirmation are required. The observation of positive cases only in older animals may suggest a higher probability of exposure or shedding in older animals.