Detection of Brucella infection in raw milk of livestock in Famenin, West part of Iran

Background: Timely diagnosis of brucellosis is the starting point for effective programs to control brucellosis in humans and animals. Aims: This study aimed to detect Brucella infection in milk samples from livestock in Famenin, an endemic region of western Iran, using a milk ring test and molecular techniques. Methods: In this cross-sectional study, 738 raw milk samples were randomly collected from cattle, sheep, and goats. Milk samples were screened using the milk ring test (MRT). In addition, polymerase chain reaction (PCR) method was applied to detect Brucella spp. in all MRT-positive samples. DNA from the milk samples was extracted and used for PCR using the BCSP31 and IS711 loci. Results: Of the samples tested using MRT, 46 (6.23%, 95% CI: 2.83-9.63%) yielded positive results. Of the 46 seropositive samples, 42 (91.30%) were from sheep and 4 (8.70%) were from goats, while no bovine samples had positive MRT results. PCR analysis confirmed that 78.26% (36/46) of MRT-positive samples belonged to the genus Brucella. Furthermore, 83.33% (30/36) of the confirmed samples were identified as B. melitensis, while 16.66% (6/36) were identified as B. abortus. Conclusion: The results obtained from MRT evaluation of milk samples did not align entirely with the findings of the molecular examinations. The PCR method has minimal biological contamination and high sensitivity and accuracy, especially for determining Brucella species. Raw milk should be routinely assessed for Brucella contamination. This work is necessary to identify hidden infections and break the chain of transmission of brucellosis.