Brucella abortus Emerges as Predominant Brucellosis Agent in Golestan Province: A Molecular Detection Study in Suspected Human Cases

Background: Brucellosis is a widespread zoonotic infection caused by Brucella species. It poses a significant public health concern in endemic regions such as Iran. Objectives: Since brucellosis is frequently reported across Iran, the present study was conducted to identify Brucella spp. in blood samples of people suspected of brucellosis, referring to diagnostic laboratories in Golestan and Gilan provinces. Methods: From 6/2019 to 6/2021, 2910 patients presenting with clinical signs were screened by Rose Bengal and Wright tests. Polymerase Chain Reaction (PCR) targeting genus- and species-specific markers was applied to 98 seropositive samples. Results: The result of the PCR showed that 31 cases out of 53 seropositive samples were positive in Golestan province. All the suspected samples obtained from people in Gilan province were negative for PCR. Among the PCR-positive samples, 25 were infected with Brucella abortus species, and six were infected with B. melitensis. Conclusions: This study found that, unlike most parts of Iran, where B. melitensis is the leading cause of Brucella infection, B. abortus is the main cause of brucellosis in Golestan province.