The surveillance of plague among rodents and dogs in Western Iran

BackgroundThe causative agent of plague, Yersinia pestis, is maintained in nature via a flea-rodent cycle. Western Iran is an old focus for plague, and recent data indicate that rodents and dogs in this region have serological evidence of Y. pestis infection. The purpose of this study was to conduct a large-scale investigation of Y. pestis infection in shepherd dogs, rodents, and their fleas in old foci for plague in Western Iran.Materials and methodsThis study was conducted in Hamadan province from 2014 to 2020. Rodents and fleas were collected from various locations throughout this region. Y. pestis was investigated in rodent spleen samples and fleas using culture, serology, and real-time PCR methods. Additionally, sera samples were collected from carnivores and hares in this region, and the IgG antibody against the Y. pestis F1 antigen was assessed using an ELISA.ResultsIn this study, 927 rodents were captured, with Meriones spp. (91.8%) and Microtus qazvinensis (2.6%) being the most prevalent. A total of 6051 fleas were collected from rodents and carnivores, most of which were isolated from Meriones persicus. None of the rodents or fleas examined tested positive for Y. pestis using real-time PCR and culture methods. Meanwhile, IgG antibodies were detected in 0.32% of rodents. All serologically positive rodents belonged to M. persicus. Furthermore, none of the sera from the 138 carnivores (129 sheepdogs, five Vulpes vulpes, four Canis aureus), and nine hares tested positive in the ELISA test.ConclusionThis primary survey of rodent reservoirs shows serological evidence of Y. pestis infection. Western Iran is an endemic plague focus, and as such, it requires ongoing surveillance. This article investigates the ongoing presence of the plague in Iran and stresses the importance of continuous monitoring in the western region, a major area for endemic plague. Rodents are the primary carriers of diseases in their natural habitats and contribute significantly to the ongoing presence of infectious cycles. The study focuses on the presence of Yersinia pestis, the bacteria responsible for the plague, in guard dogs, rodents, and fleas in the historical center of western Iran. The research confirms the presence of Y. pestis infection in rodents, specifically Meriones persicus, in western Iran through serological evidence. Given the new discoveries in Iran and the resurgence of the plague in neighboring countries, ongoing monitoring of plague infections in wildlife across various regions of the country is crucial for public health outcomes.