Evidence of Yersinia pestis DNA in rodents in plague outbreak foci in Mbulu and Karatu Districts, northern Tanzania

Abstract

Human plague remains a public health concern in Tanzania despite its quiescence in most foci for years, considering the recurrence nature of the disease. Appreciable researches have involved serological screening of rodents, fleas and humans but none has involved molecular detection and hence proving the presence of Yersinia pestis in rodents in the most recent affected foci, Mbulu and Karatu districts in northern Tanzania. The objective of the current study was to employ a simple PCR to detect Yersinia pestis plasminogen activator (pla) gene in various potential mammalian hosts/reservoirs. The study was conducted in five villages in Mbulu and one in Karatu districts during the period of no disease outbreak. Rodents and small wild carnivores were captured, anaesthetized, identified, sexed and autopsied. Liver, spleen, heart and lung specimens were collected and DNA extracted after which PCR was used to detect the Y. pestis pla gene. A total of 517 small mammals were captured; of which, 493 (95.4%) were from Mbulu and 24 (4.6%) from Karatu. Two Mastomys natalensis (one from each district) and one Gerbilliscus sp. in Mbulu district were positive for Y. pestis pla gene. In conclusion, our results have provided a proof on the presence of Y. pestis in the two rodent species (Mastomys natalensis and Gerbilliscus sp.) and thus providing indicative evidence that the two are potential reservoirs of the pathogen and hence may be responsible for maintaining the same during periods of no disease outbreaks.