Molecular surveillance of Versinia Pestis DNA from the Fleas and Rodents of Lushoto District of Tanzania
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Plague is a zoonotic disease, endemic throughout the world except Australia and Antarctica. The disease is highly infectious in humans. The causative agent is a gram-negative bacterium, Yersinia pestis (Y. pestis) which, primarily infects a wide range of rodents and is transmitted via flea vectors. The disease persists in many parts of the world with 90% of the plague cases being reported to the World Health Organization each year, come from Africa where public health and living conditions are poor. In Tanzania, plague has been endemic for many years in areas of Lushoto, Mbulu and Karatu districts. In Lushoto the disease has been quiescent for 10 years since 2003, when annual outbreaks were reported from 1980. In order to understand disease dynamics in the hosts and vectors of Lushoto district, this study was initiated. The study was designed to detect Y. pestis DNA in Lushoto district. In some areas of Mbulu and Karatu districts surveillance works revealed the presence of Y. pestis DNA despite the absence of plague outbreaks in the human population. This study was conducted in Lushoto district of Tanzania and involved four villages which had plague outbreaks previously. Live trapping of wild and commensal rodents was done after which rodent tissues and their fleas were collected for DNA extraction. The collected rodents and fleas were identified to genus and species levels. The extracted DNA was subjected to PCR for detection of Y. pestis DNA using primers targeting Y. pestis plasminogen activator gene. A total of 112 rodent tissues and 253 fleas were collected from Gologolo, Mavumo, Viti and Manolo villages in Lushoto district. There were nine species of rodents captured which are Mastomys (33%), Rattus rattus(25.9%), Praomys (14.3%), Lophuromys (14.3%), Grammomys (8%), Beamys (1.8%), Arvicanths (0.9%), Croccidura (1.8%) and Mus (0.9%), while five flea species were collected and these were Xenopsylla spp (39.5%), Ceratophylla (Dinopsyllus) spp (22.5%), Ctenocephalides spp (26.1%), Leptopsylla spp (6.3%) and Echidnophaga spp (5.5%). At the time of this study, no evidence of Yersinia pestis DNA was found neither in fleas nor in rodents, suggesting a quiescent period. During this study two rodents species (Mastomys and Rattus) were identified which have been observed to be plague bacteria reservoirs in other endemic areas. Also the oriental flea (Xenopsylla cheopis) which is the efficient vector in the propagation of Y. pestis was identified. Another flea of significance Dinopsyllus spp was observed.These findings are significant as they put Lushoto district in an re-emergence alert to encounter an outbreak in future due to the presence of important host reservoirs and the effective vectors for Y. pestis.
- Veterinary Medicine