The role of rodents and small carnivores in plague ende- micity in Tanzania

Abstract

Between 1974 and 2003, blood samples were collected from wild and commensal rodents, and wild and domestic small carnivores in selected villages of seven districts in Tanzania that have experienced human plague outbreaks and seven districts that have not experienced any outbreak of the disease. The samples were tested for antibodies against Yersinia pestis Fraction I antigen, using passive haemagglutination (PHA) or ELISA tests. Of the 3354 rodents and 558 small carnivores from the plague infected districts, 122 (3.6 %) rodents (captured in Mbulu and Lushoto districts) were plague positive ; 29 (5.2 %) small carnivores from Mbulu, Arumeru, Hai and Lushoto districts were plague positive, 28 of these were domestic dogs (Canis familiaris). PCR tests showed that 17.5 % of 211 rodents tested from Lushoto contained Y. pestis DNA. In the non-infected districts, 1545 rodents and 171 domestic dogs were tested. 11 (0.7 %) of the rodents (captured in Monduli, Chunya and Masasi districts) were plague-positive. In Masasi district, 10.4% (7/67) of the rodents and 43.6 % (17/39) of the dogs were positive for anti-Y. pestis IgG. It was concluded that wild and commensal rodents as well as wild and domestic small carnivores play a potential role as reservoirs and/or carriers of sylvatic plague in Tanzania, and that the disease exists in areas where human plague outbreaks have not occurred before. In order to update the distribution of the disease it is pro- posed that further epidemiological surveillance activities are established.