Plague, caused by infection with Yersinia pestis, persists in many parts of the world; several hundred cases are reported to the World Health Organization each year, mostly from Africa. In Tanzania, a persistent focusof human plague was discovered in 1980 in the Lushoto District, in the northeastern part of the country. By 2004, 7,603 cases had been reported from this region. The distribution of plague cases in Lushoto is limited to an area of ≈1,200 km2, and a strong variation in plague frequency and incidence is seen among the villages in this region. Although evidence of infection with Y. pestis has been observed in several wild rodent and flea species, the actual reservoir in which the infection survives between epidemics has not yet been identified, and the ecology of the infection and the source from which humans acquire infection are poorly understood. In Lushoto District, frequent plague outbreaks occur in some villages, but the disease is uncommon in other villages in the same vicinity. The aim of this study is to compare the ecologic conditions in villages having frequent outbreaks with those in villages where plague is relatively rare, with the objectives of understanding, predicting, and ultimately controlling human plague. Comparing host and vector communities is an importantpart of such studies and this has been done in various habitats : the domestic environment and the sylvatic environment consisting of natural montane rainforest, shrubs, crop fields and plantations during dry and wet season.  Trapping campaigns were carried out in Tanzania between may 2005 and january 2008,  and  simultaneousely domestic fleas were collected inside the houses of both plague endemic villages and control, plague-free villages. At each site of the 12 sites surveyed, GIS datas were recorded, soil conditions measured, and vegetation cover qualitatively described. In the meanwhile, question forms were submitted to the population to estimate the knowledge of the local people on rats and fleas nuisance and their implication in plague transmission. Results and discussions related to this survey are currently being written but some publications are already avialable on-line.