Leishmaniasis in Brazil: XVIII. Further evidence incriminating the fox Cerdocyon thous (L) as a reservoir of Amazonian visceral leishmaniasis.

Major endemic areas of visceral leishmaniasis in Brazil are located in the drier, poorly forested regions, principally in the northeastern States such as Ceará and Bahia. Cases of the human disease in the Amazon Region are rare, very sporadic, and seldom present opportunities for epidemiological study. Following the report of a fatal case near Salvaterra, the Island of Marajó, Pará State, a preliminary investigation has resulted in the isolation of a parasite regarded as Leishmania donovani chagasi from the viscera and skin of an apparently healthy fox, Cerdocyon thous, captured in the same locality. This represents the third recorded isolation of the parasite from this species of fox in the Amazon Region. The inapparent nature of the infections supports the suggestion that this canid may represent the primitive natural host of L. d. chagasi. C. thous is commonly associated with forested or wooded areas, and enzymic profiles for the enzymes ASAT, ALAT, PGM, GPI, MDH, MPI, G6PD, PEP and ACP failed to distinguish an isolate of L. d. chagasi from this animal in Pará from others obtained from cases of human visceral leishmaniasis in the neighbouring States of Maranhão, Ceará and Bahia. This suggests that the major, present-day endemics may have originated from a primary silvatic enzootic.