Canine visceral leishmaniasis in Colombia: Relationship between clinical and parasitologic status and infectivity for sand flies

We studied the reservoir competency of canines with distinct clinical prese ntations of Leishmania chagasi infection. The parasitologic status of asymp tomatic and symptomatic dogs was determined by standard culture methods Inf ectivity was assessed by multiple xenodiagnoses with Lutzomyia longipalpis, over a period of 2-11 months. Asymptomatic dogs were non-infective (0 of 5 ) while 2 of 7 oligosymptomatic dogs infected L. longipalpis, transmitting the parasites at low rates (range 0.9-5.2% of engorged flies). Polysymptoma tic dogs transmitted L. chagasi more frequently (4 of 8 dogs) and reached h igher infection rates (range 5.0-22.5% of engorged flies). The skin of the ear tended to be more infective to sand flies than that of the abdomen. Pol ymerase chain reaction hybridization (PCR-H) was a sensitive method for det ection of L. chagasi, yielding the highest positive rate in serum (16 of 17 dogs) with no distinction between clinical groups. No association between skin positivity by PCR-H and infectivity to sand flies was found. The infec tivity of dogs from clinically comparable groups from Colombian and Mediter ranean foci differed. This may be a reflection of varied nutritional condit ions or vector competency of distinct sand fly species.