Epidemiology of Trypanosoma cruzi in the oriental plains of Colombia.

Epidemiologic studies to define the domiciliary and extradomiciliary transmission cycles of Trypanosoma cruzi and Trypanosoma rangeli in the Oriental Plains of Colombia were conducted in the gallery forests near Carimagua and El Porvenir. One-hundred and seven palm trees belonging to nine genera were examined; triatomines were found in only three palm species, the leaves of which are locally used for roof thatching: 2/29 Maximiliana elegans, 1/7 Mauritia flexuosa and 7/7 Scheelea sp. Bugs were also found in 5/14 hollow Mauritia inhabited by bats, 4/21 bird nests and 1/4 armadillo burrows. Five species of triatomines were collected: Rhodnius prolixus was the most abundant, 192 of the total 207 (92%) collected; the bugs were found in Maximiliana and Mauritia but especially in Scheelea, and 8% were infected with T. cruzi and T. rangeli; Cavenicola pilosa and Triatoma maculata were found associated with bats; Psammolestes arthuri and Panstrongylus lignarius with bird nests and Panstrongylus geniculatus with armadillos. Although triatomine colonies were not found in human dwellings, flying adults of R. prolixus occasionally reached houses by their own locomotion and fed on man, but did not become established. Only 12 of 199 persons (6%) tested serologically were reactors to T. cruzi antigens and all 12 had lived in areas of domiciliary transmission elsewhere in the country, indicating that domiciliary transmission is not occurring in this region. Whether the presence of domiciliary R. prolixus in houses located in the ecologically altered piedmont of the oriental plains, a known area of domiciliary transmission of T. cruzi, is due to importation of domiciliary bugs from endemic areas or to the domiciliarization of wild R. prolixus remains to be determined.