Correlation between populations of Rhodnius and presence of palm trees as risk factors for the emergence of Chagas disease in Amazon region, Brazil.

Among the states that comprise the legally defined Amazon region of Brazil, Pará has presented the highest occurrences of acute cases of Chagas disease over the last two decades. These cases have been attributed to consumption of fruits from native palm trees. In surveys in rural and wild areas of the municipality of Oriximiná, Pará, triatomine fauna, their main ecotopes and the infection rate due to Trypanosoma cruzi were identified using active and passive search methods: manual capture and Noireau traps, respectively. A total of 582 ecotopes were surveyed using 1496 Noireau traps. Out of 442 specimens collected, 289 were identified as Rhodnius robustus and 153 as Rhodnius pictipes. The infection rate caused by T. cruzi was 17.4%. The food sources of the triatomines were found to be birds, hemolymph, horses, and rodents. The association between R. robustus and inajá palm trees (Attalea marita), which are abundant in rural areas, was confirmed. On the other hand, R. pictipes is found in several palm tree species, such as inajá (A. marita), mucajá (Acrocomia aculeata), murumuru (Astrocaryum murumuru) and patauá (Oenocarpus bataua), and in bromeliads in wild areas. These occurrences of triatomine species in regions with or without T. cruzi infection, in the vicinity of the main settlement of the municipality, suggest that there is a need for entomological and epidemiological surveillance in this region.