Geographic Distribution of Chagas Disease Vectors in Brazil Based on Ecological Niche Modeling

Abstract

Although Brazil was declared free from Chagas disease transmission by the domestic vector Triatoma infestans, human acute cases are still being registered based on transmission by native triatomine species. For a better understanding of transmission risk, the geographic distribution of Brazilian triatomines was analyzed. Sixteen out of 62 Brazilian species that both occur in >20 municipalities and present synanthropic tendencies were modeled based on their ecological niches. Panstrongylus geniculatus and P. megistus showed broad ecological ranges, but most of the species sort out by the biome in which they are distributed: Rhodnius pictipes and R. robustus in the Amazon; R. neglectus, Triatoma sordida, and T. costalimai in the Cerrado; R. nasutus, P. lutzi, T. brasiliensis, T. pseudomaculata, T. melanocephala, and T. petrocchiae in the Caatinga; T. rubrovaria in the southern pampas; T. tibiamaculata and T. vitticeps in the Atlantic Forest. Although most occurrences were recorded in open areas (Cerrado and Caatinga), our results show that all environmental conditions in the country are favorable to one or more of the species analyzed, such that almost nowhere is Chagas transmission risk negligible.

First report of Rhodnius montenegrensis (Hemiptera, Reduviidae, Triatominae) in the State of Acre, Brazil

“…In the State of Acre, researchers have reported the occurrence of four species of triatomines, namely, Rhodnius robustus (7) , Rhodnius pictipes, Panstrongylus geniculatus (8) , and Eratyrus mucronatus (9) . However, some R. robustus specimens collected in Acre may have been erroneously described by some researchers (7) because of similarities with Rhodnius montenegrensis, which had not previously been shown to exist in this region.…”

“…Surrounding areas, such as Bolivia and the Brazilians States of Amazonas and Rondônia, have 16, 10, and 6 different species, respectively (5) (8) (11) (12) (13) . Therefore, further studies are needed to determine the triatomine fauna and their distributions throughout the state, particularly for species of the genus Rhodnius, which facilitate autochthonous transmission of American trypanosomiasis (8) and are vectors of Trypanosoma rangeli, which is responsible for the occurrence of more than 2,700 human cases of rangeliosis (10) , with cases in the States of Amazonas and Bahia, Brazil (14) (15) .…”

First report of Rhodnius montenegrensis (Hemiptera: Reduviidae: Triatominae) infection by Trypanosoma rangeli

“…A total of 120 triatomines were collected, providing an average of 8.6 specimens per Attalea speciosa, which is below the average reported by other studies in the state 9,11 . Of those triatomines, only 13 (10.8%) were adults, and all were R. montenegrensis.…”

“…The transmission of T. rangeli to vertebrates is mainly related to species of triatomines of the genus Rhodnius, with 12 species reported as their natural vectors; of these 12 species, 6 are found in Brazil (Rhodnius neglectus, Rhodnius nasutus, Rhodnius neivai, Rhodnius domesticus, Rhodnius pictipes and Rhodnius robustus) 2,9,10 . The latter species may have been erroneously described in the State of Rondônia by some researchers 11,12 because of its similarity to R. montenegrensis, which had not been described at that time.…”

Variability of susceptibility to deltamethrin in peridomestic Triatoma sordida from Triângulo Mineiro, State of Minas Gerais, Brazil

“…The National Program of Chagas Disease Control (NPCDC) was observed with regularity from 1975 to 1988. In 1982, the chlorinated insecticide hexachlorobenzene (HCB), used in fi eld control strategies, was replaced with pyrethroids (deltamethrin) (3) . By using this insecticide, Triatoma infestans was eradicated from the area.…”