TriatoScore: an entomological-risk score for Chagas disease vector control-surveillance

Abstract

Background Triatomine bugs transmit Chagas disease across Latin America, where vector control-surveillance is increasingly decentralized. Locally run systems often deal with highly diverse native-vector faunas—plus, in some areas, domestic populations of non-native species. Flexible entomological-risk indicators that cover native and non-native vectors and can support local decision-making are therefore needed. Methods We present a local-scale entomological-risk score (“TriatoScore”) that leverages and builds upon information on the ecology-behavior and distribution-biogeography of individual triatomine bug species. We illustrate our approach by calculating TriatoScores for the 417 municipalities of Bahia state, Brazil. For this, we (i) listed all triatomine bug species recorded statewide; (ii) derived a “species relevance score” reflecting whether each species is native/non-native and, if native, whether/how often it invades/colonizes dwellings; (iii) mapped each species’ presence by municipality; (iv) for native vectors, weighted presence by the proportion of municipal territory within ecoregions occupied by each species; (v) multiplied “species relevance score” × “weighted presence” to get species-specific “weighted scores”; and (vi) summed “weighted scores” across species to get municipal TriatoScores. Using standardized TriatoScores, we then grouped municipalities into high/moderate/low entomological-risk strata. Results TriatoScores were higher in municipalities dominated by dry-to-semiarid ecoregions than in those dominated by savanna-grassland or, especially, moist-forest ecoregions. Bahia’s native triatomines can maintain high to moderate risk of vector-borne Chagas disease in 318 (76.3%) municipalities. Historical elimination of Triatoma infestans from 125 municipalities reduced TriatoScores by ~ 27% (range, 20–44%); eight municipalities reported T. infestans since Bahia was certified free of Trypanosoma cruzi transmission by this non-native species. Entomological-risk strata based on TriatoScores agreed well with Bahia’s official disease-risk strata, but TriatoScores suggest that the official classification likely underestimates risk in 42 municipalities. Of 152 municipalities failing to report triatomines in 2006–2019, two and 71 had TriatoScores corresponding to, respectively, high and moderate entomological risk. Conclusions TriatoScore can help control-surveillance managers to flexibly assess and stratify the entomological risk of Chagas disease at operationally relevant scales. Integrating eco-epidemiological, demographic, socioeconomic, or operational data (on, e.g., local-scale dwelling-infestation or vector-infection frequencies, land-use change and urbanization, housing conditions, poverty, or the functioning of control-surveillance systems) is also straightforward. TriatoScore may thus become a useful addition to the triatomine bug control-surveillance toolbox. Graphical abstract

Triatomine fauna in the state of Bahia, Brazil: What changed after 40 years of the vector-control program?

“…Triatomine vectors of T. cruzi can be classified as native/non native, wild/non wild, domestic/peridomestic to enable the definition of effective vector-control strategies 45 . While domestic and peridomestic populations of species of triatomines are subject to spraying of chemical pesticides, which is the main strategy of vector control, native-wild species can persistently invade or colonize the household (peri-and intradomicile).…”

Altitudinal distribution and species richness of triatomines (Hemiptera:Reduviidae) in Colombia

“…Identifying ecological drivers for triatomine co-occurrence in Colombia, especially in the case of epidemiologically important species, can be coupled with ecological niche models to describe the population more accurately at risk of acquiring Chagas disease [ 10 ]. This could be complemented by calculating the TriatoScore, a recently described entomological risk score that takes into account the epidemiological relevance of each triatomine species along with their distribution and the ecoregions in which they occur [ 34 ].…”

Triatoma costalimai, a neglected vector of Trypanosoma cruzi in the Cerrado savannas of South America: A comprehensive review

“…Since the description of the species, confirmed records of T. costalimai occurrence consistently cluster in the upper Tocantins River Basin and associated ranges/plateaus, always to the east of the Araguaia River main channel ( Fig. 1 ) ( Sherlock & Serafim, 1972 ; Mello & Borges, 1981 ; Mello, 1982 ; García-Zapata et al., 1985 ; García-Zapata & Marsden, 1992 ; Elias et al., 1994 ; Marsden et al., 1994 ; Carcavallo et al., 1999 ; Lorosa et al., 1999a , b ; Silveira et al., 2001 ; de Oliveira, 2006 ; de Oliveira & Silva, 2007 ; Gurgel-Gonçalves et al., 2012a , b ; Machiner, 2012 ; Machiner et al., 2012 ; Pereira, 2012 ; Teves, 2012 , 2018 ; Leite, 2013 ; Pereira et al., 2013 ; Ribeiro et al., 2021 ; Souza et al., 2014 ; Minuzzi, 2016 ; Brito et al., 2017a , 2021 ; Ceccarelli, 2018 ; Ceccarelli et al., 2018a , b ; Minuzzi-Souza et al., 2017 ; Teves et al., 2019 ). As far as we are aware, the only record to the west of the Araguaia is an unconfirmed record from “Dom Aquino”, state of Mato Grosso ( Fig.…”

“…Triatoma costalimai is, therefore, a species with a relatively restricted distribution in the core Cerrado biome ( Fig. 1 ) ( Sherlock & Serafim, 1972 ; Mello & Borges, 1981 ; Mello, 1982 ; García-Zapata et al., 1985 ; García-Zapata & Marsden, 1992 ; Elias et al., 1994 ; Marsden et al., 1994 ; Carcavallo et al., 1999 ; Lorosa et al., 1999a , b ; Silveira et al., 2001 ; de Oliveira 2006 ; de Oliveira & Silva, 2007 ; Gurgel-Gonçalves et al., 2012a , b ; Machiner, 2012 ; Machiner et al., 2012 ; Pereira, 2012 ; Teves, 2012 , 2018 ; Leite, 2013 ; Pereira et al., 2013 ; Ribeiro et al., 2021 ; Souza et al., 2014 ; Minuzzi, 2016 ; Brito et al., 2017a , 2021 ; Ceccarelli, 2018 ; Ceccarelli et al., 2018a , b ; Minuzzi-Souza et al., 2017 ; Teves et al., 2019 ).…”

“…It is important to emphasize that the absence of T. costalimai records from other sites in the states of Tocantins, Goiás, Bahia, and Minas Gerais (as well as from neighboring Mato Grosso and the Federal District; see Fig. 1 ) is not due to the absence of surveys: there are thousands of records, derived from routine entomological surveillance and research projects, of many other triatomine-bug species in these administrative regions (see, e.g., Sherlock & Serafim, 1972 ; Lustosa et al., 1984 ; Silveira et al., 1984 ; Silva et al., 1991 , 1995 ; Diotaiuti et al., 1995 ; de Oliveira, 2006 ; de Oliveira & Silva, 2007 ; Gurgel-Gonçalves et al., 2012a , b , c ; Maeda et al., 2012 ; Pereira, 2012 ; Leite, 2013 ; Pereira et al., 2013 ; Souza et al., 2014 ; Vinhaes et al., 2014 ; Galvão & Gurgel-Gonçalves, 2015 ; Minuzzi, 2016 ; Brito et al., 2017b , 2021 ; Browne et al., 2017 ; Ceccarelli, 2018 ; Ceccarelli et al., 2018a , b ; Minuzzi-Souza et al., 2017 ; Ribeiro et al., 2019 , 2021 ). Also important is the absence of T. costalimai records from areas where “Cerrado rupestre” and/or “mata seca decídua calcária” are present, including parts of Goiás, Mato Grosso, Minas Gerais, or Bahia (see Fig.…”