Journal Article

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

dos Santos, Roberto F., de Carvalho, Cristiane M. M., Reis, Renato B., Gurgel-Gonçalves, Rodrigo, Reis, Mitermayer G., Abad-Franch, Fernando, dos Santos, Carlos G. S., Fonseca, Eduardo O. L., Ribeiro-Jr, Gilmar, Cunha, Gabriel M., de Sousa, Orlando M. F.

2021

Overview

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

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Animals / Biogeography / Biomedical and Life Sciences / Biomedicine / Brazil / Brazil - epidemiology / Chagas disease / Chagas Disease - epidemiology / Chagas Disease - parasitology / Chagas Disease - transmission / Control / Decision making / Disease control / Disease transmission / disease vectors / Diseases / Dwellings / Entomology / Environment / Environmental aspects / Epidemiology / Geographical distribution / Grasslands / Health risk assessment / Health risks / Health surveillance / Housing / Housing Quality / Humans / Indigenous species / Infectious Diseases / Infestation / Insect Vectors - classification / Insect Vectors - parasitology / Insect Vectors - physiology / Introduced species / Land use / land use change / Latin America / Methods / Municipalities / Native organisms / Native species / Nonnative species / Parasitology / Poverty / Protozoa and protozoan diseases / Public health / Risk / Risk Factors / Risk stratification / Savannahs / Sentinel health events / Strata / Surveillance systems / Triatoma infestans / Triatominae / Triatominae - classification / Triatominae - parasitology / Triatominae - physiology / Tropical Medicine / Trypanosoma cruzi / Trypanosoma cruzi - physiology / Urbanization / Vector control / Vector surveillance / Vector-borne diseases / Vectors / Vectors (Biology) / Veterinary Medicine/Veterinary Science / Virology