BackgroundThe identification of Trypanosoma cruzi and blood-meal sources in synanthropic triatomines is important to assess the potential risk of Chagas disease transmission. We identified T. cruzi infection and blood-meal sources of triatomines caught in and around houses in the state of Bahia, northeastern Brazil, and mapped the occurrence of infected triatomines that fed on humans and domestic animals.MethodsTriatominae bugs were manually captured by trained agents from the Epidemiologic Surveillance team of Bahia State Health Service between 2013 and 2014. We applied conventional PCR to detect T. cruzi and blood-meal sources (dog, cat, human and bird) in a randomized sample of triatomines. We mapped triatomine distribution and analyzed vector hotspots with kernel density spatial analysis.ResultsIn total, 5906 triatomines comprising 15 species were collected from 127 out of 417 municipalities in Bahia. The molecular analyses of 695 triatomines revealed a ~10% T. cruzi infection rate, which was highest in the T. brasiliensis species complex. Most bugs were found to have fed on birds (74.2%), and other blood-meal sources included dogs (6%), cats (0.6%) and humans (1%). Trypanosoma cruzi-infected triatomines that fed on humans were detected inside houses. Spatial analysis showed a wide distribution of T. cruzi-infected triatomines throughout Bahia; triatomines that fed on dogs, humans, and cats were observed mainly in the northeast region.ConclusionsSynanthropic triatomines have a wide distribution and maintain the potential risk of T. cruzi transmission to humans and domestic animals in Bahia. Ten species were recorded inside houses, mainly Triatoma sordida, T. pseudomaculata, and the T. brasiliensis species complex. Molecular and spatial analysis are useful to reveal T. cruzi infection and blood-meal sources in synanthropic triatomines, identifying areas with ongoing threat for parasite transmission and improving entomological surveillance strategies.

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

Authors' contribution: GR-Jr, RG-G, and MGR conceived the study. MGR raised funds and administered the project. GR-Jr, RG-G, MGR, contributed to the design of trial methods. RFA, CMMC, GMC, FCL, DLPM, OMFS, CGSS, EOLF, RFS, and RBR performed research. GR-Jr and MGR supervised students involved in field and laboratory research. CMMC, RFA, GMC, OMFS, CGSS, RFS obtain the databases, GR-Jr curated the dataset and analyzed the data. GR-Jr, RG-G, and MGR drafted the first version of the manuscript. All authors contributed to the interpretation of results, read and commented on manuscript drafts, and approved the final version. Conflict of Interest:All authors disclose no conflicts of interest during the development of this study. We certify that there is no conflict of interest with any relationships or support.Financial Support: Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB).

O alto consumo de agrotóxicos na Bahia e o impacto do uso de agrotóxicos na saúde e no ambiente exigem a aplicação de metodologias integradoras de vigilância e atenção à saúde das populações expostas. O texto relata uma experiência de educação em saúde voltada para a construção de metodologias e práticas integradas de vigilância e atenção à saúde de populações expostas a agrotóxicos, por meio da capacitação de técnicos das secretarias estadual e municipais de saúde, dos âmbitos central, regional e municipal. Nessa experiência, adotou-se a metodologia dialógica, valorizando as experiências individuais. Utilizaram-se instrumentos e mecanismos que permitiram a construção coletiva com base em uma determinada temática, potencializando a reflexão crítica da realidade. A abordagem teve como princípio a articulação intra e interinstitucional, a gestão da informação para a ação e a qualificação das equipes de saúde para atuarem em situações de rotina e em eventos inusitados. O Grupo de Trabalho de Agrotóxicos da Secretaria da Saúde do Estado da Bahia elaborou o plano de ação estadual, identificando estratégias para sua operacionalização, dentre elas o curso para técnicos de municípios definidos como prioritários, das áreas de Vigilância em Saúde e Centro de Referência Regional em Saúde do Trabalhador, bem como das respectivas Diretorias Regionais de Saúde. A experiência vivenciada pelos participantes durante o processo de concepção e realização do curso foi transformadora enquanto metodologia participativa e aprendizado coletivo, possibilitando a reflexão sobre a prática e o agir dos sujeitos. Palavras-chave: Vigilância em saúde pública. Agroquímicos. Metodologias de aprendizagem (ou educacionais). Exposição a produtos químicos. Atenção primária à saúde.

Background: This study presents a descriptive analysis of the occurrence of synanthropic triatomine species in the state of Bahia, before and after the implementation of the vector control program. Methods: Occurrence and number of collected specimens in the municipalities were analyzed in two periods: (A) 1957 to 1971, before systematic vector control actions; and (B) 2006 to 2019, after the certification of interruption of Chagas disease transmission by Triatoma infestans. Results: In total, 17 species were recorded during period A and 21 during period B. Panstrongylus megistus was the most frequent species in period A (42%), while Triatoma pseudomaculata (42%) and T. sordida (38%) were more frequent in period B. In period A, T. infestans was found in 26 (9%) municipalities, and in period B it was found in 7 (2%). During period B, most triatomines (88%) were captured at the peridomestic habitats, with a predominance of T. sordida (85%). Species with greatest relative abundance within the household were T. sordida (49%), T. brasiliensis (27%), and T. pseudomaculata (15%). Conclusions: We have observed a clear reduction in the occurrence of P. megistus and T. infestans and an increase in the relative abundance and geographical distribution of T. sordida and T. pseudomaculata after 40 years of the vector-control program. High frequency of other triatomine species in the municipalities of the state of Bahia and a great abundance of T. sordida in recent years, highlight the need to reinforce permanent entomological surveillance actions for Chagas disease.