Dataset Information

Towards environmental detection of Chagas disease vectors and pathogen.

ABSTRACT: Chagas disease vector control relies on prompt, accurate identification of houses infested with triatomine bugs for targeted insecticide spraying. However, most current detection methods are laborious, lack standardization, have substantial operational costs and limited sensitivity, especially when triatomine bug densities are low or highly focal. We evaluated the use of FTA cards or cotton-tipped swabs to develop a low-technology, non-invasive method of detecting environmental DNA (eDNA) from both triatomine bugs and Trypanosoma cruzi for use in household surveillance in eastern Colombia, an endemic region for Chagas disease. Study findings demonstrated that Rhodnius prolixus eDNA, collected on FTA cards, can be detected at temperatures between 21 and 32 °C, when deposited by individual, recently blood-fed nymphs. Additionally, cotton-tipped swabs are a feasible tool for field sampling of both T. cruzi and R. prolixus eDNA in infested households and may be preferable due to their lower cost. eDNA detection should not yet replace current surveillance tools, but instead be evaluated in parallel as a more sensitive, higher-throughput, lower cost alternative. eDNA collection requires virtually no skills or resources in situ and therefore has the potential to be implemented in endemic communities as part of citizen science initiatives to control Chagas disease transmission.

SUBMITTER: Gysin G

PROVIDER: S-EPMC9194887 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Towards environmental detection of Chagas disease vectors and pathogen.

Gysin Grace G Urbano Plutarco P Brandner-Garrod Luke L Begum Shahida S Kristan Mojca M Walker Thomas T Hernández Carolina C Ramírez Juan David JD Messenger Louisa A LA

Scientific reports 20220614 1

Chagas disease vector control relies on prompt, accurate identification of houses infested with triatomine bugs for targeted insecticide spraying. However, most current detection methods are laborious, lack standardization, have substantial operational costs and limited sensitivity, especially when triatomine bug densities are low or highly focal. We evaluated the use of FTA cards or cotton-tipped swabs to develop a low-technology, non-invasive method of detecting environmental DNA (eDNA) from b ...[more]

PMID: 35701602

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Project description:BackgroundTriatoma infestans-mediated transmission of Tripanosoma cruzi, the causative agent of Chagas disease, remains as a major health issue in southern South America. Key factors of T. infestans prevalence in specific areas of the geographic Gran Chaco region-which extends through northern Argentina, Bolivia, and Paraguay-are both recurrent reinfestations after insecticide spraying and emerging pyrethroid-resistance over the past ten years. Among alternative control tools, the pathogenicity of entomopathogenic fungi against triatomines is already known; furthermore, these fungi have the ability to fully degrade hydrocarbons from T. infestans cuticle and to utilize them as fuel and for incorporation into cellular components.Methodology and findingsHere we provide evidence of resistance-related cuticle differences; capillary gas chromatography coupled to mass spectrometry analyses revealed that pyrethroid-resistant bugs have significantly larger amounts of surface hydrocarbons, peaking 56.2+/-6.4% higher than susceptible specimens. Also, a thicker cuticle was detected by scanning electron microscopy (32.1+/-5.9 microm and 17.8+/-5.4 microm for pyrethroid-resistant and pyrethroid-susceptible, respectively). In laboratory bioassays, we showed that the virulence of the entomopathogenic fungi Beauveria bassiana against T. infestans was significantly enhanced after fungal adaptation to grow on a medium containing insect-like hydrocarbons as the carbon source, regardless of bug susceptibility to pyrethroids. We designed an attraction-infection trap based on manipulating T. infestans behavior in order to facilitate close contact with B. bassiana. Field assays performed in rural village houses infested with pyrethroid-resistant insects showed 52.4% bug mortality. Using available mathematical models, we predicted that further fungal applications could eventually halt infection transmission.ConclusionsThis low cost, low tech, ecologically friendly methodology could help in controlling the spread of pyrethroid-resistant bugs.

Project description:BackgroundThe developmental time of vector insects is important in population dynamics, evolutionary biology, epidemiology and in their responses to global climatic change. In the triatomines (Triatominae, Reduviidae), vectors of Chagas disease, evolutionary ecology concepts, which may allow for a better understanding of their biology, have not been applied. Despite delay in the molting in some individuals observed in triatomines, no effort was made to explain this variability.MethodologyWe applied four methods: (1) an e-mail survey sent to 30 researchers with experience in triatomines, (2) a statistical description of the developmental time of eleven triatomine species, (3) a relationship between development time pattern and climatic inter-annual variability, (4) a mathematical optimization model of evolution of developmental delay (diapause).Principal findings85.6% of responses informed on prolonged developmental times in 5(th) instar nymphs, with 20 species identified with remarkable developmental delays. The developmental time analysis showed some degree of bi-modal pattern of the development time of the 5(th) instars in nine out of eleven species but no trend between development time pattern and climatic inter-annual variability was observed. Our optimization model predicts that the developmental delays could be due to an adaptive risk-spreading diapause strategy, only if survival throughout the diapause period and the probability of random occurrence of "bad" environmental conditions are sufficiently high.Conclusions/significanceDevelopmental delay may not be a simple non-adaptive phenotypic plasticity in development time, and could be a form of adaptive diapause associated to a physiological mechanism related to the postponement of the initiation of reproduction, as an adaptation to environmental stochasticity through a spreading of risk (bet-hedging) strategy. We identify a series of parameters that can be measured in the field and laboratory to test this hypothesis. The importance of these findings is discussed in terms of global climatic change and epidemiological consequences.

Project description:BackgroundChagas disease is a neglected tropical disease and Trypanosoma cruzi (its etiological agent) is mainly transmitted by triatomines (Hemiptera: Reduviidae). All triatomine species are considered as potential vectors; thus, their geographic distribution and habitat information should be a fundamental guide for the surveillance and control of Chagas disease. Currently, of the 137 species distributed in the Americas (Justi and Galvão 2017), 17 species are cited for Argentina: Panstrongylus geniculatus, P. guentheri, P. megistus, P. rufotuberculatus, Psammolestes coreodes, Triatoma breyeri, T. delpontei, T. eratyrusiformis, T. garciabesi, T. guasayana, T. infestans, T. limai, T. patagonica, T. platensis, T. rubrofasciata, T. rubrovaria and T. sordida. Almost 20 years have passed since the publication of the "Atlas of the Triatominae" by Carcavallo et al. (1998) and no work has been done to provide an updated complete integration and analysis of the existing information for Argentinean triatomine species. Here we provide a detailed temporal, spatial and ecological analysis of updated occurrence data for triatomines present in Argentina.New informationThis is the first database of the 17 triatomine species present in Argentina (15917 records), with a critical analysis of the temporal, spatial and ecological characteristics of 9788 records. The information spans the last 100 years (1918-2019) and it was mostly obtained from the DataTri database and from the Argentinean Vector Reference Center. As 70% of the occurrences corresponded to the last 20 years, the information was split into two broad periods (pre-2000 and post-2000). Occurrence data for most species show distribution range contractions, which, from the pre-2000 to post-2000 period, became restricted mainly to the dry and humid Chaco ecoregions. Concurrently, the highest species richness foci occurred within those ecoregions. The species T. infestans, T. sordida, T. garciabesi and T. guasayana mostly colonise human dwelling habitats. This study provides the most comprehensive picture available for Argentinean triatomine species and we hope that any knowledge gaps will encourage others to keep this information updated to assist health policy-makers to make decisions based on the best evidence.

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Towards environmental detection of Chagas disease vectors and pathogen.

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Towards environmental detection of Chagas disease vectors and pathogen.

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