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.

Triatomine bugs of the genera Triatoma and Rhodnius are vectors of Chagas disease, a neglected tropical disease of humans in South America caused by Trypanosoma cruzi. Triatoma virus (TrV), a natural pathogen of Triatoma infestans, has been proposed as a possible tool for the bio-control of triatomine bugs, but research into this virus has been hampered by a lack of suitable host cells for in vitro propagation. Here we report establishment and partial characterisation of continuous cell lines from embryos of T. infestans (TIE/LULS54) and Rhodnius prolixus (RPE/LULS53 and RPE/LULS57). RNAseq screening by a sequence-independent, single primer amplification approach confirmed the absence of TrV and other RNA viruses known to infect R. prolixus, indicating that these new cell lines could be used for propagation of TrV.

Background: Accurate surveillance of triatomine household infestation is crucial for Chagas disease vector control. However, no gold standard detection method with high levels of sensitivity or specificity is currently available. Several intrinsic features of triatomine bug behaviour and the lifecycle of Trypanosoma (T.) cruzi lead to deposition of environmental DNA (eDNA) in infested houses. This study evaluated the use of FTA cards and cotton-tipped swabs as low-technology, cost-effective tools for simultaneous detection of T. cruzi and vector eDNA in the laboratory and field. Methods/Principal Findings: This study had two components: (1) laboratory evaluation and optimisation of QIAcard® FTA® classic cards to detect Rhodnius (R.) prolixus eDNA by altering five different environmental variables (darkness, triatomine number, temperature, feeding status and degradation at ambient temperature); (2) detection of R. prolixus and T. cruzi eDNA from cotton-tipped house wall swabs from an endemic region in Casanare Department, Colombia. eDNA was extracted from all specimens and amplified using a multiplex TaqMan qPCR assay targeting the R. prolixus 12S rRNA gene and T. cruzi satellite DNA region. R. prolixus eDNA from five 3rd/4th instar nymphs was successfully amplified from FTA cards after as little as 15 minutes of contact time under standard insectary conditions. Factors significantly increasing eDNA detection from FTA cards were increasing temperature from 21oC to 27-32oC, triatomine bug density from 1-25 bugs and recent blood-feeding. eDNA was detectable from FTA cards stored at room temperature for at least two weeks. In cotton-tipped swabs from the field, the sensitivity and specificity of R. prolixus eDNA detection was 60.6% (n=20/33) and 100% (n=33/33), respectively. T. cruzi eDNA was amplified from 93.9% (n=31/33) of infested houses. Conclusions/Significance: FTA cards are a highly sensitive tool for entomological surveillance of R. prolixus and exhibit little variability under different environmental conditions. Additionally, cotton-tipped swabs are a relatively sensitive tool for entomological and parasitological surveillance of R. prolixus and T. cruzi in situ, but more feasible due to low cost. Both methods could be utilised by citizen science initiatives to contribute to the control of Chagas disease in endemic communities.