Post-Control Surveillance of Triatoma infestans and Triatoma sordida with Chemically-Baited Sticky Traps

Abstract

BackgroundChagas disease prevention critically depends on keeping houses free of triatomine vectors. Insecticide spraying is very effective, but re-infestation of treated dwellings is commonplace. Early detection-elimination of re-infestation foci is key to long-term control; however, all available vector-detection methods have low sensitivity. Chemically-baited traps are widely used in vector and pest control-surveillance systems; here, we test this approach for Triatoma spp. detection under field conditions in the Gran Chaco.Methodology/Principal FindingsUsing a repeated-sampling approach and logistic models that explicitly take detection failures into account, we simultaneously estimate vector occurrence and detection probabilities. We then model detection probabilities (conditioned on vector occurrence) as a function of trapping system to measure the effect of chemical baits. We find a positive effect of baits after three (odds ratio [OR] 5.10; 95% confidence interval [CI95] 2.59–10.04) and six months (OR 2.20, CI95 1.04–4.65). Detection probabilities are estimated at p≈0.40–0.50 for baited and at just p≈0.15 for control traps. Bait effect is very strong on T. infestans (three-month assessment: OR 12.30, CI95 4.44–34.10; p≈0.64), whereas T. sordida is captured with similar frequency in baited and unbaited traps.Conclusions/SignificanceChemically-baited traps hold promise for T. infestans surveillance; the sensitivity of the system at detecting small re-infestation foci rises from 12.5% to 63.6% when traps are baited with semiochemicals. Accounting for imperfect detection, infestation is estimated at 26% (CI95 16–40) after three and 20% (CI95 11–34) after six months. In the same assessments, traps detected infestation in 14% and 8.5% of dwellings, whereas timed manual searches (the standard approach) did so in just 1.4% of dwellings only in the first survey. Since infestation rates are the main indicator used for decision-making in control programs, the approach we present may help improve T. infestans surveillance and control program management.

Production and Characterization of Porous Kaolinite Modified Pellets for Slow Release Pheromone.

“…It is expected that the pellets can replace the polyethylene vials and reduce costs in potential surveillance tools of Chagas disease vectors (13). It is noteworthy that the highest percentage of capture occurred during the first 60 days of the test, which corroborates the results observed in the release assays of benzaldehyde.…”

“…One of the potential methods that are being experimentally tested consists in using polyethylene bags, which store a substance (pheromone) to attract the vector (kissing bugs or triatomines). According to Rojas de Arias et al (13), release rates of hexanal and benzaldehyde from polyethylene vials remain only 20 days at room temperature. This rapid evaporation of the attractive substance constitutes the main disadvantage of using this strategy of release, since when the technique is being tested in a season, control activities are carried out at one, three and six months of post-spraying.…”

Modeling Disease Vector Occurrence When Detection Is Imperfect II: Drivers of Site-Occupancy by Synanthropic Triatoma brasiliensis in the Brazilian Northeast

“…Mounting empirical evidence, such as that presented here and elsewhere [13], [41], shows how naïve indices based on active bug-searches are biased down, sometimes severely (Fig. 3, Text S1).…”

Intensified Surveillance and Insecticide-based Control of the Chagas Disease Vector Triatoma infestans in the Argentinean Chaco

“…Reinfestation of human habitations and peridomestic structures after insecticide application has been documented for most of the main triatomine species [4], [6]–[8]. Sources of reinfestation for T. infestans have usually been associated with passive bug transport by people, active dispersal of bugs from residual or untreated foci, and more rarely and with less supporting evidence, from sylvatic foci [9]–[14]. For several species such as Triatoma dimidiata , Triatoma brasiliensis and Rhodnius ecuadoriensis , sylvatic foci represent the major source of bugs [15]–[18].…”