Improved detection of house infestations with triatomines using sticky traps: a paired-comparison trial in the Argentine Chaco

Gustavo Fabián Enriquez,María Sol Gaspe,Mariano Alberto Laiño,Julián Antonio Alvarado-Otegui,Marta Victoria Cardinal,Alejandra Alvedro,Ricardo Esteban Gürtler,María Carla Cecere

doi:10.1186/s13071-020-3891-z

Abstract

BackgroundWe conducted a matched-pairs trial of three methods for detecting house infestation with triatominae bugs in a well-defined endemic rural area in the Argentine Chaco.MethodsThe three methods included a simple double-sided adhesive tape (ST) installed near host resting sites; timed-manual collections with a dislodging aerosol (TMC, the reference method used by vector control programmes), and householders’ bug notifications (HN). Triatomine infestations were evaluated in 103 sites of 54 houses, including domiciles, kitchens and storerooms.ResultsIn domiciles where Triatoma infestans was collected, sensitivity of each single method decreased from 79% by ST and 77% by HN, to 57% by TMC, and increased to 92% when ST was combined with HN. In peridomestic kitchens and storerooms, TMC was relatively as sensitive as ST and significantly more sensitive than HN. On average, the number of bugs recovered by ST was 0.94 times that collected by TMC. The ST mainly collected early-instar nymphs whereas TMC yielded late (larger) stages. Triatomines caught by ST had significantly lower mean weight-to-length ratios and lower blood-feeding rates than those caught by TMC, suggesting the ST intercepted and trapped vectors seeking a blood meal host.ConclusionsThe ST may effectively replace TMC for detecting T. infestans in domiciles, and is especially apt for early detection of low-density domestic infestations in the frame of community-based surveillance or elimination programmes; decision making on whether an area should be targeted for full-coverage insecticide spraying, and to corroborate that extant conditions are compatible with the interruption of vector-borne transmission.

Highlights

We conducted a matched-pairs trial of three methods for detecting house infestation with triatominae bugs in a well-defined endemic rural area in the Argentine Chaco
Using definition 1, the sensitivity using a single method decreased from 78% as determined by sticky traps (ST) and 70% by timed-manual collections (TMC), to 54% by householdersbug notifications (HN), and increased to 88% when ST was combined with HN (Table 1)
The sensitivity of a single detection method decreased from 79% as determined by ST and 77% by HN, to 57% by TMC, and increased to 92% when ST was combined with HN

Summary

Introduction

Assessments of house infestation with triatomine bugs have classically been conducted using timed-manual collections (TMC) in the hands of skilled personnel assisted or not with a dislodging spray [16, 17] This method has limited sensitivity [16, 18,19,20,21], especially at the low triatomine densities that typically prevail after community-wide insecticide spraying campaigns. Given the substantial operational costs associated with TMC [22] and the absence of a “gold standard method” for establishing house infestation status, several passive devices have been developed and trialed under field conditions [20,21,22,23]. The validity of householder-based triatomine surveillance is affected by the vagaries of voluntary participation and shifting motivations, the skill of local residents, triatomine density, and whether householders provide proof of house infestation by returning triatomines to the designated receptors or not [18, 27, 30]

Methods

Results

Discussion

Conclusion