Community participation in Chagas disease vector surveillance: systematic review

Abstract

Background: Vector control has substantially reduced Chagas disease (ChD) incidence. However, transmission by household-reinfesting triatomines persists, suggesting that entomological surveillance should play a crucial role in the long-term interruption of transmission. Yet, infestation foci become smaller and harder to detect as vector control proceeds, and highly sensitive surveillance methods are needed. Community participation (CP) and vector-detection devices (VDDs) are both thought to enhance surveillance, but this remains to be thoroughly assessed.

Methodology/principal findings: We searched Medline, Web of Knowledge, Scopus, LILACS, SciELO, the bibliographies of retrieved studies, and our own records. Data from studies describing vector control and/or surveillance interventions were extracted by two reviewers. Outcomes of primary interest included changes in infestation rates and the detection of infestation/reinfestation foci. Most results likely depended on study- and site-specific conditions, precluding meta-analysis, but we re-analysed data from studies comparing vector control and detection methods whenever possible. Results confirm that professional, insecticide-based vector control is highly effective, but also show that reinfestation by native triatomines is common and widespread across Latin America. Bug notification by householders (the simplest CP-based strategy) significantly boosts vector detection probabilities; in comparison, both active searches and VDDs perform poorly, although they might in some cases complement each other.

Conclusions/significance: CP should become a strategic component of ChD surveillance, but only professional insecticide spraying seems consistently effective at eliminating infestation foci. Involvement of stakeholders at all process stages, from planning to evaluation, would probably enhance such CP-based strategies.

Figure 1. Flow diagram of the systematic review process.

Figure 2. Geographical-ecological coverage of studies on Chagas disease vector control and surveillance.

Study site locations (black dots) are overlaid on the World Wildlife Fund ecoregional map of Latin America (available with detailed ecoregion legends at www.conserveonline.org/docs/2001/06lac_ecoregions.jpg).

Figure 3. Detection of Chagas disease vectors by notification by residents vs. alternative methods: estimated odds ratios and 95% confidence intervals.

NR, notification of vector presence by residents; AS, active searches by vector control staff (ASfo, using a flushing-out agent); DDgn, vector-detection devices (Gómez-Núñez boxes); (h), results regarding bug presence inside houses; (p), results in the peridomestic area; the reference number and sample size are indicated in parentheses; studies were ranked by mean effect size; the vertical dashed line indicates no effect; effects are significant at the 95% level when the CI does not cross the dashed line; point estimate values >1 indicate a positive effect of the first method in the comparison; see Table 2 for details.

Figure 4. Detection of Chagas disease vectors by vector-detection devices vs. alternative methods: estimated odds ratios and 95% confidence intervals.

AS, active searches by vector control staff (ASfo, using a flushing-out agent; ASkd, using full insecticide application to ‘knock-down’ the bugs); DD, vector-detection devices (DDgn, Gómez-Núñez boxes; DDmb, ‘María’ boxes; DDb, box; DDps, paper sheet; DDp, plastic boxes); (p), results in the peridomestic area; the reference number and sample size are indicated in parentheses; studies were ranked by mean effect size; effects are significant at the 95% level when the CI does not cross the dashed line; point estimate values >1 indicate a positive effect of the first method in the comparison; see Table 3 for details.