Effectiveness of stand-alone anti-adult mosquito control strategies against Aedes-borne diseases: scoping review with meta-analysis.

Background: The world is witnessing the emergence of infections transmitted by Aedes mosquitoes. However, preventing large outbreaks challenges the health systems of endemic countries. Targeting infected adult Aedes mosquitoes may be a better means for resource-constrained health systems where integrated vector control may be less feasible. We reviewed the evidence of the effectiveness of stand-alone adult mosquito control measures against Aedes mosquito-borne diseases in this scoping review and meta-analysis.

Methods: The MEDLINE, Embase, Scopus and Cochrane Library (Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials [CENTRAL] and Cochrane Methodology Register) electronic bibliographic databases for randomised controlled trials (randomised for individual or cluster of houses), blinded at any level or open-label, conducted anywhere in the world during the period 1 December 2012 to 31 November 2022 and published in the English language. The search terms included only terms relating to or describing the intervention, combined with the Cochrane/MEDLINE filter for the eligible studies. The searches were rerun just before the final analyses and further studies were retrieved for inclusion. A narrative synthesis of the findings from the included studies was provided. Risk of bias (quality) assessment was done using Cochrane's risk of bias assessment tool. Summaries of the intervention effects for each study were provided by calculating the odds ratios for dichotomous outcomes and standardised mean differences for continuous outcomes. Data analysis was done using Review Manager version 5.4. Heterogeneity was assessed using the Cochrane χ2 test, I2 statistic and τ2 test. Potential publication bias was evaluated and illustrated using funnel plots. The data were pooled using a fixed/random effects meta-analysis and the effect measures, their 95% confidence intervals (CIs) and two-sided p-values for each outcome. Subgroup analyses were used as the sensitivity analysis. Results were plotted using forest plots for all outcome variables in the study.

Results: The standardised mean reduction in the number of indoor adult Aedes aegypti mosquitoes was 1.81 (95% CI 0.76 to 2.86) because of anti-adult interventions. The reduction in the incidence of dengue in houses deploying measures against adult A. aegypti mosquitoes was 28%, but statistically not significant (pooled odds ratio [Mantel-Haenszel, random]) was 0.72 (95% CI 0.28 to 1.86). However, the effect measure could be influenced by co-interventions like decreased insecticide actions and lack of community engagement. Subgroup analysis revealed that all the measures targeting adult Aedes mosquitoes are effective in reducing A. aegypti abundance.

Conclusions: Interventions targeting adult Aedes mosquitoes are significantly reducing the indoor adult A. aegypti abundance and hence the risk of Aedes-borne infections. However, the effect could decrease over time and care should be exercised in the sustainability of such interventions. More evidence should be generated for epidemiological outcomes such as a reduction in infections rather than entomological outcomes such as larval indices and vector abundance.