Effectiveness of integrated vector management on the incidence of dengue in urban Malaysia: a cluster-randomised controlled trial

Abstract

Background: Malaysia is one of the southeast Asian countries hardest hit by dengue. We implemented a proactive integrated vector management (IVM) approach in a large non-blinded, cluster-randomised controlled trial to quantify its effectiveness on dengue incidence in urban settings.

Methods: In this cluster-randomised controlled trial we enrolled low-cost and medium-cost residential housing blocks in the Federal Territory of Kuala Lumpur and Putrajaya with recurrent dengue outbreaks. Of the 329 eligible sites, 139 were randomly allocated to receive IVM measures (community engagement, targeted outdoor residual spraying using K-Othrine Polyzone, and deployment of autodissemination devices to target both larval and adult mosquitoes) and 141 received routine vector control activities, stratified by block housing cost. The primary outcome was the comparison of dengue incidence between the two groups using information provided by the national e-Dengue surveillance system. Routine vector control activities continued in both control and intervention sites. The trial was retrospectively registered (ISRCTN81915073).

Findings: Between Feb 10, 2020, and Sept 30, 2022, we carried out our IVM approach in the 139 randomly selected intervention sites. 903 834 individuals (447 149 intervention, 456 685 control) were living in the study areas. Dengue was reported in 1434 individuals in the intervention group (mean incidence per 100 person-years of 0·16 [SD 0·18]) compared with 1663 in the control group (0·18 [0·19; risk ratio 0·86, 95% CI 0·70-1·06; p=0·17). No adverse effects were reported.

Interpretation: Our study did not show an effect on the primary endpoint of the overall dengue incidence. Several factors such as substantial decrease in dengue incidence during the COVID-19 pandemic could have reduced the statistical power to detect significant differences between the two groups. Preventive and long-lasting approaches such as our IVM should be further tested to see if targeted interventions could help limit the number of cases in high-risk transmission areas.

Funding: Ministry of Health Malaysia, Fondation Innovation en Infectiologie, the Australian Government, UK International Development from the UK Government, Envu.

Translation: For the Malay translation of the abstract see Supplementary Materials section.