Efficacy and Safety of Indoor Residual Spray for Dengue Vector Control

This quasi-experimental interventional study was conducted over 1 year, from May 2024-May 2025 at Station Health Organization, Combined Military Hospital, Peshawar Cantonment. Two comparable localities in Peshawar Cantonment were selected based on previous dengue incidence reports. Non-Probability consecutive sampling technique was used. Prior approval was sought from Station Commander, Station Headquarters Peshawar to conduct the study in Peshawar Cantonment. Hospital ethical review certificate was obtained (vide CMH Peshawar Letter No: 00254/25). Written informed consent was taken from the participants for inclusion in the study. One locality was designated as the intervention area (Indoor Residual Spray applied), and the other as the control area (Indoor Residual Spray not applied). Households were selected using a non-probability consecutive sampling technique.

In the intervention area, indoor residual spraying was conducted using Deltamethrin 2.5% WP, following WHO guidelines. Spray teams were trained and monitored to ensure proper application on interior walls, dark corners, and mosquito resting sites. Spraying was repeated every three months.

Entomological surveys were conducted at baseline and monthly thereafter in both areas, using larval/pupal indices (House Index and Breteau Index). Adult mosquito density was measured using backpack aspirators and resting catches. Dengue case data was collected by the Station Health Organization from CMH Peshawar and cross-checked with the Pathology department of the same hospital. The study was conducted as pilot study of the organization.

Data was analyzed using Statistical Pacakage for Social Sceinces version 27. Mean mosquito density, larval indices, and dengue incidence were compared between intervention and control areas using paired t-test. A p-value < 0.05 was considered statistically significant.