Efficacy and cost‑effectiveness of outdoor residual spraying with α‑cypermethrin, pirimiphos‑methyl, and deltamethrin against sand flies: a pragmatic cluster randomised controlled field trial in Uganda

Authors

• Livingstone kamoga, Department of Nursing, Makerere University College of Health Sciences, Makerere, Uganda
• Edwin Kigozi, Department of Nursing, College of Health Sciences, Makerere University, Kampala, Uganda
• Nelson Ssewante, Child Health and Development Centre, College of Health Sciences, Makerere University, Kampala, Uganda.
• Blaise Kiyimba, Department of Medicine, College of Health Sciences, Makerere University, Kampala, UgandaFollow
• Shamim Nabidda, The Aga Khan UniversityFollow
• Elvis Seremba, Department of Medicine, College of Health Sciences, Makerere University, Kampala, Uganda
• Andrew Munerya, Amudat Church of Uganda Hospital, Amudat District Local Government, Amudat, Uganda
• Richard Achuma, Amudat Church of Uganda Hospital, Amudat District Local Government, Amudat, Uganda
• Damiano Lomokol, Amudat Church of Uganda Hospital, Amudat District Local Government, Amudat, Uganda
• Nantume Olivia, Department of Pharmacy, Kampala School of Paramedicals, Kayunga, Uganda
• Patrick Banadda Matovu, Department of Medicine, College of Health Sciences, Makerere University, Kampala, Uganda
• Daniel Tamale, Department of Nursing, College of Health Sciences, Makerere University, Kampala, Uganda
• Patrick Sagaki, Amudat Church of Uganda Hospital, Amudat District Local Government, Amudat, Uganda
• Joshua Joshua Epuitai Joshua Epuitai, Department of Nursing, Busitema University, Mbale, Uganda
• Felix Bongomin, Department of Medical Microbiology and Immunology, Faculty of Medicine, Gulu University, Gulu, Uganda
• Scovia Nalugo Mbalinda, Department of Nursing, College of Health Sciences, Makerere University, Kampala, Uganda

Document Type

Article

Department

School of Nursing and Midwifery, East Africa

Abstract

Introduction:  Visceral leishmaniasis (VL) is a significant public health challenge in East Africa. Achieving the WHO 2030 target of reducing VL mortality to below 1% requires novel control strategies. In this study, we evaluated the efficacy and cost-effectiveness of three insecticide formulations for outdoor residual insecticide spraying (ORS) in selected villages of Amudat district, Uganda.

Methods:  A pragmatic clustered randomised controlled field trial was conducted in five clusters. Three clusters were randomly allocated to receive ORS with either α-cypermethrin, pirimiphos-methyl, or deltamethrin, while two clusters served as untreated controls. The primary outcome was the change in sandfly counts per trap-night, measured using CDC light and sticky traps before and after the intervention. These were compared using the Wilcoxon signed-rank test to assess reductions independent of other villages. Then, we used negative binomial regression with a log link of trap-nights to model sandfly counts, which were included as an offset to account for variation in sampling effort.

Results:  After spraying the insecticides in the intervention villages, the sandfly population declined by 62%, 60%, and 49% with α-cypermethrin, pirimiphos-methyl, and deltamethrin, respectively. Sandfly captures increased by fourfold (353%) in the control villages in the same period. Using a negative binomial regression with villageclustered standard errors, α-cypermethrin reduced sandfly counts by 92% compared to the change in control villages (IRR=0.08, 95% CI 0.07–0.38, p< 0.001). Pirimiphos-methyl and deltamethrin reduced counts by 91% (IRR=0.09, 95% CI 0.07–0.45) and 89% (IRR=0.11, 95% CI 0.10–0.56), respectively. A cost-effectiveness analysis showed that α-cypermethrin emerged as a more cost-effective option, followed by deltamethrin and lastly pirimiphos-methyl, with annual cost per village of $382, $390 and $408, respectively.>

Conclusion:  Our findings provide tentative observations that may guide vector control programmes. The relatively high efficacy and favourable cost-effectiveness of α-cypermethrin are suggestive that it could be a suitable option for inclusion in integrated vector management strategies targeting outdoor sandfly populations in this region.

DOI

https://doi.org/10.1186/s41182-026-00985-9

Recommended Citation

kamoga, L., Kigozi, E., Ssewante, N., Kiyimba, B., Nabidda, S., Seremba, E., Munerya, A., Achuma, R., Lomokol, D., Olivia, N., Matovu, P. B., Tamale, D., Sagaki, P., Joshua Epuitai, J., Bongomin, F., Mbalinda, S. N. (2026). Efficacy and cost‑effectiveness of outdoor residual spraying with α‑cypermethrin, pirimiphos‑methyl, and deltamethrin against sand flies: a pragmatic cluster randomised controlled field trial in Uganda.
Available at: https://ecommons.aku.edu/eastafrica_fhs_sonam/605