Irrigation-Induced Environmental Changes Sustain Malaria Transmission and Compromise Intervention Effectiveness
Guofa Zhou, Elizabeth Hemming‐Schroeder, Brook Jeang, Xiaoming Wang, Daibin Zhong, Ming‐Chieh Lee, Yiji Li, Lauren Bradley, Sabrina R Gobran, Randy E. David, Benyl M. Ondeto, Pauline Winnie Orondo, Harrysone Atieli, John I. Githure, Andrew K. Githeko, James W. Kazura, Guiyun Yan
Abstract
BACKGROUND: Irrigated agriculture enhances food security, but it potentially promotes mosquito-borne disease transmission and affects vector intervention effectiveness. This study was conducted in the irrigated and nonirrigated areas of rural Homa Bay and Kisumu Counties, Kenya. METHODS: We performed cross-sectional and longitudinal surveys to determine Plasmodium infection prevalence, clinical malaria incidence, molecular force of infection (molFOI), and multiplicity of infection. We examined the impact of irrigation on the effectiveness of the new interventions. RESULTS: We found that irrigation was associated with >2-fold higher Plasmodium infection prevalence and 3-fold higher clinical malaria incidence compared to the nonirrigated area. Residents in the irrigated area experienced persistent, low-density parasite infections and higher molFOI. Addition of indoor residual spraying was effective in reducing malaria burden, but the reduction was more pronounced in the nonirrigated area than in the irrigated area. CONCLUSIONS: Our findings collectively suggest that irrigation may sustain and enhance Plasmodium transmission and affects intervention effectiveness.