Combining next-generation indoor residual spraying and drug-based malaria control strategies: observational evidence of a combined effect in Mali

• Published in: Malaria Journal
• Main Authors: Joseph Wagman, Idrissa Cissé, Diakalkia Kone, Seydou Fomba, Erin Eckert, Jules Mihigo, Elie Bankineza, Mamadou Bah, Diadier Diallo, Christelle Gogue, Kenzie Tynuv, Andrew Saibu, Jason H. Richardson, Christen Fornadel, Laurence Slutsker, Molly Robertson
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2020
• Subjects: Indoor residual spraying; Observational analysis; Seasonal malaria chemoprevention; Combined malaria control strategies; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-020-03361-y; https://doaj.org/article/3ffe6f40beeb4b03922535e400a5fc93

Abstract Background Ségou Region in central Mali is an area of high malaria burden with seasonal transmission. The region reports high access to and use of long-lasting insecticidal nets (LLINs), though the principal vector, Anopheles gambiae, is resistant to pyrethroids. From 2011 until 2016, several high-burden districts of Ségou also received indoor residual spraying (IRS), though in 2014 concerns about pyrethroid resistance prompted a shift in IRS products to a micro-encapsulated formulation of the organophosphate insecticide pirimiphos-methyl. Also in 2014, the region expanded a pilot programme to provide seasonal malaria chemoprevention (SMC) to children aged 3–59 months in two districts. The timing of these decisions presented an opportunity to estimate the impact of both interventions, deployed individually and in combination, using quality-assured passive surveillance data. Methods A non-randomized, quasi-experimental time series approach was used to analyse monthly trends in malaria case incidence at the district level. Districts were stratified by intervention status: an SMC district, an IRS district, an IRS + SMC district, and control districts that received neither IRS nor SMC in 2014. The numbers of positive rapid diagnostic test (RDT +) results reported at community health facilities were aggregated and epidemiological curves showing the incidence of RDT-confirmed malaria cases per 10,000 person-months were plotted for the total all-ages and for the under 5 year old (u5) population. The cumulative incidence of RDT + malaria cases observed from September 2014 to February 2015 was calculated in each intervention district and compared to the cumulative incidence reported from the same period in the control districts. Results Cumulative peak-transmission all-ages incidence was lower in each of the intervention districts compared to the control districts: 16% lower in the SMC district; 28% lower in the IRS district; and 39% lower in the IRS + SMC district. The same trends were observed in the u5 ...