An observational analysis of the impact of indoor residual spraying with non-pyrethroid insecticides on the incidence of malaria in Ségou Region, Mali: 2012–2015

• Published in: Malaria Journal
• Main Authors: Joseph Wagman, Christelle Gogue, Kenzie Tynuv, Jules Mihigo, Elie Bankineza, Mamadou Bah, Diadier Diallo, Andrew Saibu, Jason H. Richardson, Diakalkia Kone, Seydou Fomba, Jeff Bernson, Richard Steketee, Laurence Slutsker, Molly Robertson
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2018
• Subjects: Indoor residual spraying; Malaria incidence; Observational analysis; Mali; Next generation IRS; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-017-2168-2; https://doaj.org/article/107a3a470dc44e5ab52f6c8363f39c8a

Abstract Background Ségou Region in Central Mali is an area of high malaria burden with seasonal transmission, high access to and use of long-lasting insecticidal nets (LLINs), and resistance to pyrethroids and DDT well documented in Anopheles gambiae s.l. (the principal vector of malaria in Mali). Ségou has recently received indoor residual spraying (IRS) supported by Mali’s collaboration with the US President’s Malaria Initiative/Africa Indoor Residual Spraying programme. From 2012 to 2015, two different non-pyrethroid insecticides: bendiocarb in 2012 and 2013 and pirimiphos-methyl in 2014 and 2015, were used for IRS in two districts. This report summarizes the results of observational analyses carried out to assess the impact of these IRS campaigns on malaria incidence rates reported through local and district health systems before and after spraying. Methods A series of retrospective time series analyses were performed on 1,382,202 rapid diagnostic test-confirmed cases of malaria reported by district routine health systems in Ségou Region from January 2012 to January 2016. Malaria testing, treatment, surveillance and reporting activities remained consistent across districts and years during the study period, as did LLIN access and use estimates as well as An. gambiae s.l. insecticide resistance patterns. Districts were stratified by IRS implementation status and all-age monthly incidence rates were calculated and compared across strata from 2012 to 2014. In 2015 a regional but variable scale-up of seasonal malaria chemoprevention complicated the region-wide analysis; however IRS operations were suspended in Bla District that year so a difference in differences approach was used to compare 2014 to 2015 changes in malaria incidence at the health facility level in children under 5-years-old from Bla relative to changes observed in Barouéli, where IRS operations were consistent. Results During 2012–2014, rapid reductions in malaria incidence were observed during the 6 months following each IRS campaign, though ...