PMI Supports Indoor Residual Spraying (IRS) of Homes to Prevent Malaria in Africa

Malaria is transmitted to humans by the bite of female Anopheles mosquitoes that are infected with malaria parasites. In Africa, these mosquitoes generally feed on people indoors at night and, after feeding, tend to rest on walls. Indoor residual spraying (IRS) consists of spraying the interior walls of homes with insecticides to kill mosquitoes that land on the walls to rest after feeding. These insecticides remain effective three to 10 months, depending on the insecticide used, the type of wall surface, and whether the homeowner washes or replasters the wall after spraying. In order for an IRS program to be fully effective, the World Health Organization (WHO) recommends that at least 80 percent of houses in a targeted area be sprayed, usually once or twice a year, depending on the length of the transmission season and the duration of effectiveness of the insecticide.

PMI has supported IRS activities in 15 focus countries. PMI activities include assessing the environment to ensure safe and effective use of insecticides, educating residents about the benefits of IRS, training local personnel to conduct spray operations, procuring insecticide and equipment, and monitoring and evaluating spray activities.

Across Africa, insecticide resistance is emerging as a major threat to both IRS and insecticide-treated nets. Insecticide resistance is of particular concern in West and East African countries. PMI is working with WHO and other partners to develop robust resistance monitoring and mitigation strategies.

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