Insecticide-treated bednets (ITNs) are widely promoted as a malaria prevention tool. The role and cost-effectiveness of indoor residual house spraying (IRS) for malaria control have received less attention. Research by the Kenya Medical Research Institute and other institutions found that IRS might be more effective and cheaper than ITNs in communities prone to epidemics of infection.

In Kenya, nearly seven million people (23 percent of the population) live in the 15 highland districts at risk of malaria epidemics. The researchers investigated the cost-effectiveness of IRS and ITNs used in an emergency relief operation in an epidemic-prone area of western Kenya. They selected 590 homesteads: 200 with no mosquito control, 200 with IRS and 190 with ITNs. They found that:

• The prevalence of malaria infection among household members not protected by either IRS or ITN is 13 percent.
• Sleeping under a treated bednet reduces the risk of infection by 63 percent and sleeping in a room sprayed with insecticide cuts the risk by 75 percent.
• The economic cost per infection case prevented by IRS is US$ 9 compared to US$ 29 for ITNs. IRS is consistently cheaper than ITNs, even taking into account cost recovery from the sale of ITNs.
• For ITNs, nearly two-thirds of the costs are attributed to community groups responsible for distributing nets and insecticide and the remaining 38 percent to buying supplies. Three-quarters of the costs for IRS are consumed by the price of the insecticide.
• IRS is well received in homesteads. All households wanted to have their homes sprayed again the following year and 96 percent suggest they would be willing to pay for this.

The detection and containment of malaria epidemics in Africa have re-emerged as international priorities as part of the WHO's Roll Back Malaria campaign. However, recommendations to governments on best practice for early warning and detection systems or how to manage epidemics effectively are rarely based on empirical evidence. As a result, Health Ministries in the most affected countries face considerable problems in developing responses to the public health crises caused by malaria epidemics.

This study shows that a single round of IRS is less than half as expensive as providing ITNs and three times more cost-effective in reducing malaria infection in western Kenya. The researchers conclude that IRS could play an important role in controlling malaria in often densely populated and economically important areas of Africa.

Source(s):
'Malaria prevention in highland Kenya: indoor residual house-spraying vs. insecticide-treated bednets', Tropical Medicine and International Health 7 (4): 298-303, by H. Guyatt, S. Corlett, T. Robinson, S. Ochola and R. Snow, 2002
HINARI subscribers can access the full-text article here. Full document.

Funded by: The Wellcome Trust

id21 Research Highlight: 10 June 2002

Further Information:
Helen Guyatt
Kenya Medical Research Institute/Wellcome Trust Collaborative Programme
PO Box 43640
Nairobi
Kenya

Fax: +254 2 711673
Contact the contributor: hguyatt@wtnairobi.mimcom.net

Kenya Medical Research Institute

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