A Kenyan study has shown that using clothes and bed sheets treated with insecticide can cut the risk of malaria by 42 per cent*, but whether the approach is feasible remains to be seen.

The study, published on 27 July in Malaria Journal, used an insecticide called permethrin, which is in the same class as chemicals used to treat bednets.

The World Health Organisation recommends such nets as they can halve people's chances of being infected with malaria.

But at US$6 each, the nets are too costly for many people, and families living in small dwellings may not have enough room to hang them. In many parts of Africa where malaria is rife fewer than three per cent of households have a net.

These communities need more appropriate malaria control strategies, say the researchers, led by Elizabeth Kimani of the African Population and Health Research Center in Kenya.

Kimani's team worked with 198 Somali refugees living in camps in Kenya. Half the participants had their clothes and bedding treated regularly with insecticide. The other participants' clothes and bedding were treated with plain water.

Those with treated clothing and sheets were 42 per cent* less likely to be infected with malaria and their dwellings contained significantly fewer mosquitoes.

None of the participants had side effects after wearing the treated clothes.

The researchers say this tactic should be considered for use among people such as slum dwellers, street children and refugees, especially during an influx to malaria-prone regions.

But malaria researcher Chris Curtis of the London School of Hygiene and Tropical Medicine, United Kingdom, questions the approach's feasibility.

He points out that while bednets only need to be treated once a year, much more insecticide would be needed for clothes over the same period, eliminating the cost-advantage of the method in the long-term.

Kimani's team treated clothes and bedding every three weeks because the insecticide wore off after about five washes.

Curtis adds that although bednets are too expensive for refugees, it would not be very expensive for aid agencies to provide them for free.

He also points out that malarial mosquitoes bite at night, so clothes worn during the day
would not be worth treating.

*Corrected on 7 August from 70 per cent, as published on 2 August

Link to full paper in Malaria Journal

Reference: Malaria Journal 5, 63 (2006)