Project Lead(s): Harrysone Atieli
Controlling mosquitoes in developing countries to prevent malaria is a major challenge. One of the best preventive measures is to stop the indoor entry of mosquitoes that bite inhabitants inside a house.
In many rural parts of Africa, the typical house has a funnel-shaped overhanging roof with an open eave. Studies have shown that malaria vector host-seeking behaviour is well adapted for entering houses because they fly upwards when encountering a vertical surface, thus entering through the open eaves.
Simple changes in house design, using locally available, non-chemical materials, could be an effective and relatively cheap method of reducing vector–human contact and consequently malaria transmission.
An innovative malaria vector control strategy was carried out in Kenya and involved modifying a typical rural house by installing relatively-inexpensive, ventilated ceilings made from local mats.
A randomized controlled study was undertaken to determine the effects of house design modification on the densities of indoor resting mosquitos in the lowlands of western Kenya.
Intervention houses were fitted with locally made and available ceilings from papyrus mats, locally known as majamvi. The ceiling was fixed below the open eave to provide a mechanical barrier to vectors entering through the eaves to the living room.
A one square foot insecticide-treated net (ITN) was embedded in the ceiling in the sleeping room as a decoy trap to kill on contact mosquitoes flying up the eave space.
Control houses from the same location were not fitted with the ceiling.
The study showed that adding ventilated papyrus mat ceiling modification to houses reduced house entry densities (by An. gambiae s.l and An. funestus) by between 78–80% and 86% respectively, compared to unmodified houses.
Although the differences were not statistically significant, this strategy reduced human–malaria vectors contact, as the incidence of malaria was lower (29%) in residents of modified houses compared to those of unmodified houses (42%) – a 30.9% reduction in malaria incidence, attributable to the house design modification.
The community responded overwhelmingly well to this mode of vector control. A report on the strategy aired live on national television and was published in one of the leading national daily newspapers.
The project team plans to apply for Phase II Transition To Scale funding, with the main aim of creating a malaria-free model region using their strategy, together with other complementary malaria intervention strategies.