1. Fully screened houses for malaria vector control, a new paradigme
Ole Skovmand1, Ojera Odhiambo²,3, Rune Bosselmann1, John Vulule², Afrane Yaw2,3, Maurice Ombok². 1Intelligent Insect Control,118 Chemin des Alouettes, Castelnau-le-Lez, France ; ²Centre for Global Heath Research, Kenya Medical Research Institute, P O Box 1578, Kisumu, Kenya. 3Jaramogi Oginga Odinga University of Science and Technology, P.O Box Bondo, Kenya
The study was designed as a two cluster matched pair study, where houses with bed nets only were compared to houses with bed nets and fully screened. The mosquito indoor density was measured in all houses before and after the intervention by early morning pyrethrum spray. Collected mosquitoes were separated to species and the An gambiae complex analyzed by PCR. Further, people were interviewed for satisfaction, colour and material preference for FSH materials.
Insecticide content was analyzed in bednets, eave nets and other material.
The nets were fixed on the timber of the eves, since people replaster the walls with 1-2 years intervals. Otherwise, after 1 year 30 % to 50 % of nets would need to be displaced. For net attachment, a stapple gun was used combined with nales to resist resting cats (!)
Door nets were fixed by inhabitants at the sides of the door to give free access in day time; by evening, it would be folded back, but the door also closed.
Lamels delivered as a double bundle hung from the upper door frame and people were expected to enter between the lamels in day time, but the also displaced these to the sides. In future programs, these door nstallations will not be made since in practise, they were not used.
Curtains were fixed to the top and one side of the windows so that people could open the window for ventilation (which is not possible if the window opening is covered by e g a wall lining).
With some training, a ladder, nets delivered in rollers, a staple gun, a hammer and broad nales, lamels in double stranded bundles, time for setting up was minutes depending on house size. People does not have to move out furniture, cover food etc as preparation for IRS. Staff does not need masks etc. for application and there is no need for cleaning stations. Campaigns are thus less demanding. Eave nets are not touched daily and not washed. Therefore, they can hold more types of insecticide compared to bed nets and wall lining. The total netting compares to that of 2-3 bed nets depending on house size, but use and protection does not demand daily compliant behaviour.

2. Fully screened houses for malaria vector control, results after 2 years
Category
species
Mean Density
Univariate (RR 95%)
Multivariate (95%)
FSH+LLINS+LLIN
An. arabiensis
0.75
0.30( ) P<.0001
0.31( )**
LLIN-only
2.51
Ref
An. funestus
0.71
0.18( ) P<.0001
0.20( )**
3.86
Blood Fed
0.36
0.22( )P<.0005
0.22( )***
1.67
0.50
0.16( )P<.0001
0.17( )
3.22
Culicines
1.14
0.95( )P<.087
0.92( )*
1.24
There was no difference in numbers of mosquitoes caught per house in the two clusters (neighbour villages) before installation of FSH and bednets (data not shown), but there was a consistent difference during the two years after, though not significant in the dry seasons, where mosquito populations were small. Bednets alone had 4-5 times more indoor resting mosquitoes than FSH + bednets and also 4-6 times more blood fed. There was no difference in Culicines, Culex do not enter by the eaves.
Most eave nets were intact after 2 years, but 2 of 40 had rat holes. 20 out of 40 eve nets were still in place and functional after 4 years, compared to 2 bed nets out of 200.
Conclusions
Fully screened houses with bednets provide much better protection against indoor biting than do bednets alone as seen from indoor resting blood fed mosquitoes.
Eave nets last much longer than bed nets and protect every body inside. Net costs are lower for than for bed nets and installation staff in Africa replace cut and sewing staff in Asia thus meeting the demand form many African countries to move job to Africa for donor financed projects that target Africa. Calculated in better coverage and longer durability, eave nets with installation are much cheaper than bed nets. However, not all countries in Africa have village houses with open eaves.
Future
Eve nets are accepted by WHO in the group of interventions called « lethal house trap ». The product group still needs to document epidemiological impact on malaria.
To prove the concept as a stand-alone-tool, it must be scaled up and show impact on malaria
transmission. An extended group of institutes from Kenya and Tanzania co-operate to find funding for the epidemiological study, but such studies are very expensive.
We argue that eve nets protect everybody staying indoor after dark, including school children that has the lowest use rate of bed net and the highest infection rate of all age groups.