Inexpensive and efficacious interventions that avert childhood deaths in sub-Saharan Africa have failed to reach effective coverage, especially among the poorest rural sectors. One particular example is insecticide-treated bed nets (ITNs). In this study, we present repeat observations of ITN coverage among rural Kenyan homesteads exposed at different times to a range of delivery models, and assess changes in coverage across socioeconomic groups.
Methods and Findings
We undertook a study of annual changes in ITN coverage among a cohort of 3,700 children aged 0–4 y in four districts of Kenya (Bondo, Greater Kisii, Kwale, and Makueni) annually between 2004 and 2006. Cross-sectional surveys of ITN coverage were undertaken coincidentally with the incremental availability of commercial sector nets (2004), the introduction of heavily subsidized nets through clinics (2005), and the introduction of free mass distributed ITNs (2006). The changing prevalence of ITN coverage was examined with special reference to the degree of equity in each delivery approach. ITN coverage was only 7.1% in 2004 when the predominant source of nets was the commercial retail sector. By the end of 2005, following the expansion of heavily subsidized clinic distribution system, ITN coverage rose to 23.5%. In 2006 a large-scale mass distribution of ITNs was mounted providing nets free of charge to children, resulting in a dramatic increase in ITN coverage to 67.3%. With each subsequent survey socioeconomic inequity in net coverage sequentially decreased: 2004 (most poor [2.9%] versus least poor [15.6%]; concentration index 0.281); 2005 (most poor [17.5%] versus least poor [37.9%]; concentration index 0.131), and 2006 with near-perfect equality (most poor [66.3%] versus least poor [66.6%]; concentration index 0.000). The free mass distribution method achieved highest coverage among the poorest children, the highly subsidised clinic nets programme was marginally in favour of the least poor, and the commercial social marketing favoured the least poor.
Rapid scaling up of ITN coverage among Africa's poorest rural children can be achieved through mass distribution campaigns. These efforts must form an important adjunct to regular, routine access to ITNs through clinics, and each complimentary approach should aim to make this intervention free to clients to ensure equitable access among those least able to afford even the cost of a heavily subsidized net.
Noor and colleagues found low levels of use of insecticide-treated mosquito nets when nets were mainly available through the commercial sector. Levels increased when subsidized nets were introduced and rose further when they were made available free.
Malaria is one of the world's most important killer diseases. There are over a million deaths from malaria every year, most of those who die are children in Africa. Frequent attacks of the disease have severe consequences for the health of many millions more. The parasite that causes malaria is spread by bites from certain species of mosquito. They mostly bite during the hours of darkness, so sleeping under a mosquito net provides some protection. In some countries where malaria is a problem, bed nets are already used by many people. A very much higher level of protection is obtained, however, by sleeping under a mosquito net that has been impregnated with insecticide. The insecticides used are of extremely low toxicity for humans. As insecticide-treated nets (ITNs) are a relatively new idea, people do need to be persuaded to buy and use them. ITNs must also be re-impregnated regularly, although long-lasting ones that remain effective for 3–5 y (or 21 washes) are now widely distributed. The nets are inexpensive by Western standards but the people who are most at risk of malaria have very little income. Governments and health agencies are keen to increase the use of nets, particularly for children and pregnant women. The main approach used has been that of “social marketing.” In other words, advertising campaigns promote the use of nets, and their local manufacture is encouraged. The nets are then sold on the open market, sometimes with government subsidies. This approach has been very controversial. Many people have argued that ways must be found to make nets available free to all who need them, but others believe that this is not necessary and that high rates of ITN use can be brought about by social marketing alone.
Why Was This Study Done?
It has been known for more than ten years that ITNs are very effective in reducing cases of malaria, but there is still a long way to go before every child at risk sleeps under an ITN. In Kenya, a country where malaria is very common, a program to increase net use began in 2002, using the social marketing approach. In 2004 most of the nets available in Kenya were those on sale commercially. In October 2004 health clinics started to distribute more heavily subsidized ITNs for children and pregnant women and, in 2006, a mass distribution program began of free nets for children. The researchers, based at the Kenya Medical Research Institute (KEMRI), wanted to find whether the number of children sleeping under ITNs changed as a result of these changes in policy. They also wanted to see how the rate of net use varied between families of different socioeconomic levels, as the poorest children are known to be most likely to die from malaria.
What Did the Researchers Do and Find?
This is a large study involving 3,700 children in four districts of Kenya. The researchers conducted surveys and then calculated the rates of net use in 2004, 2005, and 2006. In the first survey, when nets were available to most people only through the commercial sector, only 7% of children were sleeping under ITNs, with a very big difference between the poorest families (3%) and the least poor (16%). By the end of 2005, the year in which subsidized nets became increasingly available in clinics, the overall rate of use rose to 24%. By the end of 2006, following the free distribution campaign, it was 66%. The 2006 figure was almost exactly the same for the poorest and least poor families.
What Do These Findings Mean?
The rate of net use in the districts in the survey is much higher than expected, even though one-third of children were still not protected by ITNs. The sharp increases—particularly among the poorest children—after heavily subsidized nets were introduced and then after the free mass distribution suggests that this is a very good use of the limited amount of funds available for health care in Kenya and other countries where malaria is common. If fewer Kenyan children have malaria there will be cost savings to the health services. While some might claim that it is obvious that nets will be more widely used if they are free, there has been heated debate as to whether this is really true. Evidence has been needed and this research now provides strong support for free distribution. The study has also identified other factors which will be important in the continuing efforts to increase ITN use.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0040255.
The US Centers for Disease Control and Prevention provide information on malaria and on insecticide-treated nets (in English and Spanish)
The MedlinePlus encyclopedia contains a page on malaria (in English and Spanish). MedlinePlus brings together authoritative information from the US National Library of Medicine, National Institutes of Health, and other government agencies and health-related organizations
Information is available from the World Health Organization on malaria (in English, Spanish, French, Russian, Arabic, and Chinese) and from the Roll Back Malaria Partnership on the use of insecticide-treated nets
For information about the Medical Research Institute see the organization's Web site
The BBC Web site has a “country profile” about Kenya
Malaria data and related publications can be found on the Malaria Atlas Project Web site, which is funded by the Wellcome Trust, UK and is a joint project between the Malaria Public Health & Epidemiology Group, Centre for Geographic Medicine, Kenya and the Spatial Ecology & Epidemiology Group, University of Oxford, UK
The Kenya Ministry of Health, Division of Malaria Control Web site has useful information on malaria epidemiology and policies for Kenya