The global resurgence of malaria requires renewed and concentrated efforts to gain control(1). Strategies like the spraying of residual insicticides and chemotherapy, however, cannot be applied as easily as in the past because of insecticide resistance in almost all malarious areas of the world. Also, the rapid spread of parasite resistance to chloroquine and other antimalarials has made case treatment and chemoprophylaxis more difficult and less successful.
Since the time when mosquitos were implicated in the transmission of malaria parasites, mechanical barriers like bednets have been used to protect humans. However, their effectiveness in preventing infection and disease was in doubt and could not be demonstrated in controlled trials(2). In the beginning of the 1980s a hitherto little used insecticide, permethrin, was used to impregnate bednets. This greatly improved the protection of persons under the net because a large proportion of mosquitos was killed when they contacted the net and those that did not touch the net were repelled. Pyrethroid-impregnated nets have been shown to be not only an effective means of malaria control(3-7), but also selective and sustainable, thereby fulfilling the criteria for inclusion in the global malaria control strategy as defined at the Ministerial Conference in Amsterdam in 1992.(a) Since impregnated mosquito will be used in national malaria control efforts in the future, the economic aspects of their implementation and use have to be reviewed.
Health policies are chosen on the basis of effectiveness, need, and economic reasoning. The use of any measure can only be justified as long as the benefits derived from it outweigh the costs incurred. In a recent review of the economics of malaria control, Hammer (8) developed a conceptual framework for the settings of priorities in health, based on economic considerations; examination of the link between epidemiology and economics will show the relation between disease risk and the outcome effects of policies. Application of these ideas to the implementation and use of impregnated nets for malaria control at the national and household levels calls for investigation of the marginal benefits and costs as well as the marginal effects. Although the costs of bednets and their impregnation are given in a number of papers and the benefits (in terms of morbidity and mortality reduction) have been investigated, the benefits and costs have not been related. Health planners are at a loss to assess the economic implications of impregnated nets as an element in an integrated approach to malaria control. This article therefore presents and analyses the data found in a number of publications from different malarious areas.
Costs and benefits
The cost of impregnated mosquito nets
Mosquito nets are made out of a wide meshed cloth that allows air, but not mosquitos, to pass through. The cloth can be woven from many different materials including synthetic fibres. As specialized mechanical looms are required for their production, they are expensive and require an industrial setting. Only few malarious countries possess the infrastructure to produce the cloth for mosquito nets. Provided the cloth is available, the nets can be sewn locally, even at the village and household level. Local production may be geared to specific demand, but mass-produced nets tend to be cheaper. The market price of nets depends on the price of the cloth, labour costs, the demand and the capacity of the market to react to demand and to sell the product. The special cloth used to make bednets is produced cheaply in countries like Thailand and China, but import duties and other taxes may increase the cost substantially in other countries. Unfortunately, mosquito nets are still considered a luxury item by many officials in developing countries. The potential buyers of nets will weigh their cost against that of other household needs. …