Cost-comparison of DDT and alternative insecticides for malaria control

In anti-malaria operations the use of DDT for indoor residual spraying has declined substantially over the past 30 years, but this insecticide is stil l considered valuable for malaria control, mainly because of its low cost r elative to alternative insecticides. Despite the development of resistance to DDT in some populations of malaria vector Anopheles mosquitoes (Diptera: Culicidae), DDT remains generally effective when used for house-spraying a gainst most species of Anopheles, due to excitorepellency as well as insect icidal effects. A 1990 cost comparison by the World Health Organization (WH O) found DDT to be considerably less expensive than other insecticides, whi ch cost 2 to 23 times more on the basis of cost per house per 6 months of c ontrol. To determine whether such a cost advantage still prevails for DDT, this paper compares recent price quotes from manufacturers and WHO supplier s for DDT and appropriate formulations of nine other insecticides (two carb amates, two organophosphates and five pyrethroids) commonly used for residu al house-spraying in malaria control programmes. Based on these 'global' pr ice quotes, detailed calculations show that DDT is still the least expensiv e insecticide on a cost per house basis, although the price appears to be r ising as DDT production declines. At the same time, the prices of pyrethroi ds are declining, making some only slightly more expensive than DDT at low application dosages. Other costs, including operations (labour), transporta tion and human safety may also increase the price advantages of DDT and som e pyrethroids vs. organophosphates and carbamates, although possible enviro nmental impacts from DDT remain a concern. However, a global cost compariso n may not realistically reflect local costs or effective application dosage s at the country level. Recent data on insecticide prices paid by the healt h ministries of individual countries showed that prices of particular insec ticides can vary substantially in the open market. Therefore, the most cost -effective insecticide in any given country or region must be determined on a case-by-case basis. Regional coordination of procurement of public healt h insecticides could improve access to affordable products.