Dichlorodiphenyltrichloroethane (DDT) for Indoor Residual Spraying in Africa: How Can It Be Used for Malaria Control?

Abstract

In 2006, the World Health Organization issued a position statement promoting the use of indoor residual spraying (IRS) with dichlorodiphenyltrichloroethane (DDT) for malaria vector control in epidemic and endemic areas. Other international organizations concurred because of the great burden of malaria and the relative ineffectiveness of current treatment and control strategies. Although the Stockholm Convention of 2001 targeted DDT as 1 of 12 persistent organic pollutants for phase-out and eventual elimination, it allowed a provision for its continued indoor use for disease vector control. Although DDT is a low-cost antimalarial tool, the possible adverse human health and environmental effects of exposure through IRS must be carefully weighed against the benefits to malaria control. This article discusses the controversy surrounding the use of DDT for IRS; its effective implementation in Africa; recommendations for deployment today, and training, monitoring, and research needs for effective and sustainable implementation. We consider the costs and cost effectiveness of IRS with DDT, alternative insecticides to DDT, and the importance of integrated vector control if toxicity, resistance, and other issues restrict its use.

Insecticides for Vector-Borne Diseases: Current Use, Benefits, Hazard and Resistance

“…DDT is therefore credited with wholesale suppression and even complete disappearance of vector species such as Anopheles sergenti and Anopheles funestus from sizeable areas of Egypt, South Africa, Madagascar and Mauritius (Pampana, 1963;Curtis and Lines, 2000). Unfortunately, few African countries participated in the GMEC and even so, the reductions obtained were not sustained after the eradication period because limited resources were devoted to malaria control (Rogan and Chen, 2005;Sadasivaiah et al, 2007).…”

“…In India, IRS with DDT has been the mainstay of vector control for more than 5 decades. In general, reports to the WHO showed that the use of DDT for malaria vector control increased substantially among the African nations during 2000-2005 (Table 5), but decreased almost to zero in the Americas due to the signing of the North American Agreement on Environmental Cooperation, a side accord to the North American Free Trade Agreement (Sadasivaiah et al, 2007).…”

“…Compare to 1990s, there is a global decline trend in DDT use, but still on an average, 40,000 tonnes of DDT were used annually during 2006 -2007 for vector control (Figure 2). This is similar to the annual amount used during the malaria eradication period of 1955-1970. Concerns about the continued use of DDT are fuelled by recent reports of high levels of human exposure associated with IRS amid accumulating scientific evidence on chronic health effects (Sadasivaiah et al, 2007 During [2006][2007], about 90% of the total quantity of all classes of insecticides was reportedly used for IRS for vector control, followed by space spraying (4%), larviciding (3.8%), treatment of mosquito nets (0.3%) and other applications (0.6%). All regions 2000-2002 OC 307 445 725 0 0 879 761 0 1 187 931 OP 34 170 358 136 58 988 6 660 1 482 000 6 205 1 946 158 C 331 2 811 1 481 133 1 237 0 6 993 PY 2 688 460 940 7 901 ...…”

“…This provision was approved without any objection by approximately 150 national delegations (Stockholm Convention on Persistent Organic Pollutants, 2001). However, still the possible adverse human health and environmental effects of exposure through IRS must be carefully weighed against the benefits of DDT as being low-cost antimalarial tool (Sadasivaiah et al, 2007). WHO has therefore approved the use of DDT under specific condition when "locally safe, effective, and affordable alternatives are not available".…”

Co-Intercalation of Insecticides with Hexadecyltrimethylammonium Chloride in Mozambican Bentonite

“…Presently DDT is used for this method as it lasts longer than other insecticides currently approved by WHO [7]. DDT is however too stable and therefore is classed as a persistent organic pollutant that bio-accumulates in the ecosystem [8].…”