Why was DDT used to try to control the spread of malaria?
DDT has several characteristics that are of particular relevance in malaria vector control. Among the 12 insecticides currently recommended for this intervention, DDT is the one with the longest residual efficacy when sprayed on efficacy ceilings (6-12 months depending on dosage and nature of substrate). In similar conditions, other insecticides have a much shorter residual efficacy.Depending on the duration of the transmission season, the use of DDT alternatives might require more then two spray cycles per year, which would be very difficult to achieve and sustain in most settings.
