It is very interesting to compare the costs of carrying out bioenvironmental control measures and chemical spray ing. "It is the cheapest way of preventing malaria, cheaper even than DDT,' confirms V P Sharma, director, Malaria Research Centre, New Delhi. "And on a national basis, it will turn out even cheaper,' he adds.

According to a study conducted by the National Environmental Engineering Research Institute (NEERI), Nagpur, the per capita cost of bioenvironmental control is Rs 7.1, whereas application of DDT and HCH costs Rs 9.91 and Rs 8.97, respectively. Lindane, a chemical pesticide introduced in 1996 as a substitute for HCH, costs more than double that of bioenvironmental control. Medicated mosquito bednets and larvicides (chemical and biological) are three to four times more expensive.

"With bioenvironmental control measures, we also have attached employment and income generation schemes such as fish culture and social forestry. They will themselves be enough to carry the cost,' Sharma points out. It should also be noted that the estimate of bioenvironmental control does not take into account the long-term savings from better health, hygiene and environment.