Right from the "60s, DDT resistance of the malaria parasite host, Anopheles culicifacies, was detected in Gujarat. It was a rising trend. Another important vector, A stephensi, became so rugged that it can now grow in stagnant water found in coolers, used tyres -- just about anywhere.

DDT remains the mainstay for the NMEP, despite resistance of the vectors to it. Worldwide criticism of DDT"s carcinogenic effects and ICMR studies showing its presence even in infant milkfood formulae does not deter the NMEP officials from using it. "Under the present circumstances, it will be foolish to discard DDT," says Sharma.

Sharma looks at the issue in economic terms: "While the government spends Rs 45 to 50 lakh for the purchase of DDT, it has to shell out Rs 3.5 crore for Malathion and Rs 4 crore for Deltamethrin, a more advanced and effective insecticide. Insecticide costs account for Rs 50 crore of the Rs 110 crore budget of the malaria eradication programme."

The MRC has looked into a few alternatives against malaria. One of its major achievements is the development of novel ways to use neem oil against mosquitos (Down To Earth, Vol 1, No 10). The MRC has done research on 4 larvicidal bacteria, commonly called biolarvicides, and 2 species of fish that feed on mosquito larvae. The fish -- Gambusia (Gambusia affinis) and Guppy (Poecilia reticulata) -- have been found most effective in controlling the mosquito larvae. Says a MRC spokesperson, "Although they (the fish) are good, they cannot be used everywhere, especially in shallow, polluted or temporary waterbodies." Among biolarvicides, Bactoculicide and Spherix powder formulations of Russian origin have given "highly satisfactory" laboratory results in the first quarter of the 2-year research project. But conventional methods of mosquito control will dominate the scene in the next 5 years at least, caution MRC scientists.

Of late, the sandfly has also been showing resistance to DDT, especially in the Samastipur and Muzaffarpur districts of Bihar, says Thakur, quoting the Indian Journal of Medical Research and the WHO.

Environmental changes also enhance insecticide resistance among vectors. For instance, in Rajasthan, the water brought in by the Indira Gandhi Canal encouraged water-intensive crops such as wheat and cotton. DDT used against pests in the fields also promoted resistance in mosquito larvae (Down To Earth, Vol 3, No 13).

Internationally, one main problems in dealing with the poor person"s diseases is that there is a dearth of research funds. Says Tore Godal, director, Research and Training in Tropical Disease programme, "Despite the fact that 90 per cent of the global disease burden occurs in the tropics, only about 5 per cent of global health research and development investment is directed at reducing that burden." TB drug research gained new momentum only when the resurgence started in the West. Kala-azar is still treated with ancient antimonials as it is a tropical problem, not of interest to profit-seeking drug multinationals. The research interest mainly comes from the TDR programme.

Ironically, the national interest in these diseases has also been less than desirable. Says Rattan, "We have been suffering all these diseases; but it came into the agenda only when they started hitting the developed countries." While funds flow for novel methods in contraception, including vaccines, tropical disease drug research is still in its squalling infancy in India. Banerjee blames fund amputations. He points out that the budget was drastically cut in 1991-92 for disease control programmes, owing to the liberalisation policy, which had a direct impact on programmes like malaria eradication. Thakur says that the primary healthcare system in the kala-azar belt in Bihar is inadequate, with meagre facilities and the state government often sitting on the funds.

Ramalingaswami stresses on the need to beef up the control measures for TB, malaria, kala-azar and cholera. He calls for accurate documentation, integrated ecobiological studies and rapid-response information systems and also a political will for change. Otherwise, a spate of epidemics could play havoc with the Indian populace.

Mosquito moorings

Malaria profile of Southeast Asian nation