Back with a vengeance

Malaria is making a comeback. Parasites and mosquitoes have developed resistance to drugs and insecticides and new drugs are too costly and their effect short-lived

 
Published: Sunday 31 August 1997

Back with a vengeance

considering the amount of money that has gone into it, failure to control malaria is one of the more outstanding setbacks on the health front in independent India. According to an estimate, malaria cost the country between us $0.5 and 1 billion (Rs 1787.5 and 3575 crore) in 1991. In 1994-95, the per capita cost of spraying insecticides such as dichlorodiphenyl trichloroethane (ddt ), hexachlorocyclohexane ( hch ) and malathion was Rs 9, Rs 8.89, and Rs 36.12 respectively.

The 1990s mark a resurgence of malaria. Cases vary from 2.5 to 2.9 million annually. Of late, small malaria outbreaks have blown into epidemics involving an entire eco-epidemiological zone. In the last few years, devastating epidemics have occurred in western and eastern Rajasthan, Manipur, Tripura, the Indo-Bhutan border, and the Mewat region of Haryana.

The approach to malaria control through chemical insecticides has lost its impact and can no longer be relied as an umbrella approach to malaria control. The parasites that cause malaria have increasingly developed resistance to the most effective of the drugs available in the market, and mosquitoes that transmit the killer disease have developed resistance to insecticides that have been used indiscriminately. New drugs and insecticides to combat resistance are too costly to be used in India and their effectiveness is temporary.

The fall and rise of malaria

Before the introduction of ddt in 1945, malaria was affecting an estimated 75 million people, 800,000 of whom died annually. During epidemics, these figures increased substantially. ddt spraying was started in small projects in many states. Wherever ddt was sprayed malaria was wiped out. This was an instant success and malaria eradication seemed imminent. Successful demonstration of malaria control by ddt spraying led to the launching of National Malaria Control Programme ( nmcp ) in 1953.

In 1958, the Union government converted nmcp to National Malaria Eradication Programme ( nmep ). nmep started as a time bound eradication programme with the final goal of freedom from malaria within seven to nine years. The euphoria of initial success in controlling the disease was so overwhelming that malaria was considered a disease of the past and all future work was gradually de-emphasised.

But due to inadequate vigilance in the maintenance and consolidation phases and shortages of insecticides, malaria cases started to multiply from 1964. In the mid 1970s, incidence of malaria climbed steeply to about 6.5 million cases across the country. Previously confined to rural areas, it had started spreading in urban areas. Large-scale distribution of drugs such as chloroquine accompanied by the spraying of ddt helped control malaria. But in the 1990s, it is making a comeback. And dealing with it has never been more difficult.

Drug resistance Treatment of malaria is becoming problematical and expensive due to increasing drug-resistance in malarial parasites. At present, most cases of malaria are caused by resistant parasites and mosquitoes. In a recent study in Senegal, malarial deaths have increased eleven-fold due to resistance in P falciparum ( Pf ) to chloroquine. In India, resistance to chloroquine in Pf was first detected in 1973 in Diphu and Karbi Anglong districts in Assam. It remains the cause for more deaths due to malaria than any other parasite. Monitoring of drug-resistance in Pf began in 1978. Resistance has been spreading westwards step by step.

By 1984 the problem of resistance had spread to the entire country. Drug resistance is largely distributed along the tribal settlements, highly industrialised pockets, international borders, and in regions with rapid changes in demographic profile. On an average, 30 per cent of Pf cases tested positive for resistance to chloroquine, which remains the most commonly used drug against malaria.

In severe cases of resistance to Pf , sulphadoxine and sulphalene pyrimethamine combination drug therapy is used. The parasite is slow in developing resistance to sulpha drugs but of late, there has been a systematic rise in resistance, largely because of self medication. New drugs such as mefloquine and artemisinin have been added to treat drug resistant malaria. Due to the long half-life of mefloquine, resistance develops rapidly. This has already happened in Surat, Gujarat. Another malarial parasite, P vivax , has also developed resistance to chloroquine.

Resistance to insecticides in mosquitoes has compounded the problem. Anopheles culicifacies is the most common vector of malaria in India. Almost all cases of malaria in rural plains and peri-urban areas are caused by it. The vector has become resistant to the most widely-used insecticides such as ddt , hch and malathion. Moreover, it has an inherent tendency to become resistant to new insecticides.

In urban areas, most cases of malaria are caused by A stephensi . It breeds in clear water stored for domestic use in the overhead water storage tanks, cisterns, sumps, wells and rain water collection in and around houses. A stephensi has also become resistant to ddt and hch and in some areas to malathion but resistance is not an obstacle in its control, as the methods used are anti-larval.

Heavy price
Malaria largely inflicts the poor localities as they provide the ideal conditions for the mosquitoes and the parasites. The cost of treatment, especially when the parasites and mosquitoes have developed resistance, is out of the reach of a large section of India's population. Cost of treatment of sensitive strains of P vivax and P falciparum is about Rs 8 for 10 tablets of chloroquine. If chloroquine injections are to be given for three days, the cost increases to Rs 50. In case of chloroquine resistant falciparum malaria, the cost of three tablets of sulphalene or sulphadoxine primathemine is Rs 25. This treatment is unsuitable for chloroquine resistant vivax strains.

Cost of treatment of chloroquine resistant vivax and sulpha resistant P falciparum with quinine and tetracycline increases to Rs 240 (Rs 210 for 42 tablets of quinine and Rs 30 for 28 capsules of tetracycline). A three-day course of quinine injection and oral quinine can cost Rs 150.

In contrast, treatment cost of mefloquine varies from Rs 2,000 to 3,000. This does not include the costs of supportive therapy or consultation fees. Treatment cost of a serious and complicated malaria case in hospitals vary from Rs 3,000 to 5,000 for children and up to Rs 25,000 for adults.

Bioenvironmental malaria control
The Malaria Research Centre has been pioneering the cause of bioenvironmental malaria control as the first line of attack on malaria. A beginning was made in 1984 in Nadiad Taluka, Kheda district, Gujarat. Malaria had struck the rural areas causing high morbidity and deaths, and vector control by insecticide spraying was not productive. At this stage bioenvironmental interventions were applied in the control of malaria. Water collection sites were filled and levelled, drainage was improved, larvivorous fishes were introduced in ponds and other stagnant water bodies, communities were involved in various environmental management methods and intensive weekly surveillance was instituted for early case detection and prompt treatment of positive cases.

Successful demonstrations were also carried out in Panaji, Goa, where every 10th person had malaria and the problem of P falciparum and drug resistance was on the rise. Bioenvironmental interventions successfully controlled malaria in two years. In Chennai, larval control by fish, mosquito proofing of overhead tanks, and source reduction were successful in controlling the disease. Similar successes were demonstrated in the control of malaria at Bharat Heavy Electricals Ltd ( bhel ), Hardwar.

This project was reviewed by a high-power committee chaired by S Pattanayak and appointed by the Indian Council of Medical Research ( icmr ) in 1995. "Despite commendable achievements of the project, the committee members were surprised to find that the technology has not been utilised by the nmep or the state governments in any big way except isolated examples of Kolar district in Karnataka and Madras city (now Chennai). Even at the bhel , where malaria control has saved enormous loss to the industry and Goa where tourism has been saved, the technology did not find replacement in the existing control set up," said the report of the committee.

Need for policy changes
Malaria control has to rely on preventive vector control to be effective in the future. This is an attainable goal by the constitution of intersectoral committees at the district, state and central level. The committees should have members drawn from various development agencies which create mosquitogenic conditions such as the departments of irrigation, public works department and other construction agencies, agriculture and fisheries, forestry, industries, health, voluntary agencies and any other agency identified which may be helpful in reducing vector breeding potential. Similarly, towns should have their own committees.

Malaria is a local phenomenon and therefore solution lies in the support and involvement of communities in the programme tailored as a holistic approach to control malaria. Malaria Research Centre has demonstrated the positive role of communities in malaria control, but this requires the knowledge of local transmission dynamics of malaria; a mix of appropriate and indigenous control strategies; emphasis on information, education and communication; and, involvement of the local voluntary agencies.

A revised malaria control strategy is currently under implementation. Under the revised malaria control strategy, responsibility for financial, technical and administrative aspects of malaria control would be shared by major establishments and institutions in the private and public sectors.

V P Sharma is director of the Malaria Research Centre, New Delhi.

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