Getting to grips with malaria: a view from India
The Indian national malaria eradication programme in Delhi dictates a single control strategy that all local state governments must follow. But this generalised approach, which worked in the 1940s and 1950s because of the initial effectiveness of DDT, no longer works as well now that many mosquitoes are resistant to the chemical.
A 'one size fits all' approach is also inappropriate in view of the environmental variations across India.
Malaria also exists as different 'ecotypes', categorised according to the habitat within which they are found — for example, urban malaria, forest malaria, rural malaria and coastal malaria.
The variations in ecotypes are caused by differing distribution of mosquitoes and parasites, resistance to insecticides and drugs, human living conditions — such as thatched houses that allow mosquitoes in, and climate.
And since the patterns of disease transmission for each ecotype differs greatly, control programmes need to be tailored accordingly.
Photo Credit: WHO
Malaria is caused by the parasite Plasmodium, and spread by mosquitoes. The main malaria-carrying mosquito in rural India is Anopheles culicifacies. This species carries the two main malaria parasites Plasmodium vivax and P. falciparum, which together cause about 65 per cent of malaria cases.
The rapidly spreading resistance of P. falciparum parasites — which cause the deadliest form of malaria — to existing drugs means that India’s treatment strategy needs to be urgently re-thought. Artemisinin combination therapies (ACTs) are emerging as the only effective way to treat this form of malaria. That they are used in combination is crucial because it massively reduces the likelihood of resistance emerging.
It is time India abandoned its policy of using anti-malarial drugs on their own, and switched to ACTs instead.
After a brief period of success in the mid-1960s, insecticide-resistant mosquitoes, insecticide shortages, financial constraints and administrative bottlenecks have allowed the disease to make a comeback.
Only a major overhaul of India’s malaria strategy will have a large enough impact on the disease.
Millions of unreported cases
India’s official figures show that every year, malaria infects 1.5-2 million people, killing 500 to 800 of them. But these figures are huge underestimates. The World Health Organization (WHO) says there are 100 million cases of malaria in its South-East Asia Region (which includes India), with 70 per cent contributed by India. This would imply that India has a staggering 70 million cases.
Most malaria cases in India are unlikely to be reported. The reason is that reporting deaths as malaria-related requires proof that the person had malaria parasites in their blood when they died. This evidence is nearly impossible to obtain in most malaria deaths because they tend to occur at home and in remote areas.
And these figures are set to rise. Investigations by the national eradication programme, state governments, the Delhi-based Malaria Research Centre and others have shown that surveillance, insecticide supplies and transport, and the spraying of DDT — a potent insecticide that kills mosquitoes — are all inadequate to combat the country’s growing malaria epidemic.
Several other factors compound the problem. Health workers are inadequately trained, and environmental changes — such as changing rainfall patterns and irrigation — help mosquitoes survive. And through migration, people carry the infection as they move from malaria-ridden regions to areas previously free of the disease.
Growing resistance to insecticides and drugs
In the mid-20th century, malaria seemed invincible in India. Records from 1947, for example, showed a massive 75 million cases of malaria and 800,000 deaths per year.
The advent of DDT heralded a new era of improved malaria control. In 1953, a specially created national malaria control programme began spraying DDT inside houses and cattle sheds in regions where malaria was widespread. Within a decade, new cases of disease dropped sharply to 100,000, following the launch of the country’s malaria eradication programme, which expanded DDT across the whole country.
But malaria continued to persist in India’s poverty-stricken, inaccessible regions.
Slowly, India began to lose its control of the disease, and malaria re-emerged. By 1976, it had reached 6.5 million cases.
Around 75–80 per cent of the budget for malaria control is spent on tackling A culicifacies, mainly through spraying DDT — which continues to be cheap and available — and other insecticides. But not only is the mosquito now largely resistant to DDT, it has also become resistant to other insecticides, including chemicals called pyrethroids, which are used to treat bednets.
The 2004 Stockholm Convention on Persistent Organic Pollutants banned the use of DDT. Although India is a signatory to the convention, it opted out on banning DDT, so that it could continue to try to control mosquitoes.
And the parasites are growing resistant to drugs too. Until the 1980s, P. falciparum caused 15–20 per cent of cases. But it now accounts for nearly half of all cases, and is found all over India, particularly in tribal settlements and in forests.
The parasite has started to take over because it has increasingly become resistant to widely used drugs such as chloroquine and sulfadoxine-pyrimethamine. In some areas P. falciparum is resistant to several drugs. For now, most cases of P. vivax — the other main malaria parasite in India — can be cured with chloroquine. Controlling P. falciparum, therefore, must be the country’s top priority.
India needs artemisinin combination therapies
Drug resistance is being amplified by India's inadequate drug policy, which still supports using a single drug for treating malaria.
Artemisinin, a derivative of the Chinese wormwood shrub, shows great promise for treating P. falciparum malaria. The WHO recommends using combinations of two or more drugs, one of which must be artemisinin, for all P. falciparum infections.
Using combinations of drugs means resistance is much less likely — since the chance that a parasite would simultaneously develop resistance to all the drugs in the combination is extremely small.
Despite the urgent need for ACTs in India — endorsed by the WHO and made official policy in several African countries, the country is refusing to implement them nationwide, despite exporting a form of artemisinin to 30 countries worldwide.
India does allow the use of an artemisinin drug as an injection in the private sector or for people hospitalised for severe malaria, but does not allow routine use.
Struggling to keep control
India’s efforts to control malaria over the past few decades have had mixed success. A programme to contain the spread of P. falciparum in 1977-1987 failed because it lacked focus, and overemphasised the use of DDT and surveillance over other control methods.
A 1970s scheme to quell urban malaria – spread by the mosquito A stephensi – tried to eliminate mosquito breeding sites by draining, filling or sealing water sources, and killing mosquito larvae with predatory fish. Despite its promise, the scheme was never successful.
But the idea of biological control is now working in some Indian states. The World Bank helps malaria control projects that have integrated treatment into a network of more than 1,000 primary healthcare centres in tribal settlements.
This initiative now helps limit mosquito populations by using fish to eat mosquito larvae in stagnant water.
This innovative method now forms the basis for effective malaria control in Maharashtra and other states.
The way ahead
India needs to decentralise malaria control. State governments should be allowed to tailor programmes to their local needs.
In addition, national anti-malarial drug policy must include ACTs for treating P falciparum malaria. To boost supplies of artemisinin, farmers should be encouraged to grow Artemisia annua in partnership with the pharmaceutical industry.
Community involvement can be vital. For example, community-based health workers can now operate reliable, easy-to-use diagnostic kits to detect P falciparum malaria. These kits are quicker than specialist techniques, and are vital since early diagnosis can save lives. And experience shows that at the local level communities can be very helpful in controlling mosquito breeding.
Integrated mosquito control requires knowledge about how different mosquitoes respond to treatments, the dynamics of malaria transmission, and maps showing the risk of malaria in a particular region.
New technologies must be adopted, such as long-lasting insecticide-treated nets and using fish to eat mosquito larvae. And hospitals need to be better equipped to manage severe and complicated malaria.
Until malaria is brought under control, the disease will continue to devastate communities and destroys local economies. If India is serious about freeing itself from the shackles of the disease, it needs to take these recommendations on board.
V.P. Sharma is a fellow at the Centre for Rural Development and Technology, Indian Institute of Technology, New Delhi, India. He is also the former director of the Malaria Research Centre in Delhi.