Plasmodium vivax accounts for about 50 per cent of the total malaria cases in India

Just how effective is the common anti-malaria drug Chloroquine? The malaria parasite Plasmodium vivax is frequently said to be resistant to the drug.

A new study, published in the September 2006 issue of the Transactions of the Royal Society of Tropical Medicine and Hygiene, an internationally acclaimed peer reviewed medical journal, suggests that the Plasmodium vivax accounts for about 50 per cent of the total malaria cases in the country — and that Chloroquine may be still an effective anti-malarial drug in India. The researchers found that though Plasmodium vivax has shown resistance to Chloroquine in different parts of the world, in all the 287 Indian patients involved in the study the drug showed excellent efficacy.

The study was conducted by Indian researchers led by Neena Valecha from the Malaria Research Centre (now renamed the National Institute of Malaria Research), one of the institutes of the Indian Council of Medical Research and researchers from the World Health Organisation, Switzerland. They looked at 287 patients in various parts of India. “Since few cases of treatment failure have been reported from India, this study was undertaken to generate data systematically on the efficacy of Chloroquine in 287 patients from different epidemiological regions,” the researchers write in the journal. Chloroquine has been considered the drug of choice for controlling malaria caused by Plasmodium vivax. “(With Chloroquine), cure rates for 28 days were 100 per cent and there was a rapid parasite clearance rate in all age groups from all study sites,” the researchers found. When reports from various corners of the globe say that malaria caused by Plasmodium vivax may be resistant to Chloroquine, in India the scenario is different. Chloroquine is still an effective remedy for malaria in this country, the study suggests.

“The study is impressive. A large number of malaria cases do respond well to chloroquine. We should not ignore this while treating our patients,” says Dr Bikram Kumar Saha, a former assistant professor of medicine at R.G. Kar Medical College Hospital, Calcutta. “Malaria is vectored by mosquitoes and is caused by four species of the malaria parasite: Plasmodium vivax, Plasmodium falciparum, Plasmodium malariae and Plasmodium ovale. Chloroquine is effective against all the species of malaria parasite, but Plasmodium falciparum (the parasite that causes falciparum malaria) has shown evidence of resistance to the drug in some parts of the country,” he adds.

Dr Bhupinder Singh Kalra of the department of pharmacology, Maulana Azad Medical College, Delhi, says, “Chloroquine is the prototype anti-malarial drug, most widely used to treat all types of malarial infections. It is also the cheapest, time tested and among the safest anti malarial agents.” He adds, “Almost all cases of Plasmodium vivax malaria respond to Chloroquine and resistance to this drug has been reported only in sporadic cases in countries like Iran, Myanmar, Papua New Guinea and Vanuatu. But Plasmodium falciparum has shown significant resistance to Chloroquine. Originally, both Plasmodia vivax and falciparum were sensitive to chloroquine, but, in recent years, more and more Plasmodium falciparum are developing resistance to Chloroquine,” says he.

According to a statement relating to the government’s World Bank-assisted Malaria Control Project, “Both Plasmodium vivax and Plasmodium falciparum contribute almost equally to India’s malaria burden; although, of course, malaria is not neatly distributed and both strains can occur in the same place, indeed in the very same patient. Recent data from the National Vector-borne Disease Control Programme indicates that only 52 districts of India’s total 602 districts show signs of Chloroquine resistance in P. falciparum.”

However, in places, where Chloroquine-resistant falciparum malaria cases are seen, a relatively new drug, Artemisinin, has been found to be effective. With Artemisinin and other anti-malaria agents, a new treatment approach has been implemented, and it’s called Artemisinin-based combination therapies (ACT). The statement on the World Bank-assisted Malaria Control Project adds, “Following increasing instances of Chloroquine-resistant falciparum cases, the Government of India, in keeping with the World Health Organisation’s 2003 recommendation, has begun administering ACT in high-risk areas... We respect the government’s policy to limit the use of ACT to only those areas showing Chloroquine resistance, while concurrently strengthening surveillance to identify emerging areas of chloroquine resistance.”

All this has to be seen in the context of the criticism that the drugs available to treat malaria aren’t doing enough to control the disease. Currently, about 2 million cases of malaria are reported in India. The number of deaths reported annually from malaria has dramatically dropped, from about 8 million in 1947, to 500-800 a year. Says Dr Saha, “India has done appreciable work to control malaria; keeping this in account, unnecessary criticism of malaria-controlling initiatives should be avoided. Criticism should be based on proper documentation, otherwise it will just lead to confusion among people and health care professionals.”

An article by Lawrence M. Barat of the Global Health, Population, and Nutrition Group Academy for Educational Development in the US published in January 2006 in The American Journal of Tropical Medicine and Hygiene backs the point. “While many countries struggle to control malaria, four countries, Brazil, Eritrea, India and Vietnam, have successfully reduced the malaria burden,” he says.