India’s malaria map

Malaria has always been one of humanity’s biggest killers, but it may be far bigger than we realised. An unprecedented survey of the disease suggests that it kills between 125,000 and 277,000 people per year in India alone. In contrast, the World Health Organization puts India’s toll at just 16,000.

Other countries using similar accounting methods, such as Indonesia, may also be underestimating deaths from malaria. That means it could be killing many more than the WHO’s official estimate of nearly 1 million people a year worldwide, suggesting more money should be spent to fight it.

Estimates of malaria deaths in India are based on death rates recorded in clinics. They are corrected in an attempt to account for people missed by the health system, but a new study by an international team of researchers has found that these numbers have been vastly underestimated. This is partly because so many cases never make it to a clinic and because these people are more likely to die than those that get medical help.

Word of mouth

The researchers behind the survey include a group from the Centre for Global Health Research at the University of Toronto, Canada, which is collaborating with the Indian government on the Million Death Study, surveying 1.1 million households across India to improve the country’s health statistics. That includes gathering “verbal autopsies”, in which householders describe how family members died, to count deaths that were never officially diagnosed.


Each verbal autopsy was diagnosed by two local doctors. Their interpretation was the main source of potential error in the malaria study, says co-author Richard Peto of University of Oxford. However, the location and timing of the malaria deaths diagnosed matched the expected pattern for malaria but not for other feverish illnesses, suggesting they were accurate (see maps).

To estimate malaria’s yearly death toll, the researchers applied the percentage of deaths from malaria in the survey to the total number of deaths in India. When they included only the most certain diagnoses, in which both doctors immediately fingered malaria, the toll was 125,000 a year. Adding cases in which only one doctor diagnosed malaria raised the total to 277,000. The most likely toll, they conclude, is around 200,000.

Lessons from Africa

“When we’ve done studies of malaria control in Indian villages, we’ve seen so many really nasty cases of the disease that I always wondered why the official estimate was so low,” says Peto. “Malaria deaths happen out in the countryside. They’re invisible to the healthcare system.”

Bob Snow, a malaria epidemiologist with the University of Oxford’s research programme in Kenya, says the results suggest that some of the methods being used to fight malaria in Africa might work in India too. “Some states are not enormously different to what we see in highly malarial areas in Africa, suggesting universal coverage with insecticide-treated bed nets and access to prompt treatment will be cost-effective.”

Snow says he is not surprised the study found more malaria deaths then the official estimate, but calls it “startling” that as many as 86 per cent never saw a doctor. “India has a space programme but cannot provide prompt access to malaria treatment in Orissa state [where deaths are highest],” he said. “This study will surely be a wake-up call.”

Journal reference: The Lancet, DOI: 10.1016/s0140-6736(10)60831-8