The number of people who die every year from malaria in India could be 13 times higher than current estimates, according to a study published online today in The Lancet. As with all estimates of malaria deaths, however, some researchers have doubts that the new figure is valid.
The report, part of the Indian government's Million Death Study, estimates that some 205,000 Indians under age 70 die annually from the disease. Previous World Health Organization (WHO) reports put the figure at 15,000. But several feel the WHO number is a gross underestimate because it relies mostly on government and health records. Many malaria deaths occur outside of hospitals and thus aren't easily recorded. And unlike more prolonged diseases, malaria can strike fast, making it even harder to track.
"Something like malaria, where within 48 hours a patient can actually be in coma and on their way out, they're far more likely to get missed," says Bob Snow, a tropical health scientist at the Kenya Medical Research Institute, who was not part of the study.
To try to get a better fix on malaria's toll, the authors—a team of scientists from India, Canada, the United Kingdom, and the United States—sent surveyors to randomly selected areas of India to gather information on deaths that had occurred there between 2001 and 2003. In conducting these so-called verbal autopsies, the surveyors asked families and other witnesses to describe what had happened to the victims. They asked whether they had suffered a fever, what kind of fever, and any other questions that might tip them off to malaria. In all, 130 physicians reviewed the reports, with two looking at each one.
When the results came back, 3.6% of roughly 75,000 deaths were attributed to malaria. That translates to 205,000 malaria deaths nationwide every year, according to the study, led by Neeraj Dhingra of the National AIDS Control Organisation in New Delhi. Ninety percent occurred in rural areas, and 86% occurred outside of any sort of health facility.
But the new figures could be vastly exaggerated, says Robert Newman, the director of WHO's Global Malaria Programme, who notes that using verbal accounts to diagnose a disease like malaria is incredibly risky. "For a disease that's got something that's very distinctive, let's say a very distinctive rash or paralysis associated with it, you can make a pretty accurate diagnosis through verbal autopsy," he says. "The problem with malaria is the symptoms associated with malaria, especially fever, are very nonspecific. So a lot of deaths that had fever associated with it are not necessarily malaria."
According to Newman, WHO tested the accuracy of such verbal autopsies in India before. A mere 4% of the ones that claimed to diagnose malaria actually did. "Malaria remains an important public health problem in India," he says, "but I just don't believe that we're talking about an order of magnitude difference."
Although verbal autopsies are "a blunt tool," Snow says he still believes The Lancet paper's estimate is legitimate. That's partly because so many deaths do slip through the cracks of India's health-information systems and partly because, at least in terms of geography, the study's stats match up with state-reported malaria deaths. There's also the fact that India is just so huge. "One state in India is several African countries," he says.
Snow says a study like this could force scientists to rethink WHO's global malaria statistics, especially in other heavily populated remote regions such as Myanmar, Bangladesh, and Pakistan. Newman says WHO will continue to work with Indian health officials and examine their data, though he emphasizes that these are things they do routinely.
Meanwhile, Snow hopes the Indian government will make fighting malaria an even larger priority—although the fact that the disease is largely concentrated in rural states may draw less attention to it.