Malaria Kills Twice as Many People as Previously Estimated, UW Researchers Say

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Here's a happy thought to start your week: malaria's global death toll in 2010 was roughly 1.2 million people, about twice as high as experts previously believed. The staggering new casualty count is the result of some exhaustive research by scientists at the University of Washington, and it could have serious implications for global health organizations.

The research, published earlier this month in the British medical journal The Lancet, is the work of Professor Stephen Lim and his colleagues at the University of Washington's Institute for Health Metrics and Evaluation. Since the spring of 2007, Lim and others have attempted to quantify the "global burden of disease," calculating how many people die each year from specific illnesses, injuries, and other factors.

It is an exercise in the macabre, but an important one. If the World Health Organization and other agencies like it aren't sure what diseases are killing the most people and where, they can't be sure that the measures they're taking to prevent those deaths (delivering medicine, education initiatives, etc.) are effective or worthwhile.

For malaria, the researchers analyzed mortuary records and death registries from countries around the globe. In places that don't keep meticulous records -- including many areas in sub-Saharan Africa, where malaria is most prevalent -- the assessment was done via thousands of "verbal autopsies." As the name implies, a trained interviewer quizzes family members of the deceased about the symptoms that led to the demise of their loved one. Based on those interviews, epidemiologists can infer the cause of death. Some global health officials have disputed this method, with one WHO leader claiming that the verbal autopsies resulted in "overdiagnosis."

What Lim and his colleagues concluded is that previous studies vastly underestimated the number of adults who died from malaria. "Traditional thinking is that when children are exposed to malaria at a young age, they develop immunity," Lim explains. "Malaria mortality is still highest in very young children -- almost 60 percent in very young children -- but what that means is not that immunity develops, it's just to a lesser degree than previously thought."

Using the data from the verbal autopsies, Lim adjusted the death rate accordingly and used some advanced statistical analysis to calculate the disease's true body count. According to his figures, 1.2 million people died from malaria in 2010. That's actually a 32 percent decrease from 2004, but an overall increase from 1980.

The vast majority of the deaths occurred in sub-Saharan Africa. The deadly, mosquito-borne disease claimed the lives of 1.1 million Africans in 2010, down from 1.8 million in 2004, but far more than the 995,000 who succumbed to malaria in 1980. Outside of Africa, malaria deaths steadily decreased over the years, falling from 502,000 in 1980 to 104,000 in 2010.

The climbing malaria death toll in recent years is troubling considering that funding to combat malaria in Africa has skyrocketed over that same period. Development assistance for malaria increased from $149 million in 2000 to almost $1.2 billion in 2008, with about two-thirds of that money coming from the Global Fund to Fight AIDS, Tuberculosis and Malaria.

Lim says the problem is largely the result of anti-malaria campaigns tending to focus on children and pregnant women while overlooking adults. That strategy make some sense, he says, since more than half of the people who die from malaria are kids younger than five, but it is also the reason that eight times as many African adults died from malaria compared to other parts of the world.

"The most important interventions are things like making sure all individuals are covered by insecticide-treated bed nets," Lim says. "Not just woman and children, but older individuals. Our study showed increasing drug resistance to cloroquinine was driving in increases in mortality, so making sure populatoins at risk have access effective anti-malaria medication is also important."

Unfortunately, funding for those sorts of life-saving initiatives is running dry. The Global Fund to Fight AIDS, Tuberculosis and Malaria announced recently that it has run out of money for future grants. The Bill and Melinda Gates Foundation, which also paid for Lim's research, has stepped up to fill the void, but the future remains uncertain.

For Lim, the funding shortfall is troubling. While he deals with abstract numbers that reflect millions of deaths, he doesn't overlook the reality that each of those is an individual life lost.

"To some degree we always sit back and are reminded that all the numbers we deal with at the Institute represent real people," Lim says. "That's an important thing for us working in the kind of things we do to remember that."

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