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Shots - Health Blog
Thu February 2, 2012
Researchers Say Malaria Deaths Are Twice The Official Count
Originally published on Thu February 2, 2012 6:31 pm
If the new numbers are right, it means there's little chance that malaria deaths can be cut to near-zero by 2015, just three years from now. That's the official goal set last year by the World Health Organization.
"We estimate that if decreases from the peak year of 2004 continue, malaria mortality will decrease to less than 100,000 deaths only after 2020," write Christopher Murray and his colleagues in this week's edition of The Lancet.
The group does ratify what a Lancet editorial calls the "phenomenally successful" campaign that has reduced malaria deaths in Africa by 30 percent since the 2004 peak.
"It's rare in global health that we see such a clear quantitative story," Murray told Shots. "You can see the money flowing in, you can see the expansion of interventions, and you can see the outcome."
He says the success has been driven by the distribution of insecticide-treated bed nets (145 million in 2010 alone) and effective combination drug therapy (181 million courses in 2010).
Murray, whose specialty is triangulating disease and death incidence from maddeningly sparse and incomplete data, says there's more uncertainty about malaria deaths than from any other cause.
After all, death certificates and cause-of-death data are nonexistent in many of the 99 countries where malaria is still a problem.
One of the principal ways the researchers get around this is to use "verbal autopsies." The technique involves extensive interviewing of families and neighbors of deceased people to put together a picture of their symptoms and infer the cause of death.
"With a lot of effort, we ended up with 163 verbal autopsy studies that met our quality criteria," Murray said.
With those studies, other kinds of fill-in-the-gap indicators and a lot of fancy extrapolation, the team has come up with what it calls "the most systematic assessment to date of malaria mortality."
Their most important finding is that in 2010 there were 433,000 more malaria deaths worldwide among people over age 5 than the WHO estimates.
This challenges a widespread belief about malaria deaths – that they mainly involve young children. The WHO says 86 percent of such deaths are children under 5, and 91 percent occur in Africa.
But Murray says his group's finding runs counter to the traditional wisdom "at least as I learned it in medical school, that you acquire immunity as a child and don't die of it as an adult." In other words, children who don't die of it grow up to be resistant to the malaria parasite, more or less. They may get sick from it, but they're not very likely to die, as conventional wisdom has it.
That's the reason one tenet of anti-malaria strategy is to focus prevention efforts, such as distribution of bednets, on young children and mothers.
Murray acknowledges that young children are much more likely to die of malaria – perhaps 10 times more likely – but "there are a lot of people over age five, so even a lower risk adds up to a lot of deaths."
The new estimates are likely to prove controversial, just as previous work was questioned when it suggested a much higher malaria death rate in India, using such techniques as verbal autopsies. (The Murray group also says India contributes far more malaria deaths to the global total than the WHO estimates.)
"I would be very cautious" about the new estimates, Sarah Kline, director of the UK branch of the advocacy group Malaria No More told Shots. "It is a dramatic increase from what the WHO says, and it contributes to the overall discussion, but it's unclear if it will lead to significant policy change. The tools to combat malaria are the same."
The problem is, will the funds keep flowing to use those tools? The Global Fund to Fight AIDS, TB and Malaria, which has lately accounted for two-thirds of the world's anti-malaria spending, is in fragile condition. It suspended its next round of grants last fall, and everyone is wondering when and if the fight to end malaria will get back on track.