New study: Containing malaria does not require global eradication
Published: Friday, February 22, 2013 at 2:05 p.m.
Last Modified: Friday, February 22, 2013 at 2:05 p.m.
Countries that implemented malaria eradication programs in the past several decades have generally stayed free of the disease, leading scientists to believe that a country-by-country or regional approach to eliminating the disease trumps global eradication programs.
According to a paper published Thursday in the journal Science, malaria elimination has been remarkably stable in the 79 countries with such programs between 1945 and 2010, with 95 percent of those countries still malaria-free.
"Normal theory would suggest resumption. In fact, all the countries still have mosquitoes and the climatic conditions, yet there have been very few outbreaks," said Andrew Tatem, a geography professor at the University of Southampton in the United Kingdom and a former faculty member at the University of Florida who was one of the paper's authors.
So what has led to the successful elimination in countries such as Chile, Argentina, Namibia and Swaziland — all in the Southern hemisphere, where malaria has been concentrated?
Several factors have contributed to malaria's decline, Tatem said, including urbanization, city-centric traveling, improved surveillance programs and improved living conditions, such as houses with screens on their doors.
Mosquitoes, the carriers of malaria, prefer rural areas, so urbanization naturally has helped eliminate the disease, Tatem added, and people are better about reporting cases right away.
David Smith, also an author of the paper and a professor at the Johns Hopkins Bloomberg School of Public Health, said not all the reasons for elimination are fully understood, but their paper "sends an optimistic message about elimination."
"If a country is able to commit its resources to elimination — and it's going to take money and time — then it's quite possible it will join this club of countries that has kept it out," Smith said.
Smith also cautioned against a one-size-fits-all approach to eliminating malaria, since the elimination program "would depend entirely on the cause."
For example, containing the sporadic malaria outbreak in November in Greece — where the disease had previously been successfully eliminated — involved an entirely different elimination scenario than would need to be carried out in Iraq, which has endemic malaria transmission and is surrounded by other countries with malaria, Smith said.
Malaria used to be in every country of the world, Tatem said. The U.S. eliminated it in 1951, but sporadic, contained outbreaks have occurred in Virginia and Florida. According to the World Health Organization, a country must prove that it has no local cases for three years in order to be considered malaria-free.
Various elimination methods have been used against malaria, including insecticide-treated bed nets, indoor spraying with low doses of DDT, treatment of mosquito breeding sites with larvicide, and landscape modifications to remove breeding sites, Tatem said.
Malaria is prevalent in 100 countries, and 35 of those have national elimination plans, Tatem said.
"Still, a child dies of malaria every 45 seconds, especially in sub-Saharan Africa," he added.
Elimination in these and other countries must involve spending more money on improving their surveillance and health care systems, Smith said.
"We need to double or triple the influx of money to do some of things we would like to do," Smith said, adding that the investment would be worthwhile. "Improving your surveillance system is helpful in other ways."
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