[Editors] MIT: Fighting malaria by changing the environment

[Teresa Herbert]

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How to fight malaria by changing the environment
--MIT computer modeling finds leveling land can help control disease’s  
spread
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For Immediate Release
FRIDAY, DEC. 19, 2008

Contact: Teresa Herbert, MIT News Office
E: therbert at mit.edu, T: 617-258-5403


CAMBRIDGE, Mass. — Modifying the environment by using everything from  
shovels and plows to plant-derived pesticides may be as important as  
mosquito nets and vaccinations in the fight against malaria, according  
to a computerized analysis by MIT researchers.

The researchers have developed a new computer model for analyzing  
different methods of trying to control the spread of malaria, one of  
the world’s most-devastating diseases. Among their findings using the  
model is that environmental measures such as leveling the land to  
eliminate depressions where pools can form can be an important part of  
the strategy for controlling the disease.

Reports on the work, carried out by Professor of Civil and  
Environmental Engineering Elfatih Eltahir and graduate students Arne  
Bomblies and Rebecca Gianotti, were presented this week at a meeting  
of the American Geophysical Union in San Francisco.

Malaria, Eltahir explained, is “a significant global health challenge”  
that accounts for one-third of all deaths of children under 5  
worldwide. By developing new software to analyze the impacts of  
different methods of attempting to limit malaria’s spread, which  
involves a complex chain of transmission between larvae, mosquitoes  
and humans, “we have made significant progress” toward better control  
of the disease, he said.

While most efforts at dealing with malaria have focused on the human  
side, such as attempts to develop a vaccine, Eltahir said that efforts  
to control environmental factors —such as working to eliminate the low  
spots where pools of water collect during the rainy season, or  
applying locally grown plant materials to limit the growth of  
mosquitoes — can have a dramatic effect on controlling malaria’s  
spread. And unlike importing expensive medicines, such an approach can  
rely on local efforts as simple as having people with shovels fill in  
the low spots in the terrain.

“By using local tools and local labor, our approach relies less on  
high-technology equipment from outside the region, which tends to make  
the local people more dependent,” he said.

In addition, the new comprehensive computer model will provide a tool  
for analyzing how different areas’ vulnerability to malaria will be  
affected by a changing climate.

To validate the accuracy of the computer modeling of conditions, the  
team has been working for the last four years in a remote area of  
Niger, which lies in the Sahel desert region of northern Africa.  
“Africa is the hot spot for malaria in general,” Eltahir explained, so  
this fieldwork provides substantial validation of the model.

In the field, Bomblies and others have monitored every aspect of  
malaria’s lifecycle, including doing counts of mosquito larvae and  
adult mosquitoes, identifying the exact species of mosquitoes (since  
only specific varieties carry the malaria parasite), and mapping the  
topography and monitoring the size and duration of pools of water  
where the mosquitoes breed. “We gathered data that would serve as  
validation for the model that we were developing,” Bomblies said.

Eliminating pools of standing water, or increasing drainage so that  
such pools last less than the seven to 10 days it takes for the  
mosquitoes to mature, can be an effective strategy, the analysis  
shows. In addition, it allows comparison of different methods. Filling  
in the low spots using shovels, it turns out, is as effective at  
controlling the disease as plowing the land so that water more rapidly  
percolates down into the soil.

That is not a new idea, but the new software provides a quantitative  
way to compare its impact with other approaches, and to develop  
specific strategies for a given region. Filling in low spots “is an  
established technique,” said Bomblies, who has spent a total of 13  
months leading the fieldwork in Niger. “But it hasn’t been  
specifically applied in the region in which we’ve been working.”

And unlike other approaches such as vaccinations or mosquito nets, it  
has a relatively permanent impact. “Once a breeding site is gone, it’s  
gone” Bomblies said.

Other methods the team has studied include spreading ground up seeds  
from the neem tree, which grows locally, in the ponds, which can  
reduce the mosquito population by about 50 percent.

“For the first time, we have a detailed computer model” of all the  
different factors in the disease’s spread, Eltahir said. By making it  
possible to run detailed simulations of a wide variety of strategies,  
“we can do a lot of things, in this region or elsewhere, that we could  
never do in the past. It can allow you to do things in a more cost- 
effective way.”

This project has been funded by the ocean and human health program of  
the National Oceanographic and Atmospheric Administration (NOAA), and  
the National Science Foundation.

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Written by David Chandler, MIT News Office
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