A spatial distribution map was published on February 25, 2008 in PLoS
Medicine describing areas of risk for a deadly form of malaria. It
indicates that more than 2.3 billion people (about 35 percent of the
world's population) live in areas that put them at risk for this
disease.
Malaria is a disease that is caused by a protozoan parasite, most
notably Plasmodium falciparum, that
alternates its life cycle between the blood and the liver of its host.
It generally occurs in tropical and subtropical regions of the world,
where infected Anopheles mosquitoes bite humans and
transmit the disease. 500 million cases of malaria are reported every
year, and one million people die as a result of these infections. Most
often, the victims are children living in sub-Saharan Africa.
When designing campaigns to control this disease, a good geographical
picture of the areas of higher risks could be instrumental. This map
was created by Robert W.
Snow and colleagues at the Malaria Atlas Project (MAP), which is a
collaboration between Kenyan Medical Research Institute and the
University of Oxford, and is funded by the Wellcome Trust. They
assembled information about malaria cases in thousands of communities
in 87 different countries. Their sources included nationally reported
data on cases of infection, travel advisories, and surveys in specific
areas.
Other factors that affect the life cycle of the parasite, and thus the
likelihood of active transmission, were also integrated -- these
especially include climatic conditions. For instance, when infected
mosquitoes inhabit a climate with a particularly low temperature,
infected mosquitoes have a short enough natural lifespan that the
parasite does not mature to its infectious stage. This means that
malaria transmission will not occur, and lowers the risk of
transmission.
The resulting map shows the locations that have the highest risk of P.
falciparum. Additionally, it provides an idea of what
proportion of the population lives in areas of transmission where
existing control strategies could theoretically eliminate the parasite.
This study implies that this should be possible in more areas than was
previously thought, and will help future malaria prevention efforts to
focus further.
The resulting map is published online in an open access journal and
available via their website, map.ox.ac,
to be updated as new data become available. In doing this, the authors
intend to guarantee universal availability and expedite further
updates.
About PLoS Medicine
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is an open access, freely available international medical journal. It
publishes original research that enhances our understanding of human
health and disease, together with commentary and analysis of important
global health issues. For more information, visit plosmedicine.
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The Limits and Intensity of Plasmodium falciparum
Transmission: Implications for Malaria Control and Elimination Worldwide
Carlos A. Guerra, Priscilla W. Gikandi, Andrew J. Tatem, Abdisalan M.
Noor, Dave L. Smith, Simon I. Hay, Robert W. Snow
PLoS Med 5(2): e38
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Anna Sophia McKenney