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Malaria on the
Move: Human Population Movement and Malaria Transmission
Pim Martens and
Lisbeth Hall
Maastricht University, Maastricht, the Netherlands
| Reports of malaria
are increasing in many countries and in areas thought free of
the disease. One of the factors contributing to the reemergence
of malaria is human migration. People move for a number of
reasons, including environmental deterioration, economic
necessity, conflicts, and natural disasters. These factors are
most likely to affect the poor, many of whom live in or near
malarious areas. Identifying and understanding the influence of
these population movements can improve prevention measures and
malaria control programs. |
Malaria, the world's most prevalent
vector-borne disease, is endemic in 92 countries, with pockets of
transmission in an additional eight countries. Approximately 41% of
the world's population is at risk, and each year 300 million to 500
million clinical cases of malaria, >90% of them in Africa, are
reported. Worldwide, approximately 2 million deaths per year can be
attributed to malaria, half of these in children under 5 years of age.
Historically, population movement has
contributed to the spread of disease . Failure to consider this factor
contributed to failure of malaria eradication campaigns in the 1950s
and 1960s . The movement of infected people from areas where malaria
was still endemic to areas where the disease had been eradicated led
to resurgence of the disease. However, population movement can
precipitate or increase malaria transmission in other ways as well. As
people move, they can increase their risk for acquiring the disease
through the ways in which they change the environment and through the
technology they introduce, for example, through deforestation and
irrigation systems . Such activities can create more favorable
habitats for Anopheles mosquitoes; at the same time, workers
may have increased exposure to the vector. Furthermore, people can
inadvertently transport infectious mosquitoes to malaria-free areas,
reintroducing disease. Population movement is also increasingly
implicated in the spread of drug resistance in malaria .
The unprecedented increase in mobility in
the last few decades has led to greater concern about the relationship
between mobility and malaria. There are a number of reasons for
increased mobility. First, sophisticated forms of transport now permit
the swift movement of people over huge distances. Air travel has
increased by almost 7% a year in the last 20 years and is predicted to
increase by >5% a year during the next 20 years . Second, in the
developing world a rapidly increasing population is putting pressure
on scarce resources, leading to major population redistribution. This
particularly involves the movement from rural to urban areas. Third,
natural disasters such as droughts and floods have created
approximately 25 million environmental refugees . Finally, conflict,
often a result of population pressures and environmental degradation,
displaces vast numbers of people. We examine the impact of population
movement on malaria transmission.
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