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The effects of urbanization on global <it>Plasmodium vivax</it> malaria transmission
oleh: Qi Qiuyin, Guerra Carlos A, Moyes Catherine L, Elyazar Iqbal R F, Gething Peter W, Hay Simon I, Tatem Andrew J
Format: | Article |
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Diterbitkan: | BMC 2012-12-01 |
Deskripsi
<p>Abstract</p> <p>Background</p> <p>Many recent studies have examined the impact of urbanization on <it>Plasmodium falciparum</it> malaria endemicity and found a general trend of reduced transmission in urban areas. However, none has examined the effect of urbanization on <it>Plasmodium vivax</it> malaria, which is the most widely distributed malaria species and can also cause severe clinical syndromes in humans. In this study, a set of 10,003 community-based <it>P</it>. <it>vivax</it> parasite rate (<it>Pv</it>PR) surveys are used to explore the relationships between <it>Pv</it>PR in urban and rural settings.</p> <p>Methods</p> <p>The <it>Pv</it>PR surveys were overlaid onto a map of global urban extents to derive an urban/rural assignment. The differences in <it>Pv</it>PR values between urban and rural areas were then examined. Groups of <it>Pv</it>PR surveys inside individual city extents (urban) and surrounding areas (rural) were identified to examine the local variations in <it>Pv</it>PR values. Finally, the relationships of <it>Pv</it>PR between urban and rural areas within the ranges of 41 dominant <it>Anopheles</it> vectors were examined.</p> <p>Results</p> <p>Significantly higher <it>Pv</it>PR values in rural areas were found globally. The relationship was consistent at continental scales when focusing on Africa and Asia only, but in the Americas, significantly lower values of <it>Pv</it>PR in rural areas were found, though the numbers of surveys were small. Moreover, except for the countries in the Americas, the same trends were found at national scales in African and Asian countries, with significantly lower values of <it>Pv</it>PR in urban areas. However, the patterns at city scales among 20 specific cities where sufficient data were available were less clear, with seven cities having significantly lower <it>Pv</it>PR values in urban areas and two cities showing significantly lower <it>Pv</it>PR in rural areas. The urban–rural <it>Pv</it>PR differences within the ranges of the dominant <it>Anopheles</it> vectors were generally, in agreement with the regional patterns found.</p> <p>Conclusions</p> <p>Except for the Americas, the patterns of significantly lower <it>P</it>. <it>vivax</it> transmission in urban areas have been found globally, regionally, nationally and by dominant vector species here, following trends observed previously for <it>P</it>. <it>falciparum</it>. To further understand these patterns, more epidemiological, entomological and parasitological analyses of the disease at smaller spatial scales are needed.</p>