Risk factors for Anopheles mosquitoes in rural and urban areas of Blantyre District, southern Malawi
Background Although urban malaria transmission is low and seasonal, it remains a major public health problem. This study aimed at demonstrating the presence of Anopheles mosquitoes and their potential to transmit malaria in urban settings. Methods Two cross-sectional surveys were carried out in Blan...
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Published in: | Malawi medical journal 2018-02, Vol.28 (4) |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Online Access: | Get full text |
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Summary: | Background Although urban malaria transmission is low and seasonal, it
remains a major public health problem. This study aimed at
demonstrating the presence of Anopheles mosquitoes and their potential
to transmit malaria in urban settings. Methods Two cross-sectional
surveys were carried out in Blantyre District, Malawi, during the dry
and wet seasons of 2008 and 2010, respectively. A map of Blantyre was
divided into a grid of 400 cells, of which 60 cells were randomly
selected. Five households located within 100 m from the centre of each
selected cell were enrolled, a standard questionnaire was administered,
and indoor resting mosquitoes were sampled. Results In 2008 and 2010, a
total of 960 and 1045 mosquitoes were collected, respectively.
Anopheles funestus comprised 9.9% (n = 95) and 10.3% (n = 108) during
the two surveys, respectively. Anopheles gambiae sensu lato (s.l.) was
rarely detected during the second survey (n = 6; 0.6%). Molecular
identification was performed on samples collected during the first
survey, and An. funestus sensu stricto (s.s.) was the only sibling
species detected. All the Anopheles mosquitoes were collected from
households located in rural areas of Blantyre and none from urban
areas. In univariate analysis, the presence of open eaves was
associated with increased Anopheles prevalence, both during the dry
(incidence rate ratio, IRR = 4.3; 95% CI 2.4 - 7.6) and wet (IRR
= 2.47; 95% CI 1.7 - 3.59) seasons. Chances of detecting
Anopheles spp. decreased with increasing altitude (IRR = 0.996; 95% CI
0.995 - 0.997) and during the dry season, but increased during
the wet season (IRR = 1.0017; 95% CI 1.0012 - 1.0023). These
factors remained significant following a multiple Poisson regression
analysis. No association was found between insecticide-treated bednet
ownership and the number of Anopheles mosquitoes detected. Conclusions
The presence of An. funestus s.s and An. gambiae s.l. in the periphery
of Blantyre city was an indication that malaria transmission was
potentially taking place in these areas. |
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ISSN: | 1995-7262 |