CASE-CONTROL STUDY OF MOSQUITO NETS AGAINST MALARIA IN THE AMAZON REGION OF COLOMBIA

NEAL ALEXANDER London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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MAURICIO RODRÍGUEZ London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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LIGIA PÉREZ London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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JUAN CARLOS CAICEDO London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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JESÚS CRUZ London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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GUILLERMO PRIETO London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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JOSÉ ANTONIO ARROYO London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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MARIA CRISTINA COTACIO London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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MARTHA SUÁREZ London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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FERNANDO DE LA HOZ London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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ANDREW J. HALL London School of Hygiene and Tropical Medicine, London, UK; Secretaría de Salud del Amazonas, Leticia, Amazonas, Colombia; Universidad Nacional de Colombia, Leticia and Bogotá, Colombia

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The degree of effectiveness of mosquito nets against malaria in the Americas has remained uncertain. We carried out a case-control study of net use and mild malaria in the Amazonas state of Colombia. Two hundred ninety cases were enrolled via the Health Department services, and 977 community-based controls matched for age, sex, and place of residence. We found that a large proportion of the population (96% of controls) slept under nets. Nevertheless, we found a benefit of impregnated nets compared with no net use: adjusted odds ratio (OR) for mild malaria 0.44, 95% confidence interval (CI) 0.20–0.98. Nonimpregnated nets had a benefit that was only slightly smaller but not statistically significant (OR for mild malaria 0.54, 95% CI 0.25–1.18). Travel in the previous month had an odds ratio of 6.2 (95% CI 3.1–8.8) and a population attributable fraction of 13% compared with 11% for failure to use an impregnated net. We conclude that, in the Amazon region, promotion of mosquito net use and impregnation is justified, and that there is a need for measures to protect travelers from malaria.

Author Notes

Reprint requests: Neal Alexander, Infectious Disease Epidemiology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK. Telephone: (+44) 20 7927 2483, Fax: (+44) 20 7636 8739, E-mail: neal.alexander@lshtm.ac.uk.
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