Dengue fever occurrence and vector detection by larval survey, ovitrap and MosquiTRAP: a space-time clusters analysis.

Diogo Portella Ornelas De Melo,Luciano Rios Scherrer,Álvaro Eduardo Eiras,Immo A Hansen

doi:10.1371/journal.pone.0042125

Diogo Portella Ornelas De Melo, Luciano Rios Scherrer + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0042125

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Journal: PloS one	Publication Date: Jul 25, 2012
Citations: 86	License type: CC BY 4.0

Affiliation: Universidade Federal de Minas Gerais

Abstract

The use of vector surveillance tools for preventing dengue disease requires fine assessment of risk, in order to improve vector control activities. Nevertheless, the thresholds between vector detection and dengue fever occurrence are currently not well established. In Belo Horizonte (Minas Gerais, Brazil), dengue has been endemic for several years. From January 2007 to June 2008, the dengue vector Aedes (Stegomyia) aegypti was monitored by ovitrap, the sticky-trap MosquiTRAP™ and larval surveys in an study area in Belo Horizonte. Using a space-time scan for clusters detection implemented in SaTScan software, the vector presence recorded by the different monitoring methods was evaluated. Clusters of vectors and dengue fever were detected. It was verified that ovitrap and MosquiTRAP vector detection methods predicted dengue occurrence better than larval survey, both spatially and temporally. MosquiTRAP and ovitrap presented similar results of space-time intersections to dengue fever clusters. Nevertheless ovitrap clusters presented longer duration periods than MosquiTRAP ones, less acuratelly signalizing the dengue risk areas, since the detection of vector clusters during most of the study period was not necessarily correlated to dengue fever occurrence. It was verified that ovitrap clusters occurred more than 200 days (values ranged from 97.0±35.35 to 283.0±168.4 days) before dengue fever clusters, whereas MosquiTRAP clusters preceded dengue fever clusters by approximately 80 days (values ranged from 65.5±58.7 to 94.0±14. 3 days), the former showing to be more temporally precise. Thus, in the present cluster analysis study MosquiTRAP presented superior results for signaling dengue transmission risks both geographically and temporally. Since early detection is crucial for planning and deploying effective preventions, MosquiTRAP showed to be a reliable tool and this method provides groundwork for the development of even more precise tools.

Highlights

The Dengue fever is an arboviral disease with a wide geographical range and high case numbers
The LIRAa category registered the largest number of surveys, 5,971, though there was a lower percentage of positivity
We found seasonal patterns of dengue fever and vector population size, with a higher risk of dengue during warmer and wetter periods

Summary

Introduction

The Dengue fever is an arboviral disease with a wide geographical range and high case numbers. 50 million infections are estimated, 500,000 cases progress to dengue hemorrhagic fever (DHF), and there are more than 20,000 deaths per year [1]. Dengue viruses (Flaviviridae) are transmitted to humans by certain species of mosquitoes (Diptera: Culicidae) belonging to the genus Aedes. Aedes (Stegomyia) aegypti is the main vector worldwide, and is present in urban environments. Aedes (Stegomyia) albopictus, is currently considered of secondary importance in transmission, except in Asian countries, being present in rural or semi-urban habitats [2]. In the Americas, where the species probably arrived by passive transport during slave trade, Ae. aegypti is commonly found inside human dwellings where it can both rest and obtain blood meals [3,4]

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