Abstract
BackgroundDengue is an important neglected tropical disease, with more than half of the world’s population living in dengue endemic areas. Good understanding of dengue transmission sites is a critical factor to implement effective vector control measures.MethodsA cohort of 1,811 students from 10 schools in rural, semi-rural and semi-urban Thailand participated in this study. Seroconversion data and location of participants’ residences and schools were recorded to determine spatial patterns of dengue infections. Blood samples were taken to confirm dengue infections in participants at the beginning and the end of school term. Entomological factors included a survey of adult mosquito density using a portable vacuum aspirator during the school term and a follow up survey of breeding sites of Aedes vectors in schools after the school term. Clustering analyses were performed to detect spatial aggregation of dengue infections among participants.ResultsA total of 57 dengue seroconversions were detected among the 1,655 participants who provided paired blood samples. Of the 57 confirmed dengue infections, 23 (40.0%) occurred in students from 6 (6.8%) of the 88 classrooms in 10 schools. Dengue infections did not show significant clustering by residential location in the study area. During the school term, a total of 66 Aedes aegypti mosquitoes were identified from the 278 mosquitoes caught in 50 classrooms of the 10 schools. In a follow-up survey of breeding sites, 484 out of 2,399 water containers surveyed (20.2%) were identified as active mosquito breeding sites.Discussion and ConclusionOur findings suggest that dengue infections were clustered among schools and among classrooms within schools. The schools studied were found to contain a large number of different types of breeding sites. Aedes vector densities in schools were correlated with dengue infections and breeding sites in those schools. Given that only a small proportion of breeding sites in the schools were subjected to vector control measures (11%), this study emphasizes the urgent need to implement vector control strategies at schools, while maintaining efforts at the household level.
Highlights
The global incidence of symptomatic and asymptomatic dengue infections per year is estimated at about 400 million, and it is expected to rise [1]
The main objective of this study is to explore whether schools are likely dengue transmission sites for school children by assessing dengue infections and Aedes vector abundance in schools
Based on the clustering of dengue infections among school children within school and classroom, the significant correlations between dengue infections and the number of Aedes mosquitoes caught in the classrooms together with the active breeding sites in the environment of the schools, our study suggests that schools may be a potential dengue transmission site among school children
Summary
The global incidence of symptomatic and asymptomatic dengue infections per year is estimated at about 400 million, and it is expected to rise [1]. More than half of the world’s population lives in dengue endemic areas with more than 70% of those at risk reside in Asia Pacific region, and further geographic expansion of dengue is anticipated because of globalisation, urbanisation, and climate change [2,3,4,5]. Thailand is experiencing steadily increasing urbanization; the urban population increased from roughly 45% of the total population in 2000 to 49% of total population in 2014 [6]. This transition from rural towards urban patterns of living has directly affected dengue infection rates [4]. Good understanding of dengue transmission sites is a critical factor to implement effective vector control measures
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