UMMS Affiliation

Department of Medicine; Center for Infectious Disease and Vaccine Research

Publication Date


Document Type



Adolescent; Asymptomatic Infections; Child; Dengue; Dengue Virus; Female; Humans; Incidence; Male; Prospective Studies; Risk Factors; Schools; Students; Thailand


Life Sciences | Medicine and Health Sciences | Women's Studies


BACKGROUND: Dengue viruses are a major cause of morbidity in tropical and subtropical regions of the world. Inapparent dengue is an important component of the overall burden of dengue infection. It provides a source of infection for mosquito transmission during the course of an epidemic, yet by definition is undetected by health care providers. Previous studies of inapparent or subclinical infection have reported varying ratios of symptomatic to inapparent dengue infection.

METHODOLOGY/PRINCIPAL FINDINGS: In a prospective study of school children in Northern Thailand, we describe the spatial and temporal variation of the symptomatic to inapparent (S:I) dengue illness ratio. Our findings indicate that there is a wide fluctuation in this ratio between and among schools in a given year and within schools over several dengue seasons. The most important determinants of this S:I ratio for a given school were the incidence of dengue infection in a given year and the incidence of infection in the preceding year. We found no association between the S:I ratio and age in our population.

CONCLUSIONS/SIGNIFICANCE: Our findings point to an important aspect of virus-host interactions at either a population or individual level possibly due to an effect of heterotypic cross-reactive immunity to reduce dengue disease severity. These findings have important implications for future dengue vaccines.

Rights and Permissions

This is an open-access article distributed under the terms of the Creative Commons Public Domain declaration which stipulates that, once placed in the public domain, this work may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose.

DOI of Published Version



PLoS Negl Trop Dis. 2011 Mar 1;5(3):e975. Link to article on publisher's site

Journal/Book/Conference Title

PLoS neglected tropical diseases

Related Resources

Link to Article in PubMed

PubMed ID




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