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Open Access Highly Accessed Research article

Duration of shedding of respiratory syncytial virus in a community study of Kenyan children

Emelda A Okiro12*, Lisa J White34, Mwanajuma Ngama5, Patricia A Cane6, Graham F Medley7 and D James Nokes57

Author Affiliations

1 Malaria Public Health & Epidemiology Group, Centre for Geographic Medicine Research - Coast, Kenya Medical Research Institute, Nairobi, Kenya

2 Centre for Tropical Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, UK

3 Centre for Clinical Vaccinology and Tropical Medicine, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK

4 Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand

5 Centre for Geographic Medicine Research - Coast, Kenya Medical Research Institute, Kilifi, Kenya

6 Centre for Infection, Health Protection Agency, London, UK

7 Department of Biological Sciences, University of Warwick, Coventry, UK

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BMC Infectious Diseases 2010, 10:15  doi:10.1186/1471-2334-10-15

Published: 22 January 2010

Abstract

Background

Our understanding of the transmission dynamics of respiratory syncytial virus (RSV) infection will be better informed with improved data on the patterns of shedding in cases not limited only to hospital admissions.

Methods

In a household study, children testing RSV positive by direct immunofluorescent antibody test (DFA) were enrolled. Nasal washings were scheduled right away, then every three days until day 14, every 7 days until day 28 and every 2 weeks until a maximum of 16 weeks, or until the first DFA negative RSV specimen. The relationship between host factors, illness severity and viral shedding was investigated using Cox regression methods.

Results

From 151 families a total of 193 children were enrolled with a median age of 21 months (range 1-164 months), 10% infants and 46% male. The rate of recovery from infection was 0.22/person/day (95% CI 0.19-0.25) equivalent to a mean duration of shedding of 4.5 days (95%CI 4.0-5.3), with a median duration of shedding of 4 days (IQR 2-6, range 1-14). Children with a history of RSV infection had a 40% increased rate of recovery i.e. shorter duration of viral shedding (hazard ratio 1.4, 95% CI 1.01-1.86). The rate of cessation of shedding did not differ significantly between males and females, by severity of infection or by age.

Conclusion

We provide evidence of a relationship between the duration of shedding and history of infection, which may have a bearing on the relative role of primary versus re-infections in RSV transmission in the community.