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

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.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.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.Respiratory syncytial virus (RSV) is the major viral cause of lower respiratory tract infection in children worldwide [1-4]. Our understanding of the mechanisms of persistence and spread of the virus in the population is fundamental to the development of appropriate control methods. In this respect the process of recovery from infection is of intrinsic interest. Primary RSV infection predominantly arises in the first two years of life [5-10]. However, due to imperfect immunity RSV repeatedly infects, probably throughout life [11,12]. Given that most infections are therefore repeat infections, their role in the overall transmission of the virus within a population is potentially of fundamental importance, and highly