Frequent Asymptomatic Respiratory Syncytial Virus Infections During an Epidemic in a Rural Kenyan Household Cohort

Abstract

Background. The characteristics, determinants, and potential contribution to transmission of asymptomatic cases of respiratory syncytial virus (RSV) infection have not been well described.Methods. A cohort of 47 households (493 individuals) in coastal Kenya was recruited and followed for a 26-week period spanning a complete RSV season. Nasopharyngeal swab specimens were requested weekly, during the first 4 weeks, and twice weekly thereafter from all household members, regardless of illness status. The samples were screened for a range of respiratory viruses by multiplex real-time polymerase chain reaction.Results. Tests on 16 928 samples yielded 205 RSV infection episodes in 179 individuals (37.1%) from 40 different households. Eighty-six episodes (42.0%) were asymptomatic. Factors independently associated with an increased risk of asymptomatic RSV infection episodes were higher age, shorter duration of infection, bigger household size, lower peak viral load, absence of concurrent RSV infections within the household, infection by RSV group B, and no prior human rhinovirus infections. The propensity of RSV spread in households was dependent on symptom status and amount (duration and load) of virus shed.Conclusions. While asymptomatic RSV was less likely to spread, the high frequency of symptomless RSV infection episodes highlights a potentially important role of asymptomatic infections in the community transmission of RSV.

Risk factors and patterns of household clusters of respiratory viruses in rural Nepal

“…Last, we collected weekly specimens and our findings may be biased if non-infant younger children had longer shedding duration compared to older children. However, this has not been demonstrated in studies of RSV and HRV shedding duration [28,30]. Our large cohort allowed us to use a multivariable analysis to identify the risk factors and protective characteristics associated with the incidence of transmission.…”

Respiratory virus infection among hospitalized adult patients with or without clinically apparent respiratory infection: a prospective cohort study

“…It is possible that these respiratory viruses are transient, colonizing the patients' upper respiratory tract but not actually causing the symptoms or disease. However, although asymptomatic infections due to adenovirus and PIV are often found in children [11,27,28], adenovirus and PIV are rarely detected among healthy asymptomatic adults [11,29].…”

“…Second, the fever/RS group and non-fever/RS group were matched for age and sex. The matching of age is particularly important because previous studies have shown that the proportion of patients with symptoms varies according to age [28]. Another unique feature in this study is that we have included patients with fever but without respiratory symptoms in the fever/RS group because many clinicians test respiratory viruses in febrile patients without respiratory symptoms.…”

Continuous Invasion by Respiratory Viruses Observed in Rural Households During a Respiratory Syncytial Virus Seasonal Outbreak in Coastal Kenya

“…The intensive surveillance provided detailed infection data that allowed comprehensive investigation of the circulation of the respiratory viruses in the community. Previous reports have described the data on respiratory syncytial virus (RSV) in detail [4][5][6][7], and here we present data on a wide range of respiratory viruses. and Demographic Surveillance System [8].…”

“…The study period spanned from 8 December 2009 to 5 June 2010. The study design and the details of field operations have been previously described [4][5][6][7]. Identifying who infects the infant with RSV in the household was the primary objective of the study [6].…”