Prospective evaluation of rhinovirus infection in healthy young children

Background: Although the incidence of human rhinovirus (HRV) infection is highest in young, no study has yet been published concerning the types of HRV circulating in this population, the incidence of symptomatic infections due to the different types, or duration of shedding. Objectives: This prospective study evaluated the circulation of HRV species and types, and established the incidence of asymptomatic and symptomatic infections in young children. Study design: The study enrolled 93 healthy children aged <2 years, 88 of whom completed the follow-up of weekly household visits from November 2013 to February 2014. At each visit, a record was made of any signs and symptoms of acute infection, and a nasopharyngeal (NP) swab was taken in order to identify the HRVs by means of RT-polymerase chain reaction and to construct the phylogenetic tree of the HRV-positive cases. Results: A total of 1408 NP samples were obtained and 326HRV infections were diagnosed (23.1%), leading to a mean number of 3.7 ± 2.3 infections per child: HRV-A in 72 cases (22.1%), HRV-B in 29 (8.9%), HRV-C in 122 (37.4%), and non-typeable HRV in 103 (31.6%). Shedding was significantly longer for HRV-A (14 days) and HRV-B (14 days) than HRV-C (7 days; p= 0.002 and p= 0.012). Most of the HRV infections (209/326, 64.1%) remained asymptomatic and, when symptomatic, were of marginal clinical relevance. Conclusions: In healthy young children, HRV infection is extremely frequent, generally asymptomatic or with a mild clinical presentation, and viral shedding is limited in time.