Clinical and Molecular Epidemiology of Human Rhinovirus C in Children and Adults in Hong Kong Reveals a Possible Distinct Human Rhinovirus C Subgroup

Background. A novel human rhinovirus (HRV) species, HRV-C, was recently discovered, but its clinical features and epidemiology, compared with HRV-A and HRV-B, remains poorly understood, especially in adults. Methods. One thousand two hundred nasopharyngeal aspirate samples obtained from hospitalized children and adults during a 1-year period were subject to reverse-transcriptase polymerase chain reaction to detect HRV. The clinical and molecular epidemiology of the 3 HRV species was analyzed. Results. HRVs were detected in 178 (29.7%) of 600 nasopharyngeal aspirate samples from children and 42 (7%) of 600 nasopharyngeal aspirate samples from adults. HRV-A was most prevalent (n = 111), followed by HRV-C (n = 91) and HRV-B (n = 18). Although upper respiratory tract infection was the most common presentation in children, 8 (62%) of the 13 adults with HRV-C infection had pneumonia, compared with 6 (27%) of the 22 adults with HRV-A infection (P < .05). Wheezing episodes were also more common among individuals with HRV-C (37%) and HRV-A (20%) infection than among those with HRV-B (0%) infection (P < .05). Clinical and molecular data analysis revealed HRV- C as a frequent cause of community and institutionalized outbreaks. A diverse set of HRV-C genotypes was circulating throughout the year, among which a potential distinct subgroup of strains was observed. Conclusion. HRV-C is associated with pneumonia in adults and outbreaks of respiratory infections requiring hospitalization. A potential novel HRV-C subgroup was identified.