title: Human rhinovirus species and season of infection determine illness severity.
abstract: BACKGROUND
  Human rhinoviruses (HRVs) consist of approximately 160 types that cause a wide range of clinical outcomes, including asymptomatic infections, common colds, and severe lower respiratory illnesses.
  
  
  OBJECTIVE
  To identify factors that influence the severity of HRV illnesses.
  
  
  METHODS
  HRV species and types were determined in 1,445 nasal lavages that were prospectively collected from 209 infants participating in a birth cohort who had at least one HRV infection. Questionnaires were used during each illness to identify moderate to severe illnesses (MSI).
  
  
  RESULTS
  Altogether, 670 HRV infections were identified, and 519 of them were solitary infections (only one HRV type). These 519 viruses belonged to 93 different types of three species: 49 A, 9 B, and 35 C types. HRV-A (odds ratio, 8.2) and HRV-C (odds ratio, 7.6) were more likely to cause MSI compared with HRV-B. In addition, HRV infections were 5- to 10-fold more likely to cause MSI in the winter months (P < 0.0001) compared with summer, in contrast to peak seasonal prevalence in spring and fall. When significant differences in host susceptibility to MSI (P = 0.004) were considered, strain-specific rates of HRV MSI ranged from less than 1% to more than 20%.
  
  
  CONCLUSIONS
  Factors related to HRV species and type, season, and host susceptibility determine the risk of more severe HRV illness in infancy. These findings suggest that anti-HRV strategies should focus on HRV-A and -C species and identify the need for additional studies to determine mechanisms for seasonal increases of HRV severity, independent of viral prevalence, in cold weather months.
authors.affiliation: Biological Mimetics Inc., 124 Byte Drive, Frederick, MD 21702, USA. wlee5hkg@gmail.com
authors.forename: Wai-Ming
authors.initials: WM
authors.lastname: Lee
authors.forename: Robert F
authors.initials: RF
authors.lastname: Lemanske
authors.forename: Michael D
authors.initials: MD
authors.lastname: Evans
authors.forename: Fue
authors.initials: F
authors.lastname: Vang
authors.forename: Tressa
authors.initials: T
authors.lastname: Pappas
authors.forename: Ronald
authors.initials: R
authors.lastname: Gangnon
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Jackson
authors.forename: James E
authors.initials: JE
authors.lastname: Gern
mesh_terms: D003139:Common Cold / Q000821:virology; D006801:Humans; D007223:Infant; D016015:Logistic Models; D017817:Nasal Lavage Fluid / Q000821:virology*; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000145:classification / Q000821:virology*; D012229:Rhinovirus / Q000145:classification* / Q000235:genetics; D012621:Seasons; D012720:Severity of Illness Index; D014922:Wisconsin