title: The relationship between allergic rhinitis and viral infections.
abstract: OBJECTIVE
  Viral airway inflammation is one of the most common respiratory conditions. The clinical symptoms of viral rhinitis, especially watery rhinorrhea and nasal congestion, may be similar to the symptoms of allergic rhinitis. Both conditions affect considerable numbers of patients and can lead to many upper airway consequences, especially secondary bacterial infection. Viral infection can also lead to lower respiratory traction conditions such as bronchitis, bronchiolitis, pneumonia and, especially, asthma. This article will review the existing scientific literature examining the linkage and relationship between viral infection and allergic airway disease.
  
  
  RESULTS
  The relationship between viral and allergic airway inflammation can be discussed in terms of the influence of pathogenesis from one condition to the other. Recently, many studies show how early infection can decrease the chance of allergic development. However, there is some evidence demonstrating that viral infection can deteriorate the clinical symptoms of airway allergy.
  
  
  CONCLUSIONS
  Viral infection can affect the immune system and allergy as both 'enhancing effect' and 'protective effect'. The influential factors depend on the virulence of the viral strain, the innate immune system and the environmental conditions.
authors.affiliation: Division of Rhinology and Allergy, Department of Otolaryngology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Pongsakorn
authors.initials: P
authors.lastname: Tantilipikorn
mesh_terms: D006801:Humans; D065631:Rhinitis, Allergic / Q000175:diagnosis* / Q000628:therapy / Q000821:virology*; D014777:Virus Diseases / Q000150:complications* / Q000175:diagnosis* / Q000628:therapy