ORIGINAL ARTICLE EPIDEMIOLOGY AND GENETICS Does allergic rhinitis exist in infancy? Findings from the PARIS birth cohort M. Herr 1 , B. Clarisse 1 , L. Nikasinovic 1 , C. Foucault 2 , A.-M. Le Marec 3 , J.-P. Giordanella 2 , J. Just 1,4 & I. Momas 1,3 1 Universite ´ Paris Descartes, EA 4064, Laboratoire Sante ´ Publique et Environnement, Paris; 2 Centre d’Examens de Sante ´ de l’Enfant Amelot, CPAM de Paris; 3 Cellule Cohorte de la Direction de l’Action Sociale, de l’Enfance et de la, Sante ´ de la Mairie de Paris; 4 Centre de l’Asthme et des Allergies, Groupe Hospitalier Trousseau-La Roche Guyon, Assistance Publique – Ho ˆ pitaux de Paris, Paris, France To cite this article: Herr M, Clarisse B, Nikasinovic L, Foucault C, Le Marec A-M, Giordanella J-P, Just J, Momas I. Does allergic rhinitis exist in infancy? Findings from the PARIS birth cohort. Allergy 2011; 66: 214–221. Despite the recognition that allergic rhinitis (AR) affects an increasing proportion of preschool children, there is a paucity of data regarding epidemiology of AR in infancy (1). This is partly because of the difficulty of recognizing symptoms related to allergy and symptoms related to infections. Because they often share similar clinical symptoms (sneezing, nasal congestion and nasal discharge), AR and nonallergic rhinitis are difficult to differentiate (1). The relation of rhinitis symptoms with atopy has been shown in children aged 4 years (2, 3) but the existence of such a relation is still discussed in infancy. Nevertheless, identifica- tion of an early onset of AR is important because AR has been shown to be associated with impairments in quality of life, sleep disorders, learning problems and medical complica- tions affecting ears and sinus (4). In addition, recent findings from Chawes et al. (5) suggested the irreversible nature of nasal airways obstruction caused by AR in childhood. Their results indicated that AR could lead to chronic inflammation and structural remodelling of the nasal mucosa in children as young as 6 years. Apart from this, there is epidemiological evidence of a relation between AR and asthma (6), AR being a risk factor for the development of asthma in childhood (7). This study is part of the PARIS (Pollution and Asthma Risk: an Infant Study) birth cohort, a population-based study Keywords eosinophils; epidemiology; IgE; paediatrics; rhinitis. Correspondence Prof. Isabelle Momas, Laboratoire Sante ´ Publique et Environnement, EA 4064 – Faculte ´ des Sciences Pharmaceutiques et Biologiques, 4 avenue de l’Observatoire, 75006 Paris, France. Tel.: 33 1-53-73-97-26 Fax: 33 1-43-25-38-76 E-mail: isabelle.momas@parisdescartes.fr Accepted for publication 10 July 2010 DOI:10.1111/j.1398-9995.2010.02467.x Edited by: Wytske Fokkens Abstract Background: Early onset of allergic rhinitis (AR) is poorly described, and rhinitis symptoms are often attributed to infections. This study analyses the relations between AR-like symptoms and atopy in infancy in the PARIS (Pollution and Asthma Risk: an Infant Study) birth cohort. Methods: Data on AR-like symptoms (runny nose, blocked nose, sneezing apart from a cold) were collected using a standardized questionnaire administered during the health examination at age 18 months included in the follow-up of the PARIS birth cohort. Parental history of allergy and children’s atopy blood markers (blood eosinophilia ‡470 eosinophils/mm 3 , total immunoglobulin E ‡45 U/ml and presence of allergen-specific IgE) were assessed. Associations were studied using multivariate logistic regression models adjusted for potential confounders. Results: Prevalence of AR-like symptoms in the past year was 9.1% of the 1850 toddlers of the study cohort. AR-like symptoms and dry cough apart from a cold were frequent comorbid conditions. Parental history of AR in both parents increased the risk of suffering from AR-like symptoms with an OR 2.09 (P= 0.036). Significant associations were found with the presence of concurrent biological markers of atopy, especially blood eosinophilia and sensitization to house dust mite (OR 1.54, P= 0.046 and OR 2.91, P= 0.042) whereas there was no relation with sensitization to food. Conclusions: These results support the hypothesis that AR could begin as early as 18 months of life. Suspicion of AR should be reinforced in infants with parental history of AR or biological evidence of atopy, particularly blood eosinophilia and sensitization to inhalant allergens. Allergy 214 Allergy 66 (2011) 214–221 ª 2010 John Wiley & Sons A/S