title: Prevalence of asthma, allergic rhinoconjunctivitis and allergic sensitization in Mongolia.
abstract: BACKGROUND
  Studies in countries, such as Mongolia, which are in transition from farming to industrial society permit evaluation of the impact of environmental change on atopic diseases.
  
  
  METHODS
  In the screening study, questionnaire data were obtained from 9453 subjects aged 10-60 years. In the clinical study, a subsample of 869 subjects (participation rate 50.0%) was examined. A questionnaire-based interview, clinical examination, skin prick tests, spirometry and bronchodilation test or methacholine challenge test were used to define the clinical diagnoses. The prevalences of atopic diseases were evaluated at the population level using two-phase data and sampling weights.
  
  
  RESULTS
  The prevalences of asthma, allergic rhinoconjunctivitis and allergic sensitization with 95% confidence intervals were 1.1% (0.3-2.0%), 9.3% (4.0-14.6%) and 13.6% (7.4-19.9%) in Mongolian villages, 2.4% (1.4-3.5%), 12.9% (8.2-17.7%) and 25.3% (17.1-33.6%) in rural towns and 2.1% (1.3-3.0%), 18.4% (13.3-23.4%) and 31.0% (24.5-37.5%) in Ulaanbaatar city, respectively. The prevalence of allergic rhinoconjunctivitis (P = 0.02) and allergic sensitization (P = 0.003) increased significantly with increasing urbanization.
  
  
  CONCLUSIONS
  The prevalences of atopic diseases were low in rural Mongolia and increased with increasing urbanization suggesting that rural living environment protects against atopy.
authors.affiliation: Department of Pulmonary Diseases and Clinical Allergology, University of Turku, Turku, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Viinanen
authors.forename: S
authors.initials: S
authors.lastname: Munhbayarlah
authors.forename: T
authors.initials: T
authors.lastname: Zevgee
authors.forename: L
authors.initials: L
authors.lastname: Narantsetseg
authors.forename: Ts
authors.initials: Ts
authors.lastname: Naidansuren
authors.forename: M
authors.initials: M
authors.lastname: Koskenvuo
authors.forename: H
authors.initials: H
authors.lastname: Helenius
authors.forename: E O
authors.initials: EO
authors.lastname: Terho
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology*; D001985:Bronchial Provocation Tests; D002648:Child; D003233:Conjunctivitis, Allergic / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007114:Immunization; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D008986:Mongolia / Q000453:epidemiology; D015995:Prevalence; D012221:Rhinitis, Allergic, Perennial / Q000453:epidemiology*; D012307:Risk Factors; D012882:Skin Tests; D013147:Spirometry; D011795:Surveys and Questionnaires; D014507:Urbanization
chemical_list: D000485:Allergens; D016210:Methacholine Chloride