title: Sensitization to common ragweed in southern Bavaria: clinical and geographical risk factors in atopic patients.
abstract: BACKGROUND
  Sensitization to common ragweed (Ambrosia artemisiifolia) is associated with a variety of risk factors, which are incompletely defined. Our aim was to evaluate the association of a variety of clinical, geographical and demographical variables with ragweed sensitization and also to determine its frequency in southern Bavaria.
  
  
  METHODS
  In this cross-sectional multicentre study, we enrolled 977 patients with a documented or suspected atopic disease or food allergy. Data were collected on aeroallergen sensitization, age, sex, type and history of allergic disease, place of residence and potential local ragweed exposure. For this last variable, county ragweed cover was taken as a surrogate variable. Relative rates were calculated with multiple additive logistic regression models. Randomly selected patients with ragweed sensitization had a conjunctival provocation test.
  
  
  RESULTS
  According to skin prick tests, 190 patients (19.5%) were sensitized to ragweed. The frequency of this finding increased significantly with a rising number of additional sensitizations. Other less important predictors for a ragweed sensitization were male gender, mugwort sensitization, food allergy and a maximum of complaints in September or October. County of residence, extent of local ragweed cover or type of residential area were without relevance. Of 48 sensitized patients, 26 (54.2%) had a positive conjunctival provocation test.
  
  
  CONCLUSIONS
  Patients with multiple sensitizations may be more readily sensitized to a new aeroallergen. Local geographic or environmental conditions are presumably of minor importance for becoming sensitized to ragweed. The frequency of ragweed allergy among sensitized patients might be high.
authors.affiliation: Department of Dermatology and Allergology, Ludwig-Maximilian University, Munich, Germany. Franziska.Rueff@med.uni-muenchen.de
authors.forename: Franziska
authors.initials: F
authors.lastname: Ruëff
authors.forename: Bernhard
authors.initials: B
authors.lastname: Przybilla
authors.forename: Annett
authors.initials: A
authors.lastname: Walker
authors.forename: Jennifer
authors.initials: J
authors.lastname: Gmeiner
authors.forename: Matthias
authors.initials: M
authors.lastname: Kramer
authors.forename: Daniel
authors.initials: D
authors.lastname: Sabanés-Bové
authors.forename: Helmut
authors.initials: H
authors.lastname: Küchenhoff
authors.forename: Thomas
authors.initials: T
authors.lastname: Herzinger
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D031164:Ambrosia / Q000276:immunology*; D003430:Cross-Sectional Studies; D005260:Female; D005858:Germany; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000453:epidemiology* / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D008875:Middle Aged; D011058:Pollen / Q000276:immunology*; D012307:Risk Factors; D012882:Skin Tests
chemical_list: D000485:Allergens; D007073:Immunoglobulin E