title: Risk factors for allergy due to the two-spotted spider mite (Tetranychus urticae) among table grape farm workers.
abstract: BACKGROUND
  Recent studies have reported an increased prevalence of respiratory symptoms among farm workers. The aim of this study was to identify risk factors associated with spider mite allergy among table grape farm workers.
  
  
  METHODS
  A cross-sectional study of 207 workers in table grape farms was conducted. Skin prick tests used extracts of 8 common aeroallergens, grape mould (Botrytis cinerea) and Tetranychus urticae. Specific IgE to T. urticae was quantified using ImmunoCAP (Phadia). Erythrocyte cholinesterase levels were determined using the Test-mate ChE Cholinesterase Test System (model 460).
  
  
  RESULTS
  The average duration of employment of workers was 10 years and 12% were pesticide crop sprayers. Work-related wheeze (26%), ocular-nasal (24%) and urticaria/skin symptoms (14%) were more prevalent in the orchards. The prevalence of sensitization (skin prick test) was highest to T. urticae (22%) followed by house dust mite (16%), with 25% being atopic. The prevalence of allergy to T. urticae (skin reactivity and work-related symptoms) was 9.5%, with respiratory allergy (6%) more common than skin allergy (3%). Work-related ocular-nasal (OR = 4.9) and skin (OR = 3.7) symptoms were more commonly reported by pesticide crop sprayers. Workers with T. urticae-allergic rhino-conjunctivitis and probable asthma were more likely to be atopic, spray pesticides and have low (<30 U/g hemoglobin) erythrocyte cholinesterase levels.
  
  
  CONCLUSIONS
  This study demonstrated that spider mite, T. urticae, is an important outdoor allergen among table grape farm workers. The increased risk of spider mite allergy appears to be related to high pesticide exposure among crop sprayers.
authors.affiliation: Occupational and Environmental Health Research Unit, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa. Mohamed.Jeebhay@uct.ac.za
authors.forename: M F
authors.initials: MF
authors.lastname: Jeebhay
authors.forename: R
authors.initials: R
authors.lastname: Baatjies
authors.forename: Y-S
authors.initials: YS
authors.lastname: Chang
authors.forename: Y-K
authors.initials: YK
authors.lastname: Kim
authors.forename: Y-Y
authors.initials: YY
authors.lastname: Kim
authors.forename: V
authors.initials: V
authors.lastname: Major
authors.forename: A L
authors.initials: AL
authors.lastname: Lopata
mesh_terms: D000328:Adult; D000382:Agricultural Workers' Diseases / Q000453:epidemiology* / Q000276:immunology; D000383:Agriculture; D000485:Allergens / Q000276:immunology; D000818:Animals; D001249:Asthma / Q000453:epidemiology* / Q000276:immunology; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology* / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012882:Skin Tests; D040102:Tetranychidae / Q000276:immunology*; D027843:Vitis
chemical_list: D000485:Allergens; D007073:Immunoglobulin E