title: Clinical and immunochemical profiles of food challenge proven or anaphylactic shrimp allergy in tropical Singapore.
abstract: BACKGROUND
  Shellfish allergy in Singapore is highly prevalent, and shrimp allergy is the most common.
  
  
  OBJECTIVE
  This study aims to evaluate the clinical characteristics and immunological phenotype of shellfish allergy in this population.
  
  
  METHODS
  Patients with self-reported shellfish allergy were recruited from outpatient clinics of three large hospitals and from a population survey. Open oral food challenges (OFC) to glass prawn (Litopenaeus vannamei) and tiger prawn (Penaeus monodon) were carried out on all patients except for those who had a history of severe anaphylaxis. Skin prick tests (SPT) and specific IgE to crude and recombinant allergens were carried out to evaluate shrimp and dust mite sensitization. Immunoblots were used to assess IgE-binding proteins.
  
  
  RESULTS
  The 104 patients recruited were categorized into shellfish allergic (SA) when OFC was positive or had a history of severe anaphylaxis (n = 39), shellfish tolerant (ST) when OFC was negative (n = 27), and house dust mite positive controls (HDM(+) ) who were ST (n = 38). Oral symptoms (87.1%) were the predominant clinical manifestation. Positive challenge doses ranged from 2 to 80 g of cooked shrimp, with 25/52 patients reacting to either one or both shrimps challenged. The presence of specific IgE to shrimp either by SPT and/or ImmunoCAP(®) assay provided diagnostic test sensitivity of 82% and specificity of 22.2%. The inclusion of specific IgE to shrimp tropomyosin and IgE immunoblots with shrimp extracts did not improve the diagnostic proficiency substantially.
  
  
  CONCLUSIONS
  This study highlights the predominance of oral symptoms in shrimp allergy in tropical Asia and that a high provocation dose may be necessary to reveal shrimp allergy. Furthermore, specific IgE diagnostic tests and immunoblots were of limited use in this population.
authors.affiliation: Paediatrics, Khoo Teck Puat-National University Children's Medical Institute, National University Health System, Singapore.
authors.forename: M
authors.initials: M
authors.lastname: Thalayasingam
authors.forename: I F A
authors.initials: IF
authors.lastname: Gerez
authors.forename: G C
authors.initials: GC
authors.lastname: Yap
authors.forename: G V
authors.initials: GV
authors.lastname: Llanora
authors.forename: I P
authors.initials: IP
authors.lastname: Chia
authors.forename: L
authors.initials: L
authors.lastname: Chua
authors.forename: C J A O
authors.initials: CJ
authors.lastname: Lee
authors.forename: L D H
authors.initials: LD
authors.lastname: Ta
authors.forename: Y K
authors.initials: YK
authors.lastname: Cheng
authors.forename: B Y H
authors.initials: BY
authors.lastname: Thong
authors.forename: C Y
authors.initials: CY
authors.lastname: Tang
authors.forename: H P S
authors.initials: HP
authors.lastname: Van Bever
authors.forename: L P
authors.initials: LP
authors.lastname: Shek
authors.forename: M A
authors.initials: MA
authors.lastname: Curotto de Lafaille
authors.forename: B W
authors.initials: BW
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000485:Allergens / Q000008:administration & dosage / Q000276:immunology; D000707:Anaphylaxis / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology*; D005260:Female; D005502:Food / Q000009:adverse effects*; D005512:Food Hypersensitivity / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D012758:Shellfish / Q000009:adverse effects*; D012846:Singapore / Q000453:epidemiology; D012882:Skin Tests; D055815:Young Adult
chemical_list: D000485:Allergens; D007073:Immunoglobulin E
keywords: Cross-reactivity; dust mites; food challenge; recombinant; shrimp; tropomyosin