Evaluation of consistency between local and imported seafood allergen extracts

Seafood is a common cause of food allergy in Thai adults and children. Skin prick test is a safe and convenient way to screen seafood allergy. To date, the Allergy Unit, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University uses imported extracts for seafood skin prick test. The extracts are expensive and may not be the same species as seafood in Thailand.

To compare the consistency between local seafood allergen extracts prepared by the Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University and imported seafood allergen extracts.

The study was a prospective comparative trial performed in children who attended the Pediatric Allergy Clinic, Siriraj Hospital from March 1999 to October 2000. The skin prick test was performed with the local seafood allergen extracts prepared by a pharmacist from the Department of Pharmacology and the imported seafood allergen extracts included shrimp, fish and crab. Histamine and normal saline were used as positive and negative control respectively. The positive result was recorded when wheal reaction was > or = 3 mm larger than negative control.

Eighty eight patients (57 boys and 31 girls) were included in this study. The average age was 7.7 years (1-15 years). Half of the patients had a history of seafood allergy. The study showed probable consistency between imported and local skin prick test of shrimp and crab extracts (kappa = 5-7) but no consistency between imported and local skin prick test of fish extracts (kappa < 5). The study also showed no consistency between history of seafood and skin prick test result.

Local seafood allergen extracts from the Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University are safe but they cannot replace the imported seafood allergen extracts. Further investigations about sensitivity and specificity of both kinds of allergen extracts are necessary.