Food allergy in Sri Lanka - A comparative study.

Background: The incidence of IgE mediated food allergy (FA) is increasing in the west. Cow's milk (CM), hen's egg, wheat, soy, peanut, tree nut, fish, and shellfish are responsible for 90% of food allergy in the west; however, local dietary habits may result in specific allergies. Data on food allergies in South Asia is scarce. The present study aims to evaluate the foods that cause immediate type hypersensitivity in Sri Lanka, and to compare with Asia and the developed west. Methods: Records of patients referred to an Immunology clinic from 2010-January 2022 were reviewed. The diagnosis of food allergy was based on standard guidelines. Confirmation of the specific food implicated was based on the history and the presence of specific IgE or component resolved diagnostics by in vitro methods (Phadia ImmunoCap) or by skin prick testing with commercial extracts (Alk Abello). Prick to prick testing was performed for fruits and vegetables when commercial extracts were unavailable. Results: Three hundred and forty-six patients were confirmed with food allergy. CM allergy (CMA) was the commonest (31.2%) followed by red meat allergy (27.7%) and food dependent exercise induced anaphylaxis (FDEIA) (17.9%). Allergy to alpha-gal crustaceans, eggs, gelatin, wheat, coconut milk, and mollusks were seen in 2-10% of patients.The onset of CMA was mainly in childhood. However, in 23/108 patients, onset was after 5 years, including 8 patients in adulthood, and in 14 of the 23, it was preceded by red meat allergy. Onset of primary red meat allergy was predominantly in children, but in 33/96 (34.3%) of patients, it was in adults. Most patients with alpha-gal allergy (21/29, 72.4%) had initial symptoms in childhood and adolescence.Anaphylaxis was diagnosed in 213 patients. FDEIA is the commonest cause (24.7%) followed by red meat allergy (23%), CMA (21.5%) and alpha-gal allergy (10.3%). Allergy to peanuts and fruits were rare.Patients with red meat allergy and/or CMA developed allergy, including anaphylaxis, to vaccines containing bovine/porcine products. Conclusion: CM was the most common food allergy in children, but egg allergy was uncommon. Primary red meat allergy was the second most common, and was associated with allergy to vaccines containing bovine products, such as the measles, mumps and rubella (MMR) vaccine. Allergy to peanuts and fruits were rare. Primary red meat allergy may be responsible for late onset CMA.