435 Increasing Incidence of Food Allergy in Zimbabwe

BACKGROUND: Data relating to allergic diseases in general and food allergies in particular in the Central African region is scant. Despite observations by the ISAAC studies that airborne allergen sources were common, little has been reported about food allergens. We reviewed data from our laboratory and outpatient records of patients consulted to estimate the magnitude of the disease in our population. METHODS: Patients attending the only specialist allergy diagnostic facility in the country (Asthma, Allergy and Immune Dysfunction Clinic) were offered semi-quantitative allergen specific IgE antibody determination as part of their diagnostic work-up. Alongside skin-prick testing, the Euroimmun immunoblots were used to establish IgE reactivity to a variety of allergen sources. RESULTS: Six hundred thirty five patients were enrolled between January 2009 and April 2011. These were born between 1931 and 2010. IgE reactivity to egg, codfish, cows milk, wheat flour, rice, soya bean, peanut, hazelnut, carrot, potato and apple was investigated using the immunoblot technique. Results were scored negative or positive. The grades of positive were weak (±), low (+), moderate (++) and high (+++). Overall, 47% of the patients reacted to one or multiple allergen sources. Across the age spectrum, allergen specific IgE reactivity was most frequent against potato (16%) and peanut (15%) and lowest against milk (2.7%) and codfish (2.7%), others were intermediate. Egg white reactivity was highest in those below the age of 5 years (7%). IgE reactivity in patients born before 1959 was less than 1%. This increased to 3.4%, 4.8% and 64% respectively in those born before 1969, 1979 and 1989. Nineteen (19%) of patients born in 1990 to 1999 were reactive to a variety of food allergen sources. Likewise, 12% of those born between 2000 and 2011 were reactive. Food allergen reactivity paralleled inhalant allergen source sensitisation in all age groups. CONCLUSIONS: In this sample of symptomatic patients we have shown that allergen specific IgE reactivity to dietary sources was high. An exponential increase in IgE reactivity in patients born between 1990 and 2011 was a surprising observation. Possible explanations include urbanisation, life-style and dietary changes in this predominantly urban population. The results call for a systematic investigation of the predisposing factors.