Food allergy in nursery children of Kawasaki city, Japan

Background: Food allergies are often life threatening. In order to establish appropriate food allergy measures in nursery children, it is important to analyze local epidemiological data on the food allergy prevalence in nursery children. However, no such data are currently available for the city of Kawasaki, Japan. Objective: The present study retrospectively evaluated food allergy prevalence among nursery children in Kawasaki city. Methods: Data from children with food allergies requiring food avoidance in the nurseries of Kawasaki city between 2007 and 2016 were evaluated. Results: From 2007 to 2016, the prevalence of food allergies among nursery children in Kawasaki city increased from 2.7% to 5.3%. The increase of food allergy prevalence was higher in 2-5 year-old children than in 0-1 year-old children (2.0% to 4.7% vs. 5.3% to 7.0%, respectively). The top five most common food allergies were hen's egg (73.0%), cow's milk (29.3%), nuts (9.7%), soy (8.9%), and wheat (6.5%). Hen's egg was consistently identified as a causative food of food allergy in more than 70% (73.0-89.1%) of food avoidance cases over the 10 year period. The increase of egg allergy prevalence was higher in 2-5 year-old children than in 0-1 year-old children (1.7% to 3.2% vs. 5.2% to 6.0%, respectively). Conclusions: Food allergies, to hen's egg in particular, have increased considerably among nursery children in the city of Kawasaki, Japan, and that increase was higher among older children.