Objective: To measure the prevalence, the possible causes and the influencing factors of allergy, food hypersensitivity and food intolerance in 0-36 month old infants in 8 cities in China.
Method: Totally 2632 infants from the outpatient departments of prevention and health care of two representative hospitals in 8 Chinese cities were randomly selected by applying multistage cluster sampling method from October 2011 to March 2012, and a one-on-one survey to infants' parents was conducted to investigate infants' sensitization status.
Result: Self-reported infant allergy rate was 17.97% (473/2632) ; self-reported food hypersensitivity and food intolerance rates were 6.53% (172/2632) and 4.26% (112/2632) , respectively. The proportion of self-reported food hypersensitivity of 0-12 months old infants was 4.47% (74/1656) and their top five allergens in a descending order were eggs (28.38%) , shrimp (25.68%) , fish (21.62%) , milk (18.92%) and wheat (4.05%) . The proportion of self-reported 13-36 months old infant's food hypersensitivity was 10.05% (98/976) . The top five allergens were shrimp (33.93%) , fish (26.79%) , eggs (23.21%) , milk (12.50%) and soy (3.57%) in 13-24 months group, while fish (38.24%) , shrimp (35.29%) , eggs (20.59%) , milk (20.59%) and peanuts (2.94%) in 25-36 months group. Both 7-12 and 13-24 month old were the highest incidence (both of them were 11.98%, 58/484) of age for developing food hypersensitivity and 7-12-month old was also the highest incidence (8.47%, 41/484) of age for food intolerance. The self-reported food intolerance rate was 3.68% (61/1656) and 5.23% (51/976) in the two age groups, respectively. Age, parental history of allergy and father's educational level (OR was 2.452, 1.482 and 2.598, respectively, P < 0.01) were the risk factors of food hypersensitivity; within two weeks of sickness (OR = 1.267, P < 0.05) was the risk factor of food intolerance.
Conclusion: Infancy was the most vulnerable period of life of getting allergy, therefore, it is necessary for all infants to prevent allergy through a variety of effective strategies.