Sex differences in common childhood infections in Taiwan.

Sex differences in childhood infections are commonly reported in case-only studies. In this population-based study of 278K Taiwanese children followed from 3 months to 18 years old during 2000-2012, we compared age-trajectories of monthly numbers of all-cause healthcare visits and monthly rates of infection-specific healthcare visits in boys and girls. In all-cause healthcare visits and in healthcare visits related to conjunctivitis, respiratory tract infections, enteritis, hand-foot-mouth disease and herpangina, there was good resemblance of age trajectories between boys and girls. Despite this resemblance, there was evidence of a slightly higher rate in boys than in girls under age 6 years (i.e. a male tendency, or male-to-female ratio >1.0) across all diagnoses except herpangina. For urinary tract infection where age-specific sex difference is well reported in case-only studies, we confirmed in this population-based study that there was a much higher rate of kidney infection among boys compared to girls during infancy, and a higher rate of kidney and bladder infection among girls compared to boys after this period. The age-specific sex difference in urinary tract infections was so strong that the age trajectories in boys and girls were qualitatively different. Our report confirms previously reported sex differences in other countries whilst placing this in the context of age dynamics in childhood infection.