Seasonal Pathogens and Henoch-Schönlein Purpura Save

Epidemiologic studies of Henoch-Schönlein purpura (HSP) have suggested seasonal variation in occurrence rates (higher from September-April, lower in June-August), suggesting a role for infectious triggers. The importance of infection was recently shown with nonpharmaceutical interventions (NPIs) such as social distancing and mask wearing during the COVID-19 pandemic.

A French cohort study included 9790 children (< 18 yrs) with HSP and 757110 children with an infectious disease, identified from 2015 to 2023. The main outcomes were the monthly incidence of HSP per 100 000 children, and whether HSP incidence was potentially associated with 14 selected common seasonal pathogens over the same period.

They found the HSP incidence decreased significantly after implementation of COVID restrictions (NPIs) with a −53.6% drop in March 2020. By comparison, relaxation of NPIs in April 2021 resulted in a significant increase (37.2%) in HSP.

A time-series analysis 37.3% of HSP incidence was potentially associated with Streptococcus pneumoniae and that 25.6% of HSP incidence was potentially associated with Streptococcus pyogenes and human rhino enterovirus accounted for 17.1%. In contrast, all other seasonal pathogens played a minor role. 

Nearly 60% of HSP incidence was potentially associated with pneumococcus and group A streptococcus, suggesting that  preventive measures against these pathogens could reduce the incidence of pediatric HSP.