Although the specific etiology of Henoch-Schonlein purpura (HSP) is still unknown, several kinds of infectious triggers have been proved to participate in its pathogenesis. The objectives of present study were to analyze the association of the infectious triggers with childhood HSP in Anhui province, China. 1200 HSP children were recruited from January 2015 to December 2017. Serum antistreptolysin O titer, TORCH, Epstein-Barr virus, helicobacter pylori (HP), Mycoplasma antibodies (MP-Ab), tubercle bacillus antibody (TB-Ab), respiratory pathogens (legionella pneumophila, chlamydia pneumoniae, adenovirus, respiratory syncytial virus, influenza A virus, influenza B virus, rickettsia, parainfluenza virus) were determined. Patients' histories were obtained by interviews and questionnaires. The annual incidence of HSP was 8.13-9.17 per 100,000. HSP occurred more commonly in spring and winter than in summer with an obvious west-to-east gradient. On admission, several potential infections were identified in 611 cases (50.92%). The infectious agents including streptococcus, HP, MP, parainfluenza, respiratory syncytial virus, TB and toxoplasma gondii were identified in 205 cases (17.08%), 71 cases (5.92%), 58 cases (4.83%), 6 cases (0.5%), 1 case (0.08%), 1 case (0.08%) and 1 case (0.08%) respectively. 123 cases (10.25%) relapsed or recurred more than one time; the mean number was 2.92, and the mean interval was 11.4 weeks. The infection was the most frequent trigger regardless of clinical phenotypes and relapse/recurrence. Symptomatic treatment plus adjunctive anti-infectious agents could significantly improve the remission rate of purpura in the infectious cases (x²=24.60, p<0.01). Streptococcus is the most frequent infectious agent in HSP children regardless of clinical phenotype or relapse/recurrence. The complete elimination of infectious triggers may help relieve cutaneous purpura.

Background: The present study focuses on the associations of streptococcal infection with the clinical phenotypes, relapse/recurrence and renal involvement in Henoch-Schönlein purpura (HSP) children. Methods: Two thousand seventy-four Chinese children with HSP were recruited from January 2015 to December 2019. Patients’ histories associated with HSP onset were obtained by interviews and questionnaires. Laboratory data of urine tests, blood sample and infectious agents were collected. Renal biopsy was performed by the percutaneous technique. Results: (1) Streptococcal infection was identified in 393 (18.9%) HSP patients, and served as the most frequent infectious trigger. (2) Among the 393 cases with streptococcal infection, 43.0% of them had arthritis/arthralgia, 32.1% had abdominal pain and 29.3% had renal involvement. (3) 26.1% of HSP patients relapsed or recurred more than 1 time within a 5-year observational period, and the relapse/recurrence rate in streptococcal infectious group was subjected to a 0.4-fold decrease as compared with the non-infectious group. (4) No significant differences in renal pathological damage were identified among the streptococcal infectious group, the other infectious group and the non-infectious group. Conclusions: Streptococcal infection is the most frequent trigger for childhood HSP and does not aggravate renal pathological damage; the possible elimination of streptococcal infection helps relieve the relapse/recurrence of HSP.