Abstract: Objective: To explore the seroprevalence and risk factors of syphilis infection among general population in Shandong Province, China, and to evaluate the data of syphilis report in shandong province infectious disease network direct reporting system. Methods: A total of 8074 general population aged 18~49 in 12 counties and districts were selected by multi-stage complex sampling. The sociodemographic characteristics and risk factors of syphilis infection were collected. The risk factors of syphilis infection were analyzed using univariate and multivariate regression. The incidence of syphilis in the general population in Shandong was estimated and compared with the syphilis data in the infectious disease Network direct reporting system. Results: A total of 7256 valid samples were included in this study. 23 cases were seropositive for syphilis, and the syphilis serum positivity rate was 0.30% (95%CI 0.06%-0.53%). The positive rate of serum syphilis in Ludong district was 0.77% (95%CI 0.67%-0.86%), which was 1.71-11.00 times higher than that in other areas. The positivity rate of syphilis in urban residents was 0.47% (95%CI 0.19%-0.74%), 6.71 times higher than that rural residents. Multivariate logistic regression analysis showed that the risk factors for syphilis infection were living in urban areas (aOR=6.67, 95%CI 1.59-25.00), migrant workers (aOR=4.81, 95%CI 2.78-8.31), the per capita monthly income of the family in the past year was > 1000 yuan (aOR=10.51, 95%CI 2.28-48.39), the interval between drinking less than 7 days (aOR=2.66, 95%CI 1.07-6.59), no knowledge of condom use (aOR=2.19, 95%CI 1.17-4.11), visited entertainment place in the past year (aOR=1.94, 95%CI 1.31-2.87) and the number of new sexual partners in the past year more than 2 (aOR=5.63, 95%CI 1.14-27.86). The estimated incidence of syphilis in the general population of Shandong Province was 41.32/10⁵, which 2.67 times (95%CI 1.91-4.42) higher than the reported incidence (15.46/10⁵). Conclusion: The prevention and treatment of syphilis in Shandong Province should focus on the eastern Shandong region and urban residents, as well as the migrant workers, and the population with low education level, alcoholism, frequent access to entertainment places and multiple sexual partners. The reported incidence of syphilis is lower than the actual level, and the management of syphilis report in medical institutions should be further strengthened.

Key words: syphilis, seroprevalence, influencing factors, general population