Estimating the population of immigrants with syphilis by Bayesian Back-calculation

Background: Syphilis is a sexually transmitted disease and infects tens of millions of people every year. In China, syphilis has its characteristics in spreading patterns: this disease always spreads with the migration of the floating population. But rarely quantitative modeling studies have been conducted in this field. Method: Based on the Bayesian back-calculation method and datasets collected in Zhejiang Province, China, a novel model to analyze the syphilis transmission and immigration process is constructed. Results: The results show that immigrant patients are the main source of syphilis in the Zhejiang province. By using the PRCC method to analyze the relationship between parameters and infected cases, we find two main effective measures to control syphilis: the patients paying attention to their behaviors and using sexual protection measures. Conclusion: With the increase of intensive personnel exchange among different countries and regions, it is becoming more important to study the transmission of diseases within the floating populations. The method we use in this manuscript provides a quantitative research method by using the diagnosed cases. All the methods and models in this manuscript could be used in the studies of other diseases where immigrant patients should be considered.