[Syphilis infection and related factors among men who have sex with men in sentinel surveillance in Yunnan Province, 2019-2024].

Objective: To understand the syphilis infection rate, changing trend and related factors of syphilis infection among men who have sex with men (MSM) in Yunnan Province from 2019 to 2024. Methods: From 2019 to 2024, a cross-sectional survey was conducted at monitoring sentinel sites in Yunnan Province from April to July each year. Recruitment methods such as snowball sampling, activity venues, and social software were adopted to recruit men who aged 16 and above, and engaged in homosexual behavior (anal or oral sex) in the past year as subjects. The χ2 trend test was used to analyze the changing trend of syphilis infection, and a multinomial logistic regression model was used to analyze the related factors of syphilis infection among MSM. Statistical analysis was performed using SPSS 19.0 software. Results: From 2019 to 2024, a total of 15 998 MSM were involved in sentinel surveillance of Yunnan, and among them, 15 987 participated in serological test. The syphilis infection rates from 2019 to 2024 were 4.3% (116/2 729), 3.6% (93/2 608), 2.7% (70/2 608), 3.7% (97/2 610), 3.5% (91/2 607), and 3.4% (95/2 825), respectively. Overall, there was no statistically significant trend in the syphilis infection rate (trend χ2=1.59, P=0.207). However, the downward trend of syphilis infection rate among divorced/widowed individuals, those with a high school education or above, and MSM in the central Yunnan region was statistically significant (all P<0.05). The syphilis infection rates of MSM in the central Yunnan region in 2019 and 2022 (6.6% and 4.9%) were higher than those in the western Yunnan region (2.8% and 2.3%) (all P<0.05). In the past six months, the proportion of MSM who consistently used condoms when having sex with different types of sexual partners has all shown an upward trend (all P<0.05).The proportion of sexually transmitted disease cases in the past year showed a downward trend (all P<0.05). The results of multinomial and multivariate logistic regression analysis showed that being under 30 years old, unmarried, married/cohabiting, and having a household registration in Yunnan Province were positive related factors for syphilis infection among MSM, while having a junior high school education or below and having a homosexual orientation were negative related factors. Conclusions: From 2019 to 2024, the syphilis infection rate among MSM in Yunnan Province was relatively high. However, the overall changing trend was stable. The syphilis infection rate among MSM with a high school education or above and in the central Yunnan region showed a downward trend. Sexual health education, comprehensive intervention, sexually transmitted diseases screening, referral and standardized diagnosis and treatment should be strengthened for MSM to further reduce the risk of syphilis infection among MSM.