日本性感染症学会誌 Journal of Japanese Society for Sexually Transmitted Infections

This study examined the stages and transmission routes of syphilis separately for reinfection and first infection. During the 4.5 years of study from January 2019 to June 2023, of 128 patients diagnosed with syphilis, 10% (13/128) were reinfected, and 90% (115/128) were first infected. The stages of the 13 reinfected patients were primary 3, secondary 5, and asymptomatic 0 in 8 men and 1, 2, and 2 in 5 women, respectively. The stages of the 115 first-infected patients were primary 42, secondary 28, and asymptomatic 8 in 78 men and 9, 13, and 15 in 37 women, respectively. Regarding the transmission route, 25% (2/8) of men had a history of sex industry use and 38% (3/8) were homosexual, and 80% (4/5) of women had a history of sex industry engagement among the reinfected patients. These rates among the first-infected patients were 50% (32/64), 14% (11/78), and 76% (28/37), respectively. For reinfection and first infection, the important transmission routes are a history of sex industry use and homosexual transmission for men and a history of sex industry engagement for women.