◆ Increase in Syphilis notifications and characteristics of reported cases, as of October 2015
November 13, 2015
From epidemiologic week 1 to 43, 2015 (December 29, 2014 to October 25, 2015), 2037 cases of syphilis were diagnosed and officially reported by physicians according to the Infectious Diseases Control Law (as of October 28, 2015). This represents a 1.5-fold increase in notifications compared to the same period in the previous year. 1,463 cases were male (1.4-fold increase relative to the same period last year), and 574 cases were female (two fold increase relative to the same period last year), indicating a substantial increase in female cases.
As for the reported routes of transmission, among male cases, 615 reported heterosexual transmission (1.7-fold increase relative to the same period last year) and 487 reported homosexual transmission (i.e. men who have sex with men [MSM]; 1.0-fold increase relative to the same period last year). Among female cases, 405 reported heterosexual transmission (2.1-fold increase relative to the same period last year).
Increase in primary and secondary (P&S) syphilis cases were observed among both genders. Among male cases, 990 were P&S cases, representing a 1.6-fold increase relative to the same period last year. Among female cases, 323 were P&S cases (2.4-fold increase relative to the same period last year), and three quarters of these cases were aged 15-35 years. Notably, with 177 cases, those aged 20-24 years made up the largest proportion of the female P&S cases, and represented a 2.7-fold increase relative to the same period last year. Furthermore, 10 cases of congenital syphilis have been reported so far as of Oct 2015 (9 cases during the same period in the previous year), and warrants careful monitoring of the situation.
In summary, while increase in reported syphilis cases associated with MSM were observed during 2010-2013 (1-4), 2015 has seen a continuing increase in cases associated with heterosexual transmission (5). The current situation warrants ongoing monitoring of trends in syphilis, and raising awareness among high-risk groups is imperative. Specific messages include the following: having casual sexual contact with multiple partners is a risk factor, and that the risk of syphilis infection can increase without proper use of condoms under those circumstances, that syphilis can be transmitted through oral or anal sex, and that having syphilis once does not prevent reinfection (6, 7).
If signs or symptoms suspicious of syphilis occur, early diagnosis and treatment are important. If a patient is diagnosed as syphilis, the case requires notification under the Infectious Diseases Control Law. And, communication to and testing of sex partners is also important. Further information regarding syphilis such as transmission, signs and symptoms, treatment, and prevention are provided on the “Syphilis Q&A” site (http://www.mhlw.go.jp/seisakunitsuite/ bunya/kenkou_iryou/kenkou/kekkaku-kansenshou/seikansenshou/qanda2.html [in Japanese]).
References
1. Infectious Agents Surveillance Report. IASR 36: 17-19, February 2015.
http://www.niid.go.jp/niid/en/iasr-vol36-e/865-iasr/5413-tpc420.html
2. Infectious Diseases Weekly Report. (in Japanese).
http://www.niid.go.jp/niid/ja/id/741-disease-based/ha/syphilis/idsc/idwr-topic/5228-idwrc-1447.html
3. Infectious Agents Surveillance Report. IASR 35: 79-80, March 2014. (in Japanese). http://www.niid.go.jp/niid/ja/syphilis-m/syphilis-iasrd/4497-pr4095.html
4. Infectious Agents Surveillance Report. IASR 35: 132-134, May 2014. (in Japanese).
http://www.niid.go.jp/niid/ja/id/743-disease-based/ha/syphilis/idsc/iasr-news/4582-pr4112.html
5. Infectious Diseases Weekly Report. (in Japanese). https://www0.niid.go.jp/niid/idsc/idwr/IDWR2015/idwr2015-18-19.pdf
6. Sexually transmitted infections (in Japanese).
7. Syphilis Q&A (in Japanese).
http://www.mhlw.go.jp/seisakunitsuite/bunya/kenkou_iryou/kenkou/kekkakukansenshou/seikansenshou/qanda2.html
Infectious Disease Surveillance Center
National Institute of Infectious Diseases, Japan