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Epidemiology of syphilis among female sex workers and pregnant women during a period of increasing syphilis among women in Japan, 2019–2021
  1. Ayu Kasamatsu1,
  2. Miyako Otsuka1,
  3. Takuri Takahashi1,
  4. Yuzo Arima1,
  5. Takeshi Arashiro1,
  6. Hanae Ito2,
  7. Takuya Yamagishi3,
  8. Yuki Ohama4,
  9. Shu-ichi Nakayama4,
  10. Yukihiro Akeda4,
  11. Motoi Suzuki1
  1. 1 Center for Surveillance, Immunization, and Epidemiologic Research, National Institute of Infectious Diseases, Tokyo, Japan
  2. 2 Field Epidemiology Training Program, National Institute of Infectious Diseases, Tokyo, Japan
  3. 3 Center for Field Epidemic Intelligence, Research and Professional Development, National Institute of Infectious Diseases, Tokyo, Japan
  4. 4 Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
  1. Correspondence to Dr Yuzo Arima, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan; arima{at}

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Japan has been facing an unprecedented increase in syphilis, largely among women who have sex with men and men who have sex with women.1–3 Notifications among women have increased >15-fold over the past decade (figure 1A),1 2 and female sex worker (FSW) status has been found to be associated with incident syphilis.4 These epidemiological trends necessitate urgent action to prevent transmission and adverse consequences, including the risk of congenital syphilis due to infections among pregnant women.

Figure 1

(A) Trends of reported syphilis cases among women, women reporting FSW status and pregnant women, Japan, 2010–2021. Proportion of syphilis cases among women by stage, Japan, 2010–2021. (B) Cases with FSW status. (C) Cases among pregnant women. Seventy cases (1%) were reported as both FSW status and pregnant. FSW, female sex worker.

In Japan, all laboratory-confirmed cases of syphilis must be notified.5 The notification form was modified in 2019 to include information regarding (1) history of providing commercial sex within the previous 6 months and (2) pregnancy status. Here, we describe reported syphilis cases among women (female sex at birth) reporting FSW status and among pregnant women during 2019–2021 (as of 8 October 2022).

Among women reporting FSW status, the number of syphilis diagnoses increased from 740 in 2019 to 1010 …

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  • Handling editor Anna Maria Geretti

  • AK and MO contributed equally.

  • Contributors AK, MO, TT and Y Arima designed the study. AK, MO, TT, Y Arima, TA, HI, TY and MS verified the data. AK, MO, TT, and Y Arima analysed and interpreted the data. AK and MO wrote the first draft of the manuscript. TT, Y Arima, TA, HI, TY, YO, SN, Y Akeda and MS reviewed and provided important comments on the draft manuscript. TY obtained the funding. Y Arima and MS provided administrative or material support. All authors read and approved the manuscript.

  • Funding This work was supported by grants from the Ministry of Health, Labour and Welfare, Japan (grant no. 21HA1003).

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.