Number of cases of syphilis in Japan: 2018–2022.

Some countries have reported a post-pandemic resurgence in syphilis prevalence, but trend data in the World Health Organization Western Pacific Region (WHO-WPRO), including Japan, are severely lacking. Thus, the present study compares the number of syphilis cases before and after the COVID-19 pandemic in some WHO-WPRO countries. In addition, temporal trends in the number of syphilis cases in Japan pre- and post-pandemic are described. Annual numbers of syphilis cases during the study periods from China, New Zealand, Australia and Japan were compared. Annual trends of the numbers of syphilis cases during the same study periods were examined in Japan. In 2020, the number of syphilis-positive cases decreased in all four countries. In 2021, though, China, Australia and Japan all showed an increase in the numbers of syphilis cases. However, the rate of increase in China (+2.8%) and Australia (+4.8%) was low compared to Japan (+36.0%). The number of syphilis cases in New Zealand in 2021 was 12.6% lower than in 2020. In 2022, the number of cases of syphilis in China was 7.4% lower than in 2021. The increase of syphilis-positive cases was approximately 6.3-fold higher in Japan compared to Australia (+66.2% vs. +10.5%) in 2022. In conclusion, post-pandemic resurgence of syphilis occurred in Australia and Japan, but not in China and New Zealand. The reason for the substantial increase in syphilis-positive cases in Japan remains unclear. Post-pandemic, prevention and control of sexually transmitted infections still require attention.

已有多个国家报告新冠疫情后梅毒（syphilis）患病率出现反弹，但包括日本在内的世界卫生组织西太平洋区域（WHO-WPRO）的相关趋势数据仍极度匮乏。为此，本研究对比了WHO-WPRO部分国家在新型冠状病毒肺炎（COVID-19）疫情前后的梅毒病例数，并描述了日本疫情前后梅毒病例数的时间变化趋势。本研究对中国、新西兰、澳大利亚及日本在研究周期内的年度梅毒病例数进行了对比，同时分析了日本同期梅毒病例数的年度变化趋势。2020年，上述四国的梅毒阳性病例数均有所下降。但到2021年，中国、澳大利亚及日本的梅毒病例数均出现增长，其中中国（+2.8%）与澳大利亚（+4.8%）的增幅远低于日本（+36.0%）；而新西兰2021年的梅毒病例数较2020年下降了12.6%。2022年，中国的梅毒病例数较2021年下降了7.4%；同年日本的梅毒阳性病例增幅约为澳大利亚的6.3倍（日本+66.2% vs. 澳大利亚+10.5%）。综上，澳大利亚与日本出现了新冠疫情后的梅毒反弹现象，而中国与新西兰则未出现此情况。日本梅毒阳性病例数大幅增长的具体原因目前仍不明确。新冠疫情后，性传播感染（sexually transmitted infections）的防控工作仍需予以重视。