Thx 日本ほど顕著ではないがアメリカでも梅毒「だけ」が増え方が顕著なのが分かりました
理由についてはサイトには特に詳しく議論されていないようですね、ざっと見ただけですが
イギリス見つけましたよ https://www.bbc.com/news/health-44384289
But nevertheless, there has been a steady rise with the number of diagnosed cases more than doubling in a decade - 7,137 last year up from 2,874 in 2008.
The increase in syphilis was almost all among gay, bisexual and other men who have sex with men, according to government agency Public Health England, accounting for 78% of all cases diagnosed last year.
Public Health England said it plans "to increase numbers and frequency of tests in populations at higher risk of infection, to promote early detection and treatment".