The Syphilis Crisis Japan Isn’t Talking About

In September 2026, Japan’s Ministry of Health, Labour and Welfare updated its quarterly syphilis report. For all of 2025, there were 13,530 cases, more than a thousand fewer than in 2024. The number was moving downward, but penicillin was still out of stock in pharmacies. At a sexually transmitted infection clinic in Tokyo, a nurse typed “STELUES” into the inventory system and got “0.” She closed the page and took the next call. On the other end was a pregnant woman whose screening form said syphilis-positive. This scene is not an isolated case. It pulls two lines together: the infection curve and the supply-chain curve.

I. The curve: twentyfold growth in ten years, then a high plateau

Japan reported just over 600 syphilis cases in 2010. By 2015, the number had passed 2,500. By 2021, it was close to 8,000. In 2022, it broke 10,000 for the first time. In 2023, it hit a peak of 15,055. In 2024, 14,663. In 2025, 13,530. In the first half of 2026, cases fell by about 17.8% compared with the same period a year earlier. The steepest climb came between 2013 and 2023, when the number increased more than twentyfold in ten years. Then it began to decline, but slowly. The 2025 figure was still nearly double the 2021 level.

By gender, men account for roughly two-thirds of cases, with increases across age groups from their 20s to their 60s. Women are concentrated in their 20s. This distribution is hard to explain with a single cause. It points to differences in sexual behavior patterns, testing access, willingness to seek care, and social support systems.

Other sexually transmitted infections in Japan have not surged in the same way. New cases of gonorrhea and HIV have generally declined or remained flat over the past decade or so. Only syphilis has shown leapfrog growth. This suggests that the return of syphilis has a more specific transmission chain and more specific social conditions than a general rise in STIs.

II. Empty pharmacy shelves: the penicillin shortage is not background noise

In Japan, penicillin is the first-line treatment for syphilis. For ordinary patients, alternatives are not entirely absent. Amoxicillin, minocycline, and other drugs can be used for some groups. But for pregnant women, penicillin is almost irreplaceable. It is the key drug for preventing mother-to-child transmission of syphilis. The Japan Society of Obstetrics and Gynecology has already called for priority protection of the drug supply for pregnant women.

The shortage comes from the supply chain. Pfizer’s product “STELUES” was recalled in July 2025 after foreign matter was found, and in November of the same year there was a production equipment failure. Full shipments are not expected to resume until the second half of 2027 at the earliest. This means that for some time to come, Japan’s medical system must allocate resources under conditions of limited supply: pregnant women first, severe cases first, high-transmission-risk groups first.

The relationship between drug shortage and epidemic spread is not a simple causal one. They reinforce each other. Insufficient medicine makes it harder for patients to be cured promptly, and delayed treatment makes it harder to cut transmission chains. Worry about drug availability may also lead some people to postpone testing and medical visits. The fragile points of public health are often not in the most visible places. They are in a halted production line, a recall, an equipment failure.

III. The “Three Ones”: how loneliness becomes an epidemiological variable

“One-person meals”: eating alone at a restaurant.
“One-person housing”: living alone in a capsule hotel or container unit.
“One-night quiet”: the nightlife that once bustled in Tokyo and other cities has gone quiet.

These three phrases look like descriptions of lifestyle. In fact, they point to the same thing: the continuous weakening of social connections.

Traditional family dinners, workplace socializing, community ties, and nightclub consumption once provided emotional support, a sense of belonging, and a social buffer. When these scenes shrink, individuals do not become freer. They become more isolated. One person eats, one person goes home, one person gets through the night. Over time, the body may be treated as the “last currency,” used to exchange for warmth, companionship, and confirmation that one is still needed.

Some people turn to the sex industry. Some rely on dating apps. Some seek brief comfort in anonymous, immediate sexual relationships. The risk comes from desire stripped of relationship, responsibility, and protection. It turns into a high-frequency, low-commitment, low-protection form of instant consumption.

“One-night quiet” deserves particular attention. Quiet nightclubs do not mean desire has disappeared. Desire has moved. It has moved from public space to online platforms, from acquaintance socializing to stranger matching, from bounded entertainment venues to more hidden, harder-to-regulate sexual consumption. Social media and dating apps lower the threshold for finding sexual partners and reduce patience for negotiating safety measures. When “immediate satisfaction” becomes the main logic, condom use, regular testing, and partner notification are easily pushed to the end of the list.

The “Three Ones” are a risk environment, not the direct pathogen of syphilis. They explain why syphilis can still find a transmission gap in a country with advanced medicine and a mature public health system.

IV. Global conditions: syphilis’s return in developed countries

Looking more broadly, the return of syphilis is a global phenomenon. The United States, the United Kingdom, and other developed countries have all seen sharp rises in syphilis infection rates over the past decade or so. In England, confirmed infectious syphilis cases reached 9,535 in 2024, the highest level since the 1940s. In the United States, congenital syphilis cases have risen for years, approaching 4,000 in 2024. Globally, the estimated number of new syphilis cases among adults aged 15 to 49 rose from 6.3 million in 2016 to 8 million in 2022.

The reasons are not mysterious. Over the past two decades, global public health resources have been heavily directed toward HIV prevention and control, while syphilis has been relatively neglected. The long period of low syphilis prevalence also made the public, and even some doctors, less vigilant. Many people no longer treat it as a “modern disease.” As testing technology became more sensitive, population mobility increased, and social apps became more widespread, syphilis found new opportunities in new behavioral networks.

Japan’s difference is that it has layered this global trend on top of its own social atomization, sex-industry structure, and loneliness economy. Conditions in many countries already favored a rebound. Japan’s “Three Ones” society provided an environment that caught fire more easily.

V. The Chinese comparison: 640,000 cases and 85% latent

When discussing Japan, many people naturally compare it with China. China reported 640,000 syphilis cases in 2025, an incidence rate of about 45 per 100,000, far higher than Japan’s. But behind this there is a key variable: the scale of screening.

Since 2010, China has expanded its prevention of mother-to-child transmission program to cover HIV, syphilis, and hepatitis B. All pregnant women receive free screening. Many hospitals also require four routine infectious disease tests before surgery. As a result, large numbers of asymptomatic latent syphilis cases are detected. Among newly reported syphilis cases in China, the proportion of latent syphilis rose from 32% in 2005 to about 85% in 2020. This shows that the rise in China’s case numbers is to a large extent the result of a “testing amplifier.” At the same time, mother-to-child transmission and further spread have been better controlled.

There are also differences in syphilis detection rates among pregnant women in China and Japan. In China, the combined syphilis detection rate among pregnant women from 2021 to 2024 was about 0.34%. In Japan, a 2022 study found a rate of 1/1,215, about one-quarter of China’s. The two countries are not fully comparable in their definitions of latent cases, screening strategies, and reporting standards. Therefore, it is meaningless to simply say Japan’s epidemic is “better than China’s” or “worse than China’s.” What is worth comparing is who detects earlier, who treats earlier, and who can better cut transmission chains.

Another change in China is the rising proportion of older infected people. Among newly reported syphilis cases, the share of patients aged 55 and above rose from 14.74% in 2005 to 40.09% in 2020. Longer life expectancy, higher divorce rates, and lower condom use among older people are all driving this trend.

VI. The next quarterly report

The report for the second half of 2026 has not yet been released. In the pharmacy refrigerator, the penicillin reserved for pregnant women is still there. The nurse turns to the next page of the appointment list. On it are names, ages, weeks of pregnancy. Outside the window, a vending machine glows. There is no slogan. Syphilis prevention depends on the next dose of medicine, the next test, the next conversation that is not avoided.

Controlling syphilis requires penicillin, testing reagents, and standardized treatment. It also requires that high-risk groups be willing to test, able to access care, and not hide their condition out of shame. It requires that pregnant women receive priority treatment. It requires prevention education that works in social apps, the sex industry, and among young people. And it requires answering a question harder than medicine: when social connections break, what do we use to replace the warmth once provided by family, community, and public space?

Otherwise, even if syphilis numbers decline in the short term, it will only be a temporary retreat. The body becoming the last currency is not an abstraction. It is written on every screening form and on the back of every capsule hotel receipt.