Photo/IllutrationThe Asahi Shimbun

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Rates of syphilis in Japan have suddenly spiked, topping the 5,000 mark for the first time in 44 years, with the number of cases this year expected to increase.

The rise last year was especially notable among people living in provincial cities and young women. Patients often do not realize they are infected and infect others before getting treatment.

Health experts recommend an immediate checkup if a person thinks he or she is at risk of having contracted the sexually transmitted disease.

A woman in her 20s in the Kanto region who worked in the sex industry was diagnosed with syphilis during a venereal disease checkup after she developed red rashes over her body several months earlier.

As the rashes disappeared within a week, the woman thought she had simply developed hives and continued having sex with clients without seeking treatment at a hospital.

After the checkup, she visited a medical center and was prescribed penicillin. It took a month for her to recover. She has since found alternative employment.

“I feel sorry that I must have spread this infectious disease without being aware I had it,” the woman said.

Syphilis is caused by the bacterium Treponema pallidum. It is mainly transmitted through the skin as well as the mucous membrane of the sex organs and mouth.

Left untreated, in worst cases it can result in brain damage and even death.

In 1948, as Japan was still recovering from the nightmare of World War II, as many as 220,000 people were diagnosed with the condition.

Patient numbers dropped drastically due to the spread of penicillin, only discovered in 1928, and a clampdown on the sex industry.

Less than 1,000 cases had been reported annually since the mid-1990s. Cases have risen rapidly over the past five years, however.

The National Institute of Infectious Diseases said 5,829 cases of syphilis were reported in 2017, 3.5 times the number for 2014. Patient numbers increased twofold or more in 38 prefectures.

A sevenfold rise, 49 cases, was reported in Takamatsu, the capital of Kagawa Prefecture, the nation's smallest prefecture, located on the island of Shikoku, in 2017. The figure for Aomori Prefecture in far northern Honshu was 63, or 31 times higher than 2014.

“Men of all ages are suffering from syphilis, but most female patients are in their teens and 20s,” said an official of the Aomori prefectural government.

Takakazu Matsuki, director of the Matsuki urology clinic in Takamatsu, said the recent surge in syphilis patients may be due to improved diagnosis technology but added a major factor was likely an increase in those frequenting sex businesses, including foreigners.

Obstetrician-gynecologist Kunio Kitamura, who serves as president of the Japan Family Planning Association, said greater promiscuity among young people may be a factor behind the increase, especially with the prevalence of dating and hookup apps.


Syphilis symptoms include lumps and ulcers in genital areas, as well as the mouth, and develop within several weeks of infection.

Patients often do not realize they are infected as the symptoms improve even without treatment.

As the pathogen spreads in the early phase of infection, it leads to red rashes on the skin and mucous membrane across the entire body. But these generally disappear fairly quickly, so carriers are often not aware they are infected.

Without proper treatment, a person can develop memory impairment and damage to the peripheral nerves.

Health experts advise people to take obvious protections if they are not sure about their partner's past sexual activity.

“Do not have sex with potential carriers in risky ways and undergo an immediate checkup if you think you are at risk,” says Takaoki Ishiji, a dermatology professor at Jikei University, who is also vice president of the Japanese Society for Sexually Transmitted Infections.

A simple blood test, often offered at public health centers at no cost, will show if a person is infected.

Antibacterial agents to treat the disease must be taken for up to 12 weeks.

Most patients are adult males, but the disease is now spreading even among women in their 20s and 30s.

Syphilis can cause pregnant women to miscarry or result in a stillbirth, while congenital syphilis can affect the fetus, particularly the liver, eyes and ears.

A report compiled by a research team of the health ministry found that 20 infants developed congenital syphilis between 2011 and 2015. Three of them died, and three others were still suffering from aftereffects, according to the report.

(This article was written by Mutsumi Mitobe, Sokichi Kuroda and Akiyoshi Abe.)