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A type of bacterial infection is on the rise in Japan. DuKai photographer/Getty Images
  • Japan is reporting a record number of streptococcal toxic shock syndrome (STSS) cases this year.
  • STSS is a severe, life-threatening complication of Group A Streptococcus, the same bacteria responsible for strep throat.
  • Group A Streptococcus cases in Japan have also been associated with the “flesh-eating” condition necrotizing fasciitis.

For the second year in a row, Japan is reporting record-setting numbers of a life-threatening bacterial infection. Experts are still trying to figure out what is behind the surge. One potential cause could be related to the effects of social distancing during the COVID-19 pandemic.

The Japan Health Ministry has reported 977 cases of streptococcal toxic shock syndrome (STSS) as of June 2nd, according to the Japan Times. That’s the most ever recorded in a single year, already outpacing last year’s record of 941 infections. Seventy-seven individuals have died from STSS in Japan between January and March.

STSS is a severe complication of Group A Streptococcus (GAS), specifically the variant Streptococcus pyogenes, which is the same bacteria responsible for strep throat. It is a potentially deadly condition with a mortality rate that can exceed 30%.

The condition is rare, but serious. It occurs when the bacteria reaches the bloodstream and causes a systemic inflammatory response and toxic shock. Ensuing life-threatening symptoms include low blood pressure, organ failure, and loss of consciousness.

The GAS infections in Japan are also reportedly associated with another serious complication: necrotizing fasciitis, which is often called a “flesh-eating” disease. Necrotizing fasciitis spreads within the fascia (lower skin layers) and causes necrosis, literally tissue death. It is a severe life threatening condition requiring emergency surgery and can result in death.

However, an infection with GAS does not always result in such extreme outcomes. It is commonly transmitted among school-age children and can manifest swelling, soreness, and rash, as well as strep throat.

“GAS can be passed readily from person to person through close personal contact, and it can be carried without symptoms in the throat, but it can also cause classical strep throat symptoms like inflammation of the throat and pussy tonsils,” William Schaffner, MD, a Professor of Infectious Disease and Preventive Medicine at Vanderbilt University, told Healthline.

Japan has experienced a surge in STSS in the past two years, both in terms of the number of cases and fatalities. In March of this year, Japan’s National Institute of Infectious Disease issued an assessment of STSS risk noting an increase in the number of cases in the country.

Given the latest number of infections, it’s clear that the trend identified in that assessment has persisted.

In an interview with The Japan Times, Ken Kikuchi, a Professor of infectious diseases at Tokyo Women’s Medical University said, “At the current rate of infections, the number of cases in Japan could reach 2,500 this year, with a mortality rate of 30%.”

He noted that most deaths happen within the first 48 hours.

“Most of these people will present to the emergency room, and they are there because they are so sick. They have evidence of multiple organ systems involved, they’ll even be admitted from the emergency room directly to the intensive care unit,” Dean Winslow, MD, a Professor of Medicine and infectious disease expert at Stanford Medicine, told Healthline.

There have been 77 deaths so far this year attributed to STSS. In 2023, 97 mortalities due to STSS occurred — the second highest number in the past two years, behind 101 deaths reported in 2019.

It is unclear at this point what is driving the surge in GAS infections in Japan over the last two years, experts told Healthline.

“We need a lot more information to sort this out,” said Schaffner.

He did offer one theory though: infections of many varieties have been on the rise in the post-pandemic era.

During the pandemic when individuals were quarantining at home, avoiding social gatherings, and keeping children home from school, there were global reductions in respiratory infections. The Centers for Disease Control and Prevention also reported a 25% drop in the number of GAS infections during that same time.

In the years since pandemic-era restrictions and quarantines have eased, other infections, strep among them, have been gaining steam.

“Now that we’ve all started to come back together again, these illnesses are, not surprisingly, coming back too. With group A strep, it came back to normal and then exceeded the norm. This has been seen in this country and in many other countries around the world,” said Schaffner.

Amesh A. Adalja, MD, a Senior Scholar at the Johns Hopkins Center for Health Security, echoed those sentiments, telling Healthline, “The most likely hypothesis is that decreased circulation of the bacteria during the pandemic years left an immunity debt and the increase is related to that phenomenon.”

A GAS infection will first appear with symptoms including chills, fever, and headache. If you’re experiencing strep throat, there are also visible signs, most notably red, swollen tonsils and throat. White patches, pus, and red spots, known as petechiae, may also be present in the mouth and throat.

Doctors treat a common GAS infection, such as strep throat, with antibiotics like penicillin and amoxicillin.

However, if the infection progresses into STSS, the patient will require emergency and often intensive care. An STSS infection can progress very rapidly. In some cases, the infection can progress within hours to develop life-threatening low blood pressure.

A strep infection has progressed to STSS if you notice other serious symptoms, including:

  • Rapid heart rate (tachycardia)
  • Change in mentation or difficulty thinking
  • Rapid breathing
  • Absence of urine
  • Bleeding and bruising
  • Eyes turning yellow
  • Low blood pressure

The infection is treated primarily with the antibiotic clindamycin, but additional care is also required to treat the shock.

“The antibiotics really work to kill the streptococci quickly, but the inflammatory response that they have initiated, that’s part of the toxic shock syndrome, and that can linger. You kill all those streptococci within 12 to 24 hours, but you have the residual inflammation that’s already begun,” said Schaffner.

Doctors will administer a range of treatments for shock, including oxygen, intravenous hydration, and blood pressure medication.

In some cases, patients will require surgery to remove dead tissue from the infection.

Japan is experiencing a record-setting number of streptococcal toxic shock syndrome (STSS) cases. STSS is a rare but severe complication of Group A Streptococcus infection, the same bacteria responsible for strep throat.

STSS has resulted in 77 deaths so far in Japan this year; the condition results in death in more than 30% of cases.

It is unclear what is driving the surge of cases in Japan. Experts contacted by Healthline pointed out two possible factors including: an increase in many types of infection following the easing of quarantining during the pandemic.