You may have seen alarming headlines warning of a deadly outbreak in Japan over the past few days.
Some outlets have used terms like "flesh-eating bacteria" and "kills in two days", which has sparked international interest.
But Japanese authorities say this wording is an exaggeration of a potential symptom of an infection that is rarely spread to others.
Let's unpack what we know about the disease and the story spreading around the world.
What is the bacterial infection in Japan?
The clinical term for the disease is streptococcal toxic shock syndrome (STSS).
According to NSW Health, it's an infection caused by group A bacteria entering the bloodstream or deep tissue.
This kind of bacteria usually causes mild infections like strep throat in children but certain strains can escalate quickly and lead to invasive group A streptococcal disease (iGAS).
If that sounds familiar, you may have read about cases of iGAS on the rise in Australia last year.
STSS is considered a complication of iGAS that can "develop very quickly into a life-threatening emergency".
How quickly is STSS spreading in Japan?
Japan’s National Institute of Infectious Diseases issued a statement in March warning rates were increasing.
As of June 2, reported cases of STSS in Japan were about 977.
That's quite a leap on the previous period – Japan recorded 941 cases across the entirety of 2023.
Here are the Japanese case numbers from the past few years:
| Year | 2019 | 2020 | 2021 | 2022 | 2023 | Year to June 2 |
| Case numbers | 894 | 718 | 622 | 708 | 941 | 977 |
CNN reports this year has already seen the highest number of cases reported in Japan since the current recording method began.
It's not exactly clear why cases are on the rise but Japanese health authorities say a rise in respiratory infections is correlated with COVID-19 measures being relaxed.
Tokyo Women's Medical University professor Ken Kikuchi told Japan's national broadcaster, NHK, people's immune systems were weakened during lockdown.
"We can boost immunity if we are constantly exposed to bacteria but that mechanism was absent during the coronavirus pandemic," he said.
"So, more people are now susceptible to infection, and that may be one reason for the sharp rise in cases."
It's also worth noting the trend isn't limited to Japan.
There have also been increases recorded in Europe.
How does it spread?
It's difficult to say.
While people with open wounds are at an increased risk of contracting STSS, it's not known how the bacteria gets into the bodies of nearly half the people who are diagnosed.
The NSW Health Department says the following groups are most susceptible:
- Older adults and children
- People with diabetes
- People with alcohol use disorder
- People undergoing treatment with non-steroidal anti-inflammatory drugs
- People with an immunodeficiency
What are the symptoms of STSS?
Early symptoms include:
- Fever and chills
- Muscle aches
- Nausea and vomiting
About 24 to 48 hours after the first symptoms start, the following symptoms may develop:
- Low blood pressure
- Organ failure
- A faster-than-normal heart rate
- Rapid breathing
- The death of body tissue
The death of body tissue, which is also known as necrosis, is where the "flesh-eating bacteria" name has come from.
How is it treated?
People with STSS need to receive care at a hospital.
Australia's national public health information service Healthdirect says the disease is treated with antibiotics.
Surgery may also be required to remove the source of infection.
Are there any travel warnings?
At this stage, you don't need to cancel any travel plans.
Smartraveller, the Australian government's travel advice website, hasn't listed STSS as a health risk for travellers in Japan.
The World Health Organisation also hasn't recommended any travel restrictions for countries experiencing outbreaks.
Even though cases are on the rise, it's still considered very rare for someone with STSS to spread the infection to others.
But the CDC warns "less severe group A strep infections can turn into STSS and these bacteria are contagious".
How can I keep safe?
There's no vaccine available, so the best way to avoid infection is to maintain good hygiene.
That includes:
- Washing your hands often and using hand sanitiser
- Washing your body and hair often with soap and clean, running water
- Keeping any wounds clean and bandaged until they heal
- Avoid bodies of water like hot tubs, swimming pools, lakes, rivers and oceans if you have an open wound
