Should I be concerned if I travel to Japan?

You may have heard in recent days about a “flesh-eating bacteria” spreading in Japan, referring to an illness that can occur in cases of streptococcal toxic shock syndrome (STSS).

Media reports say the country has recorded more than 1,000 cases of STSS in the first six months of 2024, more than the total for all of 2023. However, these cases have not yet been published in peer-reviewed journals, so the reports may not be entirely accurate.

STSS syndrome is caused by Streptococcus pyogenes bacteria, or “strep A.” These bacteria are fairly common, but some strains can cause a more serious illness, called invasive group A strep disease.

Since 2022, many countries, including Australia, the United States, and European countries, have seen an increase in serious invasive group A streptococcal infections. This increase is part of an overall increase in group A streptococcal infections.

So what is STSS, why is it seeing a surge right now, and is it a cause for concern?

Who is affected by STSS?

At any given time, many people will be “colonized” with strep A, meaning the bacteria is living harmlessly in their throat or on their skin.

Strep A also causes sore throats and skin infections. Sometimes, for reasons that are not yet entirely clear, strep A causes invasive infections such as pneumonia, nasty “flesh-eating” skin infections, and Stevens-Johnson syndrome (PTSD). Strep A is thus a major cause of sepsis, a term that generally refers to a potentially fatal infection.

Stevens-Johnson syndrome is the most serious form of strep A disease, but fortunately it is very rare. It mainly affects young children and the elderly, but cases occur at any age. Pregnant women may also be at higher risk, including shortly after giving birth.

What are the symptoms?

In STSS syndrome, the bacteria produces a toxin that can cause an overwhelming immune response in some people.

The disease can progress to death within hours and has a high mortality rate: up to 40% of people who develop STSS will die.

However, early signs and symptoms of STSS can overlap with those of common viral illnesses, especially in children, making diagnosis difficult.

The first symptoms of an invasive group A strep infection are vague: fever, rash, and nausea. However, it is important to watch for signs of sepsis, which suggest that a more serious illness may be present.

Signs of more serious invasive group A streptococcal infection, including STSS, are similar to those seen in other bacterial causes of sepsis (such as meningococcal disease). These include lethargy (drowsiness), rapid breathing, a rapidly progressing rash, muscle aches, and confusion.

Stevens-Johnson syndrome can sometimes occur at the same time as a condition called necrotizing fasciitis, also caused by streptococcus A, which is the “flesh-eating” form of the infection. In this case, skin cells die in response to toxins produced by the bacteria.

Parents of young children should trust their instincts. If you are concerned that your child is sicker than usual due to a common germ, especially if he or she has cold limbs, a red rash (like a sunburn), or is reacting less well, seek prompt medical attention at the nearest emergency department.

Why now?

Studies suggest that certain more virulent strains of streptococcus A may be behind the current surge in STSS.

Additionally, in 2020-2021, at the height of the COVID-19 pandemic, when close contact between people was less frequent, exposure to strep A (and other bacteria and viruses) was also less. For young children in particular, this means that they have not developed the partial protection against serious strep A infections that comes from repeated exposure.

With increased human contact from 2022, transmission of strep A has increased, with children more vulnerable to contracting more serious illnesses, including STSS.

This phenomenon is not unique to Japan. Although rare, we have observed many cases of STSS in Australia and elsewhere.

How is STSS syndrome treated and can we prevent it?

Strep A can be eliminated by penicillin, one of the oldest and most widely available antibiotics. When strep A is diagnosed early, antibiotics can usually prevent most serious complications.

Other medications, such as immunoglobulins, may be needed to curb an out-of-control immune response, and patients often need support in an intensive care unit.

There is no vaccine to prevent STSS and other streptococcal A infections (unlike other bacteria such as meningococcus and pneumococcus, which are included in the national childhood immunization schedule).

Researchers in Australia and around the world are working hard to try to find a vaccine to prevent strep A infections.

Serious strep A infections such as STSS often follow viral infections, particularly chickenpox and influenza. So stay up to date with your national vaccination schedule (which includes chickenpox) and make sure you get the seasonal flu vaccine to reduce your risk.

Strep A can be spread by large respiratory droplets or by direct contact with infected or carrier people. Simple hygiene measures (such as washing your hands and covering your cough) reduce the amount of strep A circulating in the community.

Planning a trip to Japan? No need to cancel your vacation

Stevens-Johnson syndrome (SSJS) is a rare but serious complication of strep A infections, which can occur in humans anywhere. So unless you’re hiking alone to the South Pole, you’re at a very similar (and very low) risk of contracting a serious infection.

Make sure you are up to date on your vaccinations, including the seasonal flu vaccine. Always practice good hand hygiene and be aware of the signs of serious bacterial infections that require urgent medical attention.

This article is republished from The Conversation. It was written by: Phoebe Williams, University of Sydney; Joshua Osowicki, Murdoch Children’s Research Instituteand Yara-Natalie Abo, Murdoch Children’s Research Institute

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Phoebe Williams receives funding from the National Health and Medical Research Council.

Joshua Osowicki receives funding from the National Health and Medical Research Council of Australia, the National Institute of Allergy and Infectious Diseases of the US National Institutes of Health, and the Leducq Foundation.

Yara-Natalie Abo receives funding from the National Health and Medical Research Council and the National Heart Foundation.