“Flesh-eating” bacteria in Japan: should we fear an epidemic?

This caused its football team to cancel a qualifying match for the 2026 World Cup which was to be held in North Korea. Japan is currently experiencing a sharp increase in potentially fatal infections caused by a bacteria, group A streptococcus. Over the last three months, 517 cases of severe invasive infection due to this bacteria have been recorded in the country, according to the Center Tokyo Metropolitan Infectious Disease Surveillance Unit. This is more than half of the cases that are usually recorded there over an entire year. The news, widely reported by the international media, has brought back fears of a new pandemic for several weeks. What about it? Answer with a specialist.

The bacteria in question is actually not specific to Japan. “It is a commensal bacterium of the throat, specific to the human species, especially present in children,” describes Dr. Asmaa Tazi, bacteriologist at the Cochin hospital in Paris (APHP) and head of the national reference center for streptococci. It is therefore found both in Japan and in all European countries. Its strength lies in its ability to be discreet. In a class of 30 students, it is estimated that around 10% carry this bacteria without knowing it. Most will not get sick, although it can happen. “Group A Streptococcus is a major provider of mild illness. Angina is the most common manifestation, but it can also cause scarlet fever and impetigo,” continues the scientist.

Harmless the vast majority of the time, this bacteria - which is transmitted mainly by respiratory droplets - can also be formidable. For reasons that are poorly understood, it sometimes manages to reach the blood, leading to very severe, even fatal, invasive infections. Depending on the case, it can then attack the skin and cause necrosis (hence its nickname “flesh-eating bacteria”), but also the lungs, the heart or even the brain. These serious, very rare forms can be complicated by streptococcal toxic shock syndrome (SCTS) due to the production of a toxin. This is fatal in more than 40% of cases, despite treatment.

“It is not resistant to antibiotics, in fact it is very sensitive to a basic antibiotic, amoxicillin,” explains Dr Tazi. Its speed is what makes it particularly lethal in cases of invasive infection. “The infection is so severe that it causes several organs to fail without us having time to react. This is particularly the case for the M1 strain which has been described in Japan,” adds the doctor. Of particular concern: these invasive infections occur in people of all ages, without predisposing factors. “Infants, the elderly or immunocompromised, people with diabetes or cancer or even pregnant women are still populations at greater risk, but serious forms can also affect healthy people,” specifies the bacteriologist.

Is the situation in Japan unprecedented? Not really. In reality, France and several other European countries experienced a similar situation a little over a year ago. At the end of 2022, French health authorities even issued several alerts, without this worrying the international media. “Since September 2022, an increase in cases of non-invasive Group A Streptococcus infections such as scarlet fever has been observed in France, but also invasive infections, particularly in children,” warned the Directorate General of Health (DGS). on December 15, 2022. A phenomenon “shared on a European scale”: “the United Kingdom, Ireland, the Netherlands, Sweden… are also reporting an increase in the number of cases”, indicated the DGS.

“The peak of infections took place between December 2022 and January 2023,” reports Dr Asmaa Tazi. In the first quarter of 2023, 1,152 serious cases were reported in France, ten times more than in the first quarter of 2022, according to data transmitted to Le Figaro by the National Reference Center for Streptococci. This then represented 17 cases per 1 million inhabitants. Worse than what Japan is currently experiencing (4 cases per 1 million inhabitants)! And again, surveillance in France is not exhaustive. “We estimate that reported cases only represent 20 to 40% of the total,” says Dr. Tazi, who emphasizes that these infections are not subject to mandatory reporting by hospitals.

Now things seem to be back to normal. “Since the start of 2023, we have observed a regular decline, there is no longer any particular alert in Europe,” continues Dr Tazi. In hindsight, doctors explain this sudden increase by the health restrictions in force during the Covid-19 pandemic. “Pathogens circulated less during this period. The population was in less contact with them, everyone's immune system was less stimulated,” analyzes the doctor. This is what specialists call the immune debt theory.

Japan therefore seems to be experiencing a situation similar to that experienced in Europe, one year late. “Perhaps the lifting of health measures against Covid was later than here?” asks Dr Tazi. Still, the risk of a new pandemic seems to be averted.