‘Flesh-eating’ bacteria spreads at record rate in Japan

A deadly “flesh-eating” bacteria is spreading at a record rate in Japan, with the capital Tokyo a hotspot.

So far this year, the country has reported 977 cases of streptococcal toxic shock syndrome (STSS) – already exceeding an all time high of 941 infections detected in 2023.

The condition is caused by an unusual manifestation of the strep A bacteria.

The pathogen itself is common; between five and 20 per cent of healthy adults have latent, symptom-free infections.

But it can progress into a range of diseases, from tonsillitis and impetigo to scarlet fever and pneumonia. In some severe cases, strep A bacteria can become invasive – seeping from cuts and wounds deep into soft tissue and muscle, where it triggers necrotising fasciitis, a “flesh-eating disease”.

It is this condition that is currently spreading at record rates in Japan, according to data from the county’s National Institute of Infectious Diseases this week.

Symptoms begin with a fever or muscle aches, followed by low blood pressure – organ failure and septic shock can follow within 48 hours, and it can be deadly without rapid treatment with antibiotics.

In Japan, the capital Tokyo has been most affected by the record surge, with 145 cases in the first six months of 2024. The majority of cases are in adults over 30, while the death rate has hovered at around 30 per cent, according to the newspaper Asahi Shimbun.

“It is not unusual to see ‘surges’ in cases, [and] we have had such surges in the UK in the past,” said Prof Jon Cohen, Emeritus Professor of Infectious Diseases at Brighton and Sussex Medical School. “Occasionally the explanation is a new strain of bacteria, but otherwise there is often not a really good explanation other than local contagion.”

Pandemic rebound

In December 2022, the World Health Organization issued an alert after a spike of invasive strep A infections, including scarlet fever, in Britain, France, Ireland, the Netherlands and Sweden – though the majority of these cases affected children.

“In England the number of group A strep cases (sore throats, scarlet fever and the rarer invasive infections) plummeted during the Covid-19 pandemic… [and] younger children did not encounter group A strep as they might normally do,” said Prof Shiranee Sriskandan, a professor of infectious diseases at Imperial College London.

“There was therefore a bigger pool of children susceptible to group A strep when social mixing restrictions were lifted, and this probably led to the increase that we saw in 2022.”

She added that similar trends may now be playing out across Japan.

“It is very likely that events in Japan are a delayed rebound in cases following relaxation of social mixing restrictions during the Covid-19 pandemic, similar to what was seen in England and elsewhere.

“Restrictions were lifted at different times across the world, leading to a phased upsurge in Strep A cases. [This could explain] why Japan is seeing an increase this year. It may be that differences in seasonal timing have led to the effect on children being less evident.”

Protect yourself and your family by learning more about Global Health Security