Mysterious, deadly bacteria spreading in Japan at record pace baffles authorities

A mysterious bacterial infection is spreading in Japan at a pace never seen before even as authorities struggle to establish a cause. According to the data from the National Institute of Infectious Diseases (NIID), the number of cases of a group A streptococcal disease – streptococcal toxic shock syndrome (STSS) – in 2024 is expected to surpass the record level earlier noted in 2023. While a total of 941 cases were recorded in the last year, a whopping 378 cases have already been registered in the first two months of 2024.

“There are still many unknown factors regarding the mechanisms behind fulminant (severe and sudden) forms of streptococcus, and we are not at the stage where we can explain them,” said NIID in a statement.

Of Japan’s 47 prefectures, 45 have recorded STSS cases so far this year.

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What causes STSS?

The primary cause of STSS is a bacterium known as Streptococcus pyogenes, often referred to as strep A. This bacterium commonly causes sore throats, particularly in children, with many individuals unknowingly carrying it without showing symptoms.

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However, the highly contagious nature of the bacteria can lead to severe illnesses, complications in health, and even fatalities, especially among adults over 30, with approximately 30 per cent of STSS cases proving fatal.

Even adults fall prey to the disease

While older individuals are traditionally deemed more vulnerable, recent data from the NIID reveals a concerning trend of increased mortality among patients under 50 due to the Group A strain.

According to a report by the Asahi Shimbun newspaper, of the 65 individuals under 50 diagnosed with STSS between July and December in 2023, approximately one-third, or 21 individuals, succumbed to the infection.

Professor Ken Kikuchi, specialising in infectious diseases at Tokyo Women’s Medical University, expressed significant concerns over the sharp rise in severe invasive streptococcal infections this year.

“People’s immunological status after recovering from Covid-19 might alter their susceptibility to some microorganisms. We need to clarify the infection cycle of severe invasive streptococcal pyogenes diseases and get them under control immediately,” he was quoted as saying by the Guardian.

(With inputs from agencies)