05/09/2024
Japan on red alert for streptococcal toxic shock syndrome
Streptococcal toxic shock syndrome (STSS) is a serious bacterial infection caused mainly by Streptococcus pyogenes, a highly virulent bacterium. This severe form of infection is experiencing a worrying resurgence in Japan, where 27 of the archipelago’s 47 departments are currently on red alert.
Origin of the infection and mode of transmission
TSS is caused by group A streptococci, also known as ‘flesh-eating bacteria’ because of their ability to rapidly destroy soft tissue. The bacteria are transmitted mainly by direct contact with infected respiratory secretions, such as coughing or sneezing. Although less contagious than other pathogens such as the flu virus, this form of transmission nevertheless requires extra vigilance. The bacteria are transmitted by respiratory droplets and direct contact with nasal secretions or skin lesions, which underlines the importance of preventive measures. There are devices available today to prevent these airborne transmissions.
Evolution of the infection and impact in Japan and Europe
According to Japan’s National Institute of Communicable Diseases, 422 cases were reported between 1 January and 17 March 2024, compared with 941 cases for the whole of 2023, showing a rapid and worrying increase in this syndrome. Crucially, this increase particularly affects people under the age of 50, highlighting the increased vulnerability of this age group.
At the same time, the mortality rate remains extremely high, with 30% of people with this syndrome currently dying from it. This alarming fact makes the syndrome a real threat to public health. Forecasts indicate that the number of cases could reach 2,500 by the end of the year, making it all the more urgent to find and implement real infection prevention and control measures.
There have also been waves of invasive group A streptococcal infections in 2022-2023 in Europe, North America and Australia.
In Europe, the UK reported a 30% increase in cases in 2023 compared with the previous year, totalling more than 1,500 infections. In the United States, cases doubled in 2023, exceeding 2,000. In Australia, an increase of 25% was observed, reaching a total of 800 infections over the same period.
Symptoms and treatment of STSS
Streptococcal toxic shock syndrome is characterised by an excessive immune response to the toxin produced by the bacteria. Symptoms often include high fever, intense muscle pain and gastrointestinal distress, which can rapidly progress to low blood pressure and organ failure within 24 to 48 hours.
This rapid progression requires immediate medical intervention to avoid fatal outcomes. Treatment is based on antibiotics; however, the Institut Pasteur has noted a worrying increase in the resistance of S. pyogenes to several families of antibiotics, complicating the management of infected patients.
The ‘immune debt’: a probable cause of the resurgence
The resurgence of group A streptococcus (GAS) infections was observed from the end of 2022, in conjunction with a high circulation of respiratory viruses, particularly in children. This situation has been exacerbated by the triple epidemic of influenza, COVID-19 and bronchiolitis.
The weakening of the immune system due to prolonged barrier measures could explain, at least in part, this rebound in GAS infections. Indeed, children whose immune systems have not been in contact with the usual circulating strains are more likely to develop serious infections.
