These last weeks, the increase in the number of cases ofstreptococcal infections in Japan has caused international concern. Thursday March 21, South Korea decided to postpone a football match against Japan as part of the qualifying rounds for the 2026 World Cup, which increased speculation around contamination with this “flesh-eating bacteria” . During a press briefing on Friday March 22, the spokesperson for the Japanese government, Yoshimasa Hayashi, tried to be reassuring, saying that Japan was not the only country affected by this increase in the number of cases. “The number of patients with respiratory tract infections has increased in various countries, including Japan“, since Covid-19, he explained.
With 517 cases recorded by the Japanese National Institute of Infectious Diseases as of March 17, 2024the number of cases of streptococcal toxic shock syndrome (TSS) has been increasing in recent years after a decline during the Covid-19 pandemic, from 894 cases in 2019 to 941 cases in 2023. But the rapid rise in the latter month is particularly worrying internationally, because the number of cases since January 2024 exceeds half of all cases in 2023.
“Flesh-eating bacteria” infections: 30% of those affected have died in Japan
While older people are usually affected, the form of type A streptococcal infection circulating in Japan would affect younger people. In total, among the 65 people under the age of 50 diagnosed with streptococcal toxic shock syndrome (TSS), between July and December 2023, 30% of them (or 21 people) died.
As pointed out by Guardianhealth authorities are still struggling to identify the causes. “There are still many unknown factors concerning the mechanisms at the origin of fulminant (severe and sudden) forms of streptococcus, and we are not at the stage where we can explain them”, presents the National Institute of Infectious Diseases (NIID).
Streptococcal infections: how are they transmitted? Streptococcus A ?
Strep toxic shock syndrome (TSS) is mainly caused by a bacteria called streptococcus pyogenes, better known as group A streptococcus. It is notably the cause of strep throat which mainly affects children.
As explained by MSD Manualgroup A streptococcus is transmitted by “inhalation of droplets of secretions from the nose or throat, dispersed when a infected person coughs or sneezes” or by the direct contact with a wound. Among the places of transmission, the specialized journal lists the “crowded places”.
Regarding the Japanese situation, although experts are working to discover the causes of this increase in the number of cases, certain hypotheses are however put forward. One of them, relayed in the columns of Guardian, believes that the drop in the status of Covid-19 from class 2 to class 5 may have played a role in the development of the disease, notably causing a reduction in vigilance on actions to limit the risk of contaminationsuch as washing your hands or avoiding contact with go to closed and crowded places.
Additionally, according to Ken Kikuchi, professor of infectious diseases at Tokyo Women’s Medical University, speaking in the Guardian, “the immunological state of people after their recovery from Covid-19 could modify their sensitivity to certain microorganisms”.
Streptococcus A: what are the symptoms of infection?
When it comes to the symptoms of streptococcal infections, they can vary depending on the location of the infection. THE MSD Manual states that it can cause strep throat in children aged 5 to 15, which is characterized by throat pain, fever, headache, vomiting and severe fatigue.
As explained by the Pasteur Institute, group A streptococcus (GAS) “is responsible for common benign and non-invasive infections, such as angina and impetigo”. But it can also be the cause of serious invasive infections such as necrotizing skin infections or meningitis, the latter of which may be associated with streptococcal toxic shock syndrome.
As for the mortality rate linked to invasive streptococcal A infections, it amounts to “around 10% for all pathologies combined”, notes the Pasteur Institute, detailing that “the mortality rates are respectively 30% in the event of streptococcal toxic shock, 15% for necrotizing dermo-hypodermitis and 20% for meningitis”.
What to do to limit the risk of infection?
In its epidemiological situation update published in January 2023, Santé Publique France recommends, to limit the risks of transmission, “to adopt the same barrier gestures used against winter viruses”to know :
- hand washing,
- wearing a mask for people with respiratory infections,
- sneeze or cough into the crook of your elbow.
Moreover, the Japanese Ministry of Health called on the population to resume basic health proceduresoften forgotten since the end of the Covid-19 epidemic: “the infection is transmitted by physical contact and via droplets, so it is important to disinfect your hands and cover your mouth when you cough“.
Sources:
- ‘Flesh-eating’ bacterium cases hit record high in Japan in 2023 – The Asahi Shimbun (01/18/2024)
- Mystery in Japan as dangerous streptococcal infections soar to record levels – The Guardian (03/15/2024)
- Streptococcal Infections – MSD Manual
- Invasive Group A streptococcal infection: epidemiological situation update as of January 1, 2023 – Public Health France