They called it “flesh-eating bacterium”, or even “flesh-eating disease”. The correct medical term is streptococcal toxic shock syndrome (or STSS), and it is an extremely rare consequence of an invasive infection with Streptococcus A, or Streptococcus Pyogenes. Normally it does not represent a danger to public health, but these days we are hearing a lot about it due to an anomalous wave of cases recorded in Japan: 517 since the beginning of the year, 88 in the city of Tokyo alone.
Boom in cases of shock from “flesh-eating bacteria”, it is fatal in 30 percent of cases
Numbers approximately three times higher than those seen in the same period last year, which pushed the health authorities to issue an alert for this disease which, although usually rare, is fatal for approximately 30% of patients. Let's see better what it is.
Streptococcus A flesh-eating disease
“Type A streptococcus is a ubiquitous bacterium, which normally causes common tonsillitis in children or absolutely banal skin infections”, explains to Today.it Marco Falcone, professor of infectious diseases at the University of Pisa and secretary of the Italian Society of Infectious and Tropical Diseases (SIMIT). “In rare cases, however, these bacteria can enter the bloodstream, triggering systemic infections and causing toxic shock syndrome, which is mediated by the production of super antigenic toxins that push the body into an excessive immune reaction, the so-called cytokine storm, which causes shock and multiple organ dysfunction syndrome, making this disease particularly lethal.”
The symptoms are therefore caused in the first instance by the production of toxins by the bacteria, and then by an anomalous activation of the immune system. They include high fever, low blood pressure (hypotension), tachycardia, tachypnea, multi-organ failure and death. The toxins can also induce necrosis of infected tissue, and if they reach the skin they cause necrotic wounds that have given rise to nicknames such as flesh-eating bacteria or flesh-eating disease.
Is there a risk of epidemics?
Why a usually almost harmless bacterium causes such serious symptoms is not entirely clear. What is known, however, is that there are virulence factors that make some subtypes of Streptococcus A more dangerous. “Stss outbreaks are usually linked to the M1UK subtype, which has greater virulence and tends to cause systemic infections more often,” he underlines at Today.it Falcone. “In some countries, and this is the case in Japan in recent weeks, outbreaks of these more dangerous subtypes are created, which can cause cases to grow quickly and abnormally, especially if they spread in closed communities.”
Treating the infection itself is not difficult, because Streptococcus A is sensitive to common antibiotics. What makes STSS so lethal, however, is the fact that even once the bacteria have been eradicated, the toxins present in the body continue to cause damage, and therefore often, even if the therapies are effective, the symptoms progress too quickly to be stopped. However, with careful monitoring of patients and their contacts, M1Uk streptococcus outbreaks are easily eradicated by health authorities, with the prescription of simple antibiotics. For this reason, as serious as it is, this infection is not the type of disease that can produce large epidemics, much less pandemics.
“Since ours is a transit country, visited every year by millions of tourists, it is necessary to be vigilant to intercept the arrival of dangerous bacterial subtypes early, but these are certainly not pathogens that can cause health emergencies like those seen with Covid 19” he concludes Falcon. “Infections occur by air or by contact, but streptococcus is much less infectious than a virus like Sars-Cov-2. Anecdotal cases have been recorded in Italy to date, even with the M1 subtype, almost always imported, but we have never had any major epidemics or outbreaks.”