Scarlet fever, a contagious and sometimes fatal childhood disease, is returning. They believe that the bacterium responsible for this disease has mutated and is better adapted to humans.
Scarlet fever is a childhood disease that was thought to have been banished to the depths of history, but Australian researchers are sounding the alarm after the number of cases has risen worldwide in recent years. According to these scientists, this is due to a new bacterial mutation of the disease. In their study, published in Nature magazine on October 6, analyses of scarlet fever cases in mainland China and Hong Kong showed that this recurrence “neither specific to the EMM type (streptococcal-specific virulence factor) nor caused by the spread of a single scarlet fever-producing clone,” the scientists said. Instead, strains of multiclonal scarlet fever are generally associated with the acquisition of mobile genetic elements carrying exotoxins. Thus, the researchers suspect that scarlet fever has mutated and has become more virulent via one or more prophages.
The epidemic seems to be already here as already several regional outbreaks of scarlet fever have been reported in Northeast Asia in 2011 and in Great Britain in 2014. England counted more than 1,143 cases of scarlet fever in Kent in 2018, compared to only 362 in 2017. A sudden and exponential increase. “This global resurgence of scarlet fever has resulted in a more than five-fold increase in contamination rates and more than 600,000 cases worldwide,” the study’s authors said.
At the dawn of a new scarlet fever pandemic
However, the factors that explain the recurrence of the disease remain a mystery. “The possible triggers of these new scarlet fever epidemics remain uncertain, but increasing epidemiological evidence suggests that the new prophages and antibiotic resistance elements have played an important role in the development, virulence, and diversification of scarlet fever, which is the cause of the strains in Northeast Asia,” the Australian researchers say. The researchers also suspect that the super-antigen responsible for the “transport” of the Group A Streptococcus (GAS) bacterium may have given it some of its properties.
How do you recognize it?
Scarlet fever (38.5°C), sore throat, and skin rash. Frequently benign, it manifests itself mainly in children between 5 and 10 years of age during the winter. There is no vaccine, and scarlet fever is contagious before symptoms appear. If a child has difficulty swallowing, fever, and a characteristic appearance of the tongue – which is initially covered with a white coating, which then narrows in the middle and becomes raspberry-colored – it is necessary to go to the pediatrician to treat the child with antibiotics to limit the duration of the infection. However, if the child has a high fever (over 40°C), is drowsy, cries unexplainably, shows traces of purple on the skin or if his or her health generally deteriorates, he or she should be taken to the emergency room right away. Scarlet fever was one of the leading causes of death in children in the early 20th century, but its incidence decreased since then. It appears that this scarlet fever outbreak was slowed by the social distancing measures taken to combat Covid-19, another pandemic.