“The disease had mostly dissipated by the 1940s,” said researcher Dr. Stephen Brouwer. “After 2011, the global reach of the pandemic became evident with reports of a second outbreak in the U.K., beginning in 2014, and we’ve now discovered isolate outbreaks here in Australia.”
“This global re-emergence of scarlet fever has caused more than a five-fold increase in disease rate and more than 600,000 cases around the world.”
Bacterial clones
Because scarlet fever has been dormant for so long, the researchers were interested in discovering how the infection has reappeared in recent years. They began studying the Streptococcus pyogenes bacteria, which is what causes scarlet fever. They learned that copycat bacteria had evolved and added new toxins that produce an even greater immune response.
“The toxins would have been transferred into the bacterium when it was infected by viruses that carried the toxin genes,” said researcher Mark Walker. “We’ve shown that these acquired toxins allow Streptococcus pyogenes to better colonise its host, which likely allows it to out-compete other strains. These supercharged bacterial clones have been causing our modern scarlet fever outbreaks.”
The researchers explained that scarlet fever is spread the same way most bacterial infections are spread -- by an infected person coughing or sneezing near an uninfected person. Because young children are most susceptible to the virus, it can spread rather quickly. Case numbers have been low recently because of measures currently in place to protect consumers against COVID-19; however, the researchers worry about how that will change as children go back to school and social distancing protocols begin to ease up.
“We need to continue this research to improve diagnosis and to better manage these epidemics,” said Walker. “Just like COVID-19, ultimately a vaccine will be critical for eradicating scarlet fever -- one of history’s most pervasive and deadly childhood diseases.”