After nearly 100 years, the bacterial infection, scarlet fever, has made a comeback in Britain and in parts of Asia. And to make matters worse, it may no longer be an easy treatable infection as new research suggests that the infection is showing signs of antibiotic resistance.

“We have not yet had an outbreak in Australia, but over the past five years there have been more than 5,000 cases in Hong Kong (a 10-fold increase) and more than 100,000 cases in China,” said Mark Walker, one of the researchers, in a news release. “And an outbreak in the UK has resulted in 12,000 cases since last year.

The Washington Post reports that scarlet fever is caused by a group of A Streptococcus bacteria that can turn strep throat into scarlet fever. Most people who are affected are children between the ages of 5 and 12. The disease develops a red, sandpaper-like rash on the person’s body, and while it’s unpleasant, it can easily be treated with antibiotics. There is currently no vaccine.

“We now have a situation which may change the nature of the disease and make it resistant to broad-spectrum treatments normally prescribed for respiratory tract infections, such as scarlet fever,” said Nouri Ben Zakour, one of the researchers.

The idea that this new outbreak of scarlet fever could easily be treated was rethought when researches from the University of Queensland discovered that the new scarlet fever cases were resisting antibiotics. While penicillin is still effective, other treatments such as tetracycline, clindamycin, and erythromycin may not be, which poses an immediate threat to people who are allergic to penicillin.

The rise in scarlet fever could pre-empt a future rise in rheumatic heart disease, which causes permanent heart damage. Knowing this, researchers hope to continue studying the patterns of the disease and the effects it has on a person’s health, according to Science World Report.