An infectious childhood disease which had largely disappeared over the past 100 years has re-emerged in parts of Asia and the United Kingdom.

Using genome sequencing technique, an international group of researchers led by the University of Queensland in Australia investigated a rise in the incidence of scarlet fever-causing bacteria and an increasing resistance to antibiotics.

Scarlet fever, which mainly affects children under 10, is spread by Group A Streptococcus (strep throat bacteria) known as GAS. Symptoms include a red rash on the skin, sore throat, fever, headache and nausea.

"We have not yet had an outbreak in Australia, but over the past five years there have been more than 5000 cases in Hong Kong (a 10-fold increase) and more than 100,000 cases in China," researcher Mark Walker said in a statement. "And an outbreak in the UK has resulted in 12,000 cases since last year."

Researcher Dr. Nouri Ben Zakour said the rise in scarlet fever could pre-empt a future rise in rheumatic heart disease, which causes permanent heart damage.

"With this heightened awareness, we can now swiftly identify scarlet fever-associated bacteria and antibiotic resistance elements, and track the spread of scarlet fever-causing GAS strains," she said.

Serious illness can be treated with antibiotics; however, the study's findings show that there is an increasing resistance to treatment.

"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 in scarlet fever," Ben Zakour said.

The evolutionary forces driving the outbreaks were unknown, but bacterial causes, the immune status of people contracting scarlet fever, and environmental factors such as temperature and rainfall could all play a significant role.

"Only a continued study of the patterns, causes and effects of health and diseases will determine the full impact these recent gene changes will have on the global GAS disease burden," she said.

The findings appear in the journal Scientific Reports.