Scarlet fever infections have rocketed to the highest levels in England since 1967, according to a new study.
Recorded instances of the childhood disease reached 19,000 last year - the most in 50 years.
Last year saw a sevenfold rise in scarlet fever cases compared to 2011; the steepest recorded rise.
While the highly contagious disease mostly affects children, infections also occur in adults.
Scarlet fever was a major childhood killer in Victorian times and while the disease is rarely fatal nowadays due to advances in medicine, it can still cause pneumonia, sepsis and liver and kidney damage in severe cases.
NHS chiefs have urged parents to be able to recognise the symptoms of the disease and immediately contact their GP if they are concerned their child has the disease.
What are the symptoms?
- sore throat
- a pink red rash that feels like sandpaper.
What causes it?
- Scarlet fever is caused by bacteria known as group A streptococcus (GAS).
- It is spread through close contact with people carrying the organism, often in the throat, or by touching objects and surfaces contaminated with the bacterium.
- Cases occur year round, but mainly in the spring.
How is it treated?
- While an infection is rarely serious prompt medical attention is vital as patients will require antibiotic treatment to reduce the risk of complications and it being passed on to others.
"Whilst notifications so far for 2017 suggest a slight decrease in numbers, we continue to monitor the situation carefully.
"Guidance on management of outbreaks in schools and nurseries has just been updated and research continues to further investigate the rise.
"We encourage parents to be aware of the symptoms of scarlet fever and to contact their GP if they think their child might have it."
She said the underlying cause of the resurgence is not known although several countries in East Asia have also reported an escalation including Vietnam, China, South Korea and Hong Kong.
Added Dr Lamagni: "Whilst there is no clear connection between the situation in the UK and East Asia, a link cannot be excluded without better understanding of the drivers behind these changes. The hunt for further explanations for the rise in scarlet fever goes on."
The study published in The Lancet Infectious Diseases said scarlet fever has become much more common since 2011, with a total of 620 outbreaks last year, mostly in schools and nurseries. This followed decades of decline.