Cases of scarlet fever have risen for the third year in a row across England , according to Public Health England (PHE).
Since September 2015 there have been a total of 6157 new cases of scarlet fever, affecting all parts of the country.
Around 600 cases are being reported each week, with more increases expected in the peak season for the disease, which is usually between late March and mid-April.
The reasons behind the rise are unclear, but Public Health England said they "may reflect the long-term natural cycles in disease incidence seen in many types of infection".
- What is scarlet fever?
Scarlet fever is a bacterial illness caused by Streptococcus pyogenes bacteria, or group A streptococcus, which live on the skin and in the throat.
It can be spread through close contact with individuals carrying the organism - or though indirect contact with objects and surfaces that have been contaminated.
It's a seasonal disease - and although it was once a very dangerous infection, most cases now aren't very serious.
- Who can get scarlet fever?
Anyone can get it, although it is most common in children between the ages of two and eight years old.
- What are the symptoms?
According to NHS England, the symptoms usually take two to five days to appear and include a sore throat, headache, high temperature (38.3C/101F) or above), flushed face and swollen tongue.
A pink-red, sandpapery rash develops 12 to 48 hours later, typically on the chest, before spreading to other parts of the body.
- How is it treated?
Antibiotics can be given to minimise the risk of complications. At present, there isn't a vaccine for scarlet fever.
Symptoms usually clear up after a week and the majority of cases will resolve without complication as long as the recommended course of antibiotics is completed.
PHE is warning all health practitioners to be mindful of the increase when assessing patients.
It said that "close monitoring, rapid and decisive response" to potential outbreaks, as well as early treatment is crucial.
Dr Theresa Lamagni, PHE’s head of streptococcal infection surveillance, has said parents can play in recognising when their child needs to be seen by a doctor.
Individuals who think they or their child may have scarlet fever should seek advice from their GP without delay as prompt antibiotic treatment is needed.