Downing Street has warned parents to be "on the lookout" for Strep A symptoms after a London schoolboy became the seventh child believed to have died from the infection.
Cases of Strep A are usually mild, causing illness ranging from a sore throat to scarlet fever. However they can develop into a more serious invasive Group A Strep (iGAS) infection.
Over the weekend a 12-year-old Year Eight pupil from a Lewisham school was reported to have died after developing the illness, taking the total number of recent UK deaths to seven.
The Prime Minister's official spokesman said: "Parents will be concerned...We are seeing a higher number of cases of Strep A.
"The bacteria we know causes a mild infection, which is easily treatable with antibiotics.
"In rare circumstances it can get into the bloodstream and cause serious illness.
"It is still uncommon. But it is still important parents are on the lookout for symptoms."
He also dismissed reports that Britain is facing a shortage of amoxicillin, the drug used to treat Strep A in children.
“It’s important to reassure parents that there is no shortage as far as we are aware,” he said.
Initial symptoms of scarlet fever usually start between one and four days after infection.
They include a sore throat, fever, headaches, chills, and nausea.
Around 12 to 48 hours after the fever starts, a skin rash will appear on the neck and then on the body.
It will make the skin feel rough like sandpaper and will consist of pimples that are small, raised, and reddish in colour.
Another symptom is “strawberry tongue”. This is when the tongue is at first white with inflamed red parts.
After four to five days, it turns red and shiny.