Health authorities have sought to reassure the public after figures showed 15 children in England have died of invasive Strep A infection since September.
The vast majority of Strep A infections are mild but occasionally a serious invasive infection can be caused.
A more common result of Strep A is scarlet fever, and more cases of scarlet fever than usual are being seen in the UK for the time of year.
UK Health Security Agency data shows that in the week up to December 4, five cases of scarlet fever had been identified in Harrow, as well as cases in Camden (one), Barnet (one), Westminster (one) and Brent (four).
Higher levels were seen in Ealing (12) and Hammersmith and Fulham (12).
Dr Colin Brown, deputy director of the UKHSA, said: “Scarlet fever and ‘strep throat’ are common childhood illnesses that can be treated easily with antibiotics.
“Please visit NHS.uk, contact 111 online or your GP surgery if your child has symptoms of this infection so they can be assessed for treatment."
Symptoms of scarlet fever include sore throat, headache, and fever, along with a fine, pinkish or red body rash with a “sandpapery” feel.
“Very rarely, the bacteria can get into the bloodstream and cause more serious illness called invasive Group A strep," said Dr Brown.
“We know that this is concerning for parents, but I want to stress that while we are seeing an increase in cases in children, this remains very uncommon.
“There a lots of winter bugs circulating that can make your child feel unwell, that mostly aren’t cause for alarm.
“However, make sure you talk to a health professional if your child is getting worse after a bout of scarlet fever, a sore throat or respiratory infection – look out for signs such as a fever that won’t go down, dehydration, extreme tiredness and difficulty breathing.”
Hillingdon, Hounslow and Bromley have each had a case of invasive Strep A.
The UKHSA has said there is no current evidence that a new strain is circulating and the rise in cases is most likely due to high amounts of circulating bacteria and increased social mixing.
Full list of scarlet fever infections recorded in the week up to December 4:
Bromley - 13 infections
Bexley - 12 infections
Ealing - 12 infections
Hammersmith and Fulham - 12 infections
Lambeth - 11 infections
Lewisham - 11 infections
Croydon - 10 infections
Hounslow - 9 infections
Richmond upon Thames - 9 infections
Wandsworth - Eight infections
Sutton - Eight infections
Southwark - Seven infections
Greenwich - Six infections
Kingston upon Thames - Five infections
Hillingdon - Five infections
Harrow – Five infections
Brent - Four infections
Kensington and Chelsea - Two infections
Camden – One infection
Barnet – One infection
Westminster – One infection
Waltham Forest - 0 infections
Redbridge - 0 infections
Havering - 0 infections
Enfield - 0 infections
Barking and Dagenham - 0 infections
Tower Hamlets - 0 infections
Newham - 0 infections
Haringey - 0 infections
Islington - 0 infections
Hackney - 0 infections
City of London - 0 infections
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