Scarlet fever infections in England are continuing at a high rate for the time of year and recent fluctuations in the number of cases made it hard to predict the future trend, latest figures suggested.
A rapid decline in notifications and GP consultations in the second half of December was followed by a period of inconsistent levels, but case rates remained above the seasonal norm, the UK Health Security Agency (UKHSA) said.
Notifications of invasive group A streptococcus (iGAS) disease, although still very rare, also remain higher than expected for this time of year. In recent weeks increases have been noted among adults – particularly in those aged over 45 years – rather than the surge involving children noted in the earlier part of the season, according to the Agency, which said that elevated rates of iGAS infections could reflect increases in respiratory viruses and high levels of group A streptococcus (GAS) infection generally.
Prompt Treatment and Clinical Suspicion Needed
Patients with scarlet fever should be treated promptly with antibiotics to prevent further spread and reduce the risk of potential complications, the UKHSA said.
Clinicians should also be alert to severe complications of GAS and "maintain a high degree of clinical suspicion" when they assessed patients, particularly those with a previous viral infection, including chickenpox, or those who had close contact with scarlet fever.
The figures showed that so far this season, from 12 September 2022 to 29 January 2023, there had been 41,012 notifications of scarlet fever, compared with the 30,768 cases seen during the whole of the last comparably high season of 2017 to 2018.
There had been 1898 iGAS cases across all age groups so far, compared with 2967 recorded during 2017 to 2018. Among children, there had been 213 iGAS cases among those aged 1-4 year (194 in 2017-18), and 144 cases in children aged 5-9 (117 during 2017-18).
There had been 235 deaths from any cause of patients with iGAS across all age groups so far this season, including 30 under 18 years of age. That compares with 354 deaths, including 27 under-18s, across the whole of the 2017-18 season.
Despite the recent decline in scarlet fever cases, the Agency said it remained unclear about future trends, whilst recent increases in iGAS amongst older people required further epidemiological study. It said it was also investigating reports of an increase in lower respiratory tract GAS infections, particularly empyema, in children observed over the past few weeks.
Dr Sarah Anderson from the UKHSA said: "Although the number of scarlet fever notifications we are seeing each week has significantly fallen since the peak in December, the bacteria that cause the infection are still circulating at high levels for this time of the year.
"Early treatment of scarlet fever with antibiotics is important to reduce the risk of a more serious infection and transmission to others. Children should stay off school or nursery and adults should stay off work for 24 hours after antibiotics have started," she added.