Figure 1. Weekly scarlet fever notifications in England, by season, 2017 to 2018 onwards (weeks 37 to 50)
#17,191
We've been following the UK's recent outbreak of Scarlet Fever and iGAS (invasive Group A Strep) for several weeks (see here, and here), and while the most recent numbers (see chart above) have not been completely firmed up, the UK's Health Security Agency is calling this an `exceptional' outbreak with more than 27,000 cases reported since September 27th.
While not as pronounced, the United States is seeing a similar increase in Strep A infections (see CDC HAN #0484: Increase in Pediatric Invasive Group A Streptococcal Infections).
Not only are the number of infections greatly elevated, strep A infections generally peak in the spring, not the fall. Complicating matters, not only are hospitals filling up with sick kids, there are shortages of amoxicillin - the antibiotic of choice for treating this infection - both here and in the UK.
The latest update from the UKHSA (dated Dec 22nd) follows:
Latest data from the UK Health Security Agency (UKHSA) on scarlet fever and invasive group A strep cases.Last updated 22 December 2022
Latest data from the UK Health Security Agency (UKHSA) continues to show an out of season increase in scarlet fever and group A streptococcus infections and a higher number of cases than seen in a typical year.The UK's Research and analysis: Group A streptococcal infections: third update on seasonal activity in England, 2022 to 2023 provides much more detailed information. I've reproduced the discussion below, but you'll want to follow the link to read it in its entirety.
So far this season (from 12 September to 18 December) there have been 27,486 notifications of scarlet fever. This compares to a total of 3,287 at the same point in the year during the last comparably high season in 2017 to 2018 – although cases in that season started to rise at a different point. In 2017 to 2018 there were 30,768 scarlet fever notifications overall across the year.
Invasive group A streptococcus (iGAS) infections remain rare. So far this season, there have been 126 iGAS cases in children aged 1 to 4 compared to 194 cases in that age group across the whole year of the last comparably high season in 2017 to 2018. There have been 88 cases in children aged 5 to 9 years compared to 117 across the whole year of the last comparably high season in 2017 to 2018. The majority of iGAS cases continue to be in those over 45 years.
Sadly, so far this season there have been 94 deaths across all age groups in England. This figure includes 21 children under 18 in England. In the 2017 to 2018 season, there were 355 deaths in total across the season, including 27 deaths in children under 18.
Dr Colin Brown, Deputy Director, UKHSA, said:
- I understand how this large rise in scarlet fever and ‘strep throat’ may be concerning to parents, however the condition can be easily treated with antibiotics and it is very rare that a child will go on to become more seriously ill. At this time of year, there are lots of winter illnesses circulating that can make children unwell and I would urge all those eligible for free winter vaccines to take advantage of these.
- Most winter illnesses can be managed at home and NHS.UK has information to help parents look after children with mild illness. NHS services are under huge pressure this winter, but please visit NHS.UK, contact 111 online or your GP surgery if your child has symptoms of scarlet fever or ‘strep throat’ so they can be assessed for treatment.
Figure 2. Weekly laboratory notifications of iGAS, England, by season, 2017 to 2018 onwards (weeks 37 to 49)
Discussion
The last 2 weeks has seen a steep increase in scarlet fever notifications and GP consultations with exceptional levels of activity in this early part of the 2022 to 2023 season. Weekly numbers of scarlet fever notifications this season have been higher than any previously recorded (weeks 49 to 50; weekly records available since 1982), the previous highest being in 2018.
The rate of iGAS infection notifications is following a similar pattern, with weekly incidence trending above what would be expected during the first part of the season, particularly for recent weeks.
While the rate of iGAS infection is elevated in all age groups, incidence in children aged under 10 years is particularly elevated compared to levels reported in the last peak season, and substantially higher than in the past 2 years.
Investigations are underway following reports of an increase in lower respiratory tract GAS infections, particularly empyema, in children over the past few weeks. The current emm types have been circulating for many years. Whilst a new strain of emm1 (M1UK) was documented as having emerged and expanded in the last decade, its role (if any) in driving the current high levels of iGAS in children remains uncertain. At present, the weekly rate of iGAS in individuals over 75 years is not exceeding pre-pandemic periods and the CFR is lower than previous years, with emm1 dominant in this age group. Detailed genomic and biological investigations are underway to investigate any differences in the pathogen being seen this season.
The elevated iGAS levels in children compared to the period when pandemic control measures were in place is likely to be a consequence of the heightened scarlet fever activity given the crossover of strains associated in both presentations (1, 2). Reduced exposure to GAS infections during the pandemic are likely to have resulted in increased levels of susceptibility to these infections in children, noting the very low levels during pandemic. Prompt treatment of scarlet fever with antibiotics is recommended to reduce risk of possible complications and limit onward transmission.
Public health messaging to encourage contact with NHS 111 or GP practices for clinical assessment of patients with specific symptoms suggestive of scarlet fever has been issued along with reminders to provide ‘safety netting’ advice for parents indicating signs and symptoms of deterioration, particularly for children with respiratory viral infection. GPs and other frontline clinical staff are also reminded of the increased risk of invasive disease among household contacts of scarlet fever cases (3, 4).
Clinicians should continue to be mindful of potential increases in invasive disease and maintain a high index of suspicion in relevant patients as early recognition facilitates prompt initiation of specific and supportive therapy for patients with iGAS infection.
(Continue . . . )
