Group A streptococcal infections: first update on seasonal activity in England, 2022 to 2023 - GOV.UK

Notifications and GP consultations of scarlet fever in England are higher than normal for this point in the season, after persisting later into the previous season.

Notifications of invasive group A streptococcus (iGAS) disease are following a similar trend with higher than expected levels for this time of year. Relatively high rates of iGAS in children

are noted. This may reflect increases in respiratory viruses and high levels of group A streptococcus (GAS) circulating in children.

Medical practitioners have been alerted to this early increase in incidence and elevated iGAS infection in children. Given the potential for severe presentations, it remains important that

scarlet fever cases are treated promptly with antibiotics to limit further spread and reduce risk of potential complications in cases and their close contacts. Clinicians should continue to

be alert to the severe complications of GAS and maintain a high degree of clinical suspicion when assessing patients, particularly those with preceding viral infection (including chickenpox)

or close contacts of scarlet fever.

As per national guidance, prompt notification of scarlet fever cases and outbreaks to local UK Health Security Agency (UKHSA) HPTs, obtaining throat swabs (prior to commencing antibiotics)

when there is uncertainty about the diagnosis, and exclusion of cases from school or work until 24 hours of antibiotic treatment has been received, remain essential tools to limit spread.

Data presented within this seasonal activity update are based on data available as at 7 December 2022. An updated report will be published in a week on 15 December 2022. Weekly notifiable

disease reports are published each week throughout the year to update scarlet fever notification numbers.

Following higher than expected scarlet fever activity during the early part of this summer in England, with a drop during August, notifications during the early part of the current season

(2022 to 2023; seasons are defined from mid-September to mid-September) are increasing again and remain above what is normally seen at this time of year (Figure 1).

A total of 6,601 notifications of scarlet fever were received from week 37 to 48 this season (2022 to 2023) in England, with 1,062 notifications received in week 48. This compares with an

average of 1,774 (range 333 to 2,915) for this same period (weeks 37 to 48) in the previous 5 years. While high for this point in the season the weekly notifications are lower than the

weekly totals seen during the normal pre-pandemic peak season (February to March) where peak weekly total was 1,988 in week 12 during the 2017 to 2018 season (Figure 1).

Note: In this graph the 2022 to 2023 season goes up to week 48. Recent weeks in the current season may change due to delayed notifications being received, represented by a dotted line

between week 47 and 48.

Scarlet fever notifications to date this season showed considerable variation across England, ranging between 6.8 (London) and 18.0 (North West) per 100,000 population (Table 1); while this

may represent differential disease transmission it may also relate to differential notifications from clinicians.

Laboratory notifications of iGAS so far this season (weeks 37 to 48, 2022 to 2023) are higher than expected (Figure 2). So far this season there have been 652 notifications of iGAS disease

reported through laboratory surveillance in England, with a weekly high of 91 notifications in week 47. Laboratory notifications of iGAS are higher than recorded over the last 5 seasons for

the same weeks (average 311, range 175 to 454 notifications; Figure 2).

Note: In this graph, the most recent weeks of the 2022 to 2023 season are expected to increase due to lags in reporting timelines from laboratories. The decline in the most recent week (week

48) should not be interpreted as an actual drop in laboratory notifications: it is therefore represented by a dotted line between week 47 and 48.

While high for this point in the season, the weekly laboratory notifications are lower than the weekly totals seen during the normal pre-pandemic peak season (March to April) where the peak

weekly total was 113 in week 14 during the 2017 to 2018 season Figure 2).

During the current season to date, the highest rates so far were reported in the Yorkshire and Humber region (1.8 per 100,000 population), followed by the South East (1.4 per 100,000) and

North East, South West and North West regions (each 1.2 per 100,000; Table 1).

The highest rate was in the 1 to 4 years age group (3.2 per 100,000), followed by those aged 75 years and over (2.9 per 100,000) and the under1-year age group (2.2 per 100,000; Table 2).

Note: In this table the current 2022 to 2023 season covers weeks 37 to 48, whereas the 2017 to 18 season data covers the full season, weeks 37 to 36.

The median age of patients with iGAS infection so far this season was 47 years (range 1 year and under, to 102 years), slightly lower than the range seen at this point in the preceding 5

seasons (age 54 to 57.5 years); 24% of iGAS infections reported so far this season are in children (aged 10 years and under), higher than the range seen for the past 5 seasons (4% to 12%).

So far this season 60 deaths have been recorded within 7 days of an iGAS infection diagnosis (from any cause), with 38% (n=23) of the recorded deaths being in those aged 75 years and over,

and 17% (n=10) in children aged 10 years and under (Table 3). The case fatality rate to date is comparable this season to recent seasons. Elevations in rates of iGAS rates in children in

this early part of this season has resulted in an increased number of deaths over a relatively short period, with 13 deaths in children aged under 15 in weeks 37 to 48.

Antimicrobial susceptibility results from routine laboratory surveillance so far this season indicate tetracycline resistance in 22% of GAS sterile site isolates; this is lower than at this

point last season (45%). Susceptibility testing of iGAS isolates against erythromycin indicated 7% were found resistant (compared with 20% last season) and, for clindamycin, 7% were

resistant at this point in the season (17% last season). Isolates remained universally susceptible to penicillin.

Analysis of iGAS isolate typing data indicate a diverse range of emm gene sequence types identified this season. The results indicate emm 1 was the most common (30% of referrals), followed

by emm 12 (17%), emm 89 (7%), emm 108 and emm 33 (each 4%). In children (aged