Group A Streptococcus (GAS) quarterly surveillance report
September to December 2023
- Published
- 28 May 2024
- Type
- Statistical report
- Author
- Public Health Scotland
About this release
Our quarterly update
This release by Public Health Scotland (PHS) provides quarterly information on Group A Streptococcal (GAS) infections.
In Scotland, GAS infections are monitored using routine laboratory data.
Under the Public Health (Scotland) Act 2008, cases of invasive GAS (iGAS) are notifiable but scarlet fever is not notifiable in Scotland.
Culture and PCR-positive GAS and iGAS specimens from all laboratories in Scotland are submitted to PHS using the Electronic Communication of Surveillance in Scotland (ECOSS) system.
GAS infections are classified as invasive if they have been isolated by culture or accredited molecular methods (such as PCR) from a normally sterile body site, such as:
- blood
- cerebrospinal fluid
- joint aspirate
- pericardial peritoneal-pleural fluids
- bone
- endometrium
- deep tissue or deep abscess at operation or post-mortem
An iGAS-related death is defined as death (from all causes) within seven days of a positive iGAS specimen. PHS actively follows up outcomes for all reported cases after 30 days to make sure they are captured.
iGAS cases are also reported to PHS using an enhanced surveillance questionnaire, which provides further information on risk factors and outcomes.
Invasive GAS samples are also sent to the Scottish Microbiology Reference Laboratory (SMiRL) for further analysis and typing.
Next release
The next release of this publication will be 27 August 2024.
Main points
Activity
In Quarter 1 (Jan to Mar) 2024 there was:
- a reduction in iGAS cases of 47.2% (103 cases) when compared with Quarter 1 2023 (195 cases)
- an increase of 39.2% when compared with Quarter 4 (Oct to Dec) 2023 (74 cases)
Age
In Quarter 1 2024 the largest proportion of iGAS cases were in adults:
- aged 65 years and older (34.0% or 35 out of 103 cases)
- aged 45 to 64 years (28.2% or 29 out of 103 cases)
This compares with Quarter 1 of 2023 where the largest proportions were in adults aged 65 years and older (36.4%) followed by 15 to 44 years and 45 to 64 years (both 23.6%).
Location
In Quarter 1 2024 most iGAS cases were reported from NHS Greater Glasgow and Clyde (21.4% or 22 out of 103 cases ) followed by:
- NHS Lothian – 16.5% or 17 out of 103 cases
- NHS Grampian – 10.7% or 11 out of 103 cases
Mortality
The percentage of iGAS cases reported to have died was 7.8% (8 out of 103 cases).
This is within the range of 5.6% to 12.0% reported to have died annually between 2018 and 2023.
Typing
Emm typing was available for 71.8% (74 out of 103 cases) of iGAS cases.
Of these, emm type 3.93 accounted for 20.3% (15 out of 64 cases) of iGAS cases typed, followed by:
- emm type 1.0 – 12.2% or 9 out of 74 cases
- emm type 76.0 – 8.1% or 6 out of 74 cases
Results and commentary
Overall, iGAS case numbers vary year to year with peaks usually observed during the winter and spring months.
Data in this report are published quarterly (every 13 weeks) and comprise iGAS laboratory reports submitted to ECOSS from NHS diagnostic laboratories and the Scottish Microbiology Reference Laboratory (SMiRL).
Please note that the data presented in this update are provisional and subject to change as data continue to be received.
General trend
In Quarter 1 (Jan to Mar, weeks 1 to 13) 2024, there were 103 reports of GAS isolated from a normally sterile site (iGAS cases) (Figure 1).
This is a reduction of 47.2% when compared with Quarter 1 2023 (195 cases) but an increase of 39.2% when compared with Quarter 4 (Oct to Dec, weeks 40 to 52) 2023 (74 cases).
The iGAS case numbers in Quarter 1 between 2017 and 2024 have ranged from 11 cases (in 2021) to 195 cases (in 2023).
Age
In Quarter 1 2024, most iGAS cases were reported in adults aged 65 years and above (34.0% or 35 out of 103 cases) (Figure 2).
This is followed by those aged:
- 45 to 64 years – 28.2% (29 out of 103 cases)
- 15 to 44 years – 23.3% (24 out of 103 cases)
- 0 to 14 years – 14.6% (15 out of 103 cases)
In comparison, age distribution in Quarter 1 2023 showed most cases in those aged 65 years and over (36.4% or 71 out of 195 cases).
This was followed by those aged:
- 45 to 64 years – 23.6% (46 out of 195 cases)
- 15 to 44 years – 23.6% (46 out of 195 cases)
- 0 to 14 years – 16.4% (32 out of 195 cases)
NHS board
In Quarter 1 (Jan to Mar) 2024, iGAS cases were reported from all NHS boards except:
- NHS Orkney
- NHS Shetland
- NHS Western Isles
Most iGAS cases were reported from NHS Greater Glasgow and Clyde (21.4% or 22 out of 103 cases) followed by:
- NHS Lothian – 16.5% (17 out of 103 cases)
- NHS Grampian – 10.7% (11 out of 103 cases)
This compares to Quarter 1 2023 with:
- NHS Greater Glasgow and Clyde – 21.0% (41 out of 195 cases)
- NHS Lothian – 15.4% (30 out of 195 cases)
- NHS Lanarkshire – 11.8% (23 out of 195 cases)
iGAS deaths
In Quarter 1 2024, the percentage of iGAS cases that were reported to have died was 7.8% (8 out of 103 cases).
This is lower than the percentage reported to have died in 2023 (12.0% or 56 out of 465 cases) and within the range of 5.6% to 12.0% reported annually since 2018 (Table 1).
Most of the deaths in Quarter 1 2024 were in adults aged:
- 65 years and older – 63.6% (5 out of 8 cases)
- 45 to 64 years – 25.0% (2 out of 8 cases)
The highest case fatality rate (CFR) was also observed in adults aged:
- 65 years or older – 14.3% (5 out of 35 cases)
- 45 to 64 years – 6.9% (2 out of 29 cases)
| Year | Number of cases | Number of deaths | CFR% |
|---|---|---|---|
| 2018 | 381 | 34 | 8.9 |
| 2019 | 262 | 21 | 8.0 |
| 2020 | 180 | 10 | 5.6 |
| 2021 | 64 | 4 | 6.3 |
| 2022 | 281 | 18 | 6.4 |
| 2023 | 465 | 56 | 12.0 |
| 2024* | 103 | 8 | 7.8 |
*Data to Quarter 1 (Jan to Mar) 2024 only
iGAS emm types
Analysis of reference laboratory typing of isolates shows that in Quarter 1 2024, emm typing was available for 71.8% (74 out of 103 cases) of iGAS cases and identified 29 different types.
Emm type 3.93 accounted for 20.3% (15 out of 74 cases) of iGAS cases typed (Table 2a), followed by:
- emm type 1.0 – 12.2% (9 out of 74 cases)
- emm type 76.0 – 8.1% (6 out of 74 cases)
This reflects a change from 2023 (Table 2b) when emm type 1.0 was the most commonly identified emm type (56.0% or 204 out of 364 cases) followed by:
- emm type 12.0 (23 out of 364)
- emm type 89.0 (18 out of 364 cases)
| emm type | Number typed Q1 2024 | Percentage (%) |
|---|---|---|
| 3.93 | 15 | 20.3 |
| 1.0 | 9 | 12.2 |
| 76.0 | 6 | 8.1 |
| 4.0 | 5 | 6.8 |
| 3.1 | 4 | 5.4 | 77.0 | 4 | 5.4 |
| Others (<4 per emm type) | 31 | 41.9 |
| Total | 74 |
Total percentage may not add to 100 due to rounding
| emm type | Number in 2023 | Percentage (%) |
|---|---|---|
| 1.0 | 204 | 56.4 |
| 12.0 | 23 | 6.3 |
| 89.0 | 18 | 4.9 |
| 76.0 | 14 | 3.8 |
| 4.0 | 9 | 2.5 |
| 1.25 | 8 | 2.2 |
| 28.0 | 8 | 2.2 |
| 87.0 | 7 | 1.9 |
| 12.37 | 6 | 1.6 |
| 3.93 | 5 | 1.4 |
| 75.0 | 5 | 1.4 |
| 108.1 | 4 | 1.1 |
| 11.0 | 4 | 1.1 |
| 77.0 | 4 | 1.1 |
| 82.0 | 4 | 1.1 |
| Other (<4 per emm type) | 41 | 11.3 |
| Total | 364 |
Discussion
Overall activity
The number of iGAS cases reported in Quarter 1 (Jan to Mar) 2024 (103 cases) reduced by 47.2% when compared to Quarter 1 (Jan to Mar) 2023 (195 cases) and is within the range reported in Quarter 1 from 2017 to 2023 (11 to 195 cases).
With the exception of 2017 and 2022, iGAS activity was highest in the first quarter of each year.
As expected with seasonal patterns of iGAS activity, Quarter 1 2024 iGAS case numbers were higher than reported in Quarter 3 (72 cases) and Quarter 4 2023 (74 cases) (Figure 1).
Age
Historically, iGAS cases are more commonly reported in older adults with case numbers increasing with age.
In Quarter 1 2024, most cases were reported in those aged 65 years and above (34.0% or 35 out of 103 cases) and 34 to 64 years (28.2% or 29 out of 103 cases).
When compared with Quarter 1 2023, there were reductions in case numbers reported from all age groups and the largest proportions were in adults aged 65 years and older (36.4%) followed by 15 to 44 years and 45 to 64 years (both 23.6%) (Figure 2).
NHS board activity
In Quarter 1 2024, all NHS boards – except NHS Orkney, NHS Shetland and NHS Western Isles – reported iGAS cases with larger NHS boards reporting most cases (Figure 3):
- NHS Greater Glasgow and Clyde – 21.4% (22 out of 103 cases)
- NHS Lothian – 16.5% (17 out of 103 cases)
- NHS Grampian – 10.7% (11 out of 103 cases)
iGAS mortality
The were 8 deaths among the 103 iGAS cases reported in Quarter 1 2024 with a case fatality rate (CFR) of 7.8%. This is within the range reported annually since 2018 (Table 1).
Most of the deaths (63.6% or 5 out of 8 cases) and the highest CFR (14.3% or 5 out of 35 cases) occurred in adults aged 65 years and above suggesting that older people are more susceptible to iGAS and its complications.
iGAS emm type
In Quarter 1 2024, emm typing was available for 71.8% of cases and 29 different emm types were identified.
Historically, emm type 1 has been the most commonly identified emm type in Scotland.
However, in Quarter 1 2024 the most common was emm type 3.93 (15 cases, 20.3%) followed by:
- emm type 1.0 – 9 cases (12.2%)
- emm type 76.0 – 6 cases (8.1%)
The changing distribution of iGAS emm types and any potential impact on transmissibility and disease severity are not yet fully understood.
Contact
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About Public Health Scotland (PHS)
PHS is a knowledge-based and intelligence driven organisation with a critical reliance on data and information to enable it to be an independent voice for the public’s health, leading collaboratively and effectively across the Scottish public health system, accountable at local and national levels, and providing leadership and focus for achieving better health and wellbeing outcomes for the population.
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Metadata
- Publication title
Group A Streptococcus (GAS): quarterly surveillance report
- Description
This report describes cases of invasive Group A Streptococcus in Scotland.
- Theme
Invasive Group A Streptococcus Infections in Scotland.
- Topic
iGAS
- Format
HTML
- Data source(s)
Electronic Communication of Surveillance in Scotland (ECOSS)
- Date that data are acquired
3 May 2024
- Release date
28 May 2024
- Frequency
Quarterly
- Timeframe of data and timeliness
January 2017 to March 2024, approximately two months in arrears.
- Continuity of data
Data from 2017 to March 2024 is presented.
- Revisions statement
None
- Revisions relevant to this publication
None
- Concepts and definitions
GAS infections are classified as invasive if they have been isolated by culture or accredited molecular methods (such as PCR) from a normally sterile body site, such as blood, cerebrospinal fluid, joint aspirate, pericardial peritoneal-pleural fluids, bone, endometrium, deep tissue or deep abscess at operation or post-mortem.
An iGAS-related death is defined as death (from all causes) within seven days of a positive iGAS specimen.
Information on laboratory culture-positive reports of all GAS and iGAS infections are routinely submitted to the Electronic Communication of Surveillance in Scotland (ECOSS).
iGAS cases in Scotland are notifiable under the Public Health (Scotland) Act 2008.
- Relevance and key uses of the statistics
Data are collected as part of mandatory public health surveillance providing data to monitor the epidemiology of GAS and iGAS, informing public health planning and response.
Statistics are used by PHS for surveillance purposes and published for transparency.
- Accuracy
The data are considered accurate.
Data are validated locally by partnerships.
PHS carries out further validation checks in consultation with NHS Boards, as required.
The Code of Practice for Statistics has been followed to ensure a high standard of data value, trustworthiness and quality.
- Completeness
All data returned from ECOSS is used for analysis.
- Comparability
Scottish data is regularly compared to UKHSA Group A Streptococcal disease data and information.
- Accessibility
It is the policy of Public Health Scotland (PHS) to make its web sites and products accessible according to published guidelines.
- Coherence and clarity
The report has been produced using the standard PHS publications template and is available as HTML web pages.
- Value type and unit of measurement
Number of invasive Group A Streptococcal cases.
- Disclosure
The PHS protocol on statistical disclosure is followed.
- Official Statistics accreditation
Official statistics in development.
- UK Statistics Authority Assessment
Not assessed.
- Last published
Not applicable.
- Next published
27 August 2024
- Date of first publication
28 May 2024
- Help email
- Date form completed
7 May 2024
Glossary
- CFR
Case fatality rate for iGAS is the proportion of cases of iGAS that die within seven days of a positive specimen regardless of the cause of death.
This enhanced case information is actively followed up 30 days after initial reporting.
- ECOSS
Electronic Communication of Surveillance in Scotland system
- GAS
Group A Streptococcus
- iGAS
Invasive group A streptococcal infections
- NHS
NHSScotland is the publicly funded healthcare system in Scotland and one of the four systems that make up the National Health Service in the United Kingdom.
It operates 14 territorial NHS boards across Scotland, supported by seven special non-geographic health boards, and Public Health Scotland.
Public Health Scotland is Scotland’s lead national body for improving and protecting the health and wellbeing of all of Scotland’s people. It is an NHS board that is uniquely sponsored by the Scottish Government and the Convention of Scottish Local Authorities (COSLA).
- PCR
Polymerase chain reaction (PCR) is a technique used to make numerous copies of a specific segment of DNA quickly and accurately.
- Quarter 1
This covers January to March (weeks 1 to 13).
- Quarter 2
This covers April to June (weeks 14 to 26).
- Quarter 3
This covers July to September (weeks 27 to 38).
- Quarter 4
This covers October to December (weeks 39 to 52).