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Published on:
17 April 2014

Next update: 25 April 2014

Last updated 17 April 2014, Vol. 8, No 15 (480 KB PDF).

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  • Group A streptococcal infections: third update on seasonal activity, 2013/14

 

Group A streptococcal infections: third update on seasonal activity, 2013/14

Surveillance of scarlet fever notifications continues to indicate high levels of notified cases in England, with recent weekly totals remaining higher than any among existing weekly records dating back to 1982 [1,2,3]. GP sentinel (syndromic) surveillance continues to report high levels of GP consultations for pharyngitis/scarlet fever in all age groups compared to the same period last year [4]. Routine laboratory reports and isolate referrals do not show any widespread elevation of invasive group A streptococcal (iGAS) disease incidence.

Monitoring systems to assess the impact of the current scarlet fever upsurge and the frequency of complications are being established. Microbiological investigation of scarlet fever isolates is underway. Interim guidelines to assist local health protection staff in managing outbreaks of scarlet fever in schools and nurseries have been issued [5].

Due to rare but potentially severe complications associated with group A streptococcal (GAS) infections, continued vigilance is recommended.

Scarlet fever

A total of 7198 scarlet fever cases have been notified so far this season (week 37 2013 to week 15 2014 (figure1), with week 14 of 2014 seeing the highest number of scarlet fever notifications received in one week (1049) in England.

Scarlet fever notifications remain high across England, with rates of infection being higher than the same point last season in all parts of the country (see table). The highest cumulative rates of notification this season were seen in the East Midlands (30.5), Avon, Gloucestershire and Wiltshire (23.5), Thames Valley (19.8), North East (17.8), and Cumbria and Lancashire (15.6).

Eighty eight per cent of notifications received this season have been in children aged less than 10 years, the median age remaining at 4 years (range <1y to 90y). The proportion of notifications seen in males and females remains similar with 49% being in males overall.

Figure 1. Weekly scarlet fever notifications in England, 2008/09 onwards*
*
Dashed line indicates that numbers may increase as further notifications expected.


Geographical summary of scarlet fever seasonal activity between September 2013 (week 37) and April 2014 (week 15), counts and rates per 100,000 population, in England
PHE Centre name
2012/13 season
2013/14 season
Rate ratio
No. cases
Rate
No. cases
Rate

Anglia and Essex

170

4.1

319

7.7

1.9

Avon, Gloucestershire and Wiltshire

147

6.2

557

23.5

3.8

Cheshire and Merseyside

218

9.0

340

14.1

1.6

Cumbria and Lancashire

108

5.5

307

15.6

2.8

Devon, Cornwall and Somerset

96

4.3

239

10.8

2.5

East Midlands

215

5.6

1181

30.5

5.5

Greater Manchester

261

9.7

318

11.8

1.2

Kent, Surrey and Sussex

225

5.0

478

10.6

2.1

London

306

3.7

685

8.2

2.2

North East

309

11.9

464

17.8

1.5

South Midlands and Hertfordshire

157

5.8

380

14.0

2.4

Thames Valley

165

8.1

404

19.8

2.4

Wessex

178

6.7

341

12.8

1.9

West Midlands

214

3.8

530

9.4

2.5

Yorkshire and the Humber

445

8.4

655

12.3

1.5

England

3214

6.0

7198

13.5

2.2


Invasive Group A Streptococcus

The number of iGAS isolate referrals, defined as isolation of GAS from a normally sterile site, to the Respiratory and Vaccine Preventable Bacteria Reference Unit at Colindale PHE from laboratories in England, Wales and Northern Ireland so far this season (week 37 2013 to week 14 2014) continues to remain within normal levels, with a total of 843 isolates referred so far (range 636 to 961 for the same period between 2008/09 and 2012/13; figure 2). Laboratories in four of the English regions have referred numbers of isolates above average (previous five years) for January to March this season, the East Midlands (37), Yorkshire and the Humber (54), London (61) and the South East (80). Isolates may still be received for specimens taken in March and as such, these numbers could increase.

Currently the iGAS strain type diversity remains similar to what is normally seen; emm 1 remains the most common type identified so far in 2014 (27%). The proportion of referred isolates which have been identified as emm 3 type is slightly high this season compared to last season (22% compared with 14%), and given the increased severity of disease associated with emm 3 strains this warrants increased monitoring.

No changes have been identified in iGAS infection antimicrobial susceptibility patterns from routine laboratory reporting made this season (weeks 37 2013 to 15 2014), with 6% of those tested being non-susceptible to erythromycin, 10% tetracycline and 3% clindamycin, all similar to previous years [6]. There have been no reports of penicillin resistance in iGAS isolates in England to date.

Figure 2. Weekly count of sterile site GAS isolates referred to the national reference laboratory, England, 2008/09 onwards*
* Dashed line indicates that numbers may increase as further isolates expected.


Investigations are underway to assess the possible reasons behind the exceptional increase in scarlet fever. Microbiological investigation will be conducted through a sentinel sampling scheme being undertaken in collaboration with PHE Regional Microbiology laboratories and selected NHS laboratories. As a means to assist HPTs in managing outbreaks of scarlet fever in schools and nurseries, interim guidelines have been drafted and disseminated which provide advice on recommended public health actions [5].

Clinicians, microbiologists and HPTs should continue to be mindful of potential increases in invasive disease and maintain a high index of suspicion in relevant patients as early recognition and prompt initiation of specific and supportive therapy for patients with iGAS infection can be life-saving. Invasive disease isolates and those from suspected clusters or outbreaks should be submitted to the Respiratory and Vaccine Preventable Bacteria Reference Unit at Public Health England, 61 Colindale Avenue, London NW9 5HT.

Relevant guidelines are available on the PHE health protection website, as follows:

 

References

1. PHE. Group A streptococcal infections: seasonal activity, 2013/14. HPR 8(9): Infection (News) Report.

2. PHE. Group A streptococcal infections: an update on seasonal activity, 2013/14. HPR 8(11): news.

3. PHE. Group A streptococcal infections: second update on seasonal activity, 2013/14. HPR 8(13): news.

4. PHE. GP In Hours Syndromic Surveillance System Weekly Bulletin 2014 week 14. Available from: http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/1317141077857.

5. PHE. Interim guidelines for management of scarlet fever outbreaks in schools and nurseries, http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/StreptococcalInfections/Guidelines/.

6. PHE. Voluntary surveillance of pyogenic and non-pyogenic streptococcal bacteraemia in England, Wales and Northern Ireland: 2012.

7. Health Protection Agency Group A Streptococcus Working Group. Interim UK guidelines for management of close community contacts of invasive group A streptococcal disease. Commun Dis Public Health 2004; 7(4): 354-361.

8. Steer JA, Lamagni TL, Healy B, Morgan M, Dryden M, Rao B et al. Guidelines for prevention and control of group A streptococcal infection in acute healthcare and maternity settings in the UK. J Infect 2012 Jan; 64(1): 1-18.