Group A Strep update (Jan 2023)

A new year update on the situation of the unseasonal surge of GAS

There have been a number of interesting updates over the past week to the situation with Group A Strep (GAS) in the UK. I thought I would try and bring them altogether to provide an overview of what more we know and how the situation is evolving.

UKHSA update

In regards to the figures from England, the trend on scarlet fever notifications is…quite something. See if you can pinpoint the week the media started briefing about deaths from GAS.

As I mentioned in the last update, these numbers are not really meaningful. The spike likely reflects the amount of attention drawn to GAS rather than the true rate of scarlet fever. Whilst cases have undoubtedly been high, we can’t infer the true trend from this chart.

It certainly looks to have sharply fallen (understatement) which I think is both due to waning interest as well as a true decline in cases.

For iGAS, the numbers are more reliable as they require microbiological confirmation in severe cases, which is unlikely to be impacted much by increased attention.

Numbers are remarkably high, but given lags in reporting over the holiday period it is once more difficult to know the exact trend. Most likely it has flattened off or started to fall, and this is certainly the sense on the ground as we see fewer cases in hospital.

The proportion in children is much higher than usual (22% vs 4 - 13%), but the proportion of deaths is still much higher in the elderly (190 total deaths: 82% in those aged 65 and older, only 13% in those <10 years).

The case fatality rate is still in line with previous seasons.

New data from Scotland

A new paper has been published in The Lancet Child and Adolescent Health outlining some more detailed case data of iGAS cases of empyema over the winter.

They checked routine medical records at 3 tertiary children’s centres (Glasgow, Edinburgh and Aberdeen) during 2022 for children with empyema. There were 33 across the year; 10 until September (of which 5 were caused by Strep Pneumoniae), then 23 occurring between September and December 27th - of which 16 were caused by GAS. The median age was only 3y. PICU admission was required for 9, of which 5 were intubated. A respiratory viral panel was performed on 15, of which 9 tested positive for a virus (hMPV in 4, RSV in 2, and Flu A, VZV and Rhinovirus in 1 each).

Of the 9 cases were the specific strain has been sequenced so far, 7 were emm 1.0 - which has been the most common circulating strain over the past few years.

This figure from the supplement (GAS empyema in red) shows how striking the rise in cases has been during the winter of 2022 (panel F).

New editorials

The BMJ have published 2 excellent editorial pieces on GAS this week which I wanted to highlight.

The first, titled, “Resurgence of group A Streptococcal disease in children”, is from 2 paediatric infectious disease specialists (Liz Whittaker and Alasdair Bamford) who summarise the situation to date.

In particular, they make an astute observation that many of my colleagues have noted. The presenting features of many of the most unwell children are often just generic features of severe sepsis. There is very rarely any history of scarlet fever. This may come as a shock to many people who, understandably given the recent messaging, are extremely anxious about their own child developing scarlet fever in case they later go on to deteriorate and become extremely unwell.

The clinical impression is that children suffering from scarlet fever itself tend to go on to have a largely uneventful course (this may in part be due to the fact it is so easy to recognise and treat). The children who end up dangerously ill are often those for whom there was little sign of anything much untoward until they suddenly deteriorate. This is why GAS scares paediatricians so much.

On this note, the second editorial entitled, “The group A Strep crisis: can we do better?”, is written by a professor of primary care (Alastair Hay¹).

This article makes note of the tsunami of children presenting to primary care services following national messaging about GAS, from both health authorities and the media. In particular, that many of the children being brought for medical attention were not very unwell, or were even completely well, but whose parents were just extremely anxious and confused about what they had heard.

Services were completely overwhelmed. My own emergency department was seeing more than double the normal number of children each day, leading to dire pressures which undoubtedly put patients at risk.

The article argues that paradoxically, the messaging actually put children at more risk, as these pressures made identifying and managing children who were seriously ill much more difficult.

Some recommendations are made, including earlier warning from UKHSA to the NHS and pharmacies, more context about scarlet fever compared to other benign viral infections, consideration of how the NHS can respond or cope with demand, and further research to investigate the safety and effectiveness of public health messaging.

Summary

Cases of both scarlet fever and iGAS are extremely high by recent historical standards and may have peaked, but trends are uncertain due to possible reporting lags over Christmas. Rates of empyema from iGAS in particular have been unusually high, likely due to co-circulation with winter respiratory viruses. Children who become critically ill with iGAS usually did not have preceding scarlet fever, and often critical illness is the first sign they are unwell. Messaging about the unusual increase in GAS, particularly media coverage around deaths, may have paradoxically put children at increased risk by creating dangerous pressures on children’s primary care services.

1. I am aware many of the people mentioned in this newsletter are called Alasdair or Alastair. I am unapologetic of this fact, as it is an excellent name.