Update on Group A Strep (Dec 2022)

UKHSA update on the GAS situation in England

The UK Health Security Agency have published an update on the situation with Group A Strep activity in England. For the background to this situation please read my previous post which can be found at this link.

What follows is a quick summary update of the report, which you can read here.

Scarlet Fever

The epidemiology of Scarlet Fever, to my mind, appears now to be of very little utility. You can pinpoint precisely when the increased media reporting and UKHSA alerts came out, and the astronomical increase in the number of cases almost certainly represents extraordinary levels of awareness and reporting, and since the diagnosis can be made clinically (i.e. without a swab to confirm it really is GAS) quite possibly a significant contingent of overdiagnoses - LOTS of viral infections cause sore throat and a rash, and many may now be getting diagnosed as SF when they previously would not. Reported cases are an astonishing 15 times higher than the last significant season.

There is no doubt that levels of SF are currently very high, but the shape of this graph is probably not that reliable any more.

Invasive Group A Strep

More reliably, iGAS diagnoses are made microbiologically, and it is very unlikely that reporting of these would change dramatically even in the presence of increase awareness. This is the most reliable data, and we can see how rapidly cases have risen (and ignoring the dotted line which will be revised upwards, with the eye of faith may be starting to flatten off).

It is very difficult to compare this season to others due to the unusual timing, but so far the past 14 weeks have seen slightly lower cases than the first 14 weeks of the previous big season (960 vs 1207) - but we are still early in the season and more cases will continue to accrue.

Rates are generally highest in the North and South East of England, and in children <5 years and >70 years.

There have been 94 deaths this season, with >40% occurring in adults aged over 75 years and only 16% in children under 10 years. The chances of dying from an iGAS infection are no different to previous seasons, and antibiotic resistance is actually much lower than in previous seasons. There is no evidence of a new strain.

What is going on?

As mentioned in the previous post, UKHSA are investigating reports of increased rates of a complication of GAS called “empyema”, when pus collects in the lining between the lungs and the chest wall as a result of GAS pneumonia. This may be due to GAS circulating with respiratory viruses which it wouldn’t normally due to the rise in cases being out of normal season.

They report that increased SF and GAS are likely a result of reduced exposure during the pandemic period, when GAS stopped circulating for a prolonged period due to the measures used to suppress Covid-19.

The next few weeks will be important to determine what direction the current wave is likely to go - hopefully it will be short and sharp and rates will begin to decline shortly.

The advice to look out for has not changed - for more information please refer to my previous post on GAS or read the amazing Healthier Together link on GAS and SF.