Group A Streptococcus pyogenes is a common cause of throat infections and a more generalised illness called scarlet fever, which produces symptoms such as fatigue and a rash
By Clare Wilson
As most people in the UK will be aware, the country is in the middle of an outbreak of a bacterial infection called strep A, short for group A Streptococcus pyogenes. It comes on top of several other unusual patterns of medical conditions this year, including an outbreak of the liver disease hepatitis in children that began in April and, over the past eight months, an epidemic of mpox (formerly known as monkeypox).
I’ll get to those other illnesses shortly, but first, a recap on strep A. This bacterium is a common cause of throat infections and a more generalised illness called scarlet fever, which produces symptoms such as fatigue and a rash. A bad throat infection from this bacterium may be called tonsillitis in the UK or strep throat in the US.
Occasionally, the bacteria manage to spread deeper into the body, such as into the lungs or bloodstream, causing what is known as invasive group A streptococcal (iGAS) disease. If this isn’t spotted in time, it can be fatal.
As of Friday, 15 children had sadly died from iGAS infections in the UK since mid-September. We give a round-up of what we know so far here and there is more information from the UK Health Security Agency (UKHSA).
The headlines are alarming and it must be distressing for the families of anyone affected. But it is worth bearing in mind that there is a surge of iGAS cases most years, albeit they usually peak in late winter or early spring in the UK, spanning January-February to March-April.
Strep A can affect all age groups and there have been 60 deaths overall from this infection in England from mid-September. So the current wave hasn’t yet topped one that happened in the winter of 2017/2018, when there were 355 deaths.
As most people in the UK will be aware, the country is in the middle of an outbreak of a bacterial infection called strep A, short for group A Streptococcus pyogenes. It comes on top of several other unusual patterns of medical conditions this year, including an outbreak of the liver disease hepatitis in children that began in April and, over the past eight months, an epidemic of mpox (formerly known as monkeypox).
I’ll get to those other illnesses shortly, but first, a recap on strep A. This bacterium is a common cause of throat infections and a more generalised illness called scarlet fever, which produces symptoms such as fatigue and a rash. A bad throat infection from this bacterium may be called tonsillitis in the UK or strep throat in the US.
Occasionally, the bacteria manage to spread deeper into the body, such as into the lungs or bloodstream, causing what is known as invasive group A streptococcal (iGAS) disease. If this isn’t spotted in time, it can be fatal.
As of Friday, 15 children had sadly died from iGAS infections in the UK since mid-September. We give a round-up of what we know so far here and there is more information from the UK Health Security Agency (UKHSA).
The headlines are alarming and it must be distressing for the families of anyone affected. But it is worth bearing in mind that there is a surge of iGAS cases most years, albeit they usually peak in late winter or early spring in the UK, spanning January-February to March-April.
Strep A can affect all age groups and there have been 60 deaths overall from this infection in England from mid-September. So the current wave hasn’t yet topped one that happened in the winter of 2017/2018, when there were 355 deaths.
The UK’s current iGAS outbreak comes on top of higher rates of usual winter respiratory infections in many countries, including flu and another pathogen called respiratory syncytial virus (RSV). The most likely explanation for these high rates is a higher population susceptibility to infections caused by previous reduced social mixing because of covid-19 restrictions, says the UKHSA.
Some refer to this as our immunity debt, but others dislike the term as they think it implies our immune systems were damaged by the lockdowns, an idea for which there is no evidence. I covered this controversy in an edition of Health Check two weeks ago, but since then, some readers (and my friends and family) have been asking me more questions.
One person made the point that countries such as the UK haven’t been in constant lockdown for the past two years – in fact, UK schools were only closed to most children for a few months in 2020 and in 2021 – so why would that cause infections to be surging now?
But respiratory infections aren’t at constant levels: before the pandemic, they showed a characteristic pattern of rising and falling every winter. And while schools weren’t completely shut, countries such as the UK experienced reduced social mixing for two winters running, which clearly dampened these winter infection surges.
Cases of strep A are also being exacerbated by the surge in viruses such as flu and RSV – and flu also started rising earlier in the season than in pre-pandemic years. That’s because being infected with a respiratory virus raises your risk of a secondary bacterial infection, as UK paediatrician Alasdair Munro explains here.
A further complication is that strep A not only rises and falls each year, it also, for unclear reasons, tends to come in an especially high surge every three or four years, the UKHSA said on Thursday. With the last instance of this occurring in 2017/18, the current high surge could be delayed from the one that was due to happen one or two years ago but was blocked by covid-19 precautions.
Why aren’t other countries seeing higher cases of iGAS? They might be, but we have no way of knowing, because the UK is one of the few nations where iGAS is a “notifiable” illness, which means that if an infection is confirmed, doctors must inform public health authorities.
“In most countries, you could have a fairly big epidemic of group A strep and not know about it until death statistics came through, and they are usually delayed some weeks,” says Paul Hunter at the University of East Anglia, UK.
So, how does strep A fit with the two other unexpected infectious disease outbreaks this year? In April and May, there was an alarming spike in cases of hepatitis in young children, which thankfully faded away almost as quickly as it began. There were similar cases in some other European countries and the US.
Investigations in the UK concluded that this probably occurred due to children with a genetic vulnerability getting infected with two common viruses, one called an adenovirus and another called adeno-associated virus 2. The term “immunity debt” wasn’t being used much back in April, but doctors did say that previous reduced social mixing was indeed the likely cause.
The mpox outbreak seems to be a different phenomenon. This virus was previously found mainly in rodents in some central and West African countries, from where it would occasionally spread to people, but rarely caused person-to-person transmission.
In May, a cluster of cases in people in the UK were reported, with further outbreaks quickly being reported in other countries, including other parts of Europe and North and South America. A new feature compared with previous mpox outbreaks was that the virus was mainly spreading among men who have sex with men.
A genetic analysis shows that mpox probably started spreading between people in 2017 and was only noticed when it started spreading in Europe.
We still don’t have a good explanation as to why mpox changed its transmission pattern so strikingly. But this did provide an effective way to suppress the infection, by offering vaccines to those at higher risk. This tactic seems to be reducing case numbers in many countries, including the UK and the US.
False claims
What all these different infections have in common is that when they first emerged, there were claims that they were caused by a dangerous new strain of the pathogen or by lasting damage to people’s immune systems from a coronavirus infection. But there is no evidence that either assertion was true for liver disease and mpox, nor does it seem to be the case for strep A.
Some have also used these outbreaks to call for the reintroduction of covid-19 precautionary measures, such as wearing masks. In fact, the US Centers for Disease Control and Prevention did initially call for mask wearing among the public to avoid mpox, before a speedy U-turn.
Now, some of the same people who have long wanted greater precautions against covid-19 are again calling for children to wear masks in schools as protection against strep A, such as in this article in inews.
The debate over mask wearing is likely to rage on, but given how few people I have lately seen wearing face coverings when on public transport and while Christmas shopping, I can’t see a return of masking being likely unless something changes dramatically.
Wilson is Health reporter at New Scientist and can be reached at healthcheck@newscientist.com
