Since September, there have been 510 cases of a rare but serious invasive Strep A bacteria infection known as iGAS in England, with 16 children dying across the UK.

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Dr Colin Brown, deputy director of the UK Health Security Agency (UKHSA), has said that while iGAS is uncommon, “it is important that parents are on the lookout for symptoms and see a doctor as quickly as possible so that their child can be treated and we can stop the infection becoming serious.”

Many other healthcare professionals have warned the panic surrounding Strep A is likely to have a worse impact than the bacteria itself, with a sharp demand for antibiotics drastically driving up prices.

“There’s a lot of anxiety at the moment, but there are enough antibiotics,” Dr Elizabeth Whittaker, senior clinical lecturer in paediatric infectious diseases and immunology at Imperial College London, tells BBC Science Focus. “This bacteria is very sensitive and most antibiotics – if they’re needed – can kill this bacteria.”

So, when are antibiotics needed? Why is there such a rise in cases this year? Can adults get Strep A? And just how worried should we be? With the help of key healthcare experts, we explore all below.

What is Strep A? How does it spread?

Strep A – also known as Group A streptococcus (GAS) – is a bacteria that can be found in a person’s throat or skin. And for most people, it lives in their bodies without causing illness.

“It’s part of the normal repertoire of bacteria that people usually have transiently at some point in their lifetime. For most people, it will never cause a problem and they won’t even know they have it,” Dr Simon Clarke, associate professor in cellular microbiology at the University of Reading, tells BBC Science Focus.

The bacteria mainly spreads through coughs, sneezes or any open cuts. If somebody is showing symptoms of infection, they are far likelier to transmit the bacteria.

What are the symptoms of Strep A?

The majority of people who carry Strep A will not experience any symptoms. However, some will become ill from the bacteria.

According to Clarke, there is no one specific symptom that will absolutely indicate your illness is a Strep infection. Symptoms of a Strep A infection include:

  • A high temperature, swollen glands and an aching body
  • A sore throat (including tonsillitis)
  • Headache
  • Nausea
  • Vomiting
  • Muscle aches
  • Scarlet fever (a rash that feels rough to the touch)

It’s this last symptom that may cause concern, particularly for parents. “This is where the child has a very high fever, a sore throat and a red tongue, a red face and a very red rash. This rash should feel rough when you touch it. That’s important as children with certain skin colours may not look as red,” explains Whittaker.

“If it is scarlet fever, we would always say it’s sensible to give antibiotics to avoid it becoming a more worrying invasive infection.”

In very rare cases, the Strep A bacteria evade the body’s defences and get into areas such as the lungs or bloodstream. This more serious invasive infection, known as iGAS, can be deadly in a small number of cases.

“We’re not sure why in some people the bacteria changes into a harmful pathogen and causes disease. However, the chances of developing iGAS are slim. Very, very slim,” says Clarke.

Whittaker adds: “Most people get Strep infections in their lives. And most get better without any treatment."

Can adults get Strep A?

Yes. While much attention has been given to children that have developed disease from Strep A, adults can also carry the bacteria. In fact, the majority of people who have died from iGAS in England this year have been above the age of 45 (42 deaths, as of 8 December).

However, figures suggest younger people are more likely to become ill from Strep A than adults below 60, with 24 per cent of iGAS infections reported so far this season being in children under 10.

“Any age group can get this bacteria. There is some evidence that the bacteria are most commonly detected in children and young adults because it may be more likely to cause disease there,” says Clarke.

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“However, if this is the case, it’s not comprehensively certain why. Is it because younger people don’t have such a well-developed immune system as somebody older? Perhaps, but this is not yet clear.”

How worried should we be about Strep A?

While news of any child’s death is undoubtedly painful, the wide scientific consensus in the UK is that Strep A is not a serious crisis.

“Although the absolute number of cases has gone up, the relative risk of severe disease to an individual is still extremely low,” explains Whittaker.

Strep A is also far from the leading cause of death in children. Comparisons can be difficult, but so far this season, 13 people under the age of 14 have died in England from iGAS (12 September - 8 December). This is a small number compared to the 224 children aged 1 to 14 that have died in total during a similar period in England and Wales (9 September - 25 November 2022).

Also worthy of note: the UK has endured several waves of Strep A infections in the past. The country saw cases of iGAS rising in both 2014 and 2017, with total incidents still well below current figures.

The key difference from previous waves? This year, Strep A infections are rising much earlier than predicted.

“The numbers are higher than we would normally expect. We don't really know why that is,” says Clarke. “Some have said that we’re at the peak of cases at the moment and that the peak is much earlier than expected. But we don’t know this is the peak. So the numbers might get bigger. In that regard, watch this space.”

However, for Whittaker, this is still not reason for panic. “Ultimately, we need parents to take a deep breath and treat their child as they normally would. Take a look at the NHS Healthier Together website and check if they are at risk. If you’re worried it’s best to be objective and do a little assessment before going straight to A&E."

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Why have there been so many cases this year?

Currently, it is unclear why the number of people falling ill due to the Strep A bacteria is higher than average.

Importantly, Strep A is far from a new bacteria and has been known for decades. Additionally, according to the UKHSA, infections have fortunately not been caused by a dangerous new strain of the bacteria.

So, if the bacteria itself is largely unchanged from previous years, what is causing the spread now? While scientists can’t be sure, there are two main theories.

The first: people are simply socialising a lot more this winter than in the last two years. And with little previous in-person mixing, the population as a whole has less immunity, which increases transmission.

“To be clear, this isn’t just about schools,” says Whittaker. “Most of the Strep A infections only really started circulating when adults' behaviour changed. Lockdowns and school closures are not one of the same thing.

“As people have just gone back to normal, a lot of bugs have been able to circulate more easily.”

This theory is not proven, however. The cause may be elsewhere.

“Others have suggested that there is an increase in viruses such as the flu or respiratory syncytial virus in children. And it’s possibly this that’s making them susceptible to bacterial infections,” says Clarke.

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The exact reason behind rising child flu numbers is also unclear. According to the UKHSA, this could be partly a result of waning immunity due to COVID restrictions, or an 11 per cent fall in the uptake of the flu vaccine among 2-and-3-year-olds.

About our experts, Dr Elizabeth Whittaker and Dr Simon Clarke

Dr Liz Whittaker is senior clinical lecturer in paediatric infectious diseases and immunology at Imperial College London. She also works as a consultant at the department of paediatric infectious diseases and immunology, St Mary's Hospital, London. Additionally, Whittaker is the convener of the British Paediatric Allergy, Immunity and Infection Group.

Dr Simon Clarke is associate professor in cellular microbiology at the University of Reading. His research areas include immunology, and staphylococcal infections of the cardiovascular system.

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Authors

Thomas Ling
Thomas LingDigital editor, BBC Science Focus

Thomas is Digital editor at BBC Science Focus. Writing about everything from cosmology to anthropology, he specialises in astronomy and the latest psychology, health and neuroscience discoveries. Thomas has a Masters degree (distinction) in Magazine Journalism from the University of Sheffield and has written for Men’s Health, Vice and Radio Times. He has been shortlisted as the New Digital Talent of the Year at the national magazine Professional Publishers Association (PPA) awards. Also working in academia, Thomas has lectured on the topic of journalism to undergraduate and postgraduates at The University of Sheffield.

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