Strep A in the spotlight

Streptococcus A has found itself in the media spotlight over the last few months, thanks to an unseasonal rise in cases and, as of January 2023, 39 tragic child deaths (30 in England, five in Wales, three in Scotland and one in Northern Ireland).

Alarmist reporting on the situation, a population that’s understandably nervous three years into a pandemic and misinformation on social media – including false rumours that the nasal flu vaccine given to school children causes strep A – left families confused and worried.

Crucially, in its early February update, the UK Health Security Agency (UKHSA) noted a fall in the number of weekly notifications of scarlet fever and invasive group A strep (iGAS) in children, but also cautioned that it’s not unusual to see a drop in the number of cases before the spring and that infections could rise again in the coming months (UKHSA, 2023). So what do you need to know about Strep A?

What is strep A?

‘Humans are a great culture medium for bacteria as we provide lots of warm, dark, moist locations for them to thrive, such as in our nose and throat,’ says Dr Steve Turner, consultant paediatrician in general and respiratory paediatrics at Royal Aberdeen Children’s Hospital. ‘For every single human cell, there are 10 bacteria, and strep A is one that we are used to living alongside.’

‘The likely level of carriage is around 2% in the UK but, during an outbreak, you might find it in 25% to 40% of children in a classroom,’ says Shiranee Sriskandan, clinical professor of infectious diseases at Imperial College London. ‘Almost all will have no symptoms, a handful might report a sore throat and an even smaller number might have scarlet fever [caused by the same type of bacteria], despite the fact they’ve all been exposed to a similar level of strep A.

‘We think this is a result of having different levels of immunity due to prior exposure, although genetics might also have a part to play.’

In rare cases, it can also lead to serious and potentially fatal infections when it gets into areas of the body where it is not normally found, such as the lungs or bloodstream. This is known as iGAS, which can present as:

• Toxic shock syndrome
• Pneumonia
• Sepsis
• Necrotising fasciitis
• Meningitis.

‘The majority of people with iGAS who become critically ill will have developed sepsis,’ says Dr Ron Daniels, chief executive and founder of the UK Sepsis Trust. ‘It’s therefore vital that community practitioners are aware, and make parents aware, of the different sepsis symptoms a child might display so they can act quickly’ (see Resources).

‘It’s exceptionally rare to get an invasive infection but, if it does happen, it can progress rapidly with devastating consequences,’ says Shiranee. ‘It’s important to note that children are much less likely to die from an invasive strep infection than adults.’

What’s behind the recent rise in cases?

‘We’d normally see the peak of infections between March and May, but in 2022 the increase in numbers just kept climbing well into July, accompanied by an increase in invasive infections in children,’ says Shiranee. ‘After a brief lull in August, due to the school holidays, we saw rates pick up again, reaching what we hope was a peak just before Christmas.’

The UK isn’t alone in seeing a significant increase in cases of scarlet fever and iGAS, with a similar pattern reported in France, Ireland, the Netherlands and Sweden (WHO, 2022).

‘Nobody can say for definite why this has happened,’ says Steve. ‘We’ve had group A strep spikes for generations, and this was just one example of a particularly bad winter. What we do know is that, unlike Covid, which was a completely new illness for our bodies to deal with, children have evolved over those same generations to cope with strep A and to cope very well.’

There is no evidence of a new strain of strep A in the community, and a rise in cases is most likely due to high amounts of circulating bacteria, increased social mixing compared to the previous years and an increase in respiratory viruses (UKHSA, 2022).

Shiranee says: ‘I believe the Covid lockdowns have led to a build-up of children who didn’t get exposed to the usual strep A outbreaks in their first school year, so we now have two or three year cohorts of children all being exposed for the first time, which is driving the numbers up.’ 

Why is it hard to diagnose early?

‘There are three key problems with early diagnosis,’ says Steve. ‘Firstly, a child might have strep A but no symptoms. Secondly, they might have lots of symptoms but, until a swab is taken, you won’t know if these are the result of a strep A infection. Thirdly, other common viral conditions, such as a cold, can produce similar symptoms.’

‘We’d normally see the peak of infections between March and May, but in 2022 the increase in numbers just kept climbing well into July’

‘Another difficulty is that while strep A throat and scarlet fever can, on very rare occasions, progress to become iGAS infections, the vast majority of iGAS develop in people who haven’t suffered from either,’ says Shiranee. ‘This is because the bacteria are easily transmitted from those who have such throat infections to others via tiny droplets that can spread in the air, on hands and on objects. We therefore often see an increase in the frequency of iGAS infection in the community when we see high levels of strep throat.

The images below: Symptoms of strep A include scabs and sores around the mouth and a rough rash, while a red and swollen tongue (strawberry tongue) could be a sign of scarlet fever.

Risk factors and latest advice

‘Roughly half the people who develop iGAS will have some sort of skin or mucosal break that allows the bacteria to penetrate into the deeper tissues,’ explains Shiranee. ‘Common examples in children would be eczema or chickenpox sores, which is why there can be problems if the latter and strep A circulate at the same time in the community.’

High rates of viral respiratory viruses also put children at risk of co-infection with strep A, leaving them more susceptible to severe illness.

‘Flu A or flu B are a good example of this where, together with strep A, they can provoke pneumonia. So one way of protecting the population is through vaccination against flu and chickenpox,’ says Shiranee. ‘While we have a vaccine to combat Strep pneumoniae, we don’t have one for strep A. We’re therefore currently seeing strep A as a leading cause of some types of invasive lung infections in children, such as empyema.’

High rates of viral respiratory viruses also put children at risk of co-infection with strep A, leaving them more susceptible to severe illness

A weakened immune system can also leave children at greater risk of a strep A infection. 

Across the UK the advice remains for parents to contact NHS 111 or their GP surgery if they suspect their child has strep throat or scarlet fever (see Strep A symptoms, right) to ensure prompt treatment. Not only does this reduce the chances of a child developing iGAS, but it also reduces the risk of the infection spreading to others. 

How it’s treated

Caught early, strep A can easily be treated and most children will be given oral antibiotics to take at home.

‘We have a range of excellent antibiotics to treat strep A and it remains very sensitive to these, especially penicillin, which is great news,’ says Shiranee.

Given the unusually high level of cases, the UKHSA issued guidance in December advising GPs to have a low threshold for the prescription of antibiotics to children presenting with features of a strep A infection and for prompt referral to secondary care of any children presenting with persistent or worsening symptoms.

‘GPs have previously been encouraged not to treat sore throats unless essential or to defer treatment in case things get better on their own,’ says Shiranee. ‘However, this delay in treatment can mean an infectious child attends school, which is why the threshold for considering treatment this winter was lowered.’

‘Swab results take 48 hours, so clinicians will start antibiotics straight away if there’s a reasonable index of suspicion of strep A,’ says Steve. ‘If the swab then comes back negative they can be stopped – or, if there is some uncertainty, they will give the patient a prescription but ask them not to take it to the pharmacy until a positive result is confirmed.’

‘Children should be kept off nursery or school for at least 24 hours after starting treatment to reduce the risk of infecting others,’ adds Shiranee.

It’s also important for parents to monitor any changes, both during and after treatment, in case there’s no improvement or a sudden deterioration in a child’s condition. 

Reducing risk

‘Simple, basic hygiene and common sense are the most effective ways to reduce the risk of transmission,’ says Steve. Community practitioners (CPs) can emphasise to families the importance of:

• Regular, thorough handwashing with soap and hot water
• Using tissues when you cough or sneeze and putting these in the bin afterwards
• Not sharing cutlery or glasses when eating or drinking
• Making sure cuts and wounds are cleaned and covered, as these can be entry points for strep A
• Regular cleaning, especially of hand touch surfaces such as door handles, toilet flushes, taps and items such as phones, tablets and remote controls
• Washing sheets and towels at a high temperature
• Avoiding contact with someone you know is infected
• Keeping homes well ventilated.

How can you reassure parents?

It’s important to ensure parents have correct information. ‘Parents should not be worried but should be alert for the increased incidence of strep A and aware of the key symptoms,’ says Shiranee.

‘There are a lot of seasonal viruses going around, so many children with a sore throat or fever won’t have a strep A infection,’ says Steve. ‘If parents have a child with symptoms, suggest that, in the first instance, they try paracetamol and a sugary drink, milk or orange juice and wait 30 minutes – often this is transformational.’

You can also help parents feel confident in trusting their instincts and seeking medical attention when required.

Steve says: ‘Parents know their child best and when something doesn’t feel right, either because the symptoms are different to their “normal” coughs and colds, they seem more unwell than usual, or they can see a deterioration, it’s time to take action. Parental instinct is particularly important with very young children who can’t tell you how they’re feeling.’

Shiranee is reassuring on any future cases. ‘I would hope, by Easter, that the current strep A spike will have settled down and we will see a return to a normal pattern of cases.’

Experts were interviewed January 2023.

Resources

•  NHS information on strep A bit.ly/NHS_strep A and scarlet fever bit.ly/NHS_scarlet
• A guide to spotting sepsis in children for parents from the UK Sepsis Trust bit.ly/Sepsis_Trust_children
• Sepsis screening tools for different age groups from the UK Sepsis Trust:

          – Age five and under bit.ly/sepsis_screening_under_5

          – Age five to 11 bit.ly/sepsis_screening_5

          – Age 12+ bit.ly/sepsis_screening_12

References

NHS. (2022) Strep A. See: nhs.uk/conditions/strep-a (accessed 13 February 2022).

UK Health Security Agency. (2023) UKHSA update on scarlet fever and invasive group A strep. See: gov.uk/government/news/ukhsa-update-on-scarlet-fever-and-invasive-group-a-strep-1 (accessed 13 February 2023).

UK Health Security Agency. (2022) Group A strep – what you need to know. See: https://ukhsa.blog.gov.uk/2022/12/05/group-a-strep-what-you-need-to-know (accessed 13 February 2023).

WHO. (2022) Increased incidence of scarlet fever and invasive Group A Streptococcus infection – multi-country. See: who.int/emergencies/disease-outbreak-news/item/2022-DON429 (accessed 13 February 2023).

Image credit | Getty | Shutterstock