Nobody knows for sure why more children than usual have died due to the group A streptococcus bacterium this year, but increased mixing and viral infections may be factors
In the UK, eight children are reported to have died as a result of rare but severe complications of the infection strep A since September. Here is what we know so far:
What is strep A?
Strep A is a bacterium known as group A streptococcus, or Streptococcus pyogenes, that is common worldwide. Many people carry the bacteria in their mouth and throat without experiencing any symptoms, but, in some cases, the infection can become harmful and lead to a range of problems, varying in severity.
The most common symptom is a very sore throat, known as strep throat. Strep A may also cause a rash that feels like sandpaper, alongside a fever and headache, indicating scarlet fever.
Rarely, the bacteria enter the blood and cause extremely severe infections, known as invasive group A streptococcus disease, or iGAS, which was responsible for the eight children’s deaths. Early symptoms include fever, dizziness, confusion, low blood pressure, a rash and abdominal pain.
How does strep A spread?
The bacteria are spread via saliva and nasal mucus.
People can become carriers by sharing cups or utensils with an infected person or by breathing in droplets after an infected person coughs or sneezes.
Scarlet fever is most common in young children, but people can develop strep A complications at any age. Invasive strep A is more common in people over 75 than in children. No older people are known to have died from the condition in the current outbreak so far.
Can strep A be treated?
Yes. The infection can be treated with commonly available antibiotics. Treating strep throat and scarlet fever with antibiotics lowers the already very low risk of invasive illness.
Is eight deaths higher than usual?
Strep A-related deaths in children are rare in the UK, but there was a similar outbreak before. In 2017 and 2018, there were high numbers of strep infections and four children under 10 years of age died of invasive strep A.
In the current outbreak, the deaths have occurred in children under 10, aside from one 12-year-old fatality.
Why have there been more deaths in children than usual this year?
Nobody knows for sure, but there is speculation that it is a result of a high strep A infection rate this year after a very low rate amid the covid-19 restrictions. During this time, socialising was limited and the use of protective measures, such as face masks, warded off other infections as well as the SARS-CoV-2 coronavirus.
In other words, lots of kids who didn’t get strep A in 2020 or 2021 are getting infected this year – what some call immunity debt.
There is also a resurgence in viral conditions and, according to Shamez Ladhani at St George’s Hospital in London, viral infections increase the risk of bacterial infections.
Is the infection rate higher than in previous years?
We don’t know the total number of strep A infections that are occurring in the UK, but scarlet fever and invasive group A streptococcus are both notifiable diseases, meaning doctors must inform health authorities of any cases.
The number of cases of both conditions is at its highest level for this time of year since at least 2017, though not as high as during the UK’s 2018 spring, which spans mid-to-late March to mid-to-late June.
This year in England, there have been 2.3 cases of invasive strep A per 100,000 children aged 1 to 4, compared with an average of 0.5 from 2017 to 2019.
Could a more dangerous strain of the bacterium be to blame?
The strains causing these cases don’t appear to have changed in the past year or so.
“We are seeing the same strains that were already in circulation,” tweeted Susan Hopkins at the UK Health Security Agency.
However, a strain of S. pyogenes that produces nine times as much toxin as other strains has been circulating in the UK since 2014, and might be responsible for the increases in scarlet fever and invasive strep A disease seen since that year.
Have there been deaths in other countries?
There don’t appear to be any reports of a higher-than-expected number of deaths among children from invasive strep A disease outside the UK.
However, invasive strep A is estimated to kill 150,000 people a year globally. Another 300,000 a year die from rheumatic heart disease, caused by strep A triggering an autoimmune reaction that damages the heart. Rheumatic heart disease is rare in higher-income countries where strep A infections are treated with antibiotics, but remains common in low-income nations.
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