Please note, this page may contain outdated information or subject matter.

You are here:

Scarlet fever: reducing the spread of infection to help lower the risk of more serious life-threatening diseases

Published on


Updated on

What did the project achieve?

“Our study has improved understanding about the transmission and treatment of scarlet fever,” says Professor Shiranee Sriskandan of Imperial College London. “Our findings will directly influence updated guidance about the most effective public health measures to reduce the spread of the infection – which we hope, in turn, will help save children’s lives from more dangerous conditions caused by the same bacteria.”

Scarlet fever is a highly infectious disease caused by a type of bacteria called Group A streptococcus (sometimes known as strep A). While the illness itself is usually not serious, the same bacteria can also cause more life-threatening conditions including pneumonia, meningitis, toxic shock, necrotising fasciitis (sometimes called the ‘flesh-eating’ disease) and sepsis. Since 2014, there has been an alarming increase in the number of cases of scarlet fever, with 15,000 to 30,000 children diagnosed each year in England – up to the onset of the COVID-19 pandemic when many childhood infections like scarlet fever reduced abruptly with the closure of schools.1

The researchers visited six nurseries and school reception classes affected by a scarlet fever outbreak in spring 2018 and 2019 – and they also carried out a confidential online survey among parents of all affected children in London in 2018.

“By using DNA sequencing to track bacterial strains, we found that transmission of strep A within the classroom was much higher than expected and had often spread despite the children with scarlet fever being treated,” says Professor Sriskandan. “Healthy children who carry the bacteria during outbreaks are likely to pass it on to others – on hands, in cough droplets, and through the air.”

The team also explored the impact of antibiotic treatment on children affected by scarlet fever.

“We found that children who received prompt treatment for their infection cleared the bacteria quickly,” says Professor Sriskandan. “However, there was a delay in diagnosis in around one in five cases – which may have led to continued exposure in classrooms.”

This research has uncovered various factors that could all contribute towards the spread of scarlet fever – which will now be the focus of planned interventions to reduce transmission in nurseries and reception classes in future years.

This research was completed on

Over the past few years, doctors have been witnessing a steep and unexpected increase in scarlet fever – with more than 19,000 children reported to have been diagnosed with the infection in England and Wales in 2016.1 While the disease itself isn’t usually serious, the type of bacteria behind it (Group A streptococcus or “strep A”) can also cause more life-threatening conditions. Professor Shiranee Sriskandan at Imperial College London, together with experts at Public Health England, is carrying out an important new programme of work to find ways to slow down the spread of scarlet fever with the hope of saving children’s lives from invasive strep A infections.

How are children’s lives affected now?

Scarlet fever, a highly infectious disease, is experiencing a worrying comeback. Thankfully, it is usually not serious – with symptoms including a blotchy rash, sore throat and a high temperature usually clearing up with antibiotics.

But the strep A bacteria that cause scarlet fever can also have a much darker side – in rare cases, they can trigger more dangerous illnesses - such as pneumonia, meningitis, toxic shock, necrotising fasciitis (sometimes called the ‘flesh-eating’ disease) and sepsis.

 “Strep A infections can affect different children in very different ways – usually causing a sore throat or occasionally scarlet fever – but rarely, they can develop into something more life-threatening,” says Professor Sriskandan. “And although complications are very rare, sadly some children will die – or have long-term problems such as scarring, organ dysfunction and limb loss.”

“Given the current magnitude of scarlet fever outbreaks each year, it’s really important that we find out how we can control it better.” says Professor Sriskandan.

How could this research help?

 “We aim to build our understanding of how scarlet fever infects children and spreads so we can identify the best ways to slow down transmission in future outbreaks,” says Professor Sriskandan. “We hope that this will, in turn, save children’s lives from more dangerous conditions caused by the same bacteria.”

The team plan to identify key attributes of the bacteria that help them to spread and find out which antibiotics are most effective at slowing them down. They will also test whether current hygiene interventions and recommendations for disease control – such as hand washing, classroom cleaning, antibiotic treatment and staying away from school or nursery – are enough to reduce the risk of the spread of scarlet fever during an outbreak.

“Our results will help inform public health strategy, as surveillance could be used to monitor which strains are circulating in a season and highlight what is needed to prevent an outbreak,” says Professor Sriskandan. “Should our study suggest that the current guidelines need adjusting, our team is well-placed to ensure this happens as quickly as possible.”


Public Health England. NOIDS weekly report. Statutory notification of infectious diseases in England and Wales. Week 2016/52 ending 01/01/2017. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/581408/NOIDS-weekly-report-week_52-2016.pdf




Project Leader Professor Shiranee Sriskandan, FRCP PhD
Project Team Dr Theresa L Lamagni, MSc PhD HonMFPHDr Rebecca J Cordery, BSc MBBS MRCP MD MPH FFPH
Project Location Department of Medicine, Imperial College London
Project Location Other National Infection Service, Public Health EnglandSouth London Health Protection Team, Public Health England
Project duration Two years
Date awarded 20 July 2017
Project start date 1 August 2017
Project end date 31 January 2020
Grant amount £188,536
Grant code GN2596


We do not provide medical advice. If you would like more information about a condition or would like to talk to someone about your health, contact NHS Choices or speak to your GP.