Strep A and scarlet fever

What is strep A?

Strep A or group A Streptococcus (GAS) is a bacteria that is commonly found in the throat or on the skin of healthy individuals without causing any problems.

However, sometimes strep A can lead to infections of the skin, soft tissues (muscles, ligaments and tendons) and the respiratory system.

Most strep A infections are mild but in rare cases, a type of Strep A infection known as invasive group A Streptococcus (iGAS) infection can occur, which can be serious and even life-threatening.

Some infections caused by strep A bacteria include:

• Tonsillitis (inflammation of the tonsils)
• Pharyngitis (sore throat)
• Strep throat
• Impetigo
• Cellulitis
• Scarlet fever

What is scarlet fever?

Scarlet fever, also known as scarlatina, is a bacterial infection caused by strep A bacteria. It usually affects young children and around 90% of people affected are children under ten years old. Scarlet fever is usually mild and can be easily treated with antibiotics, but in rare cases may lead to serious complications.

Scarlet fever symptoms

Scarlet fever normally starts with flu-like symptoms such as a sore throat, swollen glands in the neck, body aches and a high temperature (fever). After about 12 to 48 hours, a distinctive rash begins to develop on the neck and chest, before spreading to the back, arms, legs, and face.

Scarlet fever symptoms include:

• Scarlet fever rash - appears as raised bumps on the skin and feels like sandpaper. It may also be itchy. The rash may appear red or pink (like a bad sunburn) on white skin, though colour changes may be less noticeable on darker skin
• Flushed/ red face with a pale ring around the mouth
• Strawberry tongue - a white coating develops on the tongue early in the infection which peels off, leaving the tongue swollen, red, and covered in small bumps
• Red lines in the folds of the body, such as the armpits, which may last for a couple of days after the rash has disappeared
• Fever - a temperature of 38.0 C or higher
• Sore throat - will look red and swollen, sometimes with white or yellowish patches
• Difficulty swallowing
• Enlarged glands in the neck (lymph nodes) that are tender to the touch
• Nausea
• Vomiting
• Abdominal pain
• Headaches
• Body aches

Is scarlet fever dangerous?

Scarlet fever is usually treatable with antibiotics. However, if left untreated, the infection can spread to other parts of the body. Rarely, scarlet fever can lead to serious or even life-threatening complications.

Complications of scarlet fever include:

• Ear infection
• Sinusitis
• Throat abscess
• Pneumonia

Very rare, but serious complications of scarlet fever include:

• Septicaemia
• Meningitis
• Rheumatic fever
• Septic arthritis
• Necrotising fasciitis
• Streptococcal toxic shock syndrome

Is scarlet fever contagious?

Scarlet fever is highly contagious, meaning it can easily spread to others.

It is spread by breathing in bacteria in the air when an infected person coughs or sneezes, touching the skin of someone with a Step A skin infection like impetigo, or sharing towels, clothes, utensils, or bed linen. You can also catch scarlet fever from people who have strep A bacteria in their throat or on their skin but don't have any symptoms.

You remain contagious until 24 hours after taking the first dose of antibiotics.

If you do not take antibiotics, you are contagious for two to three weeks after your symptoms start.

When to see a consultant?

Scarlet fever needs treatment to reduce the risk of complications and prevent spreading the infection to others.

Make an appointment with your consultant if you or your child:

• have symptoms of scarlet fever such as a sore throat, fever, swollen/tender glands in the neck, and a rash
• do not get better after a week of treatment
• become unwell again, weeks after recovering from scarlet fever - this can be a sign of a complication, such as rheumatic fever
• feel unwell and have had contact with someone who has scarlet fever

Seek urgent medical attention if your child:

• has difficulty breathing (grunting, pulling in chest muscles between the ribs, nostril-flaring), shortness of breath, noisy, or rapid breathing
• is drooling, or unable to swallow liquids or saliva
• complains of chest pain
• has persistent or severe vomiting or diarrhoea
• is showing signs of dehydration
• feels dizzy or lightheaded when sitting or standing
• is confused, lethargic or is struggling to stay awake

Babies less than 2 months old may also have the following symptoms:

• fractiousness, irritability, or inability to settle
• breathing that starts and stops repeatedly
• temperature less than 35.5C or above 38C 
• is listless or floppy

How is scarlet fever diagnosed?

Scarlet fever can usually be diagnosed by looking at your child's symptoms such as the distinctive scarlet fever rash and strawberry tongue.

Sometimes, your consultant may confirm the diagnosis by:

• A throat swab (rapid strep test or throat culture)
• A blood test.

Scarlet fever is a notifiable disease in England and Wales which means GPs, schools and nurseries must inform local health protection teams of suspected cases.

How is scarlet fever treated?

Scarlet fever is normally treated with a ten-day course of antibiotics. Symptoms usually improve within a few days of starting treatment. It's important to complete the course of antibiotics even if you or your child feel better to ensure the infection is fully cleared and prevent antibiotic resistance.

There are some things you can do at home to make you or your child more comfortable and help relieve the symptoms of scarlet fever including:

• rest
• drink plenty of cool fluids to soothe your throat and prevent dehydration
• take over-the-counter painkillers such as paracetamol to ease any pain and reduce fever
• eat soft foods if you have a sore throat
• apply calamine lotion or take an antihistamine to help reduce any itching

Can scarlet fever be prevented?

There's currently no vaccine for scarlet fever. The infection is highly contagious and can spread easily to others.

To help prevent the spread of scarlet fever:

• keep your child home from nursery or school for at least 24 hours after starting treatment with antibiotics. Adults with scarlet fever should also stay off work for at least 24 hours after starting treatment
• wash your hands frequently with warm soapy water for at least 20 seconds. Use alcohol-based hand sanitiser if soap and water are not available
• don't share dining utensils, cups, food or drinks
• cover your mouth and nose when coughing and sneezing
• wash cups and utensils in hot soapy water or a dishwasher after your child uses them.

Summary

Scarlet fever is a bacterial infection caused by Strep A bacteria. It most commonly affects children and can spread easily by coughing, sneezing, and sharing items like eating utensils and cups.

Scarlet fever is normally easily treated with antibiotics, but in rare cases can lead to complications, some of which may be serious.