Strep A symptoms: what causes throat infection to spread - and how contagious is it?

Health experts are investigating cases of Strep A infection after the deaths of seven young children and a rise in cases.

The UK Health Security Agency (UKHSA) said there had been a rise in rare invasive Group A strep this year, particularly in children under 10, with five deaths of under-10s in England since September.

A separate case has been reported in Wales, taking the known UK total to six. Group A strep bacteria can cause many different infections, ranging from minor illnesses to deadly diseases.

The range of illnesses includes the skin infection impetigo, scarlet fever and strep throat. But how does Strep A spread and how contagious is it?

Here is all you need to know:

What is Strep A - what are the symptoms?

Strep A, which refers to Group A Streptococcus (GAS), is the name given to a type of bacteria sometimes found in the throat or on the skin. It usually causes mild illnesses such as a sore throat, but can cause other infections such as pneumonia and scarlet fever.

Most people get typical flu-like symptoms. These include:

• a high temperature
• headache
• sore throat
• flushed cheeks
• swollen neck glands

The bacteria can also cause a whitish coating to appear on the tongue, which eventually peels, leaving the tongue red, swollen and covered in bumps. This is often known as “strawberry tongue”.

When an individual contracts scarlet fever, a characteristic pinkish rash will usually appear on the body. According to the NHS, the rash looks like small, raised bumps and makes the patient’s skin feel rough like sandpaper. The rash starts on the chest and stomach before spreading.

Symptoms of invasive Group A Streptococcal disease include:

• fever (a high temperature above 38°C)
• severe muscle aches
• localised muscle tenderness
• redness at the site of a wound
• dizziness
• confusion

What causes bacteria to spread and how is it passed?

Strep A is most commonly spread by direct contact with an infected person. The bacteria often lives in the nose and throat.

People who are infected spread the bacteria by talking, coughing, or sneezing, which creates respiratory droplets that contain the bacteria. If you breath in respiratory droplets that contain the bacteria you can contract Strep A.

The risk of spreading the infection is highest when a person is ill, particularly if they have “strep throat”. People who carry the bacteria but have no symptoms are much less able to spread the bacteria.

How contageous is Strep A?

Strep A is highly contagious, however the government stresses that it is usually a mild illness. It can cause scarlet fever. The bacteria also cause other respiratory and skin infections such as strep throat and impetigo.

In very rare occasions, the bacteria can get into the bloodstream and cause an illness called invasive Group A strep (iGAS). While still uncommon, there has been an increase in invasive Group A strep cases this year, particularly in children under 10.

There were 2.3 cases per 100,000 children aged 1 to 4 compared to an average of 0.5 in the pre-pandemic seasons (2017 to 2019) and 1.1 cases per 100,000 children aged 5 to 9 compared to the pre-pandemic average of 0.3 (2017 to 2019) at the same time of the year.

So far this season there have been 5 recorded deaths within 7 days of an iGAS diagnosis in children under 10 in England. During the last high season for Group A Strep infection (2017 to 2018) there were 4 deaths in children under 10 in the equivalent period.

Investigations are also underway following reports of an increase in lower respiratory tract Group A strep infections in children over the past few weeks, which have caused severe illness.

How to prevent spread of Strep A?

Good hand and respiratory hygiene are important for stopping the spread of many bugs. By teaching your child how to wash their hands properly with soap for 20 seconds, using a tissue to catch coughs and sneezes, and keeping away from others when feeling unwell, they will be able to reduce the risk of picking up or spreading infections.

Dr Colin Brown, Deputy Director, UKHSA, said: “We are seeing a higher number of cases of Group A strep this year than usual. The bacteria usually causes a mild infection producing sore throats or scarlet fever that can be easily treated with antibiotics. In very rare circumstances, this bacteria can get into the bloodstream and cause serious illness – called invasive Group A strep (iGAS).

“This is still uncommon; however, 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. Make sure you talk to a health professional if your child is showing signs of deteriorating after a bout of scarlet fever, a sore throat, or a respiratory infection.”