Scarlet fever

What is scarlet fever?
Scarlet fever is one of a number of infections caused by the bacteria Streptococcus pyogenes, also known as group A streptococci (GAS).

What are the symptoms of scarlet fever?
Scarlet fever mainly affects children under 10 years of age. Symptoms include fever, a rash, sore throat, flushed cheeks and a swollen tongue. The rash is typically most noticeable in the creases of the joints and over the stomach and can feel rough to touch like sandpaper. The tongue can develop a white coating which then peels leaving the tongue red and swollen , a typical appearance which is often described as ‘strawberry tongue’.
Scarlet fever is usually a mild infection without any complications. However, complications such as ear infection, throat abscess, and pneumonia can occur. Very rarely, more severe complications leading to kidney or heart damage can occur. Prompt treatment with antibiotics will prevent these complications.

How is scarlet fever spread?
Scarlet fever is spread by contact with secretions from an infected person’s nose or mouth through sneezing, coughing, or direct contact such as from kissing, wiping noses or sharing utensils (e.g. cups, cutlery) that will have secretions on them. After infection it takes between two and five days to develop symptoms.

How is scarlet fever diagnosed and treated?
Healthcare professionals will often be able to diagnose scarlet fever based on the symptoms alone. Sometimes a throat swab to test for the bacteria or a blood sample will be required. If diagnosed, it is treated with a 10 day course of antibiotics. It is important to take the full 10 days of antibiotic treatment to prevent complications and to prevent spreading the infection to others.

Without treatment, a person can be infectious and spread the infection to others for a number of weeks. However, after 24 hours of antibiotics, a person will not be infectious. Persons diagnosed with scarlet fever should not attend crèche, school or work until 24 hours after starting antibiotics to avoid spreading the infection.

Other important ways to prevent spreading infection include: washing hands often, especially after wiping a nose and before preparing food; not sharing eating or drinking utensils with an infected person; and washing utensils in in hot soapy water.

What is group A streptococci (GAS)?
The GAS bacteria which causes scarlet fever is a common bacteria which often lives on peoples skin and in their throat. For the majority of people the bacteria do not cause any problems. However, occasionally they cause diseases such as scarlet fever, sore throat (“strep throat”) and skin infections such as impetigo. Rarely, the GAS bacteria can cause more severe, sometimes life-threatening, infections. These types of severe infection are called “invasive GAS disease” and include streptococcal toxic shock syndrome, necrotising fasciitis, and sepsis syndrome.

Scarlet fever and the other milder infections caused by GAS bacteria are not notifiable in Ireland meaning that healthcare professional do not have to report cases to the national surveillance centre. Because of this the number of cases in Ireland is not known. In England between 2000 and 4000 cases of scarlet fever are reported each year. The more severe, invasive GAS diseases are notifiable in Ireland.

Further information on GAS infections in Ireland is available at: 

Last updated: 13 April 2016