Scarlet fever, sometimes called scarlatina, is an infectious disease caused by group A streptococcus (GAS) bacteria (also known as Streptococcus pyogenes).
It is highly infectious and can be caught through direct contact with an infected person or through the air via droplets from coughs or sneezes.
The characteristic symptom of scarlet fever is a widespread, fine pink-red rash that feels like sandpaper to touch. Other symptoms include a high temperature, a flushed face and a red, swollen tongue. The symptoms are caused by toxins produced by the streptococcus bacteria.
For more detailed information about scarlet fever please see the NHS Direct Wales website.
Scarlet fever is one of a number of notifiable diseases in the UK. Any doctor who suspects that a patient has scarlet fever is required by law to report it.
The number of notifications of scarlet fever in Wales can be viewed from our interactive data dashboard.
Scarlet fever mainly affects children aged two to eight years old, but can be caught at any age. Occasionally, outbreaks of scarlet fever occur in nurseries and schools. The disease tends to be most common in the winter and spring.
Symptoms of scarlet fever will only develop if the infected person is susceptible to toxins produced by the streptococcus bacteria. By 10 years old most people will have developed immunity to these toxins.
It is possible to catch scarlet fever more than once, although this is rare. People who are immune to the rash-causing toxins can still get streptococcal sore throats and other infections caused by the same bacterium.
Scarlet fever was both more common and could be more severe in the past, but severe cases of scarlet fever are now rare and it is treatable with antibiotics.
Most cases of scarlet fever cause no complications, especially if the condition is properly treated. However, complications in the early stages of the disease can include ear infection, throat abscess, sinusitis, pneumonia and meningitis.
Very rare complications include rheumatic fever, kidney damage, liver damage, bone infection, blood poisoning and toxic shock syndrome which can be life-threatening.
Most mild cases of scarlet fever will clear up on their own, but it is still best to seek medical advice. Having treatment for the illness speeds recovery, reduces the risk of complications and makes the patient non-infectious more quickly.
The usual treatment for scarlet fever is a 10-day course of antibiotics. The fever will normally disappear within 24 hours of starting antibiotics and the other symptoms usually go within a few days. However, the whole course of treatment must be finished to make sure the infection is fully cleared.
Scarlet fever can be highly contagious, especially where susceptible people are in a closed environment. People with scarlet fever should be kept away from others until they have been on a course of antibiotics for at least 24 hours.
Practicing good infection-control measures around someone who is infected will help reduce the spread of infection. These include washing or disposing of all contaminated tissues or handkerchiefs immediately, washing hands frequently and thoroughly with soap and water and not sharing eating utensils, clothes, bedding and towels.
There is no vaccination against scarlet fever.
Public Health Wales guidance on infection prevention and control in childcare settings against the spread of infectious diseases such as scarlet fever is available from Infection Prevention and Control for Childcare Settings 2014.
Scarlet fever was once a common childhood disease before the mid-20th century. Although it is has been much less common in recent years, 2016 saw very high numbers of cases reported in Wales (1532 for the whole year) and in the UK as a whole.
Group A streptococcus (GAS) bacteria are commonly found on the skin or in the throat, where they can live without causing problems. Under some circumstances, however, these bacteria can cause disease.
Apart from scarlet fever, there are some other diseases that are caused by GAS bacteria ranging in severity from mild to life-threatening.
The most common presentations of GAS infection are a mild sore throat ('strep throat') and skin/soft tissue infections such as impetigo and cellulitis. More rare complications of GAS infection include acute rheumatic fever and poststreptococcal glomerulonephritis (heart and kidney diseases caused by an immune reaction to the bacteria).
However, GAS can cause more serious invasive infections (referred to as iGAS infections) such as bacteraemia (an infection of the bloodstream), necrotising fasciitis (a severe infection involving death of areas of soft tissue below the skin) and streptococcal toxic shock syndrome (rapidly progressive symptoms with low blood pressure and multi-organ failure).
iGAS infections are most common in the elderly, the very young or people with an underlying risk factor such as injecting drug use, alcoholism, immunosuppression or cancer. Although the incidence of more serious invasive infections is low, approximately 15 - 25% of people diagnosed with an invasive GAS infection will, unfortunately, die.
One important role of Public Health Wales is the collection and interpretation of data about the levels of infectious disease in the Welsh population. Key infections, including scarlet fever and iGAS, are under constant surveillance, to detect significant trends, to evaluate prevention and control measures and to alert appropriate professionals and organisations to infectious disease threats.