Scarlet fever is a disease caused by infection by group A Streptococcus or "group A strep". It is also known as scarlatina and is not usually a serious health concern. However, it must be treated since there is a risk of severe complications. The disease is typically found in people who have the bacteria in their throat or who already suffer from skin infections caused by it. In most cases, it is treated with antibiotics which speed up healing and greatly reduce the risk of contagion.
Nobody is immune to scarlet fever but it is considered one of the childhood diseases, since it is the most common among kids between 5 and 15 years old. It causes a distinctive red rash that gives skin a rough surface, resembling sandpaper.
Group A strep bacteria are very common and live in the throat and nose of many people. It is contagious and can be transmitted to others through tiny drops of saliva produced by sneezes and coughs. Some people touch their nose or mouth after making contact with such droplets and thus become infected. Since it is transmitted by saliva, it also spread after sharing a plate or glass with an infected person. Group A strep can also infect the skin and cause skin lesions, contact with them is contagious and causes scarlet fever. The disease has a short lifespan and usually the rash is gone after only one week. Skin peeling might continue for some time after healing, until full recovery.
The condition is already contagious even before the initial symptoms appear. Antibiotics drastically reduce the risk of contagion, after just one day since starting a cure the disease can no longer be transmitted. Without antibiotics, scarlet fever remains contagious in the next two or three weeks.
Complications of scarlet fever are rare but can be very serious. There is a small chance that the infection will spread from the skin to other areas of the body. The bacteria can attack the lungs, causing pneumonia, or the ears.
Scarlet fever can be caused by several bacteria, usually Streptococcus pyogenes. Other related bacteria from the exotoxin-producing group A beta-hemolytic streptococci (GABHS) can also be responsible. The disease gets its name from the distinctive red rash on the skin, which is actually triggered by a toxin produced by these bacteria. Usually, scarlet fever starts after the so-called strep throat, which is a pharyngeal infection. About 10% of all people with strep throats end up with scarlet fever as well. However, streptococcal infections of other body areas can also trigger it, for example on the skin.
The disease mostly starts during winter or spring, when the immune system is less effective. However, it can happen at any time of the year. The bacteria live in the body of many people who are just passive carriers without any symptoms but can still pass the disease to others through small drops of saliva. Of course, airborne particles from people with scarlet fever are also contagious. It is possible to become infected through food infestation or direct contact with the body fluids of a scarlet fever patient. Schools or other crowded areas, where an infected person can come in close contact with many others, increase the chances of contagion.
It takes between 1 and 4 days from the moment of infection until the first symptoms appear. It starts with an inflamed and sore throat, usually red but in some cases with white or yellow areas as well. The second sign is a high fever, usually greater than 38.3°C, which might also lead to chills. After 12 to 48 hours, the distinctive red rash appears on the skin.
The rash starts with red dots, which later evolve into a red or pink rash, similar in appearance to sunburn. Another distinctive feature of the condition is the sandpaper-like roughness of the rash. It can affect any area of the body but is commonly found on the neck, ears, chest, elbows, inner thighs or groin. While the face is usually spared, there can be other signs in the area, such as red cheeks or a paler zone surrounding the mouth. The rash becomes white at any point, if a glass is pressed on its surface. The rash is healed after about 6-7 days.
Sometimes, scarlet fever causes only the rash. However, other symptoms are possible. These include headaches, itchiness, uncomfortable swallowing, abdominal pain, nausea, vomiting, loss of appetite or a general feeling of sickness. Sometimes, the disease causes the so-called strawberry tongue, which is a red and swollen tongue after it develops a white surface. In some cases, scarlet fever leads to Pastia's lines, which are ruptured blood vessels in skin folds such as the neck, armpits, groin, elbows or knees. Like all infections there is a chance that lymph nodes or neck glands become swollen, tender and painful when touched.
The most severe symptoms are diarrhea, muscle aches or vomiting. Doctors have to investigate toxic shock syndrome and other potential issues. Even after the rash is healed completely, the skin can continue to peel for 4 to 6 weeks, especially on the arms and legs.
Since the cause of the disease is a bacterial infection, the treatment is a cure of antibiotics for a period of 10 days. The treatment is effective and kills the bacteria but some symptoms, such as swollen lymph glands, might persist for some time.