Scarlet fever natural history

Prognosis
Illness usually begins with a fever and sore throat. There also may be chills, vomiting, and abdominal pain. The tongue may have a whitish coating and appear swollen. It may also have a "strawberry"-like (red and bumpy) appearance. The throat and tonsils may be very red and sore, and swallowing may be painful.

One or two days after the illness begins, the characteristic red rash appears (although the rash can appear before illness to as many as 7 days later). Certain strep bacteria produce a toxin (poison) which causes some people to break out in the rash—the "scarlet" of scarlet fever. The rash may first appear on the neck and chest, then spread over the body. Typically, the rash begins as small, flat red blotches which gradually become fine bumps and feel like sandpaper.

Although the cheeks might have a flushed appearance, there may be a pale area around the mouth. Underarm, elbow and groin skin creases may become brighter red than the rest of the rash. These are called Pastia's lines. The scarlet fever rash generally fades in about 7 days. As the rash fades, the skin may peel around the finger tips, toes, and groin area. This peeling can last up to several weeks.

Scarlet fever is treatable with antibiotics. Since either viruses or other bacteria can also cause sore throats, it's important to ask the doctor about a strep test (a simple swab of the throat) if your child complains of having a sore throat. If the test is positive, meaning your child is infected with group A strep bacteria, your child's doctor will prescribe antibiotics to avoid possible, although rare, complications.

Complications
Although complications may arise if not treated, scarlet fever goes away after a course of antibiotics.

The complications of scarlet fever include septic complications due to spread of streptococcus in blood and immune-mediated complications due to an aberrant immune response. Septic complications, today rare, include otitis, sinusitis, streptococcal pneumonia, empyema thoracis, meningitis and full-blown septicaemia ( malignant scarlet fever).

Immune complications include acute glomerulonephritis, rheumatic fever and erythema nodosum. The secondary scarlatinous disease (or secondary malignant syndrome of scarlet fever) included renewed fever, renewed angina, septic ORL complications and nephritis or rheumatic fever and is seen around the 18th day of untreated scarlet fever.

Resources
CDC Scarlet fever