Scarlet fever, formerly scarlatina, is a contagious disease that is caused by the group A β-haemolytic bacilli Streptococcus pyogenes. It typically affects children between the ages of 3 and 15.
The disease is caused by an exotoxin released by S. pyogenes, the same bacteria that causes strep throat and necrotizing fasciitis. The incubation period for the disease is never less than twenty-four hours and the disease itself lasts for around three weeks.
There are many symptoms of scarlet fever. After an incubation period of up to a week, the patient experiences fever, vomiting, chills, abdominal pain and malaise with swollen tonsils and throat. The tongue is white with red and swollen papilla but within five days changes to red. A rough rash appears on the trunk of the body within the twelve hours following the onset of fever. In full-blown disease, faint lines in the elbow creases called Pastia's lines will appear. After several days, the skin affected by the rash begins to slough off.
The preferred treatment is with a full course of ten days of penicillin, and if the course is not finished, there is an increased risk for conditions like rheumatic fever. In the case of penicillin allergy, other options like erythromycin are used.
There are three severe kinds of scarlet fever that are worth mentioning:
- Scarlatina anginosa causes extensive necrosis and ulceration of the throat.
- Scarlatina haemorrhagica causes hemorrhage into the skin and mucous membranes.
- Scarlatina maligna is an acute and usually lethal form of scarlet fever.