Idiopathic Group

Roseola infantilis is the name given to roseola when it is seen in infants. It roughly resembles measles minus the catarrh; it runs an irregular course as regards precursory symptoms, which vary in degree, and in the extent, degree, and seat of eruption. It may be quite general but patchy, or it may be limited to the arm, or the neck, or trunk; the roseblushes often come and go for several days capriciously, and are accompanied by local heat and itching, which are often marked at night. No catarrhal symptoms, as in measles, are present. The redness generally lasts a dozen or more hours.

When the disease assumes the form of rings (and this is generally observed about the buttocks, thighs, and abdomen), developed from little rose spots, and enclosing pre­sently a healthy circle of skin an inch or so in diameter, the variety R. annulata is present. The concomitant symptoms are the same as those of the common form. It is not neces­sary to make all the varieties of roseola that are made by some authors.