Acute ITP occurs most often in children between 1 and 7 years of age subsequent to a viral infection such as measles, rubella, Epstein-Barr, chickenpox, or cytomegalovirus (CMV). The platelet count may drop below 20 x 109/L, and the patient may experience excessive bruising, nose bleeds, and petechiae, typically with a rapid onset.
Spontaneous remission usually occurs within 2 - 6 weeks of the onset of acute ITP. Treatment is often not needed unless the platelet count drops below 10 x 109/L, a level at which there is a high risk of bleeding into the central nervous system.
The usual course of action is to try to prevent trauma that could result in bleeding and then periodically check the platelet count until it returns to normal.