Viral transmission is thought to be mainly salivary exchange in one way or another. In adolescents, this is thought to be by intimate kissing, although, in theory, sharing toothbrushes or cups could transmit virus. Quarantine is unwarranted. The incubation period is 30 to 50 days, making it difficult to pinpoint contacts. Petechiae on the posterior palate are suggestive but not pathognomonic.
Swollen eyelids are common.
Clinically evident involvement of the lungs, lower gastrointestinal tract, or joints is rare. These will be considered below. Other complications, all uncommon or rare, are listed in table 1. Mild and transient neutropenia and thrombocytopenia are common, but severe cytopenias are rare. Severe hepatitis is rare.