Flu-like symptoms, sore throat and enlargement of the spleen, swelling of the lymph nodes and changes in the blood count. In most people, especially children under the age of ten, the disease progresses without symptoms.

Adults often suffer from considerable fatigue and susceptibility to other infections for months. Although the virus - as with the related chickenpox virus - remains in a person's body for life, secondary illnesses are rare. If the virus reactivates, often undetected, it is possible to shed the pathogen again.

The time between infection with the pathogen and the onset of the disease is seven to 30 days (four to seven weeks in adults). Infection is possible for weeks, mainly through infectious saliva.

Contact persons may continue to attend the community facility and should pay more attention to hygiene, e.g. wash their hands frequently and use separate towels. Sick people are allowed to return to school, Kita etc. after recovery. A doctor's certificate is not required.