Older adults can develop mononucleosis, and their illness is likely to be different from that of children or young adults. It has rarely been transmitted via blood transfusion. Symptoms of mononucleosis in college age persons consist of fever, sore throat, swollen glands in the neck, and fatigue. Most people are somewhere in between and may need to take time off from work or classes. This test usually turns positive shortly after the onset of symptoms, but in some cases the test will remain negative for 1 week or longer despite illness.
Some people never develop a positive test.
In such cases your clinician may order more specific blood tests to establish the diagnosis. Other tests called blood counts and liver tests may be ordered to help rule out some of the complications associated with mono. Symptoms develop about 4 to 6 weeks from the time of exposure during which you will feel well. The illness may last 7 to 10 days, but varies widely from person to person. The vast majority of people recover completely.