Mononucleosis is a viral infection causing fevers, sore throat, and swollen lymph glands, especially in the neck. It is usually linked to the Epstein-Barr virus (EBV), but can also be caused by other organisms such as cytomegalovirus (CMV).

See also: Infectious mononucleosis (acute CMV infection)

Mononucleosis is often transmitted by saliva. While it is known as "the kissing disease," occurring most often in 15- to 17-year-olds, the infection may occur at any age.

Mono may begin slowly with fatigue, general ill feeling (malaise), headache, and sore throat. The sore throat slowly gets worse, often with swollen tonsils covered with a whitish-yellow covering. The lymph nodes in the neck are frequently swollen and painful.

A pink, measles-like rash can occur and is more likely if the patient is given ampicillin or amoxicillin for a throat infection. (Antibiotics should NOT be given without a positive strep test.) The symptoms of mono gradually go away on their own over a period of weeks to months.

• Fever
• Sore throat
• Swollen lymph nodes, especially in the neck and armpit
• General discomfort, uneasiness, or ill feeling
• Drowsiness
• Loss of appetite
• Muscle aches or stiffness
• Swollen spleen
• Rash

Less frequently occurring symptoms include:

• Jaundice (yellow cast to skin)
• Headache
• Neck stiffness
• Sensitivity to light
• Cough
• Shortness of breath
• Chest pain
• Rapid heart rate
• Fatigue
• Nosebleed
• Hives

During a physical examination, the doctor may find swollen lymph nodes in the front and back of the neck, as well as swollen tonsils with the whitish covering. The doctor might also find a swollen liver or swollen spleen when pushing on your belly. There may be a skin rash.

Laboratory findings often include a higher-than-normal white blood cell count, and the characteristic finding of atypical lymphocytes -- unusual-appearing white blood cells that are seen when blood is examined under a microscope. Abnormal liver function tests are also characteristic.

Common tests for EBV include:

• A monospot test (positive for infectious mononucleosis)
• Epstein-Barr virus antigen by immunofluorescence (positive for EBV)
• Epstein-Barr virus antibody titers to help distinguish acute infection from past infection with EBV