Epstein-Barr Virus Infection
Epstein-Barr virus (EBV) causes a number of diseases, including infectious mononucleosis.
Infection with EBV is very common. In the United States, about 50% of all children 5 years of age and nearly 95% of adults have had an EBV infection. Most of these infections produce symptoms similar to those of a cold or other mild viral illness. Sometimes, however, teenagers and young adults develop different and more severe symptoms from EBV infection. This illness is called infectious mononucleosis. Infectious mononucleosis is named for the presence of large numbers of white blood cells (mononuclear cells) in the bloodstream. Teenagers and young adults usually catch infectious mononucleosis by kissing or having other intimate contact with someone infected with EBV.
Rarely, EBV contributes to the development of several uncommon types of cancer, such as Burkitt's lymphoma and certain cancers of the nose and throat. It is thought that specific viral genes alter the growth cycle of infected cells and cause them to become cancerous. EBV has been implicated in chronic fatigue syndrome (see Section 25, Chapter 306), although evidence for it as a cause is scanty and controversial.
Symptoms and Complications
EBV can produce a number of different symptoms, depending on the strain of the virus and several other, poorly understood factors. In most children younger than 5, the infection produces no symptoms. In adolescents and adults, it may or may not produce symptoms. The usual time between infection and the appearance of symptoms (incubation period) is thought to be 30 to 50 days.
The four major symptoms of infectious mononucleosis are extreme fatigue, fever, sore throat, and swelling of the lymph nodes. Not everyone has all four symptoms. Usually, the infection begins with a general feeling of illness (malaise) that lasts several days to a week. This vague discomfort is followed by a fever, sore throat, and enlarged lymph nodes. The fever usually peaks at around 103° F in the afternoon or early evening. The throat is often very sore, and puslike material may be present at the back of the throat. Any lymph node may be enlarged; most commonly, the nodes of the neck are affected. Fatigue is usually most pronounced in the first 2 to 3 weeks but may last 6 weeks or more.
The spleen is enlarged in more than 50% of the people with infectious mononucleosis. In most infected people, this enlargement causes few if any symptoms, but an enlarged spleen may rupture if injured. The liver may also enlarge slightly. Less commonly, jaundice and swelling around the eyes occur. Skin rashes develop infrequently; however, people with EBV infection who receive the antibiotic ampicillin usually develop a rash. Other very rare complications include seizures, various nerve abnormalities, behavioral abnormalities, and inflammation of the brain (encephalitis) or tissues covering the brain (meningitis).
The duration of the illness varies. The acute phase lasts about 2 weeks, after which most people are able to resume their usual activities. However, fatigue may persist for several more weeks and, occasionally, for months or longer.
Diagnosis
The symptoms of infectious mononucleosis also occur in many other viral and bacterial infections. Therefore, to confirm the diagnosis, doctors perform a blood test to detect antibodies to EBV. Sometimes, the first sign of infectious mononucleosis is large numbers of characteristic mononuclear white blood cells (atypical lymphocytes) in a blood sample.
Treatment
People with infectious mononucleosis should rest until the fever, sore throat, and feeling of illness disappear. Because of the risk of rupturing the spleen, heavy lifting and contact sports should be avoided for 6 to 8 weeks, even if the spleen is not noticeably enlarged.
Acetaminophen or NSAIDs (such as aspirin or ibuprofen) can relieve fever and pain. However, aspirin should be avoided in children because of the risk of Reye's syndrome, which can be fatal. Some complications, such as severe swelling of the airway, may be treated with corticosteroids. Currently available antiviral drugs have little effect on the symptoms of infectious mononucleosis and should not be used.
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