Mononucleosis
MononucleosisInfectious mononucleosis -- known popularly as "mono" or "the kissing disease" -- has been recognized for more than a century. An estimated 90 percent of mononucleosis cases are caused by the Epstein-Barr virus (EBV), a member of the herpes virus group. Most of the remaining cases are caused by certain other herpes viruses, particularly cytomegalo virus. This fact sheet focuses on mononucleosis caused by EBV. EBV is a common virus that scientists estimate has infected over 90 percent of people aged 40 or older sometime during their lives. These infections can occur with no symptoms of disease. Like all herpes viruses, EBV remains in the body for life after infection, usually kept under control by a healthy immune system. Almost anyone at any age can get mononucleosis. Seventy to 80 percent of all documented cases, however, involve persons between the ages of 15 and 30. Both men and women are affected, but studies suggest that the disease occurs slightly more often in men than in women. Doctors estimate that each year 50 out of every 100,000 Americans have mononucleosis symptoms. Among college students, the rate is several times higher. Mononucleosis does not occur in any particular "season," although authorities in colleges and schools, where the disease has been well studied, report that they see most patients in the fall and early spring. Epidemics do not occur, but doctors have reported clustering of cases. Transmission: EBV, the virus that causes most cases of mononucleosis, infects and reproduces in the salivary glands. It also infects white blood cells called B cells. Direct contact with virus-infected saliva, such as through kissing, can transmit the virus and result in mononucleosis. Someone with mononucleosis, however, does not need to be isolated. Household members or college roommates have only a slight risk of being infected unless they come into direct contact with the patient's saliva. A person is infectious several days before symptoms appear and for some time after acute infection. No one knows how long this period of infectiousness lasts, although the virus can be found routinely in the saliva of most people with mononucleosis for at least six months after the acute infection has subsided. It can be detected in the saliva of about 15 percent of people for years after first infection. Symptoms: Symptoms may take between two and seven weeks to develop after exposure to the virus and can last a few days or as long as several months. In most cases, however, they disappear in one to three weeks. In fact, mononucleosis symptoms may be nonexistent or so mild that most people are not even aware of their illness. In adolescents and young adults, the illness usually develops slowly and early symptoms are vague. Symptoms may include a general complaint of "not feeling well," headache, fatigue, chilliness, puffy eyelids, and loss of appetite. Later, the familiar triad of symptoms appears: fever, sore throat, and swollen lymph glands, especially at the side and back of the neck, but also under the...
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