Mononucleosis 3 Essay Research Paper Infectious mononucleosis

Mononucleosis 3 Essay, Research Paper

Infectious 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 arm and in the groin. A fever of 101.F to 105.F lasts for a few days and sometimes continues intermittently for one to three weeks. (High fever late in the illness suggests bacterial complications.) The swollen lymph glands, varying in size from that of a bean to a small egg, are tender and firm. Swelling gradually disappears over a few days or weeks. The spleen is enlarged in 50 percent of mononucleosis patients, and the liver is enlarged in 20 percent. Tonsillitis, difficulty in swallowing, and bleeding gums may accompany these symptoms. Rarely, jaundice or a rash that lasts one or two days is present. In young children and older adults (more than 35 years old), mononucleosis may be difficult to diagnose because the typical mononucleosis symptoms are not present. A doctor may suspect mononucleosis in older adults, however, if the patient has had a high fever for at least a week, has an enlarged liver, has abnormal liver function studies, or has neurological symptoms. In children, EBV infection can produce a different picture. A child may have a mild sore throat or tonsillitis or have no symptoms at all, and the illness often goes unrecognized by the parent or teacher. Diagnosis: As mononucleosis symptoms appear, the body reacts to the virus in certain distinctive ways that can be detected through laboratory tests. White blood cells called lymphocytes increase in number (a process known as lymphocytes), and atypical-looking (activated) lymphocytes involved in fighting the virus infection are commonly seen in blood samples. The body produces antibodies, or specific proteins, that protect against EBV. Blood tests that measure lymphocytes and antibodies aid in the diagnosis of mononucleosis. In EBV infection, the body’s immune system also produces more of substances called heterophil antibodies (Paul-Bunnell antibodies). These antibodies indicate that an EBV infection is present in the body, but they are not directed against the virus itself and do not serve a protective function. Because other types of infections and immunologic reactions also induce heterophil antibodies, their presence suggests, but does not indicate specifically, an EBV infection. Symptoms play an important role in the diagnosis of mononucleosis. But because this disease can masquerade as other diseases, symptoms can be misleading. They may resemble, for instance, the sore throat of