71 Infectious Mononucleosis

Infectious mononucleosis is an acute infectious dis­ease of children, adolescents, and young adults. It is caused by the Epstein-Barr virus (EB virus) and is followed by lifelong immunity.

Distribution and Incidence

On the basis of the populations investigated, it would seem that infectious mononucleosis occurs worldwide but attacks only those persons who have had no EBV antibodies. The virus replicates in the salivary glands, is present in the oropharyngeal se­cretions of patients ill with the disease, and contin­ues to be shed for months following convalescence. As a lifelong inhabitant of the lymphoid tissues, it is excreted intermittently into the oropharynx.

In the underdeveloped countries it is a disease of childhood, and, since it spreads by contact with oral secretions, crowding and unhygienic Siuroundings fa­vor its ready transmission. In more developed coun­tries, it strikes especially those of the 15- to 25-year age group and is recognized clinically as infectious mononucleosis. In the United States, on college cam­puses, the disease is commonly known as the “kissing disease.”

Children of low socioeconomic state almost univer­sally show antibodies to the virus. (In Ghana, 84 percent of infants have acquired antibodies by age 21 months.) In a worldwide prospective study of 5,000 children and young adults without EB virus antibodies, 29 percent developed antibodies within a period of 4 to 8 years. Among susceptible college students the annual incidence of the disease is about 15 percent.

Immunology

Specific antibodies to EB virus are demonstrable early after the onset of the disease. Although the higher titers may decrease in subsequent months, they remain at detectable levels throughout life, along with immunity to the disease.

Pathology and Clinical Manifestations

Although the pathological findings may be multivis- ceral, the predominant finding is follicular hyper­plasia of the lymph nodes.

In childhood the disease is Subclinical or masquer­ades as one of many episodes of upper respiratory infection. In the typical youthful adult, after an incu­bation period of about 5 or 6 weeks, clinical disease shows itself with prodromes of malaise, fatigue, headache, and chilliness followed by high fever, sore throat, and tender swollen cervical lymph nodes. Examination shows, in addition to the lymphadenop­athy, paryngitis often with scattered petechiae and swelling of the pharyngeal lymphoid structures, Iiepatosplenomegaly, and, not infrequently, a tran­sient maculopapular rash. Palpebral and periorbital edema may develop. Mild jaundice appears in some 10 percent of patients. Rarely are symptoms related to the central nervous system. Following an initial leukopenia, a Ieucocytosis of 15,000 to 20,000 or higher appears with an absolute lymphocytosis and with atypical lymphocytes prominent as noted above.

In most patients the disease is mild, and recovery occurs within several weeks. College students are generally up and about within a week or so. Compli­cations in the nervous system may occasionally oc­cur in adults, but death from the disease is ex­tremely rare, splenic rupture being the most serious complication.

History and Geography

This disease was described first by a Russian pedia­trician, Nil F. Filatov, in 1885, as idiopathic adenitis. Four years later, a German physician, Emil Pfeiffer, also described a disease that was epidemic in chil­dren and characterized by glandular enlargement. He gave it the name Drusenfieber (glandular fever). In 1896, J. P. West wrote of a similar epidemic in the United States, but it was only in 1920 that Thomas Sprunt, of Baltimore, gave it the name infectious mononucleosis.

R. H. Kampmeier

Bibliography

Epstein, M.A., and B. G. Achong. 1977. Pathogenesis of infectious mononucleosis. Lancet 2: 1270—2.

Davidsohn, I., and P. H. Walker. 1935. Nature of hetero- phile antibodies in infectious mononucleosis. Ameri­can Journal of Clinical Pathology 5: 455—65.

Downey, H., and C. A. McKinly. 1923. Acute lymphade­nosis compared with acute lymphatic leukemia. Ar­chives oflnternal Medicine 2: 82—112.

Henle, W., and G. Henle. 1979. The virus as the etiologic agent of infectious mononucleosis. In Epstein-Barr virus, ed. B. G. Epstein and B. G. Achong₁ New York. 1981. Clinical spectrum of Epstein-Barr virus infec­tion. In The human herpesviruses: An interdisciplin­ary perspective, ed. Andre J. Nahmias, Walter R. Dowdle, and Raymond F. Schinazi. New York.

Niederman, James C. 1982. Infectious mononucleosis. In Cecil’s textbook of medicine, ed. James B. Wyngaarden and Lloys H. Smith, Jr. Philadelphia.

Paul, John R., and Walls W Bunnell. 1932. Presence of heterophile antibodies in infectious mononucleosis. American Journal of Medical Science 183: 90—104.

Pfeifer, Emil. 1889. Drtisenfieber. Jahrbuch Kinderheil- kunde 29:257—64.

Sprunt, Thomas, and Frank A. Evans. 1920. Mononucleo­sis Ieucocytosis in reaction to acute infections (“infec­tious mononucleosis”). Bulletin of Johns Hopkins Hos­pital 31: 410—17.

Strauss, Stephen E. 1987. Editorial - EB or not EB - that is the question. Journal OfAmerican Medical Associa­tion 257: 2335—6.