Mononucleosis, or mono for short, is a viral disease affecting certain blood cells. It’s cause is the Epstein-Barr virus (EBV), actually a member of the herpes virus family. EBV has also been associated with certain cancers, including Burkitt lymphoma, immunoblastic lymphoma, and nasopharyngeal carcinoma.

The majority of people will get exposed to the Epstein-Barr virus at least once in their lives; however, most will not develop symptoms of infectious mononucleosis. In third world underdeveloped countries, people will usually be exposed in early childhood, and are not likely to develop conspicuous symptoms. But in developed regions such as North America and Western Europe, the age of initial exposure may be deferred to older childhood and adolescence, when symptoms are more likely to result. That is why it is known to be a disease affecting high school and college students.

Incidence Statistics

The incidence mononucleosis infections, short of testing for the Epstein-Barr virus (EBV), must be inferred by the presence of noticeable symptoms. This makes statistics somewhat unreliable. Information from surveys conducted in the U.K in the 1950s and 1960s ^1,2 indicates that the annual incidence of mono is on the order of 2-5 cases per populations of 10,000, or .02-.05%.

In the United States, up to 95% of adults between 35 and 40 years of age are believed to have been infected. Infants become susceptible to EBV immediately when natural maternal antibody protection, which is present at birth, disappears. When infection with EBV happens in adolescence or young adulthood, it results in infectious mononucleosis 35% to 50% of the time.

Mono Symptoms

The signs and symptoms of mono include sore throat, fever, and swollen lymph glands. Occasionally, swollen spleen or liver can develop. More rarely, heart problems or central nervous system complications occur. Infectious mononucleosis is almost never fatal.

No known linkages exist between active EBV infection and complications of pregnancy, such as miscarriages or birth defects. Symptoms of mononucleosis typically resolve in 1 or 2 months, but the virus will stay latent in a small number of cells in the throat and blood for the rest of the person's life. Epstein-Barr virus may reactivate every so often, usually without symptoms of illness.

References

1. Hobson F G, Lawson B & Wigfield M (1958) Brit. med. J. i, 845
2. Penman H G (1966) J. Hyg. (Camb.) 64, 457

Image by Alejandro Peters: Creative Commons License.