Mononucleosis Health Article

Definition

Infectious mononucleosis is caused by the Epstein-Barr virus, which in teenagers and young adults may result in acute symptoms that last for several weeks. Fatigue and low energy can linger for several months.

Description

Infectious mononucleosis (IM), also called mono or glandular fever, is commonly transmitted among teenagers and young adults by kissing or sexual activity; hence it is sometimes called the "kissing disease."

By age 35–40, approximately 95% of the population has been infected with the Epstein-Barr virus (EBV) that causes IM. Although anyone can develop mononucleosis, primary (first) infections commonly occur in young adults between the ages of 15 and 35. Symptoms of IM are particularly common in teenagers. In the developed world, 15–20% of people are infected during adolescence and about half of these teens become ill. Among adults, 30—50% of those contracting IM become ill. Although males and females are equally susceptible, in the United States whites are 30-fold more likely than blacks to contract IM.

Typically IM runs its course in 10–30 days. However people with weakened or suppressed immune systems, such as AIDS or organ-transplant patients, are especially vulnerable to potentially serious complications from mononucleosis.

Following IM, the EBV remains dormant (latent) in a few cells in the throat and blood for the remainder of one's life. Periodically the virus may reactivate and be transmitted through saliva; however IM symptoms rarely reoccur.

Causes

Infectious mononucleosis is caused by the first infection with the Epstein-Barr virus, also called herpes virus 4. It is one of the most common human viruses and is endemic throughout the world. EBV is a member of the herpes family of DNA viruses. This family of viruses includes those that cause cold sores, chickenpox, and shingles. Most people are infected with multiple strains of EBV. The different EBV strains are found in separate parts of the body: the circulating lymphocytes (white blood cells), cell-free blood plasma, or the oral cavity.

EBV is spread by contact with viral-infected saliva through coughing, sneezing, kissing, or the sharing of items such as drinking glasses, eating utensils, straws, toothbrushes, or lip gloss. Some evidence indicates that in teens and young adults IM is primarily transmitted by sexual intercourse. However EBV is not highly contagious and household members have only a very small risk of infection unless there is direct contact with infected saliva.

Symptoms

Less than 10% of children under age 10 develop symptoms with EBV infection. The incubation period after exposure to EBV is generally about 7–14 days in children and teens and 30–60 days in adults. An infected person can transmit EBV during this period and for as long as five months after symptoms disappear.

The first symptoms of IM are usually general weakness and extreme fatigue. An infected person may require 12–16 hours of sleep daily prior the development of other symptoms. IM symptoms are similar to cold or flu symptoms:

• Fever and chills occurs in about 90% of IM cases. EBV is most contagious during this stage of the illness.
• An enlarged spleen, causing pain in the upper left of the abdomen, occurs in about 50–60% of infections.
• Sore throat and/or swollen tonsils occurs in less than 50% of mononucleosis infections.
• Swollen lymph glands (nodes) in the neck, armpits, and/or groin develop in less than 50% of infections.
• Jaundice (yellowing of the skin and eyes) develops in more than 20% of patients, depending on age, and indicates an inflamed or enlarged liver.
• A red skin rash, particularly on the chest, occurs in about 5% of infections.
• loss of appetite
• stomach pain and/or nausea
• muscle soreness and/or joint pain
• headache
• chest pain
• coughing
• rapid or irregular heartbeat

These acute symptoms usually last one to two weeks.

Splenic enlargement generally peaks during the fourth week after symptoms appear and then subsides. However an enlarged spleen may rupture in 0.1–0.2% of cases, causing sharp pain on the left side of the abdomen. Additional symptoms of a ruptured spleen include light-headedness, a fast heart rate, and difficulty breathing. Splenic rupture most often occurs within the first three weeks and is the most common cause of death from mononucleosis. It requires immediate medical attention and may require emergency surgery to stop the bleeding.

There are other rare—but potentially life-threatening—complications of mononucleosis:

• Neurological complications affecting the central nervous system may develop in 1–2% of infections. Bell's palsy is a temporary condition caused by weakened or paralyzed facial muscles on one side of the face.
• The heart muscle may become inflamed.
• A significant number of the body's red blood cells or platelets may be destroyed and there may be reduced number of circulating red and white blood cells.