Mononucleosis

Infectious mononucleosis -- often referred to as simply mono -- is a contagious viral infection.


Causes/associated factors
Most cases of infectious mononucleosis are caused by the Epstein-Barr virus (EBV), a member of the herpes family. Although the infection can develop at any age, the illness is most common in adolescents and young adults in the United States and other developed countries. The condition rarely develops in adults older than age 40 because most people have been infected with EBV by this time (possibly without having any symptoms) and developed antibodies (compounds that help neutralize or destroy foreign substances in the blood) to it. If your immune system is healthy, there is little chance of the virus reactivating within your body and causing another episode of mono.

Transmission
Mononucleosis spreads mainly through saliva, even if you don't have symptoms. You may contract mono by kissing an infected person or sharing food, beverages or eating utensils with an infected person. A child may contract the infection by putting toys contaminated with infected saliva in his or her mouth. The virus may be found in the saliva for many months after the infection. After recovery, the virus lies dormant in the throat and blood cells. If it eventually reactivates (which often happens without symptoms), the virus can again be found in the person's saliva. Some people spread the virus intermittently in this way for life. Rarely, mono can spread through blood transfusions or by sharing needles or syringes. Sexual transmission of EBV may also be possible.
The incubation period (the time from exposure until symptoms appear, if they appear at all) is estimated to be 30 to 50 days, but children may have an incubation period as short as 10 to 14 days. How long you're contagious is unknown, but doctors typically assume you can transmit mono from a few days before symptoms appear, if they appear at all, to at least six months afterward.


Signs/symptoms
When symptoms appear, they vary in intensity. The most common symptoms include:
fever of 101 to 105°F for about five days (although children may have little or no fever)
sore throat or tonsillitis (inflammation of the tonsils)
fatigue
headaches
enlarged, tender lymph nodes (small, round structures that protect your body from invasion by bacteria or other organisms) in your neck and sometimes under the arm and in the groin
abdominal discomfort due to an enlarged spleen (the organ that stores and sometimes produces blood cells; the spleen helps fight many types of infections)
an enlarged liver
Other symptoms may include a rash, difficulty swallowing, loss of appetite, nausea, bleeding gums, puffy eyes, and muscle or joint pain. Young children, in particular, tend to develop quite mild symptoms that usually last from one to four weeks. About 20 to 25 percent of people who have mono also develop strep throat at the same time.


Diagnosis
The doctor will ask questions about your medical history and symptoms and do a physical exam. A variety of blood tests can help the doctor confirm your diagnosis, as well as estimate how long you've been infected.
Mono spot (heterophil) testing is used to verify the presence of nonspecific antibodies created in response to the virus in your blood. This test identifies 80 to 90 percent of mono cases by the third week of illness. For the remaining cases, blood tests that identify specific antibodies may be used.

Epstein-Barr nuclear antigen (EBNA) testing is used to detect antibodies specific to the nucleus of the Epstein-Barr virus.

Viral capsid antigen (VCA) testing is used to detect antibodies specific to the coating of the Epstein-Barr virus.

A complete blood cell count is used to evaluate the cellular components of your blood, including the number and types of blood cells and platelets (the substance in blood that helps blood to clot), the percentage of each type of white blood cell, the size and shape of blood cells, and the hemoglobin content (the protein in red blood cells that contains iron). With mono, the white blood cell count is usually elevated and certain types of white blood cells are more prevalent than usual.

Liver function studies are used to measure the levels of enzymes (proteins that help facilitate chemical reactions) or other substances in your blood to identify liver problems.

A throat culture may be done to determine if you have strep throat in addition to mono or to help distinguish between the two infections.

Treatment
There is no specific treatment for mononucleosis, other than treating the symptoms. Your doctor may offer the following suggestions:
Get plenty of rest and eat well.
If your throat is sore, eat soft foods. It may also help to suck on throat lozenges or gargle with warm salt water three to four times a day.
Drink lots of fluids, but avoid alcohol.
Due to the risk of rupturing the spleen, avoid activities that may put you at risk for abdominal trauma, such as contact sports. Also avoid vigorous exercise, lifting and straining.
Your doctor may also recommend acetaminophen or a nonsteroidal anti-inflammatory medication such as ibuprofen for fever or discomfort. Anyone age 19 or younger should not take aspirin because it's associated with an increased risk of Reye's syndrome (a serious condition involving the brain and liver). Rarely, a short-term course of oral steroids (prednisone, for example) may be prescribed. This typically happens only when there is severe swelling of the tonsils or throat or you develop serious complications involving the nervous system or blood.

Antibiotics are not used to treat mono, but they may be necessary if you develop strep throat at the same time. The antibiotics ampicillin and amoxicillin are typically avoided while you have mono because their use can result in a rash that may be mistaken for an allergic reaction to the medication.

Typically, the acute illness lasts two to three weeks and you'll be able to resume normal activity within four to six weeks. Sometime, however, symptoms can last for several months. To avoid complications, follow your doctor's recommendations. Ask when it's OK to resume your normal activities, including contact sports.


Complications
Complications of mono are rare, but can be severe and at times life-threatening. They may include:
ruptured spleen
airway obstruction from enlarged tonsils
nervous system problems such as meningitis (inflammation of the membranes surrounding the brain or spinal cord) or encephalitis (inflammation of the brain)
Guillain-Barré syndrome (a disorder of the peripheral nerves that produces rapidly worsening muscle weakness, sometimes leading to paralysis)
pneumonia (an infection of the lungs)
anemia (a condition marked by a decreased number of red blood cells or hemoglobin)
blood clotting disorders
pericarditis (inflammation of the membrane surrounding the heart) or myocarditis (inflammation of the heart muscle)
for men, inflammation of the testicles

Pregnancy-specific information
Developing mono during pregnancy appears to have no harmful effects for mother or baby.

Senior-specific information
Older people who develop mono typically have different symptoms than those found in adolescents and young adults. Older people may be severely ill with debilitating fever, fatigue and a general feeling of illness. Sore throat, swollen lymph nodes in the neck and enlarged spleen may be minimal, however.

Prevention
To prevent mono, avoid the saliva of infected people. Don't kiss an infected person or share the person's food, beverages or eating utensils. Clean the saliva from toys of children who have mono, and wash your hands often. Remember, saliva from an infected person may continue to contain EBV for many months after recovery from the acute illness, and an infected person who never had symptoms can also transmit the virus. Do not donate blood until your doctor gives the OK.