Mono (Infectious Mononucleosis) Symptoms, Causes, Treatment and Diagnosis on MedicineNet.com

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Infectious Mononucleosis (Mono)

Infectious Mononucleosis (Mono) Slideshow

Medical Revising Author: Melissa Conrad Stöppler, MD
Medical Revising Editor: William C. Shiel Jr., MD, FACP, FACR

Sore Throat: Is It Mono?

Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

Could your sore throat be a symptom of mono? Having a sore throat can be a symptom of many conditions, and many people wonder if their own sore throat might be a sign of something more serious than the common cold. Specifically, infectious mononucleosis ("mono") and infection with Streptococcus bacteria ("Strep throat") are two conditions that both produce an extremely painful sore throat.

Like the common cold, infectious mononucleosis is caused by a viral infection. The virus responsible for mono is called the Epstein-Barr virus, abbreviated EBV. EBV is a very common virus worldwide, and studies show that up to 95% of the U.S. population has been infected with EBV at some point in their lives. EBV infection, especially if it occurs early in childhood, does not always cause illness, or it may cause a very mild illness that is not distinguishable from colds or other mild illnesses of childhood. However, when infection first occurs during the teen years or in young adulthood, infectious mononucleosis will develop in up to 50% of cases.

Symptoms of mono include fatigue, sore throat, swollen lymph nodes, and fever. Enlargement of the spleen and inflammation of the liver may also occur. Severe complications are very rare, and the condition gradually resolves on its own. Since mono is caused a virus and not a bacteria, antibiotics are of no benefit. Therefore, treatment is directed at relieving the symptoms, which may persist for one to two months.

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What is infectious mononucleosis ("mono")?

Infectious mononucleosis, "mono," "kissing disease," and glandular fever are all terms popularly used for the very common illness caused by the Epstein-Barr virus (EBV). EBV is a member of the herpesvirus family. Symptoms of infection with EBV include fever, malaise, and sore throat. The designation "mononucleosis" refers to an increase in one type of white blood cells (lymphocytes) in the bloodstream relative to the other blood components as a result of the EBV infection.

What is the cause of mono?

The EBV that causes mono is found throughout the world. By the time most people reach adulthood, an antibody against EBV can be detected in their blood. In the U.S., up to 95% of adults 35-40 years of age have antibodies directed against EBV. This means that most people, sometime in their lives, have been infected with EBV. The body's immune system produces antibodies to attack and help destroy invading viruses and bacteria. These specific antibodies can be detected in the blood of people who have been infected.

While there are other illnesses falling under the broad classification of mononucleosis that can cause similar symptoms (cytomegalovirus [CMV] is one example) and an increase in blood lymphocytes, the form caused by the EBV is by far the most common.

What are the risk factors for mono?

The EBV can infect any person. As previously discussed, the majority of people have become infected with the virus by the time that they reach adulthood. Mono is most often diagnosed in adolescents and young adults, with a peak incidence at ages 15-17. However, it is also seen in children. Generally, the illness is less severe in young children and may mimic the symptoms of other common childhood illnesses, which may explain why it is less commonly diagnosed or recognized in this younger age group.

How is mono spread?

Mono is spread by person-to-person contact. Saliva is the primary method of transmitting mono. Infectious mononucleosis developed its common name of "kissing disease" from this prevalent form of transmission among teenagers. A person with mono can also pass the disease by coughing or sneezing, causing small droplets of infected saliva and/or mucus to be suspended in the air which can be inhaled by others. Sharing food or beverages from the same container or utensil can also transfer the virus from one person to another since contact with infected saliva may result.

Most people have been exposed to the virus as children, and as a result of the exposure, they have developed immunity to the virus. It is of note that most people who are exposed to the EBV don't ever develop mononucleosis. The incubation period for mono, meaning the time from the initial viral infection until the appearance of symptoms, is between four and six weeks. During an infection, a person is likely able to transmit the virus to others for at least a few weeks.

Research has shown that, depending on the method used to detect the virus, anywhere from 20%-80% of people who have had mononucleosis and have recovered, will continue to secrete the EBV in their saliva for years due to periodic "reactivations" of the viral infection. Since healthy people without symptoms also secrete the virus during reactivation episodes throughout their lifetime, isolation of people infected with EBV is not necessary. It is currently believed that these healthy people, who nevertheless secrete EBV particles, are the primary reservoir for transmission of EBV among humans.