Infectious mononucleosis, often called “mono,” refers to a group of symptoms usually caused by the Epstein-Barr virus (EBV). It typically occurs in teenagers, but you can get it at any age. The virus is spread through saliva, which is why some people call it the “kissing disease.”
People with mono often have a high fever, swollen lymph glands, and a sore throat.Fortunately, most cases of mono are mild and resolve easily with minimal treatment. The infection is typically not serious and usually goes away on its own in one to two months.
Mono is caused by the Epstein-Barr virus. According to the Centers for Disease Control and Prevention (CDC), EBV is a member of the herpesvirus family and is one of the most common viruses to infect humans around the world (CDC).
The virus is spread through direct contact with saliva from the mouth of an infected person and cannot be spread through blood contact. You can be exposed to the virus by a cough or sneeze, by kissing, or by sharing food or drinks with someone who has mono. It usually takes four to eight weeks for symptoms to develop after you are infected.
In adolescents and adults, the infection causes noticeable symptoms in 35 to 50 percent of cases. In children, the virus typically causes no symptoms and the infection often goes unrecognized (CDC).
The following groups have a higher risk for getting mono:
- young people between the ages of 15 and 25
- people on immune system–suppressing drugs
Anyone who regularly comes into close contact with large numbers of people is at an increased risk for mono. This is why high school and college students frequently become infected.
The incubation period of the virus (the time between when you contract the infection and when you start to have symptoms) is four to six weeks. The signs and symptoms of mono typically last for one to two months.
Symptoms may include:
- sore throat
- swollen lymph glands in the neck and armpits
- muscle weakness
- swollen tonsils
- night sweats
Occasionally, your spleen or liver may also swell, but mononucleosis is almost never fatal.
Mono is hard to distinguish from other common viruses such as the flu. If your symptoms do not improve after one or two weeks of home treatment such as resting, getting enough fluids, and eating healthy foods, see your doctor.
A doctor can usually diagnose mono based on the presence of symptoms such as a fever, a sore throat, and swollen lymph glands. The age of the patient is also a good indicator, since mono usually occurs in teenagers. Blood tests may be used to confirm the diagnosis:
White Blood Cell Count
A mono infection typically causes your body to produce more white blood cells as it tries to defend itself. A high white blood cell count cannot confirm an infection with EBV, but the result suggests that it is a strong possibility.
EBV Antibodies (“Mono Spot Test”)
A positive “mono spot” test is usually enough to confirm infectious mononucleosis. The mono spot test is a rapid test used to detect the presence of antibodies—proteins that your immune system releases naturally in response to a harmful substance called an antigen. Specifically, the mono spot test is used to detect antibodies to EBV antigens. According to the National Institutes of Health (NIH), you may not have a detectable level of antibodies early in the illness; therefore, the test may need to be repeated in 10 to 14 days.
There is no known treatment for infectious mononucleosis, and no antiviral drugs or vaccines are available; however, your doctor may prescribe a type of medication called corticosteroids to reduce throat and tonsil swelling. Symptoms usually resolve on their own in one to two months. Treatment is aimed at easing your symptoms. This includes using over-the-counter medicines to reduce fever and techniques to calm a sore throat, such as gargling salt water. Other home treatments that may ease symptoms include:
- getting a lot of rest
- drinking a lot of fluids (water is best)
- eating warm chicken soup
- using over-the-counter pain medication
If your symptoms get worse or you experience intense abdominal pain, contact your physician. One of the complications of mono is ruptured spleen, which is a life-threatening situation.
Mono is typically not serious. In some cases, people who have mono sometimes suffer from secondary infections such as strep throat, sinus infections, or tonsillitis. In rare cases, some people may develop the following complications:
A ruptured spleen will usually occur between four and 21 days after you begin to have symptoms.
You should wait at least one month before doing any vigorous activities or playing contact sports to avoid rupturing your spleen, since it may be swollen from the infection. Talk to your doctor about when you can return to your normal activities. A ruptured spleen in patients who have mono is rare. However, if you have mono and experience a sharp, sudden pain on the upper left part of your stomach, call your doctor immediately.
Inflammation of the Liver
Hepatitis (mild liver inflammation) or jaundice (yellowed skin and eyes) may occur occasionally in mono patients.
According to the Mayo Clinic, mono can also cause some of these extremely rare complications (Mayo Clinic):
- anemia (a decrease in your red blood cell count)
- thrombocytopenia (a decrease in platelets, the part of your blood that begins the clotting process)
- inflammation of the heart
- complications that involve the nervous system, such as meningitis or Guillain-Barre syndrome
- swollen tonsils that can obstruct breathing
The symptoms of mono seldom last for more than four months. The majority of people who have mononucleosis recover within two to four weeks, and 50 percent can return to regular activities in two weeks. However, a study reported in the Physician’s Desk Reference (PDR) found that 38 percent of a group of high school and college students took more than two months to recover after being diagnosed with mono (PDR).
An illness called chronic EBV infection can occur if symptoms last for more than six months. EBV will remain dormant in your blood cells for the rest of your life, and can occasionally reactivate without symptoms. It is possible to spread the virus to others through contact with your saliva during this time.
EBV also establishes a lifelong, inactive infection in your body’s immune system cells. Very rarely and years later, some patients who carry the virus develop one of two rare cancers: Burkitt’s lymphoma and nasopharyngeal carcinoma. These cancers are not normally found in the United States. EBV appears to play a role in the development of these cancers; however, according to the CDC, EBV is probably not the only cause.
Mono is almost impossible to prevent. This is because healthy people who have been infected with EBV in the past carry and can spread the infection periodically for the rest of their lives. According to the Mayo Clinic, almost all adults have been infected with EBV by age 35 and have built up antibodies to fight the infection (Mayo). So, patients normally get mono only once in their lives.
Written by: Jacquelyn Cafasso
Published on Aug 20, 2012
Updated on Feb 15, 2013
Medically reviewed by George Krucik, MD