Infectious mononucleosis (mono), or glandular fever, is often called the kissing disease. Kissing can spread the virus that causes this disease, but more commonly coughing, sneezing, or sharing a glass or cup transmits mononucleosis. It's not highly contagious.

Mononucleosis is caused by the Epstein-Barr virus. Mono usually isn't very serious, although the virus remains in your body for life. Some people with mono have minimal symptoms, and the infection goes unrecognized.

Most people have been exposed to the Epstein-Barr virus by the time they're 35 years old and have built up antibodies. They're immune and won't get it again. Full-blown mono is common in people ages 7 to 35, and the highest incidence is in people between the ages of 15 and 24. In non-Western countries, mononucleosis has become increasingly common in children younger than 3 years.   

Signs and symptoms

Signs and symptoms of mononucleosis may include:

• Fatigue
• Weakness
• Sore throat, perhaps a strep throat that doesn't get better with antibiotics
• Fever
• Swollen lymph nodes in the neck and armpits
• Swollen tonsils
• Headache
• Skin rash
• Loss of appetite
• Soft, swollen spleen

In children between the ages of 4 and 15, the virus may cause a mild illness that resembles a common respiratory infection. In older adults, mono causes more severe signs and symptoms and lasts longer.

The virus typically has an incubation period of four to six weeks, although in young children this period is shorter. Symptoms such as fever and sore throat usually lessen within a couple of weeks, although fatigue, enlarged lymph nodes and swollen spleen may last for a few weeks longer.

If you've been feeling tired and weak; have had a persistent fever, headache, loss of appetite, rash and muscle aches; and have had swollen lymph nodes, tonsils and spleen — these are strong indications that you have mononucleosis. If rest and a healthy diet haven't resulted in easing your symptoms within a week or two or if your symptoms recur, see your doctor.

Your doctor may suspect mononucleosis based on your signs and symptoms and a physical examination.

If there's a need for additional confirmation, a Monospot test is generally done to check your blood for antibodies to the Epstein-Barr virus. This is a screening test with a result within a day. But it may not detect the infection during the first week of the illness. Another antibody blood test requires a longer result time, but can detect the disease even within the first week of symptoms. Other blood tests that may be used look for elevated numbers of white blood cells (lymphocytes) or abnormal-looking lymphocytes.

Significant complications of mononucleosis include enlargement of the spleen. In extreme cases, the spleen may rupture, causing sharp, sudden pain in the left side of your upper abdomen. If such pain occurs, seek medical attention immediately — you may need to have surgery.

Most people with mono have mild liver inflammation (hepatitis). Jaundice occurs occasionally, usually in people older than 35. About half of the people with mono have a low count of platelets, which are blood cells involved in clotting.

Mononucleosis can also result in the following less common complications:

• Anemia, a decrease in red blood cells and hemoglobin
• Inflammation of the heart
• Complications involving the nervous system (meningitis, encephalitis, seizures, Bell's palsy, Guillain-Barre syndrome)
• Swollen tonsils, leading to obstructed breathing

The Epstein-Barr virus can cause much more serious illness in people who have impaired immune systems, such as people with HIV/AIDS or people taking drugs to suppress immunity following an organ transplant.

Growing evidence suggests a possible link between mononucleosis and an increased risk of developing multiple sclerosis — a muscle-weakening disease of unknown cause. In one study of more than 60,000 women, researchers found that study participants who had multiple sclerosis had higher antibody levels to the Epstein-Barr virus in their blood compared with those without multiple sclerosis. Another even larger study found that people with the highest level of antibodies against the Epstein-Barr virus were more than 30 times more likely to develop multiple sclerosis later than those with the lowest level of antibodies. However, because so few people exposed to the Epstein-Barr virus ever develop multiple sclerosis, scientists point out that other factors must be involved in causing the disease.

There's no specific therapy available to treat infectious mononucleosis. Antibiotics don't work against viral infections such as mono. Treatment mainly involves bed rest and adequate fluid intake.

Occasionally, a streptococcal (strep) infection accompanies the sore throat of mononucleosis. You may also develop a sinus infection or an infection of your tonsils (tonsillitis). If so, you may need treatment with antibiotics for these accompanying bacterial infections.

To ease some of your symptoms, such as swelling of your throat and tonsils, your doctor may prescribe a corticosteroid medication such as prednisone.

Mononucleosis is believed to spread through saliva. If you're infected, you can help prevent spreading the virus to others by not kissing them and by not sharing food, dishes, glasses and utensils until several days after your fever has subsided. If you've had mononucleosis, don't donate blood for at least six months after the onset of the illness.

There's no vaccine to prevent mononucleosis.

In addition to getting plenty of bed rest, these steps can help relieve symptoms:

• Drink plenty of water and fruit juices. Fluids help relieve fever and sore throat and prevent dehydration.
• Take an over-the-counter pain reliever. Use pain relievers such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others) as needed. But don't give aspirin to a child under age 16. Aspirin may trigger a rare but potentially fatal disorder known as Reye's syndrome.
• Gargle with salt water. Do this several times a day to relieve sore throat. Mix one-half teaspoon salt in a glass of warm water.

Most signs and symptoms of mono ease within a few weeks but it may be two to three months before you feel completely normal.

Returning to your usual schedule too soon can increase the risk of a relapse. If you're an athlete, be cautious about returning to strenuous activities, such as contact sports, especially if your spleen is enlarged because of the increased risk of rupturing the spleen. Children with mononucleosis and an enlarged spleen shouldn't engage in vigorous activities, roughhousing or contact sports for the same reason. Rupture of the spleen results in severe bleeding and is a medical emergency. Doctors recommend avoiding contact sports for at least one to two months after you've had mono.

Although you may not be able to return to vigorous activities right away, your doctor may recommend gradual exercise to help you rebuild your strength as you recover from mononucleosis.

Mononucleosis can be a prolonged condition, keeping you at home for weeks as you recover. But be patient with your body as it fights the infection.

For the first week, you may be so fatigued that you feel too weak to even get out of bed. But the tiredness lessens with time. Throat soreness is generally the worst for the first five to seven days of illness. Your swollen lymph glands should return to normal size by the fourth week of infection.

For young people, having mono will mean some missed activities — missed classes, team practices and parties. Without doubt, you'll need to take it easy for a while.

If you have mono, you don't necessarily need to be quarantined. Many people are already immune to the Epstein-Barr virus that causes the disease because of prior exposure to the virus as a child. But plan on staying home from class and other activities until you're feeling better.

Seek the help of friends and family as you recover from mononucleosis. College students should also contact the campus student health center staff for assistance or treatment, if necessary.