Mono — also called infectious mononucleosis in America, and glandular fever outside the United States — is caused by viruses. The most common virus that causes mono is the Epstein-Barr virus , which is a member of the herpes family and is very common in humans. A few other viruses sometimes cause mono, as well. The viruses that cause mono are spread through saliva, but the disease is not as contagious as the common cold.
Mono is most common in adolescents and young adults. This fact, combined with its ability to spread via saliva, lead to its reputation as the “kissing disease.” Kissing, however, is not the only way to contract mono. Sharing forks and spoons, drinking glasses, water bottles, soda cans, etc. can spread mono. It can be spread by coughing and sneezing as well.
Extreme fatigue and weakness are classical symptoms of mono, as well as a sore throat that does not go away with antibiotic treatment (because it is caused by a virus, not a bacterium). Other symptoms are swollen glands and tonsils, fever, headache, and possibly a skin rash. Inside the body, the spleen can become enlarged and many of the white blood cells develop large, abnormal nuclei (giving the disease its name).
Children can get mono, but it usually does not make them very sick, so it often goes unnoticed. Older adults can also get mono, and it can cause liver problems and jaundice in these patients.
Rarely, mono can cause serious complications such as heart inflammation, anemia, low blood platelets (which impairs blood clotting), encephalitis or meningitis, and a rare progressive paralysis called Guillain-Barre syndrome. People with impaired immune systems may be in severe danger from a mono infection.
There is no direct treatment for mono except for adequate rest and drinking plenty of fluids. A patient with mono likely will be so tired that he or she has no choice but to rest. Good hydration and nutrition help the body remain strong enough to fight off the infection.
Some people have such severe swelling in their throat that it impacts their breathing or swallowing; these patients may receive corticosteroids, powerful drugs that can reduce swelling. Sometimes the throat inflammation leads to a secondary bacterial infection, which can be treated with antibiotics.
And of course, people with mono should avoid kissing anyone. Just in case.
More Information About Mononucleosis
“Mononucleosis.” Mayo Clinic staff.