Is Mononucleosis (Mono) Contagious?

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Mono Complications

Fortunately, the more severe complications of mono are quite rare, and mono is very rarely fatal in healthy people. The rare severe complications include destruction of red blood cells (hemolytic anemia) and inflammation of the sac surrounding the heart (pericarditis), the heart muscle itself (myocarditis), and the brain (encephalitis). Mono tends to be more aggressive in patients with abnormal immune systems, such as people with AIDS or those who are taking medications that suppress immune function.

What is mono (mononucleosis)?

Mono (also termed mononucleosis or infectious mononucleosis) is a disease caused by the Epstein-Barr virus (EBV). Children are commonly infected with EBV and show few or no symptoms. Older individuals, teenagers, and adults may show symptoms when infected. These consist mainly of fatigue, fever, inflamed throat, and swollen lymph nodes in the neck. Infected people may also have a rash, swollen liver, or enlarged spleen. Most of the symptoms get better within two to four weeks, but some people can be fatigued for several months. The EBV virus can become inactive after infection, and some people reactivate EBV infection even years later.

Is mono contagious?

Mono is contagious from person to person, especially via an infected person's saliva. Other transmission methods include blood, semen, blood transfusions, and organ transplants. Unfortunately, EBV can also be spread by contact with objects like toothbrushes or eating utensils that are contaminated with EBV. Mono can be spread to babies, children, and adults. Individuals who have mono can be contagious without the characteristic symptoms of fever, fatigue, or swollen glands; some people can be contagious during the incubation period when no symptoms are present.

How do I know if I have mono?

Symptoms of EBV infection may include some or most of the following symptoms:

Many diseases produce similar symptoms, so the diagnosis is usually based on the patient's history, physical, and EBV antibody tests (for example, IgG, IgM, and VCA antibody tests, Monospot test, and others). Interpretation of these tests is not always definitive.

How is mono transmitted? What is the incubation period for mono?

Mono (mononucleosis) is spread from person to person. It is usually not spread by airborne droplets (it can be in some instances when saliva is sprayed and then inhaled) but by direct contact with an infected person's saliva. Because of the predominant way mono is spread (saliva), it has been termed the "kissing disease." The incubation period (from time of exposure to EBV to symptom development) is about four to seven weeks, and some people can spread the disease during the incubation period and up to 18 months later. Mono can be spread by blood, semen, and organ transplants. Saliva-contaminated toothbrushes, utensils, and contact with other EBV-contaminated objects may also spread the disease.

Medically Reviewed by a Doctor on 8/28/2015

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