What causes mononucleosis?

Mononucleosis is a contagious (but not highly contagious) disease
Mononucleosis is a contagious (but not highly contagious) disease

Mononucleosis is a contagious (but not highly contagious) disease, mostly caused by Epstein-Barr virus (EBV) infection. Hence, it is also known as infectious mononucleosis.

EBV is a herpes virus, and it is found all over the world. Most people get infected with EBV at some point in their lives. 

EBV enters into your body commonly through saliva. The body reacts by developing antibodies against the virus. This immune response results in the development of fever.

Besides EBV, other causes of mononucleosis include:

How does mononucleosis spread?

Epstein-Barr virus (EBV) is transmitted via intimate contact with body secretions, primarily saliva. The organism may also be shed from the uterine cervix and can be transmitted sexually, although it is more likely to be spread through saliva. On rare occasions, EBV spreads via blood transfusion or organ transplantation.

EBV can be spread through objects used by an infected person. These objects may be a glass or toothbrush that transmits the virus through the saliva from an infected person to a healthy person. The virus probably survives on an object that remains moist for a longer time. 

If you have been infected with EBV, you can spread the virus even before you develop its symptoms. You can continue to transmit the virus for as long as six months after mononucleosis has set in.

How common is mononucleosis?

It is estimated that up to 95% of adults in the world eventually test positive for Epstein-Barr virus (EBV). However, it is most commonly seen to affect 15- to 24-year olds. Hence, infectious mononucleosis is also referred to as “kissing disease.” Because most of the adults have been previously exposed to mononucleosis in their younger years, it is uncommon in adults.

In the United States, approximately 50% of the population tests positive for EBV before age 5 years, with much of the rest testing positive in adolescence.

Infectious mononucleosis develops in at least one out of four teenagers and young adults who get infected with EBV.

Can mononucleosis recur?

Most people who developed infectious mononucleosis will get it only once in their lifetime. Very rarely, mononucleosis recurs months or years later.

Most of the cases of mononucleosis are due to Epstein-Barr virus (EBV). The characteristic of EBV infection is that once you get infected with it, it continues to stay in your body in an inactive state. At times, it may reactivate and your saliva may test positive for EBV, but you do not develop any symptoms of mononucleosis. Only when your immunity is weakened due to acquired immunodeficiency syndrome (AIDS), there are high chances of the redevelopment of EBV mononucleosis.

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Medically Reviewed on 9/9/2020
References
Epstein-Barr Virus (EBV) Infectious Mononucleosis (Mono). Available at: https://emedicine.medscape.com/article/222040-overview#a5

Mohseni M et al. Mononucleosis. Available at: https://www.ncbi.nlm.nih.gov/books/NBK470387/

Epstein-Barr Virus and Infectious Mononucleosis. Available at: https://www.cdc.gov/epstein-barr/about-ebv.html