Mononucleosis Facts and Statistics: What You Need to Know

Known as the kissing disease, mononucleosis (mono) is a contagious condition caused mainly by the Epstein-Barr virus (EBV).

By age 30, at least 90% of the population will have antibodies for EBV. Additionally, 75% of young adults infected with EBV will be diagnosed with mono. Although it rarely happens, mono can cause severe complications in some cases.

This article discusses important facts and statistics you should know about mononucleosis.

Mononucleosis Overview

The name mononucleosis describes lymphocytosis (increased white blood cells) and abnormal mononuclear (one nucleus) cells resulting from an EBV infection. Mono often spreads through saliva during kissing or sharing drinks and utensils.

However, it can also be transmitted through bodily fluids like semen and blood. Mono has a long incubation period, taking four to six weeks for symptoms to occur after exposure to EBV.

Although 10% of young adults are asymptomatic (no signs of the disease), the typical symptoms of mono, in order of prevalence, include:

• Sore throat
• Swollen lymph nodes in the neck
• Extreme fatigue
• Upper respiratory symptoms
• Fever
  
• Rash
• Swollen spleen or liver

Most people recover from mono within a few weeks; however, fatigue can last several months. Call your healthcare provider if symptoms from mono are not improving or are becoming worse.

How Common Is Mononucleosis?

Approximately 125,000 cases of mono are reported each year, and EBV is responsible for 90% of them. By age 30, most people will have EBV antibodies, meaning they have been exposed to the virus.

In the United States, 25% to 50% of children living in lower socioeconomic circumstances will have been infected with EBV by age 4. Additionally, 75% of young adults will be diagnosed with mono after an EBV infection.

Mononucleosis by Ethnicity

The National Health and Nutrition Examination Survey (NHANES) found that between 2003–2010 EBV antibodies were higher in non-Hispanic Black people and Mexican Americans than non-Hispanic White people, especially 6-to-8-year-olds. However, the differences in antibody prevalence between White people and non-White people diminished in the teenage years.

Mononucleosis by Age & Sex

The most common ages to be infected with EBV and develop mono are between 15 and 24. Mono is rare in adults, attributing to about 2% of pharyngitis cases (sore throat). Females are slightly more likely to get mono than males.

Causes & Risk Factors of Mononucleosis

Known as one of the most common human viruses, EBV is a member of the herpes family (herpesvirus 4). When nose and mouth cells become infected with EBV, they begin to replicate and spread the virus.

Saliva is the most common way EBV spreads; salivary secretions can transmit the disease for up to six months post-infection. Once infected with EBV, it remains dormant in the body but can be reactivated intermittently throughout life.

Although 90% of mono cases are due to EBV, about 10% are caused by viruses such as:

• Cytomegalovirus (a common virus spread through body fluids)
• Toxoplasmosis (a disease resulting from a parasite infection)
• HIV
• Rubella (viral infection with a distinct rash)
• Hepatitis A, B, or C
• Adenovirus (a virus that causes cold-like symptoms)

Risk factors for contracting mono include:

• Age (adolescents)
• Low socioeconomic status
• Maternal education
• Living in overcrowded homes
• Sharing of personal items
• Lack of health insurance
  

What Are the Mortality Rates of Mononucleosis?

Mono is typically a nonfatal disease that resolves naturally. However, in rare cases (1% or less), EBV can cause significant medical conditions and even death. Complications of mono and EBV include:

• Blocked airway
• Ruptured spleen
• Viral meningitis (infection of the brain and spinal cord caused by a virus)
• Encephalitis (brain inflammation)
• Guillain-Barré syndrome (an autoimmune disease that affects the nerves)
• Peritonsillar abscess (viral infection in the throat)
• Hematologic disorders (blood and bone marrow disorders)
• Autoimmune disorders (when the immune system attacks itself)
• Cancer

Due to EBV-associated illnesses, an early stage clinical trial was launched in 2022 to evaluate the effectiveness of an EBV vaccine. Mono and EBV infections can be prevented by good handwashing and not sharing personal items such as utensils and cups.

Screening and Early Detection

Although there isn't an official screening tool for mono, anyone at risk for the condition should see their healthcare provider if symptoms appear. In addition to a physical exam, a blood test can diagnose mono. The monospot test identifies antibodies to EBV and is at least 85% accurate.

Since a viral infection causes mono, treatment includes supportive measures such as staying hydrated, resting, and taking non-steroidal anti-inflammatories (NSAIDs) to reduce pain, fever, and swelling. In some cases, a steroid may be prescribed if difficulty breathing occurs from a compromised airway.

Summary

Mono is a moderately contagious condition usually caused by the Epstein-Barr virus (EBV). Transmitted mainly by saliva, EBV antibodies are present in at least 90% of the population by age 30. About 75% of young adults who have an EBV infection will get mono. Sore throat, enlarged lymph nodes, and extreme fatigue are common symptoms. Since it's a viral infection, treatment for mono includes NSAIDs, staying hydrated, and resting. Although mono usually resolves independently after two to four weeks, severe complications can occur in 1% or less of those with EBV.