Mononucleosis: Causes, Symptoms, Diagnosis and Treatment

Mononucleosis - STDTestGuru
Mononucleosis – STDTestGuru

Mononucleosis is also known as mono or kissing disease is caused by the Epstein-Barr virus (EBV). This virus is a member of the herpes virus family and can be transmitted through sexual contact, but it’s most often transmitted through saliva. Hence, mononucleosis can be considered a sexually transmitted infection, but not all cases of mono are STIs. This disease is a common illness that can make a person feel tired and weak for weeks or months.

Mono can go away on its own, but it requires a lot of rest and good self-care. This is most often seen in teens and young adults. And even children can get the virus, it goes unnoticed as the symptoms are mild. It is estimated that 85 to 90% of American adults develop antibodies to the virus by age 40, which means they have come in contact with the virus at some point in their lives. In the US, exposure to EBV is less common during infancy and young childhood. Adolescents without previous exposure to the virus may be more vulnerable, as their immune system is less able to repel the attack.

What is Mononucleosis?

Mononucleosis is contagious which is common among teenagers and young adults. Infected people may experience extreme fatigue, fever, and body aches. Almost, 90% of Americans are infected with it by age of 35. Not everyone who has the virus develops symptoms, some people only carry the virus. As per CDC, one out of four teenagers and young adults who get infected with the Epstein-Barr virus will develop infectious mononucleosis. When a person has mononucleosis, it’s essential to be careful of certain complications like an enlarged spleen. The key to recovery is to take rest and consume enough fluids as the infected person may not be able to take part in normal daily activities. The symptoms of mononucleosis can range from mild to severe. Fortunately, symptoms gradually improve with at-home treatments.  As there’s no vaccine, the best way to prevent mono is by practicing good hygiene.

Causes of Mononucleosis

Nearly, 90% of mono are caused by the Epstein-Barr virus. This virus is very contagious and can spread through direct contact with saliva from the mouth of an infected person or even through other bodily fluids, such as blood. Mononucleosis is often called the kissing disease, but it is not only spread by kissing. One can be exposed to the virus by kissing, by a sneeze or cough, or by sharing food, drinks, or toothbrush. And it also spreads through breast milk, sexual contact, blood transfusion, and organ transplantation (unusual). People can carry the virus in the body for their entire life without ever having symptoms of mono.

The virus may remain dormant in the throat and blood cells during that person’s lifetime, even when the symptoms of mononucleosis disappear. An Epstein-Barr virus may reactivate periodically, usually without symptoms. Although EBV is the most common cause of mono, other infections like cytomegalovirus (CMV), toxoplasmosis, HIV, rubella, or German measles, hepatitis A, B, or C, adenovirus can cause mono symptoms.

Is mononucleosis contagious?

Mononucleosis is contagious. As the virus sheds in the throat, a person with mono can infect someone who comes into contact with their saliva, by kissing them or sharing eating utensils. Mononucleosis can continue to be contagious for 3 months or more.

Risk factor

The following people/groups are at higher risk for getting mononucleosis:

  • Young people (aged 15 to 30)
  • Students
  • A person who takes medications that suppress the immune system
  • Medical interns
  • Nurses
  • Caregivers

Mononucleosis Symptoms

Mononucleosis can cause different symptoms in different people and they can be mild or severe. Usually, symptoms of infectious mononucleosis appear four to six weeks after exposure. And the symptoms may appear slowly and may not all occur at the same time. Symptoms may vary widely between different age groups. Mononucleosis is typically not serious and generally goes away on its own in 1 to 2 months. Symptoms of mono include:

  • Fever
  • Extreme fatigue
  • Muscle weakness
  • Sore throat
  • Swollen lymph nodes in neck and armpits or groin
  • Swollen tonsils
  • Headache
  • Skin rash
  • Loss of appetite
  • Night sweats
  • An enlarged spleen

A swollen liver and an enlarged spleen are fewer common symptoms. Hardly, the symptoms of infectious mononucleosis can last for six months or longer. And the symptoms vary between different age groups.

Older adults

According to a study from 2006, mononucleosis is less common in adults aged over 40 years. They may not experience the common symptoms of a red throat and swollen lymph nodes. But liver problems may occur.

Teens and young adults (aged 15–24 years)

They are most likely to develop the symptoms of mono. May also have the most severe symptoms. These symptoms last for 2–4 weeks, but they can persist for longer. But the tiredness can last for weeks or months after other symptoms have gone. The reason why symptoms affect teens and young adults more severely remain unclear.

Young children

They do not have symptoms or may have mild symptoms similar to those of a common cold or the flu.  Children can be infected by sharing eating utensils or drinking glasses, or by being near an infected person who coughs or sneezes. Parents can pass on the virus to their children when it reactivates and sheds. The amount of virus spread from the infection may be lower, causing fewer, milder symptoms in a child. An infected child should wash their hands frequently, especially after sneezing or coughing and avoid physical activities.


Toddlers become infected by sharing eating utensils or drinking glasses. And they can also become infected by putting toys in their mouths that have been in the mouths of other children with mononucleosis. Toddlers rarely have symptoms. When they do have, it can be fever and sore throat, which is mistaken for a cold or the flu.

Mononucleosis: Causes and Symptoms
Mononucleosis: Causes and Symptoms

Mononucleosis Diagnosis

The doctors usually diagnose mononucleosis based on the symptoms. And they will look for signs such as swollen lymph nodes, tonsils, liver, or spleen. And might also check the upper left part of the stomach to determine if the spleen is enlarged. Blood tests will help to identify whether or not a person has had a recent or past infection with EBV.

  • Complete blood count – This blood test will help determine how severe the illness is by looking at the levels of various blood cells. For instance, a high lymphocyte count often indicates an infection.
  • White blood cell count – This infection causes the body to produce more white blood cells as it tries to defend itself. A high white blood cell count cannot confirm infection with EBV, but it indicates that there is a strong possibility.
  • Monospot test or heterophile test – The most reliable way to diagnose mononucleosis is the monospot test. This test is a blood test that is used to determine whether you have contracted the Epstein-Barr virus. Doctors may order this test when a person has symptoms of mononucleosis. This test looks for antibodies, these are proteins the immune system produces in response to harmful elements. Monospot test may not be always accurate, but it’s easy to conduct, and results are generally available within an hour or less.
  • EBV antibody test – When the monospot test is negative, the doctor may recommend an EBV antibody test. This is a blood test, which looks for EBV-specific antibodies. The antibodies are proteins that the body’s immune system releases in response to a harmful substance called an antigen.

Mononucleosis Treatment

There is no specific treatment and vaccine to protect against infectious mononucleosis. Antibiotics and antivirals cannot treat EBV. The symptoms of mononucleosis usually resolve on their own in 1 to 2 months. Consult a doctor if your symptoms get worse or if you have intense abdominal pain. Treatment mainly involves

  • Getting enough rest (sleep helps your body fight infection).
  • Eat a healthy diet.
  • Drinking plenty of fluids.
  • Nonsteroidal anti-inflammatory drugs can help to ease fever, inflammation, headaches, and muscle aches. Drugs include ibuprofen and naproxen. Acetaminophen may also work.
  • Corticosteroid medication for swelling in your throat.
  • Saltwater gargles for a sore throat.
  • Should avoid sports, as physical activity can put too much pressure on an enlarged spleen, increasing the risk of rupture.

Must avoid giving aspirin to children or teenagers as it could lead to Reye’s syndrome, a rare disorder that can cause brain and liver damage


Typically, mono is not serious. In some rare cases, it may cause complications. Which include:

  • Enlarged spleen – A ruptured spleen in people is rare, but it is a life-threatening emergency. This can cause sudden sharp pain on the left side of the upper belly. It’s important to call or consult the doctor, as it is an emergency.
  • Liver problems – Hepatitis (liver inflammation) or jaundice (yellowing of the skin and eyes) rarely occur.
  • Blood problems – Hemolytic anemia, the body might destroy too many red blood cells. Or thrombocytopenia, blood might not have enough platelets.
  • Heart problems – Myocarditis, the inflammation of the heart muscle. And may also have an uneven heartbeat.
  • Nervous system problems – Which include seizures, encephalitis (brain inflammation), or meningitis (inflammation of the tissues covering the brain).
  • Swollen tonsils – Infected people may find it harder to swallow or breathe through the mouth.

Recent evidence indicates that mononucleosis can trigger certain autoimmune diseases, which include lupus, rheumatoid arthritis, multiple sclerosis, or inflammatory bowel disease.

Mononucleosis recurrence

Mostly, people who have infectious mononucleosis will have it only once. But occasionally mononucleosis symptoms may recur months or even years later due to a reactivation of EBV. When mono returns, the virus can be the saliva, but infected people probably won’t have any symptoms unless they have a weakened immune system.

How to prevent mono?

Presently, there is no vaccine for mono. Practicing good hygiene is the best way to prevent mononucleosis. Following are the few ways to prevent mono:

  • Do not share drinks, straws, food, food utensils, toothbrush, inhalers, and cigarettes
  • Avoid close contact with infected people
  • Should avoid kissing or having sex with the infected person
  • Keep yourself healthy by eating a nutritious diet, exercising daily, and get adequate sleep for at least six to eight hours a night
  • Washing hands regularly

Facts about Mononucleosis

  • Almost 90% of Americans are infected with it by age 35.
  • In the US, the incidence of infectious mononucleosis is about 500 cases per 100,000 each year.
  • For young adults between the ages of 15 and 19 ranges is about 200 – 800 cases per 100,000.
  • According to a study among college students, about 1% to 5% of university students are developing mononucleosis annually.
  • The Epstein-Barr virus infection is extremely common worldwide and 90% of adults become antibody-positive before the age of 30.
  • More than 3 million cases of mononucleosis are diagnosed in the United States each year.

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