What is Mononucleosis?
Mononucleosis, often referred to as ‘mono’, typically involves symptoms such as fever, swollen lymph nodes, and a sore throat. The term “infectious mononucleosis” came about in the 1920s when a group of students showed similar throat illnesses and blood tests results, which revealed high levels of lymphocytes (a type of white blood cell) and unusual mononuclear cells (cells with a single nucleus). The Epstein-Barr virus, commonly known as EBV, was later identified as the main cause of mononucleosis. This was confirmed when a health care worker, exposed to the virus, developed a positive result on a heterophile test – a blood test used to detect mono.
What Causes Mononucleosis?
Mononucleosis, also known as “mono,” is usually caused by the Epstein-Barr virus (EBV). This is a type of herpesvirus that spreads through contact, often via saliva. It’s not completely certain how long a person might carry the virus in their saliva after becoming sick, but high levels can continue for around six months. Normally, this disease spreads from one person to another, but it’s important to note that mononucleosis is not highly contagious.
However, mono isn’t always caused by the Epstein-Barr virus. Other possible causes can include:
* CMV, or Cytomegalovirus
* Adenovirus, a type of common cold virus
* Hepatitis A, a virus that causes liver disease
* HIV, the virus that causes AIDS
* Toxoplasma, a parasite that usually comes from infected cat feces or poorly cooked food
* Rubella, also known as German measles
Risk Factors and Frequency for Mononucleosis
Almost 95% of adults worldwide have antibodies for the Epstein-Barr virus (EBV), showing that they’ve been infected at some point in their life. The peak infection rate is typically seen within the age group of 15 to 24. This virus often causes symptoms in adolescents and is sometimes known as the “kissing disease”. In adults, however, mononucleosis caused by EBV is not very common, accounting for about 2% of all throat diseases.
Most adults are often not susceptible to clinical illness because they’ve already been exposed to the virus at some stage. As for the infection rates in the United States, white individuals show a 30 times higher rate of noticeable infection compared to black individuals. This difference could be because if the virus is acquired during childhood, it usually does not cause noticeable symptoms, suggesting that black individuals might be exposed to the virus at a younger age.
- After exposure, EBV infects the cells of the salivary glands and the back of the throat.
- It also affects the white blood cells, or lymphocytes, in the tonsils, which then enter the bloodstream.
- Common responses to the infection include lymphoid hyperplasia, which can manifest as generalized swollen lymph nodes, tonsillitis, and enlarged liver and spleen.
- The infection in B-lymphocytes results in the production of a type of protein called immunoglobulins, also known as heterophile antibodies.
Signs and Symptoms of Mononucleosis
Mononucleosis, often called “mono,” is an infection with symptoms that can appear some time after exposure, usually within 3 to 6 weeks. People experiencing mono might not usually remember when or how they were exposed to the virus. Common symptoms of mono include fever, sore throat, feeling tired, and swollen lymph nodes (usually around the back of the neck).
Other symptoms can also include having a headache, a general feeling of discomfort or illness, and not feeling like eating. In some people, the feeling of being tired can last for months. The sore throat can often come with white patches on the tonsils, and small red spots might appear on the roof of the mouth, although this is less common.
About half of people with mono could also have an enlarged spleen; this is an important symptom to look out for, especially for people who are at risk of injuring it, like those who participate in active sports. A diffuse, red skin rash can also sometimes occur. However, this isn’t the same as rashes that appear as a reaction to certain antibiotics.
- Fever
- Sore throat
- Fatigue
- Swollen lymph nodes (often in the back of the neck)
- Headache
- General feeling of discomfort
- Reduced appetite
- White patches on the tonsils
- Larger spleen (in some individuals)
- Small red spots on the roof of the mouth (occasionally)
- Diffuse, red skin rash (occasionally)
Testing for Mononucleosis
When a doctor first examines you, they start by assessing your airway to make sure it’s clear and not at risk of getting blocked. This is extremely important, as in rare cases, swelling or an abscess can interfere with the normal functioning of the airway. Also, your doctor needs to make sure your body is stable, meaning your heart and blood vessels are working well and efficiently. This is done to rule out any injury or rupture to the spleen, which is a part of the body often affected in an illness called mononucleosis.
Your doctor will then conduct laboratory tests, which usually show an increase in a type of white blood cell called lymphocytes. In fact, they usually make up more than 50% of all white blood cells observed when someone suffers from mononucleosis. Interestingly, a condition called ‘atypical lymphocytosis’ where the percentage of unusual lymphocytes is more than 10% can also be observed on blood smear tests. Your doctor may also find an overall increase in your white blood cells (leukocytosis) and occasionally, a decrease in platelets that help in blood clotting (thrombocytopenia).
In general, imaging tests aren’t required when evaluating mononucleosis. Instead, a test called the monospot test or heterophile antibody test, which is a blood test, becomes the preferred diagnostic tool. It is almost 100% specific in identifying the disease, meaning it rarely gives a false-positive. However, the sensitivity of this test is close to 85%, implying that early in the illness, the test might give a false-negative result. In those situations, your doctor might suggest repeating the test later during the course of the disease. If your doctor is unsure if your symptoms indicate mononucleosis, they might further evaluate you for a common bacterial infection caused by streptococcus bacteria, using a rapid antigen test or throat culture.
Treatment Options for Mononucleosis
If you have mononucleosis (commonly known as mono), the standard treatment generally involves taking care of yourself. This could involve taking medications that lower your fever and reduce inflammation, which would also help with a sore throat and the general feeling of tiredness that come with this illness. It’s also important to stay well-hydrated, get plenty of rest, and eat well.
Routine use of corticosteroids — medications that reduce inflammation and suppress the immune system — is not typically advised in treating mono because of concerns that it could weaken your immune system. However, if mono causes breathing problems due to a blocked airway, then corticosteroids might be needed. This scenario may also require consultation with an ear, nose, and throat specialist, along with the appropriate steps to manage your airway.
Sometimes, antibiotics are mistakenly given to patients with mono, which could result in a widespread, bumpy (maculopapular) rash. The rash often appears after taking amoxicillin, but it can occur with other antibiotics too.
If you’re an athlete, it’s necessary to avoid sports during the early course of the illness, which is typically about three weeks. This is because roughly half of the people with mono experience enlargement of the spleen, an organ located near your stomach. When the spleen is enlarged, it’s at risk of rupturing, or bursting, which could be dangerous.
What else can Mononucleosis be?
There are a number of viral and rickettsial diseases that show symptoms similar to EBV (Epstein-Barr Virus). It can sometimes be mistaken for:
- Cytomegalovirus
- Human Immunodeficiency Virus (HIV)
- Human herpesvirus type 6
- Hepatitis B
- Tick-borne diseases such as Lyme disease
For instance, primary HIV may show up with ulcers in the mouth and skin, and skin rashes are relatively common in primary HIV but not as common in mononucleosis, a condition caused by the EBV.
What to expect with Mononucleosis
Most people who get infected with EBV, a type of virus, recover completely and develop lifelong immunity, which means their bodies learn how to control the virus if it ever becomes active again. The most severe phase of the sickness usually ends by the second week, but feelings of overall discomfort and tiredness can linger for months. In very rare cases, this virus has been associated with certain types of cancer, but more research is needed to confirm this link.
When recovering, returning to regular activities should be gradual and depend on certain factors, like the risk of injuring the spleen, which can be sensitive during recovery, and how tired the illness has made the person feel.
In some isolated cases, swelling of throat lymph nodes — small, bean-shaped glands of the immune system — can cause difficulty breathing. Some patients may also experience complications affecting the central nervous system, such as inflammation of the brain (encephalitis), severe psychological disorders, nerve damage in the head and neck, inflammation of peripheral nerves in the body, and Guillain-Barre syndrome, a condition where the body’s immune system accidentally attacks its own nerves.
Possible Complications When Diagnosed with Mononucleosis
Here are some possible health issues that could arise:
- Blockage of the upper airway due to enlarged lymph nodes
- Rupture of the spleen
- Autoimmune hemolytic anemia, a condition where the immune system destroys red blood cells faster than it can produce them
- Pancytopenia, a decrease in the number of all types of blood cells
- Hemolytic uremic syndrome, a condition resulting from the abnormal destruction of red blood cells
- Episcleritis and uveitis, inflammation of the eye tissues
- Erythema multiforme, a skin disorder resulting from an allergic reaction or infection