Infectious mononucleosis, commonly referred to as the “kissing disease,” is a viral illness caused by the Epstein-Barr virus (EBV), which is a member of the herpesvirus family. The condition is characterized by pronounced fatigue, elevated fever, and tonsillitis. Treatment primarily involves the administration of analgesics and ensuring adequate rest, with recovery typically occurring within approximately three to five weeks following the onset of initial symptoms.
What is Mononucleosis?
Infectious mononucleosis, colloquially known as the “kissing disease,” is an infection instigated by the Epstein-Barr virus (EBV). This virus is classified within the herpesvirus family.
Transmission of the Epstein-Barr Virus (EBV)
The Epstein-Barr virus, also known as herpes virus 4, is predominantly transmitted through saliva, which is the basis for its informal designations such as “kissing disease” or “fiancée disease.” Although rare, transmission can also occur through blood transfusions. Once the virus enters the body, it resides in the lymph nodes, remaining dormant for life without causing recurrent symptoms. However, individuals infected with the virus can still transmit it, as they may excrete the virus in their saliva (asymptomatic carriers).
Typically, infection occurs during childhood or adolescence. It is estimated that approximately 80% of adults are carriers of EBV, with 20-30% being asymptomatic carriers of the virus.
Important Note: The mononucleosis virus can affect very young children (under five years of age), but in such cases, it generally results in few or no symptoms, often resembling a mild upper respiratory infection.
How is Mononucleosis Diagnosed?
The incubation period for infectious mononucleosis ranges from four to seven weeks, during which no symptoms are present. The disease often commences with progressive fatigue and a moderate fever of approximately 38°C.
The hallmark symptoms of infectious mononucleosis subsequently manifest as follows:
- A fever exceeding 39°C accompanied by chills, lasting from seven to fourteen days;
- A notable change in general condition, including significant fatigue;
- Loss of appetite;
- Severe sore throat with difficulty swallowing;
- Swollen lymph nodes in the neck;
- Muscle pain;
- Headache;
- Occasionally, red rashes may appear on the trunk, thighs, and arms if the individual has taken antibiotics. This reaction is not a true allergy to the antibiotic but rather a specific response associated with EBV infection.
Diagnosis of Kissing Disease
Clinical examination typically reveals signs of angina, characterized by a reddened throat with inflamed tonsils covered by a grayish exudate, which strongly suggests the diagnosis. Enlarged lymph nodes are often observed, particularly in the neck, and may be more generalized. In approximately 50% of cases, a significant enlargement of the spleen is noted. Hepatic involvement, such as hepatomegaly and jaundice, is rare.
Additional Tests and Analyses for Mononucleosis
A complete blood count (CBC) may reveal a mononucleosis syndrome, indicated by an increase in specific cell types (hyperbasophilic lymphocytes). The appearance of this syndrome may be delayed by several days and is not exclusive to EBV infection, as it can also occur in other recent infections (e.g., toxoplasmosis, HIV, cytomegalovirus).
Isolation of the virus is challenging; therefore, serological tests to detect specific antibodies against the virus are preferred. The initial test performed is the Mononucleosis Indicator (MNI) test, which is sensitive and can broadly identify individuals with recent infections (positive in 80% of recent cases). However, this test may yield false positives in 3% of cases. Confirmation tests are necessary, including:
- Detection of IgM antibodies against VCA in cases of recent infection;
- Detection of EBV-VCA IgG and EBNA IgG antibodies in cases of later infection. These tests are primarily indicated for monitoring virus reactivation in individuals with compromised immune systems.
Further testing may be warranted in the event of complications, including:
- Blood tests such as the Coombs test to assess for hemolytic anemia or liver function tests;
- Myelogram for the evaluation of bone marrow cells;
- Lymph node biopsy if there is uncertainty regarding the diagnosis.
Disease Progression
Symptoms of infectious mononucleosis typically resolve spontaneously within a few days (1 to 2 weeks). However, the convalescence phase may extend for several weeks, characterized by significant fatigue.
Complications: Is Mononucleosis Serious?
Infectious mononucleosis can affect various major organs, including:
- The brain (encephalitis, meningitis);
- The heart (myocarditis);
- The lungs (pneumonia);
- The kidneys (nephritis).
When appropriately managed, these complications generally have a favorable prognosis and resolve within a few days.
Ruptured Spleen
During the acute phase of the infection, splenic rupture, although rare, is a notable complication of this disease.
Hematological Complications
Infectious mononucleosis may occasionally lead to:
- Anemia (a decrease in hemoglobin levels) due to accelerated destruction of red blood cells (hemolytic anemia);
- Thrombocytopenic purpura (a reduction in platelet count leading to abnormal blood clotting and the appearance of small red or purplish spots on the skin);
- Cryoglobulinemia.
These complications generally have a favorable prognosis.
Macrophage Activation Syndrome
This condition is exceedingly rare. It occurs when certain cells (macrophages) partially destroy bone marrow cells, resulting in a decline in all blood cell lines (red blood cells, white blood cells, and platelets).
Acute Vulvar Ulcer
In exceptional cases, particularly among young females, mononucleosis may be complicated by an acute vulvar ulcer, known as Lipschutz disease. This condition typically presents as a sudden onset of painful and deep ulceration in the vulvar area, without accompanying fever. The ulceration usually heals and resolves, potentially leaving a scar.
Chronic Fatigue
Infectious mononucleosis may also lead to chronic fatigue syndrome. In addition to persistent fatigue, individuals may experience:
- Pain (headaches, sore throat, muscle or joint pain);
- Neurological and psychological disturbances (visual impairments, memory issues, excessive irritability, difficulty concentrating, depression);
- Prolonged fever ranging from 37.5 to 38.5 °C;
- Moderate weight loss;
- Pharyngitis;
- Painful lymph nodes.
Cancer Risk
The Epstein-Barr virus is associated with an increased risk of developing certain malignancies, including nasopharyngeal cancers and lymphomas (such as Burkitt or B-cell lymphomas). While these cancers are rare in the general population, they occur more frequently in individuals carrying the EBV virus.
Treatment and Management of Epstein-Barr Virus
Treatment for infectious mononucleosis is primarily symptomatic, focusing on alleviating symptoms rather than targeting the virus itself. Physicians typically recommend physical rest in cases of significant fatigue and may prescribe analgesics such as paracetamol for pain relief.
In complicated cases involving hepatitis or significant anemia, corticosteroid therapy may be considered for a duration of ten days.
Prevention
To mitigate the risk of transmission, the following precautions are advised:
- Avoid direct contact with others (e.g., kissing);
- Practice regular hand hygiene, particularly after coughing or blowing the nose;
- Refrain from medical procedures involving the face (e.g., dental care);
- Cover the mouth when coughing or sneezing;
- Disinfect frequently used objects, such as telephones;
- Store toothbrushes away after use;
- Ensure proper ventilation of living spaces at least once daily;
- Exclude children or adolescents from school or community activities during the acute phase of the illness (characterized by fever and sore throat).