Infectious mononucleosis - causes, symptoms, and treatment

Infectious mononucleosis, often referred to as the “kissing disease,” represents a clinical syndrome that is most commonly (in 80-90% of cases) caused by the Epstein-Barr virus (EBV). This condition mainly affects adolescents and young adults and manifests with fever, sore throat, and enlargement of lymph nodes. Although the disease tends to run a relatively mild course in children, the clinical presentation in adults may be more severe. In this article, we will discuss the causes of infectious mononucleosis, routes of transmission, symptoms, diagnosis, and management principles.

What is infectious mononucleosis?

Infectious mononucleosis is a viral infection characterized by specific clinical signs. It is most commonly associated with the Epstein-Barr virus (EBV), which belongs to the human herpesvirus family. The disease is usually self-limiting, meaning that in most cases the body overcomes the infection without specific treatment. After the acute phase, the virus remains in the body in a latent state for life, which is why more than 90% of the world’s population is infected with this virus.

Causes of infectious mononucleosis

The majority of infectious mononucleosis cases (approximately 80-90%) are caused by the Epstein–Barr virus (EBV), also known as human herpesvirus 4. However, a mononucleosis syndrome that is EBV-negative may also develop due to other pathogens:

• Human herpesvirus 6 (HHV-6) - approximately 9% of cases;
• Cytomegalovirus (CMV) - 5-7%;
• Herpes simplex virus 1 (HSV-1);
• In rare cases: Streptococcus pyogenes, Toxoplasma gondii, HIV-1, adenovirus, Corynebacterium diphtheriae, Francisella tularensis, hepatitis A and B viruses, rubella, or enteroviruses.

How is mononucleosis transmitted?

The Epstein-Barr virus is most commonly transmitted through saliva, which is why infectious mononucleosis is often called the “kissing disease.” The virus may spread through direct contact with saliva, such as kissing or sharing utensils or drinks. There is also evidence of sexual transmission of EBV.

Clinical signs and symptoms of infectious mononucleosis

The clinical picture includes the following main symptoms:

• Fever;
• Sore throat (pharyngitis);
• Enlargement of lymph nodes (lymphadenopathy), especially in the neck region;
• Fatigue and general weakness;
• Headache;
• Muscle pain;
• Enlargement of the spleen (splenomegaly) - occurs in some cases;
• Enlargement of the liver (hepatomegaly) - rarely.

Diagnosis is based on the clinical presentation, complete blood count findings (atypical lymphocytosis), and specific serological tests such as the heterophile antibody test. Detection of EBV-specific antibodies confirms the diagnosis.

Treatment and supportive therapy

Since infectious mononucleosis is usually self-limiting, specific antiviral treatment is generally not required. Therapy is based on supportive care aimed at relieving symptoms:

• Adequate hydration: sufficient fluid intake to prevent dehydration;
• Antipyretic and analgesic agents: nonsteroidal anti-inflammatory drugs (e.g., ibuprofen) or paracetamol to relieve symptoms;
• Rest: adequate rest helps the body fight the infection;
• Restriction of physical activity: due to the risk of splenic enlargement, avoidance of physical exertion and contact sports for several weeks is recommended to prevent splenic rupture.

In cases of severe clinical course or development of complications, hospitalization may be required.

Prognosis and possible complications

In healthy individuals, the prognosis of infectious mononucleosis is generally favorable. Most patients fully recover within several weeks. Mortality is extremely rare and associated with severe, life-threatening complications such as:

• Airway obstruction (due to enlarged lymph nodes or tonsils);
• Splenic rupture (in the presence of splenomegaly);
• Neurological complications (e.g., encephalitis, meningitis);
• Hemorrhage (bleeding);
• Secondary bacterial infections.

Despite its prevalence, infectious mononucleosis is usually a mild and self-limiting disease. However, if symptoms appear, consultation with an infectious disease specialist is necessary for accurate diagnosis and appropriate management planning.

Author: Megi Kobakhidze - Infectious Disease Specialist