What is mononucleosis and the Symptoms of infectious mononucleosis?


It is known as “the kissing disease” because it is spread by coming into contact with the infected saliva. Mononucleosis is very common in children and adolescents because most adults are already immunized.

Infectious mononucleosis is a disease caused by the Epstein-Barr virus (EBV), herpes-Miridae in the family, also known as kissing disease or glandular fever.

The EBV infection is very common in adolescents and young adults in developed countries, with the majority of HIV – positive adults regarding the VEB. Primary infection is usually asymptomatic and generally occurs during childhood (the highest incidence occurs in children between 4 and 12 years of age).

How Infectious Mononucleosis Is Spread

The Epstein-Barr virus (EBV) is spread by coming into contact with an infected individual’s saliva through kissing, utensils impregnated with saliva, coughing, and inhaling saliva droplets. Sexual transmission is also possible through blood transfusions and the sharing of needles and syringes, although this is less common.

The infectious mononucleosis virus penetrates the oropharyngeal route, producing an infection that mainly affects the lymph nodes, tonsils, liver, and spleen.

The incubation period after infection lasts approximately 30 to 50 days. This disease is not very contagious because most of the people susceptible to coming into contact with those affected are already immune to the disease, so epidemics are rare.

Symptoms of infectious mononucleosis

The incubation period (between 10 and 50 days) of infectious mononucleosis or kissing disease is asymptomatic. The disease manifests itself with headaches, malaise, fatigue, and fever, with a temperature of 38 to 39ºC. However, sometimes it starts suddenly, with a high fever. The symptoms usually persist between 10 and 14 days, and the most common are:

  • Cervical lymphadenopathy.
  • Tonsillitis.
  • Fever.
  • Hepatosplenomegaly (enlargement of the liver and spleen).
  • Hepatitis (in 80% of cases, there is an alteration of liver tests).
  • Generalized maculopapular rash.
  • Rhinitis.
  • White patches on the tonsils.

Most of the symptoms of infectious mononucleosis are due to the body’s immune response to the infection.

The disease can last from two to four weeks, during which there is a significant increase in atypical T lymphocytes, called Downey cells.

Some patients may present a clinical picture with extreme chronic fatigue syndrome, accompanied by pharyngitis, lymphadenopathy, muscle weakness, and memory loss.

Complications of infectious mononucleosis

Kissing disease is usually uncomplicated, except on a few occasions when spleen rupture, thrombocytopenia, hemolytic anemia, and meningitis may occur. 1-2% of patients present with a neurological syndrome: meningoencephalitis, transverse myelitis, Guillan-Barré syndrome, peripheral and vegetative neuropathies. Viral pneumonia may also appear, affecting 5% of patients, and 6% may present electrocardiographic abnormalities.

Symptoms usually improve within two weeks and disappear entirely before four. The disease can occur more than once in the same patient, being a sequential infection produced by different germs. However, the Epstein-Barr virus (EBV) can be reactivated in immunosuppressed individuals.

Diagnosis of infectious mononucleosis

The Epstein-Barr virus (EBV) that causes infectious mononucleosis can be isolated in the laboratory from saliva, peripheral blood, or lymphoid tissue. The presence of atypical T lymphocytes (Downey lymphocytes) greater than 10% also corroborates the diagnosis.

Serological studies are performed to demonstrate the presence of heterophile antibodies, such as the Paul Bunnell-Davidson test, to diagnose infectious mononucleosis.

Another more recent technique to demonstrate the presence of these antibodies is the Mono Test (Hoff-Bauer). These tests help differentiate mononucleosis from other diseases that may present similar symptoms, such as those caused by cytomegalovirus, hepatitis or AIDS virus, toxoplasma gondii, certain drugs, etc.