Infectious mononucleosis
Last reviewed: 23.04.2024
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Infectious mononucleosis is caused by the Epstein-Barr virus (EBV, human type 4 herpesvirus) and is characterized by increased fatigue, fever, pharyngitis, and lymphadenopathy.
Fatigue can last weeks and months. Serious complications include rupture of the spleen, neurological syndromes, but are rare. The diagnosis of "infectious mononucleosis" is clinical or in the study of heterophilic antibodies. Treatment of infectious mononucleosis is symptomatic.
Anthropogenous infectious disease caused by Epstein-Bar virus with aerosol transfer mechanism. It is characterized by a cyclic course, fever, acute tonsillitis, pharyngitis, severe lymphoid tissue involvement, hepatosplenomegaly, lymphomonocytosis, the appearance of atypical mononuclears in the blood.
ICD-10 code
B27.0. Mononucleosis caused by gamma-herpetic virus.
What causes infectious mononucleosis?
Infectious mononucleosis is caused by the Epstein-Barr virus, which infects 50% of children under the age of 5 years, its owner is a man. After initial replication in the nasopharynx, the virus infects B-lymphocytes responsible for the synthesis of immunoglobulins, including heterophilic antibodies. Morphologically there are atypical lymphocytes, mainly T cells with the phenotype CD8 +.
After primary infection with the virus, Epstein-Barr remains in the body throughout life, mainly in B-cells with asymptomatic persistence in the oropharynx. It is defined in the oropharyngeal secretion of 15-25% of healthy EBV-seropositive adults. Prevalence and titer are higher in immunocompromised individuals (eg, recipients of donor organs, HIV-infected patients).
The Epstein-Barr virus is not transmitted from the environment and is not very contagious. Transmission can occur with the transfusion of blood products, but most often the infection occurs when kissing infected people who have the infection in an asymptomatic form. Only 5% of patients become infected by contact with patients with acute infection. Infection of young children occurs more often in groups with a low socio-economic level and in groups.
Epstein-Barr infection is statistically related and may be the cause of Burkitt's lymphoma, which develops from B cells in immunocompromised patients, also at the risk of developing nasopharyngeal carcinoma. The virus is not the cause of chronic fatigue syndrome. Nevertheless, it can lead to the development of unmotivated fever, interstitial pneumonitis, pancytopenia and uveitis (eg, chronic active EBV).
What are the symptoms of infectious mononucleosis?
In most young people, the primary Epstein-Barr infection is asymptomatic. Symptoms of infectious mononucleosis are more common in older children and adults.
The incubation period of infectious mononucleosis is 30-50 days. Usually, weakness develops first, for several days, a week or more, then fever, pharyngitis and lymphadenopathy appear. Not necessarily all of these symptoms occur. Weakness and fatigue can last for months, but are most pronounced in the first 2-3 weeks. The fever has a peak at lunchtime or early in the evening, with a maximum temperature rise up to 39.5 "C, sometimes reaching 40.5" C. When the clinical picture is dominated by weakness and fever (the so-called typhoid-like form), exacerbation and resolution occur more slowly. Pharyngitis can be severe, accompanied by pain, exudation and complicated by streptococcal infection. The development of adenopathy of the anterior and posterior cervical lymph nodes is characteristic; Adenopathy is symmetrical. Sometimes the enlargement of the lymph nodes is the only manifestation of the disease.
Approximately 50% of cases have splenomegaly with the maximum increase in the spleen during the 2 nd and 3 rd weeks of the disease, and usually its edge is palpable. A moderate increase in the liver and its sensitivity during percussion or palpation are revealed. Less often are spotted-papular rashes, jaundice, periorbital edema, enanthema of the hard palate.
Complications of infectious mononucleosis
Despite the fact that usually patients recover, complications of infectious mononucleosis can be dramatic.
Among the neurological complications, infectious mononucleosis should be remembered for encephalitis, seizures, Guillain-Barre syndrome, peripheral neuropathy, aseptic meningitis, myelitis, paralysis of the cranial nerves and psychosis. Encephalitis can manifest as cerebellar disorders or have a more serious and progressive course, like herpetic encephalitis, but with a propensity for self-resolution.
Hematological disorders usually pass by themselves. Granulocytopenia, thrombocytopenia and hemolytic anemia can be detected. Transient, mild granulocytopenia or thrombocytopenia occurs in approximately 50% of patients; Attachment of a bacterial infection or bleeding is less common. Hemolytic anemia develops as a result of the appearance of anti-specific autoantibodies.
Spleen rupture can be one of the most serious consequences of infectious mononucleosis. It occurs as a result of a significant increase in its size and swelling of the capsule (maximum - on the 10-21th day of the disease), and the injury occurs in approximately half of the patients. Spleen rupture is accompanied by pain, but sometimes manifests itself in the form of painless hypotension.
Rare respiratory complications of infectious mononucleosis include obstruction of the upper respiratory tract as a result of adenopathy of the laryngeal and parotracheal lymph nodes; these complications are amenable to corticosteroid therapy. Clinically asymptomatic interstitial pulmonary infiltrates are usually found in children and are well identified by X-ray examination.
Hepatic complications occur in about 95% of patients and include an increase in aminotransferases (a 2-3-fold excess of the norm and a return to baseline after 3-4 weeks). If jaundice develops and a more significant increase in hepatic enzyme activity, other causes of liver damage should be excluded.
A generalized infection with EBV sometimes occurs, but covers families, especially with X-linked lymphoproliferative syndrome. These people who have undergone EBV infection have an increased risk of developing agammaglobulinemia or lymphoma.
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How is infectious mononucleosis diagnosed?
Infectious mononucleosis should be suspected in patients with typical clinical symptoms. Exudative pharyngitis, lymphadenopathy of anterior cervical lymph nodes and fever require differential diagnosis with a disease caused by beta-hemolytic streptococcus; In favor of infectious mononucleosis, the lesion of the posterior cervical lymph nodes or generalized lymphadenopathy and hepatosplenomegaly is indicated. Moreover, the detection of streptococci in the oropharynx does not exclude infectious mononucleosis. Cytomegalovirus infection can show similar symptoms - atypical lymphocytosis, hepatosplenomegaly, hepatitis, but there is no pharyngitis. Infectious mononucleosis should be differentiated with toxoplasmosis, hepatitis B, rubella, primary HIV infection, adverse reactions when taking medications (appearance of atypical lymphocytes).
Among the laboratory methods, peripheral blood leukocyte counts and the determination of heterophilic antibodies are used. Atypical lymphocytes account for more than 80% of the total number of leukocytes. Individual lymphocytes may be similar to those in leukemia, but in general they are very heterogeneous (unlike leukemia).
Heterophilic antibodies are evaluated using an agglutination test. Antibodies are detected only in 50% of patients younger than 5 years, but in 90% of convalescents and adults who underwent primary EBV infection. The titer and frequency of occurrence of heterophilic antibodies increase between the 2 nd and 3 rd week of the disease. Thus, if the probability of the disease is high, and heterophilic antibodies are not found, it is advisable to repeat this test 7-10 days after the appearance of the first symptoms. If the test remains negative, it is advisable to evaluate the level of antibodies to EBV. If their level does not correspond to acute EBV infection, one should think of CMV infection. Heterophilic antibodies can persist for 6-12 months.
In children younger than 4 years of age, when heterophilic antibodies may not be detected in principle, acute IgE infection is indicated by the presence of IgM antibodies to the capsid antigen of the virus; these antibodies disappear after 3 months after the infection, but, unfortunately, these tests are performed only in separate laboratories.
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How is infectious mononucleosis treated?
Infectious mononucleosis usually self-resolves. Duration of the disease is different; The acute phase lasts about 2 weeks. In general, within 1 week to return to work or to school can 20% of patients, 50% - within 2 weeks. Fatigue can last for several weeks, less often - 1-2% of cases - for months. Mortality is less than 1% and is associated with the development of complications (eg, encephalitis, splenic rupture, airway obstruction).
Treatment of infectious mononucleosis is symptomatic. In the acute phase of the disease, patients should be at rest, but as weakness, fever, and pharyngitis disappear, they can quickly return to normal activity. To prevent rupture of the spleen, patients should avoid weight lifting and sports for 1 month after the disease and until the normal size of the spleen is restored (under the supervision of ultrasound).
Despite the fact that the use of glucocorticoids allows you to quickly reduce body temperature and ease the manifestation of pharyngitis, in uncomplicated disease, they are not recommended. Glucocorticoids are useful in the development of complications such as airway obstruction, hemolytic anemia, thrombocytopenia. The use of acyclovir either intravenously or intravenously reduces the isolation of the EBV virus from the oropharynx, but there is no conclusive evidence for the clinical use of these drugs.
What prognosis does infectious mononucleosis have?
Infectious mononucleosis has a favorable prognosis. Lethal outcomes are casuistically rare (spleen rupture, airway obstruction, encephalitis).