Infectious mononucleosis is an acute viral infection characterized by a predominant lesion of the oropharynx and lymph nodes, spleen and liver. A specific sign of the disease is the appearance of characteristic cells in the blood – atypical mononuclears. The causative agent of infectious mononucleosis is the Epstein-Barr virus, belonging to the herpesvirus family. Its transmission from the patient is carried out by aerosol. Typical symptoms of infectious mononucleosis are general infectious phenomena, angina, polyadenopathy, hepatosplenomegaly; spotty papular rashes are possible on various areas of the skin.
B27 Infectious mononucleosis
The spread of infection is widespread, seasonality has not been detected, there is an increased incidence during puberty (girls 14-16 years old and boys 16-18 years old). Morbidity after the age of 40 is extremely rare, with the exception of HIV-infected individuals who may develop a manifestation of latent infection at any age. In the case of infection with the virus in early childhood, the disease proceeds according to the type of acute respiratory infection, at an older age – without pronounced symptoms. In adults, the clinical course of the disease is practically not observed, since most have specific immunity by the age of 30-35.
Infectious mononucleosis is caused by the Epstein-Barr virus (a DNA-containing virus of the genus Lymphocryptovirus). The virus belongs to the herpesvirus family, but unlike them it does not cause the death of the host cell (the virus mainly multiplies in B lymphocytes), but stimulates its growth. In addition to infectious mononucleosis, Epstein-Barr virus causes Burkitt lymphoma and nasopharyngeal carcinoma.
The reservoir and source of infection is a sick person or a carrier of infection. Virus isolation by sick people occurs starting from the last days of the incubation period, and lasts 6-18 months. The virus is excreted with saliva. In 15-25% of healthy people with a positive test for specific antibodies, the pathogen is detected in oropharyngeal flushes.
The mechanism of transmission of the Epstein-Barr virus is aerosol, the predominant route of transmission is airborne, it is possible to implement by contact (kissing, sexual contact, dirty hands, dishes, household items). In addition, the virus can be transmitted by blood transfusion and intranatally from mother to child. People have a high natural susceptibility to infection, but infection mainly develops mild and erased clinical forms. A slight incidence among children under one year old indicates an innate passive immunity. Immunodeficiency contributes to the severe course and generalization of infection.
The Epstein-Barr virus is inhaled by a person and affects the epithelial cells of the upper respiratory tract, oropharynx (contributing to the development of moderate inflammation in the mucous membrane), from there the pathogen with a lymph current enters the regional lymph nodes, causing lymphadenitis. When it enters the blood, the virus is introduced into B-lymphocytes, where it begins active replication. The defeat of B-lymphocytes leads to the formation of specific immune reactions, pathological deformation of cells. With the blood flow, the pathogen spreads through the body. Due to the fact that the virus is introduced into immune cells and immune processes play a significant role in pathogenesis, the disease is classified as AIDS-associated. The Epstein-Barr virus persists in the human body for life, periodically activating against the background of a general decrease in immunity.
Infectious mononucleosis symptoms
The incubation period varies widely: from 5 days to one and a half months. Sometimes there may be nonspecific prodromal phenomena (weakness, malaise, catarrhal symptoms). In such cases, there is a gradual increase in symptoms, malaise increases, the temperature rises to subfebrile values, nasal congestion, sore throat is noted. Examination reveals hyperemia of the oropharyngeal mucosa, tonsils may be enlarged.
In the case of an acute onset of the disease, fever, chills, increased sweating develop, symptoms of intoxication are noted (muscle aches, headache), patients complain of sore throat when swallowing. Fever may persist from several days to a month, the course (type of fever) may be different.
After a week, the disease usually enters the peak phase: all the main clinical symptoms manifest themselves (intoxication, angina, lymphadenopathy, hepatosplenomegaly). The patient’s condition usually worsens (the symptoms of intoxication worsen), there is a characteristic picture of catarrhal, ulcerative necrotic, filmy or follicular sore throat in the throat: intense hyperemia of the mucous membrane of the tonsils, yellowish, loose plaque (sometimes diphtheria type). Hyperemia and granularity of the posterior pharyngeal wall, follicular hyperplasia, mucosal hemorrhages are possible.
In the first days of the disease, polyadenopathy occurs. An increase in lymph nodes can be detected in almost any group available for palpatory examination, occipital, posterior and submandibular nodes are most often affected. To the touch, the lymph nodes are dense, mobile, painless (or the soreness is poorly expressed). Sometimes there may be moderate swelling of the surrounding fiber.
At the height of the disease, most patients develop hepatolienal syndrome – the liver and spleen are enlarged, jaundice of the sclera, skin, dyspepsia, darkening of urine may manifest. In some cases, spotty-papular rashes of various localization are noted. The rash is short-term, is not accompanied by subjective sensations (itching, burning) and does not leave behind any residual phenomena.
The height of the disease usually takes about 2-3 weeks, after which there is a gradual decrease in clinical symptoms and a period of convalescence occurs. The body temperature normalizes, the signs of angina disappear, the liver and spleen return to their normal size. In some cases, signs of adenopathy and subfebrility may persist for several weeks.
Infectious mononucleosis can acquire a chronic recurrent course, as a result of which the duration of the disease increases to one and a half or more years. The course of mononucleosis in adults is usually gradual, with a prodromal period and less pronounced clinical symptoms. Fever rarely lasts more than 2 weeks, lymphadenopathy and hyperplasia of the tonsils are poorly expressed, but symptoms associated with a functional disorder of the liver (jaundice, dyspepsia) are more often noted.
Complications of infectious mononucleosis are mainly associated with the development of secondary infection (staphylococcal and streptococcal lesions). Meningoencephalitis may occur, obstruction of the upper respiratory tract by hypertrophied tonsils. Children may have severe hepatitis, sometimes (rarely) interstitial bilateral infiltration of the lungs is formed. Also, rare complications include thrombocytopenia, overstretching of the lienal capsule can provoke a rupture of the spleen.
Non-specific laboratory diagnostics includes a thorough study of the cellular composition of blood. A general blood test shows moderate leukocytosis with a predominance of lymphocytes and monocytes and relative neutropenia, a shift of the leukocyte formula to the left. Large cells of various shapes with a wide basophilic cytoplasm appear in the blood – atypical mononuclears. To diagnose mononucleosis, it is significant to increase the content of these cells in the blood to 10-12%, often their number exceeds 80% of all elements of white blood. When examining blood in the first days, mononuclears may be absent, which, however, does not exclude the diagnosis. Sometimes the formation of these cells can take 2-3 weeks. The blood picture usually gradually returns to normal in the period of convalescence, while atypical mononuclears are often preserved.
Specific virological diagnostics is not used due to the complexity and irrationality, although it is possible to isolate the virus in the oropharyngeal flush and identify its DNA using PCR. There are serological diagnostic methods: antibodies to the VCA antigens of the Epstein-Barr virus are detected. Serum immunoglobulins of type M are often detected even during incubation, and at the height of the disease are noted in all patients and disappear no earlier than 2-3 days after recovery. The detection of these antibodies serves as a sufficient diagnostic criterion for infectious mononucleosis. After infection, specific immunoglobulins G are present in the blood, which persist for life.
Patients with infectious mononucleosis (or persons suspected of this infection) are subjected to three-fold (for the first time – during acute infection, and twice more at intervals of three months) serological examination for HIV infection, since it may also show the presence of mononuclears in the blood. For the differential diagnosis of angina in infectious mononucleosis from angina of other etiology, an otolaryngologist’s consultation and pharyngoscopy are necessary.
Infectious mononucleosis of mild and moderate severity is treated on an outpatient basis, bed rest is recommended in case of severe intoxication, severe fever. If there are signs of liver dysfunction, diet No. 5 according to Pevsner is prescribed.
Etiotropic treatment is currently absent, the complex of measures shown includes detoxification, desensitization, general restorative therapy and symptomatic remedies, depending on the available clinic. Severe hypertoxic course, the threat of asphyxia when the larynx is clamped by hyperplastic tonsils are indications for short-term prescribing of prednisone.
Antibiotic therapy is prescribed for necrotizing processes in the throat in order to suppress the local bacterial flora and prevent secondary bacterial infections, as well as in the case of existing complications (secondary pneumonia, etc.). Penicillins, ampicillin and oxacillin, tetracycline antibiotics are prescribed as drugs of choice. Sulfonamide preparations and chloramphenicol are contraindicated due to the side depressive effect on the hematopoietic system. Rupture of the spleen is an indication for emergency splenectomy.
Prognosis and prevention
Uncomplicated infectious mononucleosis has a favorable prognosis, dangerous complications that can significantly worsen it, with this disease occur quite rarely. The residual phenomena in the blood that take place are the reason for dispensary observation for 6-12 months.
Preventive measures aimed at reducing the incidence of infectious mononucleosis are similar to those in acute respiratory infectious diseases, individual measures of nonspecific prevention consist in increasing immunity, both with the help of general health measures and with the use of soft immunoregulators and adaptogens in the absence of contraindications. Specific prophylaxis (vaccination) for mononucleosis has not been developed. Emergency prevention measures are applied to children who have communicated with the patient, consist in the appointment of a specific immunoglobulin. A thorough wet cleaning is carried out in the focus of the disease, personal belongings are disinfected.