Course Of Infectious Mononucleosis Research Articles

Ebstein-Barr virus- induced dacryoadenitis in a child: An unusual sign of a common disease and review of literature

Lacrimal gland inflammation, known as dacryoadenitis, is an uncommon condition with various etiologies, ranging from infectious to autoimmune diseases. The clinical course can be acute, subacute, or chronic, with involvement on one or both sides. In the course of mononucleosis, a self-limited eyelid edema is often observed, while dacryoadenitis has been rarely reported. We present the case of an 8-year-old girl with bilateral subacute Epstein–Barr virus-induced dacryoadenitis, who underwent orbital magnetic resonance imaging and gland biopsy, and we performed a comprehensive literature review.

Clinical and laboratory aspects of infectious mononucleosis in different age groups

Infectious mononucleosis is an acute anthroponotic disease that develops as a result of human infection with viruses of the Herpesviridae family: Epstein – Barr virus (EBV), cytomegalovirus (CMV), herpes viruses of the 6th (HHV-6) and 7th types.The aim of our work was to study the clinical features and laboratory parameters of the course of infectious mononucleosis in patients of three age groups.Material and methods. A retrospective analysis of 156 medical records of patients who were on outpatient treatment by an infectious disease specialist at Clinical Medicine Center MedMix was carried out. Patients were divided into three categories according to the age criterion: the first group from 0 to 5 years consisted of 58 (37.2 %) children, the second group was represented by persons from 5 to 18 years old – 58 (37.2 %), the third group was formed by patients from 18 to 53 years old – 40 (25.6 %) people.Results and its discussion. Among children aged 0 to 5 years, boys (67.2 %) more frequently fell sick, and in the group from 18 to 53 years, females (70 %) were more likely to have the disease. Clinical symptoms such as generalized lymphadenopathy (82.7 %), nasopharyngeal lesions (79.3 %) and changes in the general blood test (86.2 %) were most frequently detected in children aged up to 5 years, while fever (81 %) and oropharyngeal lesions (74.1 %) were most frequently detected in patients aged from 5 to 18 years. Liver damage with the development of acute induced viral hepatitis was recorded in all age groups (24.1, 27.6 and 30 %). EBV infection was most frequently diagnosed among children aged from 5 to 18 years and persons aged from 18 to 53 years (in 62.1 and 70 % of cases, respectively, p < 0.05). Mixed infection with the combination of VEB + CMV + HHV-6 was significantly more frequent in children under 5 years of age (34.5 %; p < 0.05).Conclusions. In childhood, the clinical manifestations of infectious mononucleosis were more pronounced. Such intense course of the disease caused frequent visits to an infectious disease specialist and diagnostics with the establishment of an etiological agent. The dominance of EBV infection in the development of infectious mononucleosis in all groups was established. However, at the age up to 5 years, the most common mixed infections were the following combinations: EBV + CMV, EBV + HHV-6, EBV + CMV + HHV-6 and CMV + HHV-6.

Structural and functional state of blood lymphocytes in patients with infectious mononucleosis with different course

The article presents the results of our own studies. The aim was to determine the structural and functional status of blood lymphocytes in patients with acute and prolonged course of infectious mononucleosis (IM) in children. Materials and methods. 102 children were under clinical and laboratory-instrumental supervision, the children were divided into groups: group 1 – 65 children with IM with an acute course of the disease; group 2 – 37 children with a prolonged course of the disease. All children underwent standard clinical laboratory and instrumental laboratory examinations. The diagnosis of IM was confirmed by PCR (detection of EBV DNA in the blood) and ELISA (anti-EBV IgM and IgG). Research results. In the study of the structural state of the cytoplasmic membrane of the lymphocytes in the blood of patients with MI in the onset of the disease, it was found that the average values of penetration rate of the electron paramagnetic resonance of spin probes (PR EPR s. p.) in children of both groups were significantly higher than normal (P < 0.001). There are also differences between groups of patients. In this case, the value of PR EPR s. p. in patients with a prolonged course by 15.8 % exceeded those in patients with acute IM (P < 0.001). According to the rate of microviscosity of the intracellular content (MV IC), its values were reduced compared with the control – by 22.1 % (P < 0.001) in patients with acute course of the disease and by 25.1 % – with a prolonged course of IM). In addition, in patients with a prolonged course of the disease, the values were 9 % lower than in the group with acute infectious mononucleosis. When considering immunological parameters, it was found that the indicators of the T-immune system for patients with a prolonged course of the disease in comparison with the alternative group was characterized by a decrease in the content of CD3 <50 % (respectively in 51.3 % and 26.2 % of patients; P < 0.05); CD4 <31 % (62.1 % and 32.4 %, respectively; P < 0.05) and CD8 <15 % (37.8 % and 10.8 %, respectively; P < 0.01). With regard to the cytokine profile, the level of IL-1 <20.0 pg/ml was determined 3.5 times more often in patients with a prolonged course of the disease compared to the acute course (64.8 % and 18.5 % of patients, respectively); TNFα <20.0 pg/ml 1.9 times more often (48.6 % and 24.6 %, respectively) and a very high (>30.1 pg/ml) level of IL4 in 40.5 % and 20 %). From the B-system of immunity in patients with a prolonged course of IM in comparison with the acute course increased content of CD22 was more often determined, as well as low levels of IgA, IgM <1.1 g/l and IgG <10.0 g/l. Conclusions. According to the results of observations, the pathogenetic role of the violation of the structural organization of blood lymphocytes in the formation of IM is established. It was found that these disorders in the form of increased permeability of their cytoplasmic membrane and reduced viscoelastic properties of their intracellular environment are more pronounced with a prolonged course of the disease, which is a factor in the prolongation of the disease. It is determined that the indicators of cellular and humoral parts of the immune system affect the course of IM. During formation of an acute course of IM in children already in the acute period of a disease activation of both cellular and humoral links of immunity, which is shown in the form of increase in relative content of CD3+, CD4+, CD8+ and CD22+ and levels of immunoglobulins M, A, is noted. For the prolonged course of the disease depression of T-cell immunity in the form of a decrease in the relative content of CD3+, CD4+ and CD8+ lymphocytes and an increase in CD22+, as well as inhibition of antibody genesis are characteristic. It was found that the variant of IM depends on the type of reaction of T-helper clones, namely – in the initial period of manifestation of IM with its acute course there is activation of T1 and T2 helper response, which manifests itself in a significant increase in IL-1, TNFα and moderate IL-4. Prolonged course of the disease is formed against the background of weak activation of pro-inflammatory interleukins (IL-1, TNFα) and significant – anti-inflammatory IL-4.

Особливості клінічних проявів інфекційного мононуклеозу мікст-етіології в дитини 3 років життя

У статті описані особливості клінічного перебігу інфекційного мононуклеозу в дитини, викликаного збудниками сімейства герпесвірусів (Епштейна — Барр та герпесу 6-го типу).

THE OROPHARYNX MICROBIOME PROFILE OF CHILDREN WITH INFECTIOUS MONONUCLEOSIS EPSTEIN-BARR VIRAL ETIOLOGY

Relevance. The microbiota of the oral cavity is individual and the consistency of its composition provides a protective function that is regulated by the immune system. Dysbiotic changes in the oral microbiota composition lead to a devastation of local immunity and provide to the disease's development. Herpes virus infection аctivation suppresses the immune response which increases the level of oral mucosa bacteria colonization in particular during the acute course of infectious mononucleosis (IM).
 Objective: to study the features of the oral microbiome composition and its sensitivity to antibacterial drugs in patients with infectious mononucleosis and acute tonsillitis.
 Materials and methods. We examined 306 children aged 7 to 236 months. The main group (n = 280) – children with IM. Comparison group (n = 26) – children diagnosed with acute tonsillitis. The main group was divided into two subgroups: subgroup I – 234 children with MI caused by the Epstein-Barr virus (EBV), and subgroup II – 46 children with co-infection with the EBV virus and cytomegalovirus (CMV). The examination was performed according to the treatment protocol: general and biochemical analysis of blood, determination of IgM antibodies to Epstein-Barr virus and cytomegalovirus, bacteriological examination of oropharyngeal mucus, followed by determination of the sensitivity of the identified pathogens to antibacterial drugs.
 The results. In oral microbiome of children with IM caused by EBV and CMV co-infection pneumococcus dominant. In children with acute tonsillitis, Staphylococcus aureus, S. pyogenes infection, and yeast-like fungi were predominant. S. pyogenes, in children with co-infection, has a high level of resistance to β-lactam antibiotics. Higher levels of antibiotic-resistant strains were found among Enterococcus spp. Isolates, especially in children with EBV-induced MI and co-infection of EBV and CMV.
 Conclusions. The development of MI is accompanied by microecological dysbiosis of the mucous membranes of the oropharynx and tonsils, which do not provide enough level of colonization resistance, contributing to the spread of antibiotic resistance among resident and transient microbiota.

RETRACTION NOTICE: Serum amyloid A protein in the course of infectious mononucleosis.

[This retracts the article DOI: 10.1177/2049936118811208.].

Scrub typhus mimicking the clinical course of infectious mononucleosis: a case report.

Objective: Scrub typhus is a relatively common life-threating disease; its symptoms are non-specific and similar to those of other viral infections. Therefore, scrub typhus might be underdiagnosed.Patient: Herein, we report a patient with scrub typhus whose clinical course mimicked that of infectious mononucleosis. A 63-year-old male patient with hypertension presented to our hospital complaining of symptoms including prolonged fever, pharyngeal discomfort, and a mild headache. He showed the appearance of a rash after amoxicillin administration. At the same time, he did not show a crusted rash on his body surface.Results: After a comprehensive examination, Epstein-Barr virus and cytomegalovirus infections were ruled out. We suspected that this patient suffered from scrub typhus on the basis of his usual lifestyle. Finally, polymerase chain reaction analysis showed a positive result for deoxyribonucleic acid of Orientia tsutsugamushi in his blood sample. Fortunately, he recovered naturally with only supportive treatment during his hospitalization.Conclusion: We should observe and monitor patients with infectious mononucleosis-like symptoms and emphasize the importance of a clinical interview.

A 2D COS study of lymphocytes in the course of infectious mononucleosis

Activation of lymphocytes during contact with the Epstein–Barr virus (EBV) was studied. The lymphocytes were obtained from patients treated due to the acute phase of infectious mononucleosis in the Jagiellonian University Hospital in Krakow. The changes in the averaged Raman spectra of the lymphocytes during their treatment, on the 1st, 3rd, 5th, 9th and 12th day of hospitalization, were analyzed using the 2D-COS method. The most interesting activation marker was the Raman band at 520 cm−1 attributed to the formation of immunoglobulins. This band does not occur in the control group samples. The 2D-COS analysis revealed some additional details of lymphocyte activation. In the 2D synchronous maps, the greatest changes occur for auto-peaks at 2929 cm−1, due to the CH vibrations in the methyl groups of lipids and proteins, at 1638 cm−1, corresponding to the changes in α -helix amide I, 1585 cm−1 corresponding to nucleic acids and some amino acids, Trp, Phe and Gln, indicating cell remodeling. 2D synchronous maps monitor the formation of a receptor complex, as a subsequent functional lymphocyte maturation. 2D asynchronous maps point to the B-cell development towards immune response, i.e., the formation of immunoglobulins.

Ultrasound criteria of splenomegaly in patients with fever and infectious mononucleosis

Ultrasound examination of the spleen is a promising approach allowing to accurately determine its normal size in various age groups as well as in pathological conditions. Objective – to evaluate spleen size changes in patients with febrile state and infectious mononucleosis. Ultrasound morphometric examination of the spleen was carried out in patients with febrile state (group “A”, n = 22) and infectious mononucleosis (group “B” n = 24) by assessing organ echo structure, contour clarity, and its uniformity. Morphometric data allowed to measure spleen weight and various coefficients by using the method proposed by Vozgoment et al. for calculating spleen weight (Wt) with formula: Wt = 0.34 * L2h, where L – the length of the spleen, h – the thickness of the spleen (cm); spleen weight coefficient (SWC) by using the formula: 1000 m / body weight (in grams), where m – the mass of the spleen; spleen weight-to-body height ratio (KI) by using the formula: spleen weight (g) / height (cm); spleen weight-to-body surface area ratio (Ks) by using the formula: spleen weight (g) / body surface area (m2). Statistical analysis was performed by using Statistica 10.0 software package. Febrile state in most cases is not accompanied by changes in spleen size. However, decreased spleen size was found in one (4.5%) patient aged 58 years, whereas splenomegaly – in 2 (9%) cases (SWC range 5.5- 5.9) in young patients aged 18 and 25 years. The course of infectious mononucleosis in 25% cases was not accompanied by change in spleen size. In other cases, both decreased (20.8%) and increased (54.2%) spleen size were observed. In particular, decreased spleen size was detected in patients with average age of 43.6±14.5 years, whereas increased spleen size (SWC range 4-8.9) was typical for young people aged 25±8 years. Febrile state in most cases is not paralleled altered spleen size. Infectious mononucleosis was associated with the three types of altered spleen size: no change, decreased spleen size characteristic to older patients, or increased spleen size observed in young subjects. Ultrasound examination of the spleen with measuring its morphometric parameters represent objective criteria allowing to fully assess the state of this immune organ and reveal degree of its involvement in the pathological process at the preclinical level.

S3520 Epstein-Barr Virus-Induced Acute Hepatitis

INTRODUCTION: Epstein-Barr virus (EBV) is a causative agent of infectious mononucleosis syndrome in young adults. It causes asymptomatic liver-associated enzyme abnormalities in 80 to 90% of cases which are often unrecognized. Jaundice might rarely develop during the clinical course which likely reflects either more severe hepatitis or Epstein-Barr virus infection-associated hemolytic anemia. We report a case of EBV induced acute hepatitis. CASE DESCRIPTION/METHODS: A 28-year-old male with a past medical history of gastroesophageal reflux disease was admitted for yellow skin, nausea, fatigue, fever, and poor oral intake for the last five days. Abdominal exam was benign, but he was noted to have yellow skin and sclera. Blood work showed WBC 9.5 K/uL (lymphocytes 71%), Hb 16.9 g/dL, creatinine 1.0 mg/dL, albumin 3.9 g/dL, AST 541 U/L, ALT 743 U/L, alkaline phosphatase 684 U/L, total bilirubin 12.9 mg/dL with direct bilirubin 10.0 mg/dL. He had acute hepatitis work up like acute hepatitis panel, CMV, Blood culture, COVID-19, HIV, ANA, ASMA which were unremarkable. Ultrasound abdomen did not show gall bladder or biliary etiology. CT abdomen/pelvis showed splenomegaly with mild portal caval lymphadenopathy. He was found to have positive monospot and EBV PCR. He subsequently had a liver biopsy consistent with EBV positive lymphocytes. He was treated conservatively with good clinical improvement. DISCUSSION: Acute viral hepatitis in human can be caused by a variety of viruses with a wide range of clinical manifestations and laboratory findings. EBV is a rare causative agent of acute hepatitis, during the course of infectious mononucleosis. Hepatic manifestations of EBV are usually mild and resolve without serious complications. Treatment in these patients is supportive—namely to remain hydrated with an adequate electrolyte balance. Precautions to avoid contact sports are also important to emphasize, as there is a 0.1%–0.5 % risk of splenic rupture, which is fatal. This case highlights the importance of including EBV in the differential diagnosis of acute hepatitis in adults.

Інфекційний мононуклеоз: багатогранність проявів. Клінічний випадок важкого перебігу інфекційного мононуклеозу у дитини раннього віку

Інфекційний мононуклеоз: багатогранність проявів. Клінічний випадок важкого перебігу інфекційного мононуклеозу у дитини раннього віку

2323. Clinical Characteristics and Disease Burden of Epstein–Barr Virus and Four β-Herpes Viruses Infections in Children Visiting Emergency Room

BackgroundIt is well known that most of infants and young children with primary EBV and CMV infection are inapparent, and primary HHV-6B and HHV-7 infection cause exanthema subitum (ES). However, the precise incidence of apparent infection of these viruses remains unclear. Therefore, we sought to elucidate clinical features and disease burdens of these viral infections in febrile children visiting emergency room (ER).MethodsBetween June 2015 and December 2017, febrile children under 5 years old, who visited ER and received hematological examination, were enrolled in this study. Detection of serum viral DNAs using real-time PCR and measurement of antibody titers in acute-phase serum were carried out. Clinical information was collected from the medical records.ResultsIn total of the 905 cases, EBV, CMV, HHV-6B and HHV-7 were detected in 18 cases (2%), 12 cases (1.3%), 104 cases (11.5%) and 23 cases (2.5%), respectively. No HHV-6A DNA was detected. Primary infection rates among EBV, CMV, HHV-6B and HHV-7-infected patients accounted for 44%, 25%, 91% and 57%, respectively. Admission rates of the primary-infected patients were 88% of EBV, 68% of CMV, 66% of HHV-6B and 42% of HHV-7, respectively. Five of the 8 cases (62.5%) of primary EBV-infected patients demonstrated typical clinical course of infectious mononucleosis (IM); however, no IM patient was seen in 9 patients with viral reactivation. No IM case was observed in CMV-infected patients, regardless of primary infection or reactivation. Clinical characteristics were compared between patients with primary HHV-6B and HHV-7 infections because of similarity of clinical features. Average age (1.5 vs. 2.8 years old; P < 0.001), duration of fever (4.5 vs. 2.9 days; P < 0.001), the highest body temperature (40.2 vs. 39.6°C; P < 0.001), and the frequency of typical skin rash (ES) (87% vs. 54%; P < 0.001) were statistically different between the two viral infections. The main reason for admission due to primary HHV-6B and HHV-7 infection was complex-type febrile seizure (58.7 vs. 66.7%; P = 0.705).ConclusionThe clinical features and disease burden of the 5 human herpesviruses infections were elucidated in the febrile children visiting ER.Disclosures All authors: No reported disclosures.

EPSTEIN-BARR VIRAL INFECTION IN CHILDREN

Today there is a growing tendency in the prevalence of diseases caused by herpes viruses. At the same time there is an increase in the incidence of infectious mononucleosis, and the Epstein-Barr virus is one of its causative agents. The level of Epstein-Barr virus infection among the adult population of Ukraine has reached almost 100%, and more than 50% among the children. Epstein-Barr virus is a respiratory infection, and can be transmitted through saliva. According to statistic data, 85% of children are carriers of this virus, but it manifests itself only when immunity weakens. In many children, infectious mononucleosis occurs as an acute respiratory viral infection or quinine, and often paediatricians do not diagnose it. Usually children under the age of 10-14 are susceptible to the disease. In a large number of children, the course of infectious mononucleosis is quite similar to an acute respiratory viral infection or quinsy, and often paediatricians do not diagnose it. Usually children under the age of 10-14 are susceptible to the disease. The disease is characterized by feverish condition, sore throat, exanthema, enlargement of the lymph nodes, liver and spleen. All children with infectious mononucleosis manifest signs of tonsillopharyngitis that develops due to the growing activity of the opportunistic bacterial microflora, which densely colonizes the oropharyngeal mucosa in the immunocompromized condition caused by a herpes viral infection. At present, infectious mononucleosis plays a significant role in the overall infectious morbidity in children and is one of the leading causes of children hospitalization. Analysis of the case histories in patients aged 1-3, 4-6, 7-10, 11-15 and over 15 years through 2014-2018 has shown that infectious mononucleosis was predominantly diagnosed in male patients (222 cases) versus 150 cases of in female patients. The highest incidence of infectious mononucleosis has been registered among the residents of Lviv (287 cases) compared with the inhabitants of the Lviv region (85 cases). Regarding the age aspect, it has been found that the overwhelming majority of patients who have been diagnosed with an infectious mononucleosis are children under the age of 3 years.

Prediction of prolonged course of infectious mononucleosis in children on the basis of structural organization of lymphocytes of blood

Objectives. The article presents the results of research on the definition of criteria for predicting the adverse course of infectious mononucleosis (IM) in children on the basis of the structural organization of lymphocytes of blood. Materials and methods. There were 68 children aged three to fifteen years suffering from IM under supervision. The diagnosis of IM was verified by PCR (detection of EBV DNA in the blood) and ELISA (anti-EBV Ig M and Ig G). The biophysical organization of the cytoplasmic membrane of lymphocytes was determined by the method of electron paramagnetic resonance (EPR) of spin probes using the method of additional broadening at microwave parameters 9.39 gHz, amplitude of high-frequency modulation 1 gauge, magnetic field scan time 200 sec, time constants 0.1 milliseconds (ms). Microviscosity of the intracellular environment of lymphocytes was determined by the mobility parameter of a water-soluble probe (nickel ferricyanide), which easily penetrates into the cytoplasm and in combination with extracellular paramagnetic ions, allows to evaluate the microviscosity of intracellular contents in relative units (r.u.). Results. According to the results of observations, it is established that at the stages of manifestation of the disease there are pronounced violations of the biophysical organization of the structure of lymphocytes in the form of a decrease of viscosity and elastic properties of intracellular content and cytoplasmic membrane of lymphocytes. It was characterized by the fact that the average values of the penetration rate of the electron paramagnetic resonance of the spin probe (PR EPR s.p) in patients of both groups were significantly higher than the normative ones. In the group with smooth course, they exceeded the norm by 1.5 times, and in patients with prolonged course by 1.8 times, and the values of the microviscosity of intracellular contents (MIC) were significantly reduced compared to the control - by 22.1% in patients with a smooth course of the disease and 25.1% - with a prolonged course of IM. Conclusions. In patients with prolonged course of IM these disorders were more pronounced than in the smooth course of the disease. In the period of convalescence, the indicators of the biophysical organization of the structure of lymphocytes of patients with a smooth course of IM did not differ from the norm, and in patients with a prolonged course of the disease, their reliable deviation was revealed.

Serum amyloid A protein in the course of infectious mononucleosis.

Background:Serum amyloid A (SAA) protein is a major acute phase protein. Increased concentrations have been reported in many inflammatory diseases. In bacterial infections, high levels correlate with those of C-reactive protein (CRP). In viral infections, where CRP changes are weaker, SAA is of value for establishing early diagnosis, monitoring the severity, and the evolution of the disease.Objective:Evaluation of SAA as a marker for diagnosis of infectious mononucleosis, including severe forms.Material and methods:A total of 31 patients with non-complicated and severe, complicated infectious mononucleosis were examined. SAA and CRP were measured by immuniturbidimetric assays at the day of admission and 4.97 ± 1.35 days later.Results:SAA increases significantly than those in a control group, without correlation with the etiologic agent. It decreases when full recovery appears. In the subgroup of subjects with complications, we observed significant increased SAA when Epstein-Barr virus /EBV/ was the etiologic agent, in the course of bacterial and viral secondary infection. SAA is higher than CRP in non-complicated group. In cases of bacterial superinfections, both increase simultaneously and treatment have to be adapted. Second, serum sample for CRP is normal in patients without full recovery where SAA stay increased.Conclusion:In viral infections, high SAA concentrations are indicative for early diagnosis, severe course of the diseases, effect of the treatment, early recovery, and disease outcome. When SAA and CRP increase simultaneously, bacterial co-infection is suspected, and relevant antibiotic treatments have to be initiated.

Features of the Course of Infectious Mononucleosis in Children at the Present Stage

Features of the Course of Infectious Mononucleosis in Children at the Present Stage

Encephalitis in Course of Mononucleosis- A Case Report

Encephalitis in Course of Mononucleosis- A Case Report

КЛІНІКО-ЛАБОРАТОРНА ХАРАКТЕРИСТИКА ПРОЯВІВ ІНФЕКЦІЙНОГО МОНОНУКЛЕОЗУ У ДІТЕЙ

&lt;p class="1"&gt;&lt;em&gt;Висвітлено клініко-лабораторні особливості перебігу інфекційного мононуклеозу у дітей у період з березня по липень 2015 р., з урахуванням етіологічного чинника, клініки та даних імунологічних досліджень слизової оболонки орофарингеальної зони.&lt;/em&gt;&lt;/p&gt;

Acute Acalculous Cholecystitis Complicating the Course of Infectious Mononucleosis

Acute Acalculous Cholecystitis Complicating the Course of Infectious Mononucleosis

Clinical and laboratory features of infectious mononucleosis caused by the Epstein-Barr virus

Aim. To study the clinical and laboratory characteristics of patients with infectious mononucleosis caused by the Epstein-Barr virus. Methods. In infectious hospital under observation there were 108 patients aged from 11 months to 31 years with a laboratory confirmed diagnosis of «infectious mononucleosis caused by the Epstein-Barr virus». Standard laboratory tests for blood serum immunoglobulin M to the capsid protein of Epstein-Barr virus, immunoglobulin class G proteins to early Epstein-Barr virus and the index of their avidity by ELISA were carried out. Tests for other infections were conducted if it is required. Results. Patients dominated by children aged 1-7 years - 73.1%. Adult patients was 1.8% (2 patients). Only 4.6% of the patients were sent to the hospital with a diagnosis of «infectious mononucleosis» or suspected of having the disease. The typical clinical picture of infectious mononucleosis was observed in 75% of cases, atypical - in 25%. Mononuclear cells in peripheral blood were found in less than half of the patients (44.4%), in 53.1% of cases with typical and in 18.5% of cases with atypical clinic. In the remaining patients, the diagnosis of infectious mononucleosis was verified by ELISA. In 90.4% of the cases the disease was in the moderate, and in 9.6% - in the severe form. Conclusion. The high frequency of atypical course of infectious mononucleosis caused by the Epstein-Barr virus justifies the need to include it into differential diagnosis process in case of unclear infectious disease, to identify the antibodies to the Epstein-Barr virus proteins, (immunoglobulin M and G) and the index of avidity antibodies (immunoglobulin G).