Epidemiology and morbidity paradoxes
The Epstein-Barr virus is characterized by ubiquitous distribution worldwide; however, epidemiological statistics demonstrate an interesting paradox. The infection rate among the adult population reaches 90–95%, whereas the incidence of the acute manifest form—infectious mononucleosis (IM)—is only 4–45 cases per 100,000 population.
This discrepancy is explained by the fact that a huge number of acute and chronic forms remain undiagnosed. Acute infection frequently proceeds latently (asymptomatically) or in a mild form, when the typical symptom complex is incomplete or inconstant. Convalescents become lifelong virus carriers, and the pathological process itself is highly prone to chronicity (with a relapsing or latent course). Nevertheless, a history of past IM is noted in half of all EBV-infected individuals, making it the most frequent clinical form in a physician's practice.
Leading clinical syndromes
The typical picture of infectious mononucleosis develops gradually. Often, at the pre-hospital stage, patients unsuccessfully take standard antipyretic or antiviral agents. The clinical presentation includes several leading syndromes:
- Intoxication syndrome: gradual increase in body temperature (up to 39.4°C), chills, sweating, marked general weakness.
- Tonsillitis and adenoiditis manifestations: from days 2–3, sore throat upon swallowing, nasal congestion, and a nasal voice tone join in. The oropharyngeal mucosa is hyperemic and non-edematous. The tonsils are hypertrophied, covered with patchy white deposits that are easily removed with a medical spatula.
- Lymphadenopathy: enlargement of the posterior, anterior, and middle cervical lymph nodes is most characteristic. They can reach the size of a bean, have a dense-elastic consistency, are tender upon palpation, and are not fused to each other or the subcutaneous tissue. The overlying skin is unchanged. Neck pain upon turning the head is characteristic.
- Hepatosplenic syndrome and hepatitis: enlarged liver and spleen are palpated in the abdominal cavity (hepatosplenomegaly). Liver involvement is indicated by facial puffiness, scleral subicterus, and dark urine ("weak tea" color).
- Exanthematous syndrome: skin rashes (less common).
Role of EBV in oncogenesis
One of the most important features of EBV is its proven involvement in the development of a number of malignant neoplasms. The diseases are divided into several groups:
- Lymphoproliferative disorders: X-linked lymphoproliferative syndrome, B-lymphoproliferative diseases (including HIV-associated and post-transplant lymphomas), Burkitt lymphoma, Hodgkin disease, and T-cell lymphoma.
- Epithelial tumors: hairy leukoplakia of the tongue, nasopharyngeal carcinoma, and gastric carcinoma.
- Tumors with suspected EBV involvement: thymoma, hepatocellular carcinoma, and leiomyosarcoma.
Differential diagnosis
A clinical picture similar to IM is termed mononucleosis-like syndrome. It can occur in diseases of a completely different etiology; therefore, differential diagnosis is performed with the following infections:
- Bacterial tonsillitis (first of all, oropharyngeal diphtheria must be ruled out).
- Viral infections: cytomegalovirus infection (CMV), acute HIV infection, adenovirus infection.
- Viral hepatitis.
- Parasitic infestations: toxoplasmosis.
- To a lesser extent: yersiniosis and leptospirosis.
Laboratory diagnostic algorithm
Epidemiological history data in mononucleosis are often of low information value, although the fact of staying in a youth collective or contact with ARVI patients within the incubation period can be useful. Diagnosis is primarily based on a comprehensive examination. The laboratory workup plan includes:
- Complete blood count (CBC) and urinalysis (UA).
- Blood chemistry panel.
- Bacteriological culture of an oropharyngeal swab for microflora.
- Serological and immunological tests: verification of infectious mononucleosis, screening for viral hepatitis and HIV infection.
Patients with suspected infectious mononucleosis are indicated for hospitalization for accurate diagnosis verification, dynamic medical monitoring, and therapy selection.
Briefly: answers to topical questions
What specific changes are found in the complete blood count in infectious mononucleosis?
The complete blood count in infectious mononucleosis reveals:
- leukocytosis or normocytosis;
- absolute lymphocytosis / absolute lymphomonocytosis;
- atypical mononuclear cells — wide-cytoplasm basophilic lymphocytes with a large nucleus, which may be eccentrically located.
The presence of atypical mononuclear cells accounting for at least 10–12% of the total number of mononuclear cells is considered diagnostically significant.
What serological markers (antibodies) confirm the acute phase of infectious mononucleosis?
The acute phase of infectious mononucleosis is confirmed by the appearance of specific immunoglobulins against Epstein-Barr virus antigens.
The following markers of acute infection are determined in blood serum:
- anti-VCA IgM — antibodies to the viral capsid antigen (a rise in their titer is detected).
- anti-EA IgG (anti-EBV EA-IgG) — antibodies to the early viral antigen, used as an early diagnostic test.
The serological profile of the peak disease period is considered to be the detection of anti-VCA IgM and anti-EA IgG with the mandatory absence of antibodies to the nuclear viral antigen (anti-EBNA IgG).
What medications are used for etiotropic therapy of infectious mononucleosis?
Etiotropic therapy for the treatment of infectious mononucleosis has not been developed to date.
The use of nucleotide analogues in this infection lacks proven clinical efficacy. As an exception, acyclovir may be prescribed, but such treatment is advisable exclusively for patients suffering from malignant blood diseases. Otherwise, management tactics are based on the use of pathogenetic, symptomatic agents and short courses of glucocorticosteroids (in severe complications).
To memorize the main manifestations of mononucleosis, use the "LIGA" rule: L — Lymphadenopathy, I — Intoxication, G — Hepatosplenomegaly, A — Angina (tonsillitis).
Class and exam questions
Why is the incidence of mononucleosis relatively low despite high virus infectivity?
This is due to the fact that a huge number of acute forms of the infection proceed asymptomatically (latently) or in a mild form, remaining undiagnosed.
Which bacterial infections are most commonly confused with mononucleosis?
First of all, differential diagnosis must be performed with bacterial tonsillitis, especially oropharyngeal diphtheria.
Does the Epstein-Barr virus disappear from the body after recovery?
No, the pathogen is capable of lifelong persistence in the body of every recovered person, which can lead to chronicity of the process.
What else to study on this topic
- Polyetiology of mononucleosis-like syndrome
- Immunopathological processes in IM at different stages
- Decoding specific serological and immunogenetic markers
- Principles of IM therapy and possible complications
- Indications for discharge and rules of follow-up observation for convalescents
Master the complete topic in the «Infectious Diseases» course
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