BACKGROUND: Every year, a steady, progressive increase in the number of atypical chronic, active forms of infections caused by herpesviruses is recorded. Diagnosing and selecting adequate therapeutic strategies for treating these infections present significant difficulties for physicians due to the polysyndromicity and many clinical manifestations.
 AIMS: This study determines the prevalence of atypical chronic, active infections caused by herpesviruses among patients infected with herpesvirus infections and studies the etiological structural features and clinical manifestations/criteria and signs of atypically occurring chronic forms of herpes viral infections.
 MATERIALS AND METHODS: Under our supervision at the Clinical and Diagnostic Center Medsi in Belorusskaya (Moscow), 98 patients of both sexes aged 23 to 60 years suffering from atypical chronic, active forms of infections caused by herpesviruses comprised the herpesviruses group. The comparison group consisted of 30 conditionally healthy subjects comparable in sex and age to patients. In addition to traditional methods (history collection, physical examination, general blood test, and others), serodiagnostic methods with ELISA were used to detect herpesvirus infections. ELISA was also used for detecting the genome of viruses in biomaterials. The study was approved by the ethics committee, and all patients received informed consent to participate in the study. Statistical analysis was performed using adequate methods.
 RESULTS: The study of the etiological structure of herpesvirus infections in patients with atypical chronic, active forms of infections caused by herpesviruses, mixed herpesvirus infections were shown to occur in 83.4% of patients, and mono herpesvirus infections in 16.6% of cases. It was shown that the EpsteinBarr virus was the dominant virus among patients with mono and mixed herpesvirus infections. A high rate of EpsteinBarr virus DNA detection was demonstrated in saliva (84.2%), posterior pharyngeal wall scrapings (73.5%), tonsils (42.9%), urine (12.6%), and blood (8.3%) is a marker of the high replicative activity of the virus. The primary clinical syndromes associated with mono and mixed atypical chronic and active forms of infections caused by herpesviruses were identified.
 CONCLUSIONS: This study identified and quantitatively assessed the viral load associated with the severity of the course and clinical manifestations of atypical chronic, active forms of infections caused by herpesviruses. Clarifying the features of clinical manifestations and syndromes in patients suffering from various mono and mixed herpesvirus infections will allow us to outline the goals for the further development of an adequate diagnostic algorithm for these atypical forms of herpesvirus infections and the concept of targeted, personalized etio- and immunopathogenetic therapy.