Proceedings of the International scientific and practical conference ―Modern Science: Challenges and Perspectives‖ (February 9-11, 2026) / Publisher website: www.naukainfo.com. - London, United Kingdom, 2026. - 121 p.

103 University for compliance with moral and legal principles in conducting medical scientific research (clinical studies), protocol No. 143/24 dated March 20, 2024. The study was conducted with written informed consent from the patient’s parents and in accordance with the principles of bioethics outlined in the Declaration of Helsinki ―Ethical Principles for Medical Research Involving Human Subjects‖ and the ―Universal Declaration on Bioethics and Human Rights‖ (UNESCO). Case report. 14-year-old girl was consulted by a pediatrician and referred for a hematology consultation with a syndrome of generalized LAP. She was hospitalized in the Department of Oncohematology and Intensive Chemotherapy of the Municipal Non-Profit Enterprise ―Ivano-Frankivsk Regional Children’s Clinical Hospital of the Ivano-Frankivsk Regional Council‖. Complaints: problems with nasal breathing, intermittent elevation of body temperature up to 37.6°C, enlargement of cervical and axillary lymph nodes, and general weakness. Disease anamnesis: at the age of 10 years, she experienced a moderate acute EBV infection. The diagnosis was confirmed by the presence of atypical mononuclear cells (18%) and lymphocytosis (61%) in the complete blood count, positive antiVCA IgM antibodies to EBV (ELISA), and positive PCR results for EBV DNA in blood. Three weeks after disease onset, the patient was discharged from the hospital in satisfactory condition. Nine months after disease onset, a clinical relapse of EBV infection occurred, confirmed by serological and virological markers: anti- VCA IgM, anti-EA IgG, anti-EBNA IgG, and viral DNA detected in saliva. Clinically, the relapse manifested with subfebrile body temperature, increased fatigue, and enlargement of anterior and posterior cervical lymph nodes. Remission was achieved after two months, with no EBV detected in blood or saliva. Subsequently, two further episodes of chronic EBV infection reactivation were recorded 7 and 11 months later. Life history: the patient grew and developed according to age. Allergic and hereditary histories were unremarkable. Preventive vaccinations were administered according to the national immunization schedule.