Viral Encephalitis (Human Herpes Virus Type 6) after COVID-19 in a Child: Clinical Case

Background. Immune system disorders early after COVID-19 are associated with high risk of other infections development, including viral ones. Their diagnosis is complicated especially in the absence of clinical symptoms of primary infection and alongside with serious disease course. There are no reports on encephalitis development due to reactivation of latent viral infection.Clinical case description. Girl, 4 years-old, had psycho-neurological symptoms followed by tonic seizures on the next day. The child was hospitalized on the 3rd day after disease onset with preliminary diagnosis of viral encephalitis. The child has contacted with patients with laboratory-confirmed new coronavirus infection 3-4 weeks before the disease onset, later she had signs of mild respiratory infection (no examination of SARS-CoV-2 was carried out). Autoimmune nature of central nervous system injury was suspected after excluding a wide range of infections (negative PCR results for SARS-CoV-2, cytomegalovirus, herpes simplex virus, Epstein-Barr virus, toxoplasma, enterovirus), however it was not confirmed later on. Human herpes virus type 6 was revealed via blood tests and oropharyngeal swаb on the 15th day of disease. High concentration of IgG antibodies to SARS-CoV-2 was found was revealed as well. Treatment (antibacterial, anticonvulsant, anticoagulant, antiviral, immunosupportive, and sedative therapy, glucocorticosteroids) did not achieve significant improvement. Brain MRI (on the 23rd day of the disease) has shown leukoencephalopathy zones in subcortical white matter of convexital surfaces of parietal and occipital lobes, subatrophic changes in white matter of cerebral hemispheres with moderate vicarious enlargement of the subarachnoid spaces. Disease progression led to patient’s death on the 32nd day after first signs appearance.Conclusion. The development of severe viral encephalitis (as a result of primary herpes virus infection or its reactivation) in the early period after mild COVID-19 is shown. Its cause-effect relations require further examination.