Clinical Features of BoDV-1 Encephalitis: A Systematic Review

Abstract

Human cases of fatal encephalitis caused by Borna disease virus 1 (BoDV-1) have been increasingly reported. We envisaged the present systematic review in order to provide a comprehensive summary of clinical features associated with BoDV-1 encephalitis. Systematic research of four databases (PubMed, EMBASE, MedRxiv, BioRxiv) was performed during July 2023, and corresponding clinical and epidemiological data were collected and analyzed. A total of 37 BoDV-1 encephalitis cases from 15 different study cases and two countries (Germany, No. 35; France, No. 2) were detected, and their features were summarized (case fatality ratio, 91.9%). Age distribution followed a “U-shaped” distribution, with a first peak in individuals younger than 14 years (18.9%) and the second one in subjects older than 50 years (43.2%). Environmental risk factors were irregularly reported, but 17 out of 37 cases either lived in rural areas or reported repeated outdoor activities (45.9%). Interaction with pets and livestock was reported in eight cases (21.6%), stressing the zoonotic potential of BoDV-1 infections. Moreover, 16.2% of cases were reported among recipients of solid organ transplantations (five kidneys; one liver). Overall survival in children/adolescents vs. adults (≥18 years) was not significantly different (Hazard Ratio 0.878; 95% Confidence Interval from 0.366 to 2.105). Magnetic Resonance Imaging identified the involvement of basal ganglia, mostly of the caudate nucleus (42.4%) and thalamus (33.3%). Cerebrospinal fluid was often characterized by pleocytosis (78.4%). On the other hand, no distinctive clinical features were identified: initial symptoms were specific and included headache, fever, and confusion. In conclusion, BoDV-1 infection can result in fatal encephalitis, whose actual burden still remains unascertained. As the epidemiology of BoDV-1 is similarly elusive, encephalitis cases of unclear cause should be routinely tested for bornaviruses.

Occurrence of Central Nervous System Complications of Respiratory Syncytial Virus Infections: A Systematic Review with Meta-Analysis

“…Not only were imaging techniques not consistently performed for all patients but also the choice of imaging study was most likely based on local availability, eventually biasing our pooled results. Moreover, a common feature of all viral encephalitis is the progressive, diachronic involvement of distinctive areas within the CNS [ 63 , 65 , 183 , 184 ]: having performed specific studies in an earlier rather than a later stage of the clinical syndrome may lead to recording falsely negative cases or, conversely, associating with RSV infection more a severe pattern due to the oversampling of cases in an advanced and more complicated stage of the disease. As previously stressed, this could be of particular significance when dealing with uncommon and later complications of RSV cases [ 175 , 176 , 177 , 178 , 179 ].…”