Charting the Neurotropism of Human Parvovirus B19 and Encephalitis: A Systematic Review of Existing Literature of 25 Years.

Parvovirus B19 (PVB19) is an infrequent, serious, yet treatable cause of infection in immunocompromised hosts. Neurological manifestations of PVB19 are encephalitis, encephalopathy, meningitis, cerebellar ataxia, transverse myelitis, stroke, and peripheral neuropathy. The objective is to identify the exact clinical and diagnostic features specific to parvovirus B19 encephalitis for the isolation and management of the pathology. This systematic review was conducted in September 2024 and included all the reported cases published between the years 2000 and 2024, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. An extensive literature search was performed from PubMed Central and Google Scholar. The literature search was conducted using a set of predefined keywords and Boolean operators (AND/OR). All case reports, case series, and original articles containing complete and confirmed cases of human parvovirus B19 infection and presenting with features of encephalitis were selected. After detailed scrutiny, 36 articles were finally used in the review. The mean age of the pediatric and adult patients was 5.78 ± 4.38 and 39.07 ± 19.4 years, respectively. About 59.7% (49) were men, 40.24% (33) were women, and 44.23% (46) did not present with any comorbidities. Most patients (29.03%) presented with altered sensorium. Fever was present in 19.35% (30) of the patients, and 14.19% (22) developed seizures. Around 47.12% (49) had no significant findings on examination. The majority of the patients had no co-infection with other viruses, which were about 88.89% (80) of cases. Polymerase chain reaction (PCR) tested positive in 36.89% (45 cases) of cerebrospinal fluid (CSF) samples. The majority of cases, 66.67% (16 patients), showed normal findings on computed tomography (CT) scans. The magnetic resonance imaging (MRI) findings in 22% (11) of the patients showed hyperintensity on diffusion-weighted imaging (DWI). Hyperintensity on T2-weighted imaging was seen in 14% (seven) of the patients. The parietal lobe was the most common site involved in five patients (11.90%). Acyclovir and intravenous immunoglobulin (IVIG) constituted the most common medications utilized, 13.01% each. Improvement was seen in 80.72% (67) after treatment. In light of recent publications, the shift in the trend of parvovirus B19 toward the central nervous system (CNS) is alarming. Despite limited information, the site of brain parenchymal involvement (parietal lobe, cerebellar hemispheres, corpus callosum, frontal lobe, and ventricles) and specific radiological findings such as hyperintensity on DWI and T2-weighted images, along with CSF PCR positivity and neurological symptoms, can point toward parvovirus encephalitis.