Metagenomic next-generation sequencing confirmed pseudorabies virus encephalitis complicated with central visual impairment: a case report

Pseudorabies virus (PRV) is an alphaherpesvirus for which domestic swine serve as the sole natural reservoir. Human PRV infection has historically been regarded as extremely rare. Since 2017, however, an increasing number of severe human PRV encephalitis cases have been identified in China, pre-dominantly among individuals with occupational exposure to pigs or pork products. The condition has been associated with substantial morbidity and mortality and remains under recognized in clinical practice. We report a 53-year-old male dockworker who presented with a 9-day history of fever followed by progressive severe headache. PRV infection was confirmed by metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid (CSF). Brain magnetic resonance imaging revealed signal abnormalities involving the right insular cortex, temporal lobe, hippocampus, and amygdala, consistent with encephalitis. The patient received intravenous acyclovir (500 mg every 8 h for 23 days), corticosteroids, and intravenous immunoglobulin. Although his level of consciousness gradually improved, he developed permanent bilateral blindness with no light perception. At 1-year follow-up, he remained alive but with persistent blindness; neuroimaging demonstrated encephalomalacia in the right temporal and insular regions. PRV can cause devastating human encephalitis with visual impairment as a frequent and serious complication, reported in up to 60% of published cases. Our case is notable in that bilateral blindness emerged after recovery of consciousness, without evidence of peripheral ocular pathology, suggesting a pre-dominantly central visual pathway injury. CSF mNGS has become a key tool for timely diagnosis of rare viral encephalitides. Clinicians should consider PRV encephalitis in patients with unexplained encephalitis and a history of swine exposure, and pursue early mNGS testing to facilitate prompt aetiological diagnosis and antiviral therapy.