Human Metapneumovirus in the Cerebrospinal Fluid of a Patient With Acute Encephalitis.

OBJECTIVE To report, to our knowledge, the first case of detection of human metapneumovirus in the cerebrospinal fluid of a patient during acute encephalitis. DESIGN Case report. SETTING University hospital. PATIENT A 10-year-old girl with acute encephalitis. RESULTS Human metapneumovirus was detected in cerebrospinal fluid and nasal-wash specimens during the initial phase of mild encephalitis. Abrupt clinical deterioration was associated with the presence of multiple areas of demyelination and cortical abnormalities. Demyelinated areas improved after immunomodulatory therapy, but cortical lesions spread in both hemispheres. Surprisingly, clinical worsening occurred when the virus became undetectable in cerebrospinal fluid. CONCLUSIONS The detection of human metapneumovirus in cerebrospinal fluid strongly suggests its causative role in acute encephalitis. The evolution of the clinical and radiological features provided insight into the pathogenesis of human metapneumovirus encephalitis.