[P2-26] Human parechovirus type 3 (HPeV3) causing acute encephalopathy in neonatal and early infantile periods—a report of two cases
[Introduction] Human parechovirus type 3 (HPeV3) has been reported as an important virus causing acute primary encephalitis in neonatal and early infantile periods. HPeV3 is often isolated from the cerebrospinal fluid (CSF) of patients irrespective of whether they have central nervous system manifestations, CSF pleocytosis, or abnormal findings on magnetic resonance imaging (MRI). On the other hand, HPeV3-induced acute primary encephalitis commonly shows diffuse white-matter involvement including corpus callosum on MRI without CSF pleocytosis. [Patient 1] An 8-day-old full-term male infant developed lethargy, fever, and reticular cyanosis. Two days after, recurrent hemiconvulsions appeared on the left and right sides, alternatively. Diffusion-weighted images (DWI) on brain MRI showed poor diffusivity in the bilateral deep white matter and the corpus callosum. [Patient 2] A 28-day-old full-term female infant was admitted for fever, cough, and abdominal distention. Two days later, repeated hemiconvulsions occurred on the right side. DWI showed slightly poor diffusivity in the corpus callosum. [Results] CSF pleocytosis was not observed in either patient, although HPeV3 was isolated from both CSF and blood in Patient 1 and from CSF in Patient 2. Interestingly, these two patients had elevated serum ferritin and urinary beta-2-microglobulin, suggesting hypercytokinemia at the onset. [Discussion] Similar to our two cases, most cases of HPeV3 encephalitis published in the literature had abnormal findings on MRI without CSF pleocytosis. Thus, these results suggest that such cases should be diagnosed with acute encephalopathy rather than acute encephalitis.