A young male develops fever, followed by headache, confusional state, focal seizures and a right hemiparesis. The MRI performed shows bilateral frontotemporal hyperintense lesion. The most likely diagnosis is:

(Herpes simplex encephalitis) Herpes simplex encephalitis (HSE) * HSV 2 in neonates, HSV 1 in children, adults (usually activation) of latent infection in Gasserion ganglion * Most common viral encephalitis * Fulminant, necrotizing, hemorrhagic viral infection * Predilection for limbic system (temporal lobes, cingulate gyri, subfrontal region), in older children, adults CT: * Often normal early in the disease. * Low-density lesions in temporal lobes with mild mass effect are common initially. * Hemorrhage is highly suggestive of HSE and is seen later in the disease course. CECT shows the ill-defined patchy or gyriform enhancement in neonatal HSE. * It shows strikingly increased density of coical gray matter and diffuse low attenuation in white matter MR: Gyral edema * Hemorrhage in late stages. * Temporal lobe hyperintense on T2 WI +- enhancement in early stage.