within a few hours A CBC may show a lymphocytosis with a left shift, and chest radiographs may sometimes demonstrate diffuse patchy infiltrates or lobar atelectasis Herpes simplex infections usually cause systemic symptoms and encephalitis at to 21 days of life Neonates present with fever, coma, apnea, fulminant hepatitis, pneumonitis, coagulopathy, and seizures History of maternal genital herpes should lead to suspicion of systemic herpes infection in the neonate, though the mother may be completely asymptomatic Focal neurologic signs and ocular findings (conjunctivitis, keratitis) may be noted Vesicular lesions on the skin are highly indicative of this infection, but they are present in only one-third to one-half of patients Rapid diagnostic studies include antigen detection tests and enzyme-linked immunosorbent assay (ELISA) antibody tests The Tzanck preparation has low sensitivity and is not recommended Direct fluorescent antibody staining of vesicle scrapings is specific but less sensitive than culture PCR is a sensitive method to detect the virus from CSF in infants suspected of herpes encephalitis and an electroencephalogram (EEG) or computed tomography (CT) scan may also be helpful to reveal abnormalities of the temporal lobe The Magnetic Resonance Imaging (MRI) is preferred over CT but may be logistically difficult The diagnosis is confirmed by culture of a skin vesicle, mouth, nasopharynx, eyes, urine, blood, CSF, stool, or rectum