In situ hybridization detection of human herpesvirus 6 in brain tissue from fatal encephalitis

A 23-month-old girl died after 2 days' illness with rash, fever, and convul sions. Neuropathologic findings were consistent with viral hemorrhagic ence phalitis in pontine tegmentum and medial thalamic areas. Human herpesvirus 6 (HHV-6) DNA was detected in pontine nuclei by in situ hybridization. In a ddition, polymerase chain reaction for HHV-6 of serum and paraffin-embedded pontine tissue was positive, and serology indicated an acute primary infec tion. This is the first case showing HHV-6 DNA in the brain cells of an imm unocompetent patient with acute encephalitis.