RT Journal Article SR Electronic T1 Cytomegalovirus encephalitis in an immunocompetent child: a sceptic diagnosis JF BMJ Case Reports FD BMJ Publishing Group Ltd SP bcr2012006796 DO 10.1136/bcr-2012-006796 VO 2012 A1 Filipa Belo A1 Isabel Mendes A1 Manuela Calha A1 Carla Mendonça YR 2012 UL http://casereports.bmj.com/content/2012/bcr-2012-006796.abstract AB The authors present the case of an apparently immunocompetent 9-year-old child with probable cytomegalovirus encephalitis. The clinical picture was characterised by fever, frontal headache and behavioural changes, associated with visual and auditory hallucinations. Cerebrospinal fluid (CSF) biochemistry and brain CT were normal. Electroencephalography showed left temporal paroxysmal activity. Diagnosis was based on cytomegalovirus (CMV) DNA detection on the CSF by PCR. Acyclovir and ceftriaxone were given until herpes simplex virus (HSV) and bacterial encephalitis were ruled out. Rapid resolution of fever and complete clinical recovery was observed. Remarkably, anti-CMV serum antibodies were not detected on admission or until 6 months later. This discrepancy led us to question the presence of an impaired specific host humoral response, immune evasion by the virus or a false-positive result for CMV DNA in CSF.