a 14-month - old boy unresponsive to verbal and tactile stimulation with high fever ( temperature 39c ) was admitted to a primary care hospital 30 minutes after the onset of generalized febrile convulsions that did not respond to 2 doses of rectal diazepam ( 5 mg ) . his weight was 8 kg , all extremities were warm and well perfused , his heart rate was 140 beats per minute ( bpm ) , and oxygen saturation was 93% in ambient air . initial clinical examination showed no purpuric or petechial lesions , no heart murmurs or pulmonary rales , and no palpable enlargement of the liver or spleen . the boy had been healthy until 2 days earlier , when rhinorrhea , mild pharyngitis , and cough developed without signs of lower respiratory tract involvement . on the day of admission , he vomited once in the morning and than refused to drink . in the afternoon of the same day , a high fever developed , and seizures began , with extension and struggling of all extremities but without opisthotonos . the patient initially turned both eyes upwards but later stared straight ahead with no spontaneous eye movements and fixed pupils of 3 to 4 mm in diameter . the boy had been born at 34 weeks gestational age ( weight 2,300 g ) , and he was treated for a few days with antimicrobial drugs after prolonged rupture of amniotic sac membranes , even though early - onset infection had not been confirmed . his neonatal period was uneventful , with the exception of moderate withdrawal symptoms ( irritability , frequent bowel movements ) probably due to tobacco use by his mother during pregnancy . the primary pediatrician documented a subtle , generalized muscular hypotension at the age of 9 months but did not consider this finding remarkable enough to investigate further ( sonographic examination of the central nervous system showed normal results immediately after birth and 2 weeks later ) . clinical seizure activity subsided 2 hours after the intravenous administration of diazepam , clonazepam , phenobarbital , and lorazepam . blood pressure was stable without high volume infusion or vasosuppressor support , and oxygen saturation ( pulse oximetry ) was 100% with 2 cerebrospinal fluid ( csf ) drawn by lumbar puncture showed no pleocytosis , glucose level of 4.6 mmol / l , and a slightly elevated protein content of 116 mg / dl ( normal value < 45mg / dl ) ( table 1 ) . although leukocyte count and serum c - reactive protein did not suggest inflammation , empiric antimicrobial chemotherapy with ceftriaxone , ampicillin , gentamicin , and acyclovir was started immediately . an electroencephalogram showed generalized slow waves but no seizure activity . on the basis of abnormal findings on a magnetic resonance imaging scan ( mri ) performed 12 hours after admission ( figure 1a and 1b ) , attending physicians diagnosed meningoencephalitis of unknown origin . during the next few hours , the patient was intubated ( no gag reflex observed during the procedure ) and mechanically ventilated . he was sent to the pediatric intensive care unit of a tertiary - care hospital 24 hours after admission to have an external ventricular drain inserted . upon arrival , the patient was deeply comatose ( gcs 5 ) without response to painful stimuli ; he had rectal temperature of 32c , arrhythmic heart rate ( 90 bpm ) , and a mean arterial pressure of 29 mm hg . axial t1-weighted magnetic resonance imaging ( mri ) scan ( a ) and coronal fluid attenuated inversion recovery ( flair ) ( b ) show multifocal , mainly cortical and subcortical lesions of high signal intensity , which are most probably caused by multifocal encephalitis . c ) nonenhanced axial computed tomographic ( ct ) scan performed 2 days after the mri shows multiple , hypodense lesions and signs of general edema . additionally , it shows a hyperdense arachnoid collection that was not yet visible on the mri 2 days before ( panels a and b ) . a chest radiograph excluded a pneumonic infection and confirmed the correct position of the ventilation tube and the central venous catheter tip . the abnormal findings on a computed ( ct ) tomography scan are shown in figure 1c . intracranial pressure measured after inserting an external ventricular drain and repeatedly afterwards was constantly elevated to 90 cm h2o . brain tissue extruded locally , and the drain was removed after 2 days . repeated cultures of blood , urine , csf , brain tissue , and the tip of the external drainage did not show any bacterial ( culture ) or viral pathogen ( culture and polymerase chain reaction [ pcr ] ) ( table 2 ) . the patient did not exclusively display symptoms typical of measles or mumps , and neither of these viruses could be isolated from brain tissue . * csf , cerebrospinal fluid ; hsv , herpes simplex virus ; pcr , polymerase chain reaction ; nd , not done ; vzv , varicella  zoster virus ; hhv , human herpesvirus ; hbv , hepatitis b virus ; hcv , hepatitis c virus ; cmv , cytomegalovirus ; rt , reverse transcriptase ; rsv , respiratory syncytial virus ; elisa , enzyme - linked immunosorbent assay ; hmpv , human metapneumovirus .  before death , viral encephalitis induced by hsv and vzv was excluded by nested pcr from the csf and also from a biopsy . measles and mumps were excluded by the primary anamnestic protocol ( no exanthema or other clinical symptoms ) . postmortem specimens from brain , lung , kidney , liver , spleen , and heart were mounted on different cell lines . detailed pcr protocols are available on request . in addition , extensive acute investigations of serum and urine specimens did not confirm any underlying inborn or acquired metabolic illness . a battered - child syndrome was excluded by a normal ophthalmologic examination and radiographs of all extremities ; no sign of fresh or old fractures was found . after 10 days of supportive intensive care without clinical improvement , in accordance to the current regulations of german federal law , the child was considered to be dead and extubated after receiving informed consent from his legal guardian . the acute symptoms were managed sufficiently by the primary intensive care team , particularly in terms of oxygenation , and no signs of dehydration were seen at admission . thus , extensive discussion with the attending intensive care , neurosurgery , neuroradiology , and pediatric neurology team led to the conclusion that the time course of the illness suggested encephalitis as the primary reason for the child s symptoms and the adverse outcome . other differential diagnoses of the mri and ct findings such as postictal edema after a status epilepticus , edema due to prolonged hyperpyrexia and dehydration , or hypoxemia were considered highly improbable . tissue specimens from brain , lung , liver , kidney , and heart as well as serum and csf were intensively screened for bacterial and viral infections by using standard techniques ( table 2 ) . rna of this virus was identified by reverse transcription ( rt)pcr in both brain and lung tissue specimens . moreover , all tissue specimens were mounted routinely on different cell lines susceptible to viruses commonly known to cause encephalitis ( table 3 ) , but hmpv rna was detected by pcr only in the cell culture supernatant of a vero culture mounted with lung tissue for 3 weeks . although no cytopathic effect was observed in any of the cell cultures , the fluid from the vero cells mounted with lung tissue was repeatedly positive for hmpv rna . none of the other viruses was detected by pcr , and no cytopathic effect was seen in any of the cell cultures . * the + symbol indicates that the cell line is susceptible to the virus and was used for diagnostic procedures . hsv , herpes simplex virus ; vzv , varicella zoster virus ; cmv , cytomegalovirus ; rsv , respiratory syncytial virus ; hmpv , human metapneumovirus ; llc - mk2 , kidney cell line from rhesus monkey ; ms , monkey stable ; mdck , madin - darbin canine kidney ; rd , human caucasian rhabdomyosarcoma ; hef , human embryonic fibroblasts . amplified fragments of hmpv dna derived from the vero cell culture supernatant were subjected to direct sequencing . the alignment of the resulting sequences showed close relatedness of hmpv rna sequences present in brain and lung tissues and those obtained from the supernatant of infected cell culture ( figure 2 ) . upon phylogenetic analysis , the identified hmpv sequences were clearly separated from the sequences of other hmpv isolates obtained by our laboratory ( 13 ) . these results allowed us to exclude the possibility of contamination of the brain and lung tissues under investigation with hmpv sequences from another source . alignment of 302 nucleotide human metapneumovirus ( hmpv ) sequences amplified from brain and lung tissues of the patient and from the supernatant of infected vero cell culture . conditions of the reverse transcription  polymerase chain reaction were described elsewhere ( 5 ) . virologic data on the detection of hmpv were complemented by results of histologic and immunochemical investigations . thus , both the lung and the brain tissues showed evidence of an active inflammation . the alveolar lumina were partly or completely filled with fluid mixed with inflammatory cells , and the alveolar walls were thickened . some bronchioles had segmental loss of epithelium ; meninges were diffusely thickened by many neutrophils and a few macrophages mixed with fibrin and a few erythrocytes . unfortunately , specific immune staining of paraffin - embedded tissues did not allow us to detect hmpv antigens in the brain or lung of the patient . several reasons may explain these negative results , including low concentration of viral antigens in the infected tissues , relatively low sensitivity of the immunochemical procedures , and a high sensitivity of the rt - pcr assay . similar observations may be noted , namely , the positive rt - pcr findings of viral rna and the inflammatory response in investigated tissues in the case of nipah virus infection of the brain ( 11 ) . to our knowledge , this case report is the first of fatal encephalitis that might be associated with hmpv infection . we base a possible etiologic relationship between hmpv and the observed neurologic manifestations on the detection of hmpv rna in the brain and lung tissues . the clinical course and mri data for our patient are very similar to those observed in several patients with fatal encephalitis associated with nipah virus infection , another member of the paramyxovirus family ( 8,11 ) . definite conclusions on the possible involvement of hmpv in neurologic disorders might be drawn only after additional studies . at this stage , however , we recommend hmpv screening for patients , especially young children , with symptoms of encephalitis of unknown origin . these investigations might extend our knowledge of the clinical manifestations and consequences of hmpv infection .
we describe a fatal case of encephalitis that might be correlated with primary human metapneumovirus ( hmpv ) encephalitis . 
 postmortem hmpv rna was detected in brain and lung tissue samples from the patient . 
 furthermore , hmpv rna was found in culture fluids from cells coincubated with lung tissue .