Severe acute encephalopathy related to human parainfluenza virus type 2 infection in an infant : a case report

IP: 54.70.40.11 On: Thu, 20 Dec 2018 23:11:38 Case Report Severe acute encephalopathy related to human parainfluenza virus type 2 infection in an infant: a case report Kazuko Sugai, Hiroyuki Tsukagoshi, Ikuko Nojima, Kaori Fujiwara, Aya Kodera, Noriko Kimura, Keiji Tsuchimoto, Kazuhiro Sekimoto, Kumimi Kitada, Nobumasa Takahashi, Tooru Araki, Yosuke Fujii, Yumiko Miyaji, Masanori Ikeda, Kunihisa Kozawa, Masahiro Noda, Makoto Kuroda and Hirokazu Kimura


Introduction
Human parainfluenza viruses (HPIVs) are respiratory viruses that commonly cause respiratory infections in children (Henrickson, 2003).In recent years, the importance of extra-pulmonary symptoms of HPIV infection has become evident, and severe cases of HPIV-related encephalitis have been reported (Kim & You, 2012;Abenhaim Halpern et al., 2013).
Here, we report a case of a two-year-old girl who was diagnosed with HPIV-induced acute encephalitis, presenting with fever, seizure and reduced level of consciousness.HPIV2 was detected using next-generation sequencing (NGS), and other viruses that typically cause encephalopathy, such as the Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus (HSV), varicella-zoster virus (VZV), human herpesvirus (HHV)6 and HHV7, were not detected.

Case report
A two-year-old girl was brought to our hospital by ambulance with fever, hypoxia and generalized tonicclonic seizure.She had a mild nasal discharge and cough for half a day before admission.She had a history of severe neonatal asphyxia and an Apgar score of 2/8 and had been delivered at the gestational age of 32 weeks.However, routine follow-up revealed good development, with normal findings on brain magnetic resonance imaging (MRI) and electroencephalography (EEG).
At the time of hospital admission, the patient also had laryngomalacia, for which tracheotomy was performed.She had a depressed level of consciousness with drowsiness.Her Glasgow coma score was 6.The seizure resolved with anticonvulsant treatment, but the consciousness level did not improve.Essential laboratory data are shown in Table 1.Serum levels of aspartate aminotransferase (AST; 99 IU l 21 ), lactate dehydrogenase (LDH; 466 IU l 21 ), ferritin (143.3 ng ml -1 ) and amyloid A (153.3 mg ml -1 ) were elevated; therefore, we considered that she had severe systemic inflammation.The cerebrospinal fluid (CSF) was sampled on the day of admission, and the cell count was 1 cell ml -1 .Rapid diagnostic tests using nasal or throat swabs for respiratory syncytial virus (RSV), influenza virus, adenovirus, and human metapneumovirus were all negative.Immediately after hospitalization, although brain MRI did not suggest inflammation (Fig. 1a), brain computed tomography (CT) showed brain oedema.Based on these findings, as well as considering the persisting depressed level of consciousness, we diagnosed severe acute encephalopathy.Prior to starting treatment, we obtained the guardian's informed consent for obtaining a nasal swab, intra-tracheal sputum sample and blood samples on the day of admission.Therapy was initiated with 0.5 g D-mannitol kg 21 per dose four times per day for reducing cerebral oedema and 0.12 mg midazolam kg 21 h 21 continuously for preventing seizure.Further, 1 g high-dose intravenous immunoglobulin (IVIG) kg 21 day 21 , 30 mg methylprednisolone pulse therapy kg 21 day 21 for 3 days, 500 U thrombomodulin alfa day 21 , and 0.5 g edaravone kg 21 dose 21 twice a day were concomitantly administered, similar to the therapy for influenza-virus-associated encephalopathy.Mechanical ventilation was started for the respiratory symptoms.Further, we administered 150 mg cefotaxime kg 21 day 21 since the white blood cell count and C-reactive protein levels were elevated.However, bacterial cultures for blood and CSF were negative, and throat swab culture detected normal flora.
After the initiation of treatment, the patient's consciousness improved briefly; however, on day 4 of admission, her consciousness worsened and the laboratory data suggested severe systemic inflammation.MRI on day 6 showed high-signal areas in the anterior lobes; therefore, we restarted methylprednisolone pulse therapy and increased the D-mannitol dose (Fig. 1b).Subsequently, her consciousness and laboratory data improved gradually (Table 1).The results of EEG and brain MRI showed considerable improvements before the patient's discharge on day 42 of hospital admission.Follow-up examination at 3 months after the initial admission revealed good physical and mental development.

Investigations
We performed a comprehensive examination of pathogen genomes using NGS with MiSeq (Illumina) using the samples of nasal swab, intra-tracheal sputum and blood taken on the day of admission.Briefly, an RNA-seq library was prepared from extracted total RNA using a ScriptSeq Fig. 2. Phylogenetic tree based on the HN coding region (305 nt) using Molecular Evolutionary Genetics Analysis (MEGA) software version 5 (Tamura et al., 2011).Evolutionary distances were estimated using Kimura's two-parameter model, and a phylogenetic tree was reconstructed using the neighbour-joining method (Kimura, 1980;Saitou & Nei, 1987).The reliability of the tree was estimated using 1000 bootstrap replications (shown as percentages at nodes).Scale bar indicates nucleotide substitutions per site.
v2 RNA-Seq Library Preparation kit (Illumina), followed by 150-mer paired-end de novo sequencing with a MiSeq Reagent kit v2 (Illumina); the raw short reads (approx. 1 million reads per sample) were analysed using the MePIC server to characterize potential pathogens, as previously described (Takeuchi et al., 2014).Sequence analysis by NGS suggested that this sample contained HPIV2.Therefore, we confirmed the presence of HPIV2 in the nasal swab using the conventional PCR method with specific primers (Bellau-Pujol et al., 2005).Next, we performed phylogenetic analysis based on the haemagglutininneuraminidase (HN) coding region of HPIV2 (305 bp) using Molecular Evolutionary Genetics Analysis (MEGA) software version 5 (Tamura et al., 2011) (Fig. 2).HN glycoprotein is a major antigen in HPIV.In addition, HN glycoprotein might function as a major antigen.
In phylogenetic analysis, the reference sequences of the HN coding region were obtained by BLAST.Levels of the anti-HPIV2 antibody elevated 40-fold in the haemagglutination inhibition test after IVIG and methylprednisolone pulse therapy were started; however, they were not detected at the three-month follow-up.No pathogenic viruses, such as EBV, CMV, VZV, HHV6, HHV7 or HSV, were isolated or detected from the patient's serum (McIver et al., 2005).

Diagnosis
Acute encephalopathy related to human parainfluenza virus type 2 infection.

Treatment
D-Mannitol at a dose of 0.5 g kg 21 four times per day, 0.12 mg midazolam kg 21 h 21 continuously, 1 g high-dose IVIG kg 21 day 21 , 30 mg methylprednisolone pulse therapy kg 21 day 21 for 3 days, 500 U thrombomodulin alfa day 21 and 0.5 mg edaravone kg 21 dose 21 twice a day.They were concomitantly administered, similar to the therapy for influenza-virus-associated encephalopathy.

Outcome and follow-up
Full recovery without sequelae.

Discussion
We have reported here the case of a two-year-old girl diagnosed with acute severe encephalopathy related to HPIV2 infection.
Recently, several extra-pulmonary symptoms caused by respiratory viruses have been reported (Eisenhut, 2006;Kim & You, 2012;Miyamoto et al., 2013;Abenhaim Halpern et al., 2013).RSV infections affecting other organs have been reported (Miyamoto et al., 2013), with the RSV antigen detected in the CSF, myocardium, liver and peripheral blood.Further, a case of acute encephalopathy associated with human metapneumovirus infection in a Japanese three-year-old girl was reported in 2014, in which the human metapneumovirus was detected using PCR from a throat swab but not from CSF, with elevated levels of inflammatory cytokines in the CSF and blood samples (Niizuma et al., 2014).
HPIVs are negative-strand RNA viruses from the Paramyxoviridae family (Henrickson, 2003) with four types; HPIV2 is a member of the genus Rubulavirus (Henrickson, 2003).These HPIVs typically cause respiratory symptoms ranging from mild upper respiratory tract infections to severe lower respiratory tract illness, including croup syndromes, bronchiolitis, and pneumonia.HPIV2 is an important causative agent of upper and lower respiratory tract infections and febrile illness in children as well as severe lower respiratory tract infection in all age groups (Henrickson, 2003).
Recently, several cases of acute encephalopathy related to HPIV have been reported, especially in Asian countries (Kim & You, 2012;Abenhaim Halpern et al., 2013).In these reports, HPIV was detected from patients' nasal swabs.In these cases, anti-inflammatory treatment using prednisolone was effective, similar to that in our case.
In our case, the HPIV2 gene was detected in the patient's sputum samples, nasal swabs and blood samples using NGS.However, her anti-HPIV2 antibody levels were not elevated 3 months after admission.The anti-HPIV2 antibody level was 40-fold higher after the immunoglobulin product was used.We considered that the negative antibody was possibly due to the immunosuppressive effect of high-dose corticosteroids and high-dose IVIG.
In Japan, paediatric cases of acute encephalopathy, especially influenza-virus-associated encephalopathy, are very severe and often fatal (Kawada et al., 2003).It is well known that in cases of influenza-virus-associated encephalopathy, viral RNA is rarely detected in the CSF; moreover, viral antigens are not detected in the brain on autopsy (Kawada et al., 2003).Cytokine storm as a systemic immune response is considered to be a cause of influenza-virus-associated encephalopathy, wherein elevated levels of inflammatory cytokines, such as IL-1, IL-6 and TNF, are considered to cause the breakdown of the blood-brain barrier, leading to brain oedema (Kawada et al., 2003).In our patient, the elevated levels of AST, LDH and ferritin suggested a systemic immune response; further, the increased serum amyloid A level strongly suggested an inflammatory cytokine response involving IL-1, IL-6 and TNF (Sztein et al., 1982;Patel et al., 1998).
In conclusion, we have presented a case of severe acute encephalopathy associated with HPIV2.We detected the HPIV2 gene using NGS performed using the patient's sputum samples, nasal swabs and blood samples; however, CSF samples tested negative for the virus.Acute encephalopathy was diagnosed based on the patient's symptoms, laboratory data, and findings of brain CT, MRI and EEG.Anti-inflammatory and steroid treatment was effective, and the patient recovered without any sequelae.Our experience suggests that HPIV2 can indirectly cause extra-pulmonary illnesses via systemic inflammation, similar to that in influenza-virusassociated encephalopathy.

Fig. 1 .
Fig. 1.Diffusion-weighted images of brain MRI.(a) High-signal regions in the anterior lobes on day 1.(b) Increase in the spread of high-signal areas, especially in the left cerebral hemisphere on day 6.