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A forgotten disease in Japan

  • Author Footnotes
    # Hiroki Matsuura contributed to write manuscript, diagnosis, and discussion. Kentaro Deguchi contributed to discussion, patient care, and supervision. We do not have any funding sources in the writing of the manuscript or the decision to submit for publication. We do not have any conflict of interest.
    Hiroki Matsuura
    Correspondence
    Corresponding author: Hiroki Matsuura, MD, 3-20-1, Omote-cho, Kitanagase, Okayama-city, Okayama, 700-0962, Japan. Phone: +81-86-737-3000; Fax: +81-86-737-3019.
    Footnotes
    # Hiroki Matsuura contributed to write manuscript, diagnosis, and discussion. Kentaro Deguchi contributed to discussion, patient care, and supervision. We do not have any funding sources in the writing of the manuscript or the decision to submit for publication. We do not have any conflict of interest.
    Affiliations
    Department of General Internal Medicine, Okayama City Hospital
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  • Kentaro Deguchi
    Affiliations
    Department of Neurology, Okayama City Hospital
    Search for articles by this author
  • Author Footnotes
    # Hiroki Matsuura contributed to write manuscript, diagnosis, and discussion. Kentaro Deguchi contributed to discussion, patient care, and supervision. We do not have any funding sources in the writing of the manuscript or the decision to submit for publication. We do not have any conflict of interest.
Published:January 31, 2021DOI:https://doi.org/10.1016/j.ejim.2021.01.008

      1. Case description

      A 67-year-old woman with acute onset of fever, disorientation, and confusion was transferred to our emergency department. Physical findings revealed neck stiffness, left dominant tremulous arms with cogwheel rigidity of her extremities. Computed tomography showed mild atrophy without cerebral bleedings. Magnetic resonance imaging (MRI) with fluid-attenuated inversion recovery (FLAIR) sequence was shown in Figure (Fig. 1. on day 2, and Fig. 2. on day 5). What is the diagnosis?
      Fig. 1
      Fig. 1FLAIR-MRI on day 2 showed trivial alteration in the bilateral thalami, hippocampus, caudate nuclei, and substantia nigra.
      Fig. 2
      Fig. 2FLAIR-MRI on day 5 demonstrated marked hyperintensity signal in the bilateral thalami, hippocampus, caudate nuclei, and substantia nigra.

      2. Discussion section

      FLAIR-MRI demonstrated progressively marked hyperintense signal alterations in the bilateral thalami, internal capsules, hippocampus, caudate nuclei, and substantia nigra. A lumbar puncture was performed and the cerebrospinal fluid (CSF) revealed 62 cells/μL, for white blood cells and elevated protein level of 112 mg/dL. The CSF glucose level was normal. Her family reported an extremely limited immunization history in her childhood. However, her family also disclosed that she was hobby farmers and she didn't take measures for mosquito bite prevention. Subsequently, real-time reverse transcriptase polymerase chain reaction for Japanese encephalitis virus (JEV) in cerebrospinal fluid was positive. Based on the clinical findings, we made a diagnosis of Japanese encephalitis. Japanese encephalitis is one of the most prevalent arthropod-transmitted viral encephalitis in many Asian countries, northern Australia, and the western Pacific rim [
      • Tiroumourougane SV
      • Raghava P
      • Srinivasan S.
      Japanese viral encephalitis.
      ]. It is a viral infection caused by JEV belonging to the genus Flavivirus. JEV is transmitted to humans by infected mosquitoes, particularly Culex mosquito species [
      • Wangchuk S
      • Tamang TD
      • Darnal JB
      • Pelden S
      • Lhazeen K
      • Mynak ML
      • et al.
      Japanese encephalitis virus as cause of acute encephalitis.
      ]. Transmission principally occurs in rural agricultural areas, often related to rice cultivation and flood irrigation. The vast majority of infections with JEV are asymptomatic, and less than 1 % of JEV infections develop symptomatic neuroinvasive disease [
      • Chang YK
      • Chang HL
      • Wu HS
      • Chen KT.
      Epidemiological Features of Japanese Encephalitis in Taiwan from 2000 to 2014.
      ]. Approximately 30 % of symptomatic cases are fatal, and 50 % of survivors experience long lasting serious neurologic or cognitive complications [
      • Yun SI
      • Lee YM.
      Japanese encephalitis: the virus and vaccines.
      ]. MRI is more sensitive and specific than CT in revealing thalamic lesions in Japanese encephalitis. There are still no effective treatments for Japanese encephalitis. Current strategies for suppression of JEV infection include appropriate vaccination program of humans and swine, mosquito control, and community education.

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