title: Acute encephalitis in the immunocompromised individual.
abstract: OBJECTIVE
  This article describes recent advances in the diagnosis and management of encephalitis in immunocompromised individuals.
  
  
  RESULTS
  Herpes simplex virus (HSV) and varicella zoster virus (VZV) are common causes of encephalitis in immunocompromised individuals, although clinical manifestations may be atypical, and thus challenging to recognize. Recently, an increased incidence of HSV and VZV central nervous system infections has been reported in association with novel immunosuppressive and immunomodulatory treatments. The free-living ameba Balamuthia mandrillaris causes granulomatous encephalitis predominantly in immunocompromised individuals and is associated with nearly uniform fatality. In the setting of organ transplantation, the recipient's immunocompromised state along with the potential for donor-transmitted infections can result in a unique epidemiology of encephalitis, including infection by human herpes virus-6 and BK virus. Recent studies utilizing next-generation sequencing techniques have identified several pathogens, including Leptospira santarosai and a neurotropic astrovirus, as causes of encephalitis in immunocompromised individuals.
  
  
  CONCLUSIONS
  Diagnosis and management of encephalitis is challenging in immunocompromised individuals, in part because of atypical clinical presentations and the presence of uncommon or novel infectious agents. Unbiased techniques for pathogen discovery are likely to play an increasing role in the diagnosis of central nervous system infections in immunocompromised individuals.
authors.affiliation: Department of Neurology, Johns Hopkins Encephalitis Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Deanna
authors.initials: D
authors.lastname: Saylor
authors.forename: Kiran
authors.initials: K
authors.lastname: Thakur
authors.forename: Arun
authors.initials: A
authors.lastname: Venkatesan
mesh_terms: D000562:Amebiasis / Q000175:diagnosis* / Q000453:epidemiology; D001419:Bacteria / Q000302:isolation & purification; D001424:Bacterial Infections / Q000175:diagnosis* / Q000453:epidemiology; D059611:Balamuthia mandrillaris / Q000302:isolation & purification; D004660:Encephalitis / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D016867:Immunocompromised Host; D009894:Opportunistic Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D014777:Virus Diseases / Q000175:diagnosis* / Q000453:epidemiology; D014780:Viruses / Q000302:isolation & purification