[Virus-related neurological disorders complicating in compromised hosts]

Chance of opportunistic infections in hospitals is increasing year by year, because of the steady increase in the number of compromised hosts. Opportunistic infections in the nervous system include fungal, protozoal, bacterial and viral infections. Cytomegalovirus and herpes virus (HSV1 and HSV2) cause encephalitis, myelitis and radiculoneuritis. Varicella-zoster virus (VZV) often causes herpes zoster, which sometimes disseminates when immunodeficiency is severe. VZV also causes encephalitis. Progressive multifocal leukoencephalopathy (PML) is caused by JC virus in severely compromised hosts. HIV encephalopathy or AIDS dementia complex is one of late stage complications of HIV infection. Prevalence of PML and HIV encephalopathy among AIDS patients tend to increase as other opportunistic infections became controllable recently. Primary CNS lymphoma in immunocompromised hosts is supposed to be caused by EB virus and/or Kaposi's sarcoma-associated herpes virus (KSHV, HHV8). In this sense, CNS lymphoma and Kaposi's sarcoma can be defined as virus infection-related condition.