Organism

Encephalitis

Arboviruses (California encephalitis group, St. Louis encephalitis, eastern and western equine encephalitis, West Nile virus, Japanese encephalitis virus in summer and fall), enteroviruses (coxsackie, echo, polio), HSV (10–20%), Bartonella henselae , lymphocytic choriomeningitis virus, tick-borne encephalitis virus, measles, rubella, VZV, HHV-6, rabies (Central and South America, India, Africa), Nipah virus (Malaysia), Chikungunya virus (India and Nepal), Creutzfeldt-Jakob.

Immunocompromised: CMV, VZV, EBV, West Nile virus, JC virus, HIV, Toxoplasma gondii.

Note the increasing recognition of antibody-mediated autoimmune encephalitis as cause of acute encephalitis. In studies of acute encephalitis, 40–50% of patients had infectious cause, 20% had immune-mediated cause including anti-NMDAR (N-methyl-D-asparte receptor) encephalitis and anti-voltage-gated potassium channel (VGKC) encephalitis, and 30% remained of unknown cause.