Internal Medicine

P1: OXT/OZN/JDO P2: PSB

0521779407-E-01 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:10

Encephalitis 523

■Rabies

■HIV

■Bacterial agents include but not limited to:

➣Rickettsia; RMSF, Ehrlichia chaffensis

➣Brucella sp.

➣Leptospirosis sp.

➣Bartonella henselae (CSD)

➣Mycobacteria tuberculosis

Borrelia burgdorferi (Lyme)

Mycoplasma pneumonia

■Fungal agents include but not limited to:

➣Cryptococcus neoformans

➣Histoplasma capsulatum

■Parasitic agents include but not limited to:

➣Naegleria fowleri

➣Acanthoemeoba

➣Toxoplasma gondii

■Unknown – etiology often remains unknown

∗often postinfectious

tests

Nonspecific:

■CSF – often with lymphocytic pleocytosis and mild protein elevation

normal glucose usually

■MRI – may be normal or abnormal

■If infectious etiology not found, consider tests for above differen-

tial

Specific:

■testing should be directed by good exposure history (e.g., travel his-

tory, mosquito/tick exposure, outdoor exposure, rash illness, respi-

ratory prodrome, ill contacts, etc). Note that in many cases agent is

never identified. Important to consider and rule out treatable agents.

■PCR for HSV-1 on spinal fluid – note that false pos/neg occur

■Culture CSF – often low yield

■PCR for specific agent (as above)

➣Serology* for various agents as above – e.g., arboviruses,

Lyme, Rickettsia sp, Mycoplasma pneumonia etc. (*for serology

extremely important to obtain acute and convalescent bloods)

➣Respiratory and Stool viral cultures

Brain biopsy as last resort