WBC count normal or slightly elevated
CSF - pleocytosis with lymphocyte predominance and elevated protein
CT head- negative
MRI brain usually negative but can show focal lesion in pons, basal gang, thal
Confirmation by blood or CSF IgM
IgM does not cross BBB so CSF IgM indicated CNS infc
False positive is recently vaccinated for yellow fever, Jap enceph, or recently infected with relate flavivirus- St Louse, Dengue
Confirmation by 4X increase of acute/ conv titres of antibodies
IgM does not cross BBB so CSF IgM indicated CNS infc
West Nile virus
Meningitis
Zika virus
SAH
Heartland virus
Lyme disease
Hantavirus
Brain abscess