- Enteroviruses, herpes simplex, herpes zoster, ebv, west nile, influenza, hiv, measels, mumps
- Seasonal: summer for west nile (mosquito born); winter for influenza
- Lack of vaccination or too young to be vaccinated: measles, mumps, zoster
- Older or younger age: zoster
- Immunocompromised: HIV, other
- Acute
- Fever
- Head ache
- Neck pain
- Typical CSF Findings: normal or mildly elevated opening pressure , WBC 25-500 (lymph predominance), normal glucose, protein 20-80, gram stain -