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è â Yellow Fever
- Sub-Saharan Africa + S America endemic (NOT Asia)
- Vectors: Aedes aegypti (urban), Haemagogus/Sabethes (sylvatic)
- Biphasic illness with toxic phase (jaundice + hemorrhage + AKI + black vomit)
- Mortality 20-50% toxic phase
- YF-17D vaccine: single dose, lifelong protection (no booster required per WHO 2024)
- YEL-AVD rare adverse event (elderly highest risk)
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è â Japanese Encephalitis
- Asia + N Australia rural; rice paddy transmission
- Vector: Culex tritaeniorhynchus
- Reservoir: pigs (amplifying) + waterbirds (maintenance)
- 99% asymptomatic, 1% encephalitis (mortality 25%, sequelae 50%)
- Extrapyramidal movement + altered mental status + seizures
- Vaccines: JE-VC (Ixiaro), SA 14-14-2, CD-JEVAX
- Routine pediatric in endemic Asia + Taiwan
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è â West Nile Virus
- Worldwide (since 1999 NYC introduction)
- Bird reservoir (corvids especially); Culex vector
- Annual USA seasonal epidemic (summer + fall)
- 80% asymptomatic
- Neuroinvasive: meningitis, encephalitis, acute flaccid paralysis (polio-like, anterior horn)
- Elderly highest risk for severe
- No human vaccine; equine vaccines effective
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è â Tick-Borne Encephalitis
- Europe + Russia + Asia
- Ixodes ricinus / persulcatus
- Biphasic: fever â encephalitis 1-2 wk later
- Vaccines available (FSME-IMMUN, Encepur)
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è â Powassan
- USA NE + Great Lakes emerging
- Ixodes scapularis / cookei
- Transmits within 15 minutes (very fast vs Lyme 36-48 hr)
- Severe encephalitis
- No vaccine
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è â Diagnosis (All Flaviviruses)
- PCR (early acute)
- IgM (after day 5)
- Cross-reactivity considerations
- PRNT for definitive serotype
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è â Treatment
- All: supportive; no specific antivirals
- ICU for severe encephalitis
- Anticonvulsants
- Rehabilitation for sequelae