Where did West Nile virus come from?

West Nile virus is commonly found in humans and birds and other vertebrates in Africa, Eastern Europe, West Asia, and the Middle East. West Nile virus was first isolated in the West Nile province of Uganda in 1937 (3, 4). The first recorded large epidemics occurred in Israel from 1951 to 1954, and the largest recorded epidemic to date occurred in South Africa during 1974. Large human outbreaks of WN Encephalitis occurred in Israel in 2000 and have occurred in Southern France (1962), in southeastern Romania (1996), and in south-central Russia (1999) (5,6). Until 1999, West Nile encephalitis had not been documented in the Western Hemisphere. It is not known where the U.S. West Nile virus originated, but it is most closely related genetically to strains found in the Middle East.

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1. Where did West Nile virus come from?
2. How long has West Nile virus been in the U.S.?
3. I understand West Nile virus was found in "overwintering" mosquitoes. What does this mean?
4. How do people get West Nile encephalitis?
5. If I live in an area where birds or mosquitoes with West Nile virus have been reported and a mosquito bites me, am I likely to get sick?
6. How does West Nile virus actually cause severe illness and death in humans?
7. What proportion of people with severe illness due to West Nile virus die?
8. Is there a vaccine against West Nile encephalitis?
9. Is adulticide an effective means of controlling mosquitos?
10. ¿Se puede tratar el virus del Nilo occidental?
11. ¿Cuál es el riesgo de enfermarse del Virus del Nilo Occidental?
12. ¿Pueden infectarse los animales con el virus del Nilo Occidental?
13. ¿Todos los mosquitos portan el Virus del Nilo Occidental?