West Nile Virus - University of Washington



West Nile Virus

Classification:

• RNA virus

• genus: Flavivirus, family: Flaviviridae

• diameter: 40-60 nm. icosahedral and enveloped necleocapsid

Epidemiology:

• isolated in 1937

• widespread in Africa, Europe, Asia and Australia

• North America. The United States: in 1999

Pathology:

• incubation period: 3 and 14 days

• Three symptoms:

1. no symptoms in most people:

an asymptomatic infection, 80%

2. milder symptoms in some people:

West Nile Fever, up to 20%, incubation period of 2 to 8 days, resolved within 7 to 10 days

3. serious symptoms in a few people: fatal meningitis or encephalitis, about one in 150 people

|Encephalitis/Meningitis |Fever |Other Clinical/Unspecified |Total |Fatalities |

|508 |561 |39 |1108 |22 |

Total Human Cases Reported to CDC as of October 14, 2008

Transmission:

• Host: mainly birds but accidently infect mammals.

• amplified in birds

• the mammals are called dead-end infections

• vector: mosquito

• other transmission: exposure to infected blood, breastfeeding and even during pregnancy from mother to baby

Treatments

• no vaccine is available

• supportive care

Prevention

• Protect yourself from mosquito bites . Help reduce the number of mosquitoes in areas outdoors

• avoid bare-handed contact with dead animals[pic]

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