WEST NILE VIRUS: AN WEST NILE VIRUS: AN INVASIVE PATHOGEN TO THE INVASIVE PATHOGEN TO THE

AMERICASAMERICAS

WEST NILE VIRUS: AN WEST NILE VIRUS: AN INVASIVE PATHOGEN TO THE INVASIVE PATHOGEN TO THE

AMERICASAMERICAS

Christopher J. Brand, USGS National Wildlife Health Center, Madison, Wisconsin

Worldwide DistributionWorldwide DistributionWorldwide DistributionWorldwide Distribution

www.cdc.gov/ncidod/dvbid/westnile/index.htm

Transmission CycleTransmission CycleTransmission CycleTransmission Cycle

Thousands of crows died from deadly virus and 17 other native

bird species affected also

West Nile Virus Epizootic in Wild

Birds1999

Source of West Nile Virus in Source of West Nile Virus in North AmericaNorth America

Source of West Nile Virus in Source of West Nile Virus in North AmericaNorth America

• Infected mosquito?Infected mosquito?• Infected bird?Infected bird?• Infected human or horse?Infected human or horse?• Another vertebrate host?Another vertebrate host?• Bio-terrorism? Bio-terrorism? • Likely to remain unknownLikely to remain unknown

• Infected mosquito?Infected mosquito?• Infected bird?Infected bird?• Infected human or horse?Infected human or horse?• Another vertebrate host?Another vertebrate host?• Bio-terrorism? Bio-terrorism? • Likely to remain unknownLikely to remain unknown

Spread of WNV: 1999-2002Spread of WNV: 1999-2002Spread of WNV: 1999-2002Spread of WNV: 1999-2002

1999 200020012002

West Nile Virus in Birds, 2002West Nile Virus in Birds, 2002West Nile Virus in Birds, 2002West Nile Virus in Birds, 2002

>162 Susceptible Bird Species>162 Susceptible Bird Species>162 Susceptible Bird Species>162 Susceptible Bird Species

• Passeriformes (45%)Passeriformes (45%)

• Falconiformes (12%)Falconiformes (12%)

• Anseriformes (6%)Anseriformes (6%)

• Ciconiiformes (5%)Ciconiiformes (5%)

• Columbiformes (5%)Columbiformes (5%)

• Passeriformes (45%)Passeriformes (45%)

• Falconiformes (12%)Falconiformes (12%)

• Anseriformes (6%)Anseriformes (6%)

• Ciconiiformes (5%)Ciconiiformes (5%)

• Columbiformes (5%)Columbiformes (5%)

> 37 Mosquito Species Infected> 37 Mosquito Species Infected> 37 Mosquito Species Infected> 37 Mosquito Species Infected

• AedesAedes– albopictusalbopictus

• CulexCulex– salinarius, tarsalissalinarius, tarsalis

• OchlerotatusOchlerotatus– atropalpus, j. japonicusatropalpus, j. japonicus

• AedesAedes– albopictusalbopictus

• CulexCulex– salinarius, tarsalissalinarius, tarsalis

• OchlerotatusOchlerotatus– atropalpus, j. japonicusatropalpus, j. japonicus

West Nile Virus in Horses, 2002West Nile Virus in Horses, 2002West Nile Virus in Horses, 2002West Nile Virus in Horses, 2002

>12,038 Cases> 733 Deaths

West Nile Virus in Humans, 2002West Nile Virus in Humans, 2002West Nile Virus in Humans, 2002West Nile Virus in Humans, 2002

>4,156 Cases284 Deaths

200120022003

?

Potential Dissemination of WNV Potential Dissemination of WNV by Migratory Birdsby Migratory Birds

Potential Dissemination of WNV Potential Dissemination of WNV by Migratory Birdsby Migratory Birds

Migratory Bird SamplingMigratory Bird SamplingMigratory Bird SamplingMigratory Bird Sampling

Great Meadows NWR, MAWertheim NWR, NY

Cape May NWR, NJChincoteague NWR, VA

Croatan Nat’l Forest, NC

Savannah NWR, SC

St. Marks NWR, FL

Key West, FL

Jamaica Bay WR, NY

Merritt Island NWR, FL

JN ‘Ding’ Darling NWR, FL

Mark Twain NWR, IL

Shelby County, TN

Southeast Louisiana NWR, LA

Goose Island SP, WI

Mercedes, TXLower Rio Grand Valley NWR, TXLaguna Atascosa NWR, TX

Research Results:Research Results:WNV Transmission by ContactWNV Transmission by Contact

Research Results:Research Results:WNV Transmission by ContactWNV Transmission by Contact

Research Results:Research Results:WNV Transmission by IngestionWNV Transmission by Ingestion

Research Results:Research Results:WNV Transmission by IngestionWNV Transmission by Ingestion

Research Results:Research Results:WNV Vaccine EfficacyWNV Vaccine Efficacy

Research Results:Research Results:WNV Vaccine EfficacyWNV Vaccine Efficacy

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West Nile Virus:West Nile Virus:A Threat to Biodiversity???A Threat to Biodiversity???

West Nile Virus:West Nile Virus:A Threat to Biodiversity???A Threat to Biodiversity???