Animal HealthDiseasesWest Nile Virus

West Nile Virus


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2019 Positive West Nile Map

As of June 30, 2019



West Nile virus (WNV) is a mosquito-borne disease that was first isolated in 1937 from the blood of a woman in the West Nile district of Uganda. Since then, the WNV has been commonly found in humans and birds and other vertebrates in Africa, Eastern Europe, West Asia, and the Middle East. The WNV first appeared in the United States in 1999 in New York City and has continued to spread throughout the United States.

ReportWest Nile Virus is a reportable disease. Report any confirmed or suspected case to: MT State Veterinarian 406-444-2043 and MT USDA APHIS Veterinary Services 406-449-2220.

Animal Health Bureau

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Department of Livestock
Animal Health Bureau
PO Box 202001
Helena, MT 59620-2001
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