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West Nile Virus in Wildlife

Michigan. DNR. West Nile Virus in Wildlife. Thomas M. Cooley Rose Lake Wildlife Disease Lab Michigan Department of Natural Resources. Michigan. DNR. West Nile Virus: Reservoir Hosts. Isolated from numerous wild birds. Wetland and terrestrial species. Birds are primary amplifier hosts.

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West Nile Virus in Wildlife

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  1. Michigan DNR West Nile Virus in Wildlife Thomas M. CooleyRose Lake Wildlife Disease LabMichigan Department of Natural Resources

  2. Michigan DNR West Nile Virus: Reservoir Hosts Isolated from numerous wild birds. Wetland and terrestrial species. Birds are primary amplifier hosts. Reservoir status not known. Migratory birds have a role in the distribution and re-introduction of virus into northern latitudes. Role of mammals is not known, but they appear to be dead end hosts.

  3. Michigan DNR 194 Avian Species - 130 native/wild, 64 captive/exotic (38 Antibody positive) In the United States:USGS Data 28 Mammalian Species – 8 wild, 20 captive (7 Antibody positive) 2 Reptilian Species – 2 captive (1 Antibody positive)

  4. Michigan DNR Corvid Avian Species American Crow Blue Jay Common Raven In Michigan:

  5. Michigan DNR Non-Corvid WildAvian Species Great Horned Owl Red-tailed Hawk Northern Goshawk Sharp-shinned Hawk Cedar Waxwing Ruffed Grouse Canada Goose House Finch Bald Eagle – diagnosed in Wisconsin In Michigan: Photo Credit: Dave Kenyon DNR

  6. Michigan DNR Mammalian Species Eastern Fox Squirrel In Michigan:

  7. Michigan DNR Naturally occurring - Transmission via mosquito bite. Transmission Routes: In captivity (research) – Transmission via fecal or oral secretions. Transmission via the eating of infected prey. It has not been proven that these 2 types of transmission occur naturally.

  8. Michigan DNR Clinical Signs: Depression, anorexia (weight loss), dehydration, ataxia (loss of coordination), disorientation, inability to fly or use their legs, head tremors, eye twitching, apparent blindness, seizures/convulsions, abnormal head posture, circling, weakness, and death.

  9. Michigan DNR Great Horned Owl diagnosed with WNV in 2002

  10. Michigan DNR

  11. Michigan DNR Post Mortem Examination Many organs are affected by the virus but in most cases appear grossly normal. The heart and kidney are collected for testing.

  12. Michigan DNR Corvid avian species necropsies are performed at MSU’s Diagnostic Center for Population and Animal Health (DCPAH) Post Mortem Diagnosis Non-Corvid avian species and mammalian species necropsies are performed at the DNR’s Rose Lake Wildlife Disease Lab Testing is performed at MSU’s DCPAH

  13. Michigan DNR Gross lesions in birds are rare. Brain showing petechial hemorrhages. Gross Lesions Heart with tan areas of myocardial necrosis and myocarditis. Enlarged spleen. Intestine with pseudomembranous or necrotizing enteritis.

  14. Michigan DNR Impact on Wildlife: Reports of lower numbers of various avian and mammalian species have occurred but there is no evidence that this is or is not due to WNV. Appears avian populations may be impacted in isolated areas of the state, but not statewide.

  15. Michigan DNR Impact on Wildlife:

  16. Michigan DNR Impact on Wildlife: WNV may cause chronic infection in birds that reappears during times of stress. Birds may die of secondary organ damage in months or years following the initial infection.

  17. WN ? Michigan DNR WNV may spread to the subtropics where species are stressed by habitat destruction and where year-round mosquito transmission would be possible. Impact on Wildlife: Endangered & threatened species may be impacted where the death of even a few individuals could be significant.

  18. Michigan DNR Monitoring Impact on Wildlife: Testing of birds and mammals with central nervous system signs. Testing until at least 2 positives per species are found in the state.

  19. Michigan DNR Monitoring Impact on Wildlife: Web-based submission of data and posting of results. Tables & graphs: Summaries of dead bird and mammal reports. Summaries of test results.

  20. Michigan DNR

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