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Date: Dec 19, 2002
Posted by: Robert G McLean (Robert.G.McLean@aphis.usda.gov)

Dr. Saito

We appreciate your update on the testing results from owls and hawks. The first major question was answered in that at least some died from WNV infection. That is important because we know that thousands of American crows died from WNV but there were other causes of mortality in their populations as well. We look forward to the completed results and the evaluation of the impact of WNV on these important species.

Thanks, Bob

Robert G. McLean, Ph.D.
Program Manager Wildlife Diseases
National Wildlife Research Center
WS/APHIS/USDA
4101 Laporte Avenue
Fort Collins, CO  80521-2154
Telephone: (970) 266-6066
FAX: (970) 266-6138
e-mail: Robert.G.McLean@APHIS.USDA.GOV

Emi K Saito wrote:

I have received several inquiries as of late regarding an update on the raptor situation that was experienced from approximately mid-August through September in several states. As many of you may already know, the USGS National Wildlife Health Center (NWHC) started receiving reports from raptor rehabilitators mid-August about an influx of raptors being admitted/reported to their facilities. In an effort to determine whether these birds' symptoms/deaths were really due to WNV or to something else being overlooked because we were all concentrating on WNV and assuming a WNV-positive bird died from WNV, the NWHC, with participating state agencies, initiated a very strict protocol to accept some of these raptor cases for diagnostic evaluation. The NWHC WNV testing protocol consists of isolating virus from organ tissues (such as kidneys, spleen, brain, etc.) and then performing RT-PCR on the virus isolates to confirm WNV. Other tests run include looking for other infectious causes (bacterial, fungal or other viral) and toxin exposure. As of December 18, the NWHC has received 73 raptor carcasses from several states. Diagnostic evaluation has been completed for 30 cases : 9 died due to WNV, 6 were infected with WNV but did not show any or sufficient brain damage to explain symptoms, 4 were WNV-negative but had sufficient brain damage suggestive of viral encephalitis, and 11 died from other causes. In sum, NWHC has diagnosed 9 confirmed and 10 possible cases of WNV. Further confirmatory testing is planned for the 10 possible cases.

We do still have 43 cases pending and still are accepting some cases, depending on the history. Our preliminary findings are not meant to imply that WNV was responsible for all of the cases seen this past season, but that WNV did play some role in the caseloads seen. We have been fortunate in having the raptor rehabilitators be very cooperative and willing to share information with us about the cases they had seen. We are in the process of obtaining data to establish a baseline, to grasp the full geographical extent of the situation and to estimate the number of predatory birds affected by WNV this year.

 Emi Kate Saito, VMD, MSPH
 West Nile Virus Surveillance Coordinator
 U.S. Geological Survey
 National Wildlife Health Center
 6006 Schroeder Road
 Madison, WI  53711-6223
 office: (608)270-2456
 fax: (608)270-2415
 email: esaito@usgs.gov

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