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Wild deer disease surveillance continues; new bovine TB positive deer confirmed

Tuesday, December 22nd, 2009 at 6:39 am

With test results for the entire fall sample of hunter-harvested deer in northwestern Minnesota pending, tissue samples from one suspect deer submitted for expedited testing have come back positive for bovine tuberculosis (TB).

The National Veterinary Services Lab in Ames, Iowa, confirmed the test Dec. 16, according to the Minnesota Department of Natural Resources (DNR) and the Minnesota Board of Animal Health (BAH).”This deer is just one of more than 1,400 samples we collected from hunters since the opening of the season,” said Dr. Michelle Carstensen, DNR Wildlife health program coordinator.

“While it did not have obvious lesions in the lungs or chest cavity that are most indicative clinical signs of bovine TB, it did have an enlarged and abscessed lymph node, which is also associated with TB infection, and is why the sample was submitted for immediate testing.”

Complete results of these tests, along with the test results from the 2,685 samples collected in southeastern Minnesota for CWD testing, are not expected for about two months, she added.

The bovine TB positive deer was a 3 ½-year-old buck, which was taken within three miles of where previous bovine TB positive deer have been found.

“This finding reinforces the need to remain focused on continuing efforts to accomplish the goal of completely eliminating the disease in Minnesota,” said Carstensen.

This latest result brings the total number of wild deer found positive for bovine TB in Minnesota to 27 since the disease was first found in the state in 2005. All of the 26 previously infected deer were animals born in 2005 or earlier. This most recent bovine TB positive deer was born in 2006, but there is still no indication of significant recent infections or that the disease is efficiently spreading in the deer population.

The DNR has conducted surveillance for TB in hunter-harvested deer in the bovine TB area every fall since 2005. To date, more than 7,500 deer taken by hunters and sharp-shooters have been tested in this area and there has been a decline in the number of positive deer found over the past three years. In 2007 there were 11 bovine TB positive deer detected, in 2008 there were six and in 2009 there were three.

“This is encouraging given that we have increased surveillance efforts over the past few years and yet have detected fewer positive animals and they were all found in a relatively small geographic area,” Carstensen said

Plans for 2010 bovine TB testing

The surveillance goals for the 2009-2010 fall and winter called for at least 1,500 deer samples from inside the Modified Accredited Zone (a zone established by the Board of Animal Health to help control bovine TB in cattle) and at least 300 deer from outside that zone. Of the 1,476 samples collected for bovine TB testing this fall, 542 were from outside
the Modified Accredited Zone and 934 were from inside the zone.

The DNR’s winter plans call for obtaining additional samples in the Modified Accredited Zone, potentially removing additional positive animals, and helping maintain reduced deer densities in the area where infections have been found:

* Hold a special late-season deer hunt in deer permit area 101 from Saturday, Dec. 26, through Sunday, Jan. 10.
* Conduct an aerial deer population survey in late January or early February in the area where bovine TB positive deer have been found.
* USDA Wildlife Services staff will be contracted to do further deer removal for testing utilizing ground sharpshooting from Feb. to April (no aerial deer shooting is planned this winter – deer were taken by aerial shooting in late winter of 2008 and 2009).

Next fall, hunter-harvested deer surveillance will again be conducted within the larger bovine TB zone, but specific sampling goals have not yet been established. Wild deer surveillance for bovine TB will continue every year until no positive animals are detected for five consecutive years.

For more on the bovine TB eradication effort in deer, go to www.mndnr.gov/bovineTB.

For more on the state’s overall bovine TB eradication efforts, go to www.bah.state.mn.us/tb/index.

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