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Fact sheet: Winter Tick Infestation On Wild Elk ( DOC ) |
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| Source: | Environment Yukon | Date: | April 21, 2007 | |
FACT SHEET: WINTER TICK INFESTATION ON WILD ELKAn infestation of 'winter ticks' was verified in the Takhini and Braeburn elk herds in late March - April 2007 during radio-collaring exercises.o Eighteen female elk were radio-collared and many ticks were observed on and collected from each animal. o Collected ticks were sent to BC's Centre for Disease Control laboratory, and were identified as Dermacentor albipictus, commonly known as the 'winter tick' (or 'moose tick' or 'elk tick'). The winter tick does not pose a risk to human health. It does not carry Lyme disease nor other tick diseases transmissible to people. o The winter tick is a 'one-host tick,' which means it stays on one animal its whole life. This also makes disease transmission from animal to animal unlikely. The elk appeared healthy and in good body condition, despite hair loss around their necks and withers. o Elk are generally not affected by the ticks they carry, except for small areas of hair loss around their neck. o Many other elk in the herd also appeared to be infested, indicated by rough hair coats, scratching, and obvious areas of hair loss around their necks and withers. The current risk to moose in the Yukon from the winter ticks carried by elk is probably low, since moose numbers are low in the Takhini Valley, where the majority of elk live. o In southern jurisdictions (such as Alberta and Manitoba) severe tick infestations in moose are thought to occur in years when moose numbers are high or when warm summer and fall weather increase tick survival. o Moose infested with many winter ticks can die from emaciation and exposure. Moose lose energy from heat loss (with no hair), blood loss as ticks feed, and because they spend too much time/energy scratching and little time feeding. o Research done in captive animals showed that moose are not able to groom away as many ticks as elk or other species do. o Deer and bison can also carry a few winter ticks, but they do an even better job than elk of grooming ticks away, so few are carried through winter. o We do not know if winter ticks are present at low levels on deer or other wildlife in the Yukon. If present in low numbers, they would be very difficult to find, and likely only visible in winter - spring. The source of winter ticks to the elk is not known. o Some elk released in the early 1990s had winter ticks on them, but at that time it was believed that the ticks could not survive in the Yukon. o Warmer weather in recent years may have contributed to increased survival of ticks. o We do not know of cases of winter ticks surviving over winter in domestic animals in this area. Winter ticks have been found in some game farm animals in the past, but the ticks were eradicated. o Yukon elk reuse the same spring and fall habitat, which may be amplifying the infestation. The life cycle of the winter tick is important to understanding risks and control options. o In the fall, tick larvae cling to a passing animal and stay on that individual all winter, feeding intermittently and growing into adults. Ticks drop off the animal in the spring, and females lay eggs in the leaf litter where they drop. The eggs hatch to larvae in the summer, and in the fall the larvae climb up vegetation and wait for an animal to pass. Most ticks that drop onto snow in spring will die. Tick larvae that do not attach to a host in fall will also die. More work is needed to understand the impact on our elk and other wildlife species. o Department of Environment and the co-management partners of the Elk Management Team are investigating the risks and will consider strategies to control the infestation o Control strategies employed in other jurisdictions have had varying levels of success in reducing tick numbers. Some jurisdictions have used medicated feed stations, topical or injectable tick treatments, and controlled burns to reduce tick effects on wildlife or livestock. o Complete eradication of ticks may not be possible; instead if control is deemed necessary, the goal may be to reduce tick numbers and reduce the risk of spread to moose or other wildlife. If ticks are found, or for further information on ticks, you can contact Environment Yukon's wildlife veterinarian, Michelle Oakley, at (867) 634-2439 or 1-800-661-0408, or via email at Michelle.Oakley@gov.yk.ca. |
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