Winter Tick

Winter Tick

Causative Agent

The winter tick (Dermacentor albipictus), is a skin parasite of wild ungulates that consumes a blood meal from its host in order to complete its life cycle.
Unlike mites, ticks are visible to the naked eye. Adult winter ticks are large, reddish-brown to grayish-brown in colour.

Distribution

Geographic:

Seasonality:

All stages of this parasite on large mammal hosts occur between fall and spring.

Click on the photo to enlarge.

Ticks engorged with blood

Hosts, Transmission and Life Cycle

Hosts:

D. albipictus requires one host to complete its life cycle.
Hosts: highest tick densities found on moose, but also on elk, deer and mountain sheep.
Individual moose have been found with > 50,000 ticks.

Transmission and Life Cycle:

Ticks require blood meals from a host to complete each stage of the life-cycle.
In the host-seeking stage, larvae climb and congregate on tips of vegetation in September and October. Larvae are very resistant to cold and snow.
Once on the host, a blood meal is taken and larvae molt to nymphs and become adults by March-April.
Adults that are fully engorged with blood detach in late March through April and lay eggs among leaves or in soil in June. The adults are less resistant to cold and snow at this time.
Eggs hatch and larvae seek hosts to repeat the cycle.

Signs and Symptoms

Feeding by D. albipictus can result in local inflammation, edema, hemorrhage, irritation, and hair loss from grooming.
Heavily infested hosts groom extensively and may suffer from extensive hair loss, loss of body fat stores, loss of blood and even death from exposure and starvation. The incessant need to groom can seriously interfere with feeding.
Moose may rub up against trees and other objects in attempts to remove ticks.
Moose with extensive hair-loss look white or grey in appearance and are often called “ghost moose”. They are prone to heat loss in winter.
Other ungulate species are less affected by winter ticks than moose, and although there can be significant hair loss, it is rare to see other species in as poor condition.

Meat Edible?

Meat is edible but the quality may be reduced if the animal is in poor condition.

Human Health Concerns and Risk Reduction

D. albipictus may feed on humans but this appears to be rare.
Transfer of D. albipictus to domestic animals may occur. The response of domestic animals to tick infestation is similar to that of wild mammals.

Samples for Diagnosis

Remove tick from hide while being careful not to leave mouth parts embedded in the skin.