American dog tick

Definition

A species of hard tick (family Ixodidae), Dermacentor variabilis, distributed across eastern and central North America. A three-host tick that parasitizes mammals including dogs, deer, and humans, and is the primary vector of Rickettsia rickettsii (Rocky Mountain spotted fever) and Francisella tularensis (tularemia) in its range. Adults are recognized by ornate scutal patterns and relatively large size among ixodid ticks.

Etymology

Common name reflects North American distribution and frequent association with domestic dogs as hosts; "wood tick" reflects woodland habitat preference.

Example

In the eastern United States, peak adult activity of the American dog tick occurs in spring and early summer, when questing females on vegetation pose the principal risk of Rocky Mountain spotted fever transmission to humans walking through brushy areas.

Synonyms

• wood tick
• Dermacentor variabilis

Related Terms

• hard tick
• Ixodidae
• Dermacentor
• Rocky Mountain spotted fever
• Tularemia
• three-host tick
• questing behavior
• vector competence

Usage Notes

Often confused with the brown dog tick (Rhipicephalus sanguineus), which is a one-host tick primarily of domestic dogs and rarely transmits RMSF. The common name "wood tick" is shared with Dermacentor andersoni (Rocky Mountain wood tick) in western North America; geographic context clarifies which species is intended. In medical entomology, "American dog tick" specifically denotes D. variabilis, not merely any tick found on dogs in the Americas.