Dermacentor variabilis

style="background:#Template:Taxobox colour;"|Dermacentor variabilis
style="background:#Template:Taxobox colour;" | Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Arachnida Subclass: Acari Superorder: Parasitiformes Order: Ixodida Family: Ixodidae Genus: Dermacentor Species: D. variabilis
Binomial name
Dermacentor variabilis (Say, 1821)
Normal range in red; other reports in blue Normal range in red; other reports in blue

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ilan Dock, B.S.

Overview

Dermacentor variabilis, also known as the American dog tick or Wood tick, is a species of tick that is known to carry bacteria responsible for several diseases in humans, including Rocky Mountain spotted fever and tularemia (Francisella tularensis). It is one of the most well-known hard ticks. Diseases are spread when it sucks blood from the host, which could take several days for the host to experience some symptoms.

Life Cycle

This image displays an example of the tick lifecycle, based on stages and the months that they are most likely to occur during.

• A tick's life cycle is composed of four stages: hatching (egg), nymph (six legged), nymph (eight legged), and an adult.
• Ticks require blood meals to survive through their life cycle.
• Hosts for tick blood meals include mammals, birds, reptiles, and amphibians. Ticks will most likely transfer between different hosts during the different stages of their life cycle.
• Humans are most often targeted during the nymph and adult stages of the life cycle.
• Life cycle is also dependent on seasonal variation.
• Ticks will go from eggs to larva during the summer months, infecting bird or rodent host during the larval stage.
• Larva will infect the host from the summer until the following spring, at which point they will progress into the nymph stage.
• During the nymph stage, a tick will most likely seek a mammal host (including humans).
• A nymph will remain with the selected host until the following fall at which point it will progress into an adult.
• As an adult, a tick will feed on a mammalian host. However unlike previous stages, ticks will prefer larger mammals over rodents.
• The average tick life cycle requires three years for completion.
  • Different species will undergo certain variations within their individual life cycles.

Dermacentor variabilis Transmitted Diseases

Primary organisms as well as corresponding diseases transmitted by Dermacentor variabilis include:

• Anaplasma phagocytophilum, the causative agent of HGE (human granulocytic ehrlichiosis), and Ehrlichia chaffeensis, the causative agent of HME (human monocytic ehrlichiosis).
• tick paralysis by elaboration of a neurotoxin that induces rapidly progressive flaccid quadriparesis similar to Guillain-Barré syndrome.

• Rickettsia Ricketsii, the causative agent of Rocky Mountain spotted fever.
• F. tularensis, the causative agent of Tularemia.
• D. variabilis may be exposed to Borrelia burgdorferi, the causative agent of Lyme disease, these ticks are not competent vectors for the transmission of this disease.

Geographic Distribution

• Areas along the Pacific, West coast
• East of the Rocky Mountains until the Eastern coast

Geographic distribution of the American Dog tick in the United States.

External links

• Ohio State University Extension Fact Sheet
• Illinois photographs
• Iowa tick images
• Dealing with dog ticks
• American dog tick on the University of Florida / Institute of Food and Agricultural Sciences Featured Creatures website

Gallery

• Common name: American dog tick
• Scientific name: Dermacentor variabilis
• Reservoir: small rodents (larvae and nymphs); dogs and mammals (adult ticks)
• Geographic distribution: Rocky Mountains, Pacific Coast
• Disease transmitted: Rocky Mountain spotted fever, tularemia

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  American dog tick (Dermacentor variabilis)
  Adapted from CDC

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  Approximate distribution of the American Dog tick
  Adapted from CDC