American dog tick from Pennsylvania

On Monday 18jun07 found a large black tick, over 1/8-in long, attached to upper arm. Apparently brought home from rural NE Pennsylvania, US.

There seem to be no good web sites for general identification of ticks. The Wikipedia article is not very good.

These are Pennsylvania-oriented sites:

Pulling with tweezers did not remove it. Water had no effect. A sharp hot soldering iron in close proximity disturbed it but killed it without convincing it to withdraw. Applying heat or any other irritant is inadvisable, because it may stimulate the tick to regurgitate into the host, increasing the chance of infection. It was removed intact by cutting the attached skin, with diagonal pliers cleaned with alcohol. The officially sanctioned procedure is to grasp firmly by the head/mouth with sharp tweezers and pull slowly and firmly until it comes out. Dig out any remaining parts from the skin, and disinfect site with alcohol etc. Save the tick in case of illness so that a more accurate diagnosis can be made, in the freezer and/or alcohol.

Identification by eye was difficult, without a good gallery of images to compare to. It seemed to be an American dog tick or a Lone Star tick (adult female), partly due to the large size. Unlikely to be a carrier of Lyme disease. Small possibility of carrier of Rocky Mountain Spotted Fever.

Scanning images into the computer the next day gives a much better look. Definitely seems to be an American dog tick, Dermacentor variabilis — about the most common tick in the US. The Wikipedia article is just a stub. Here are some good sites:
*[Article on American dog tick.] Harvard University – Ticks of New England: Fact Sheet and Gallery
*[Ohio State University Extension Fact Sheet]
*[Illinois] photographs, big and beautiful
*[Iowa tick images]

American dog tick, adult female. NE Pennsylvania, US.

Note intact mouth parts, embedded in skin of host.

American dog tick, bottom view, adult female. NE Pennsylvania, US.


One Response to “American dog tick from Pennsylvania”

  1. Anonymous Says:

    Hate to burst your bubble, but the American Dog tick (Dermacentor variablis) has been shown in several scientific studies published in medical journals to carry Borrelia burgdorferi, the spirochete bacteria that causes Lyme disease.

    I have a picture from a friend with the dog tick imbedded in her leg, which is the exact spot she developed a rash 7 days later. She took photos at my advice then later tested + for Lyme.

    The dog tick is also known to carry Rocky Mountain Spotted Fever, tularemia, and ehrlichiosis diseases.

    search for these abstracts:

    PMID: 14680123
    PMID: 11268694
    PMID: 9027688
    PMID: 8780455
    PMID: 7677212
    PMID: 7943575
    PMID: 7932597
    PMID: 1460617
    PMID: 1941936
    PMID: 3926816
    PMID: 6516460

    Watch out for ticks and learn about signs of tick-borne disease!

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