Tarantula Envenomation Clinical Presentation

Updated: Sep 26, 2016
  • Author: Scott D Fell, DO, FAAEM; Chief Editor: Joe Alcock, MD, MS  more...
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Presentation

History

Bites

Unprovoked bites are uncommon because tarantulas are usually docile; patients usually are able to tell what has inflicted their injury.

Most patients bitten by tarantulas complain of mild pain similar to a pinprick. Some tarantula bites can cause severe pain, local swelling, and numbness.

Some patients have reported arthritic stiffness lasting for weeks following bites near joints. No permanent deficits have been reported.

Skin

Symptoms at the site of hair penetration include irritation, severe pruritus, edema, and erythema.

Rarely, anaphylaxis may follow such exposure.

Eye

Ocular exposure to tarantula hairs may lead to redness and an itchy or gritty sensation.

A careful history may be necessary to identify this cause of ocular symptoms because patients may not relate the symptoms directly to tarantula exposure. [4]

Respiratory

Significant allergic rhinitis may be present in patients who have inhaled hairs.

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Physical

The findings following a tarantula bite closely resemble those of Hymenoptera stings (ie, local swelling and erythema). As noted above, the exception is the bite of the funnel web spider, which is found outside the United States.

Skin

Like insect bites, tarantula bites cause local erythema and edema.

Erythema and pruritic papules may be observed in skin exposed to urticating abdominal hairs. This exposure also may lead to an allergic reaction and, rarely, precipitates anaphylaxis.

The risk of serious reactions is much higher outside the United States, where spiders with type III and type IV hairs are found.

Eye

Several cases of ocular injuries from discharged hairs have been described in the literature. [5, 6, 7, 8, 9, 10]

Patients may have a red eye [11] and associated keratoconjunctivitis. Depending on the depth of hair penetration, patients also may have conjunctival injection or anterior chamber inflammation.

Ophthalmia nodosa has been diagnosed in several individuals with resulting panuveitis that still was clinically active up to 72 months following the initial diagnosis. [5, 9]

Multiple fine intracorneal hairs may be observed on slit-lamp examination; however, they may be elusive because of their small size and location.

The right eye is affected more commonly than the left eye in patients who are right-hand dominant and handle tarantulas.

Respiratory

Allergic rhinitis signs and symptoms may be present if a patient has inhaled urticating hairs.

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Complications

Ophthalmia nodosa and panuveitis can complicate ocular exposure to tarantula hairs.

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