Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Black Widow Spider Envenomation

In the most recent issue of Wilderness & Environmental Medicine appears an article by Dr. Roy Strowd and colleagues, entitled “Black Widow Spider Envenomation, A Rare Cause of Horner’s Syndrome" (WEM 2012;23:158). Horner’s syndrome is a triad of a drooping eyelid, constricted pupil (of the eye), and lack of sweating on the face, all on the same side of the face. This has never previously been described, and the authors do an excellent job of describing Horner’s syndrome and how it might have been related to the bite.

Here’s a refresher on the clinical manifestations of a black widow spider bite: In the United States, the female black widow spider (Latrodectus mactans) is about 5/8 inch (15 millimeters) in body length, black or brown, and with a characteristic red (or orange or yellow) hourglass marking on the underside of the abdomen. The top side of the spider is shiny and features a fat abdomen that resembles a large black grape. The longest legs are directed toward the front. This species and other Latrodectus species are found scattered in rural regions, in barns, within harvested crops, and around outdoor stone walls. Some are arboreal.

The bite of the black widow spider is rarely very painful (usually more like a pinprick) and often causes little swelling or redness, although there can be a warm and reddened area around the bite. If much venom has been deposited, the victim develops a typical reaction well within an hour. Symptoms include muscle cramps, particularly of the abdomen and back; muscle pain; muscle twitching; numbness and tingling of the palms of the hands and bottoms of the feet; headache; droopy eyelids; facial swelling; drooling; sweating; restlessness and anxiety; vomiting; chest muscle spasms, causing difficulty in breathing; fever, and high blood pressure. A man may develop a persistent penile erection (priapism). A small child may cry persistently. A pregnant woman may develop uterine contractions and premature labor.

Untreated, most people recover without help over the course of 8 hours to 2 days. However, very small children and elderly victims may suffer greatly, with possible death. There is an antivenom available to medical practitioners for treating the bite of the black widow spider. It is used for severe, sometimes life-threatening, symptoms.


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Tags: Bites & Stings

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About the Author

Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.