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Spider Bites and Stings

Spiders. There are about 30,000 species of spiders in the world but only about 50 of those species bite humans, and although they may be painful, most have no medical sequelae either because the spiders have short fangs, small fangs or inadequate venom. So although they might hurt and people might say, "Iíve been bitten by a spider" most of them donít have much medical importance that you have to worry about. The biting part of the mouth of the spider.

Six species in the United States are capable of delivering necrotic bites, and the necrotic bites are the ones that we are most concerned about and the ones that we worry about, and obviously are the worst problem for the patient. Those are the ones that lead the sequelae and also cause quite a bit of pain. There are two genera in the United States that produce life-threatening bites. The violin backed spiders, particularly the Loxosceles, the Brown Recluse-type spiders and the black widow spiders. But garden spiders will produce a painful bite.

Wolf spiders are very common, they are very ugly spiders and they also produce a very painful bite. And they are very scary so somebody is going to really be upset if they get bitten by a wolf spider. There is something called a Hobo Spider, which has just started to be seen in the Northwestern part of the United States, and itís going to be a pretty bad one, I think. Aggrestus, second part of itís name, suggests that it is a little more aggressive.

This is the distribution of these spiders in the United States and this is from the CDC/MMMR report and it discusses the so-called Hobo spider, Tegenaria aggrestus. And this is the area that the Hobo spider has been reported in, but as you can see, itís kind of creeping down.

There are thirteen species of violin backed spiders. The Brown Recluse is the Loxosceles reclusa. Itís been reported in all 50 states so nobody is escaping it. But itís more common in Tennessee, Arkansas, Missouri and Kansas and thatís where the most reported bites have been. The most reported necrotic bites. They are about 1-6 cm in size, light tan to dark Brown, they key is a small body with the long thin legs, because they are very recognizable.

Hereís one right here. As you can see, it has long spindly legs, kind of a tiny slender little body. If you can appreciate that, hereís the violin, right up here and hereís the stem of the violin. This is what you see a lot, which is a crushed spider. And as you can see, if somebody describes that heís going to say, "Oh, I saw the legs." So a lot of times thatís what the patient is going to say.

Okay, what about the Brown Recluse spiders? They are very shy and nocturnal and non-aggressive, so you have to go to where they are. They donít usually come to where you are except to hide. They live in dark places; woodpiles, cellars, unfortunately closets, and unfortunately clothing folds, because thatís usually how you get bit.

How do you treat them? Iím suggesting medical management is the treatment and not do surgery until it is completely healed. And then just if you want to repair it. The treatment: Lloyd King at Vanderbilt has come up with some of this. His idea is the so-called RICE, which is rest, ice compresses and elevation. I would say if I had one thing to treat any kind of bite with it would be ice. Ice can take something that is going to be horrendous.

Iíve talked about this actually because I have these spiders where I live. I think this is the best way to get rid of them because they are big, spindly spiders. Their abdomens donít cross and spray so itís really hard to get rid of them. What this is, is this is a trap and this is against the wall where they walk, and hereís one and hereís one.

Okay, Brown Recluse spiders. I usually treat them until the redness goes away. If thereís any redness left I continue them on it. In terms of erythromycin, obviously thatís a safe drug. If I see somebody that comes in that I think has a bite but Iím not sure itís a spider bite, Iíll do the ice and Iíll do the erythromycin, I wonít do the Dapsone. But if there is a Brown Recluse bite I will put them on the Dapsone.

Dapsone inhibits polymorphonuclear leukocytes. Thatís the main function of it. Although Iíve put up the sphingomyelin as one of the Ö probably the active ingredient that causes the necrosis, it may be that itís polyís that