Necrotic arachnidism--Pacific Northwest, 1988-1996.

Although spider bites are common in many parts of the United States, most domestic spiders are not substantially venomous to man. The best known exceptions are widow spiders (Latrodectus spp., including the black widow L. mactans) and brown spiders (Loxesceles spp., particularly the brown recluse, Lox. reclusa). However, cases of arachnid envenomation from the hobo spider (Tegenaria agrestis) are being reported increasingly in the Pacific Northwest. This report summarizes investigations of three cases of T. agrestis bites among persons in Idaho, Oregon, and Washington; spider bites reported to U.S. poison-control centers during 1994; and emphasizes the need for physicians in the northwestern United States to consider the species as a cause of toxic arachnidism.