Necrotic Arachnidism

Via ProMED-mail: Press Peru reports 2264 bites, three of them fatal, by the Chilean recluse spider in 2006. Loxosceles laeta and related recluse spiders are also known as violin, corner, fiddleback, or domestic spiders.

Here's some recluse information from the Hobo Spider Web Site:

The recluse spiders, genus Loxosceles, belong to a unique family of arachnids known as the Sicariidae, or six-eyed sicariid spiders. The sicariids have six (rather than the typical eight) eyes, arranged in a horseshoe pattern in three clusters of two eyes each. The family consists not only of the recluse spiders, but also of the six-eyed crab spiders, genus Sicarius, of Central and South America, and South Africa. Recluse spiders were the first spider group to be recognized as a causative agent of the disease state now known as necrotic arachnidism, and this condition, when caused by a recluse spider, is properly termed loxoscelism. Loxoscelism was first recognized in 1872 when Chilean physicians linked a peculiar skin lesion known as the "gangrenous spot of Chile" to bites by the Chilean recluse spider, Loxosceles laeta. The brown recluse, L. reclusa, became the first U.S. spider associated with necrotic arachnidism in 1957, when it was linked to severe bites in the midwest. All recluse spiders, as well as the six-eyed crab spiders, are now considered venomous to humans.

Brown recluses are not as common in the United States as people imagine. Bites reported in areas outside its range, such as Massachusetts, are likely due to other causes---for example, the local Yellow Sac spider:

Cheiracanthium mildei was first identified as a cause of necrotic arachnidism in 1970, when it was linked with skin lesions in the Boston, Massachusetts area (where it is the most common spider found in houses); it is also common in houses in New York City, and may well be the cause of recent "brown recluse bite" rumors circulating there. In the late 1970's and early 1980's mildei produced a significant number of bites in the Provo, Utah area. C. inclusum has been reported responsible for bites in Georgia and southwestern Canada; bites by this species are probably far more common and widespread than this however, and it is likely that more reports will surface as Cheiracanthium species become better known as clinically significant spiders.