spider venom
-Furthermore, antimicrobially and cytolytically acting cupiennins have been identified
Despite public concern about spider bites, severe envenomation is rare. Few spiders have toxins in sufficient volume to harm people. Of those that do, some have limited habitats. Spider behavior may be caused by limited human interaction. Spider defense against predators include camouflage, and escape by falling or running. Biting is a last resort and the amount of venom injected varies greatly. Spider venom toxicity can be evaluated in experimental animals, or reported from accidental bites. Different experimental animals have different reactions to the same venom. The dose that is lethal to half of the animals poisoned is the LD50 and those values for mice is below. The LD50 of many poisons is known for humans but not that of spider venom.
Serious bites develop symptoms quickly, within the hour. While a serious medical condition may result (see latrodectims and loxocelism) fatalities are exceedingly rare. Appropriate medical treatment can improve speed of recovery. The scenario given in movies such as Arachnophobia, where bite victims die within minutes, does not occur. Small children are considered an exception because the amount of venom dispersed throughout the body is many times the concentration in an adult. There is at least one recorded case of a small child dying within 15 minutes of a bite from a Sydney funnel-web spider; that death occurred before the development of an antivenom. Since the antivenom was developed there have been no fatalities due to this species.
The neurotoxic venoms of the Sydney funnel-web spider and the Brazilian wandering spider are both known to have lethal complications. For the Brazilian wandering spider only 1 out of 200 bites is serious Atraxrobustus has a limited distribution and few bites are reported yearly.
The geographical range-
of the widow spiders is very great. As a result, far more people are exposed, worldwide, to widow bites than any other spider. Widow spiders bites are most often mild but may rarely cause serious complications in people. Fatalities had been reported as high as 5% of bites and as low as 0.2% of bites.
Loxosceles live in areas of South America and the southern United States. There are populations of desert and Arizona recluse in the Western deserts of the United Statesbut bites are rarely reported from these species. In established areas many spiders may populate the home. Even still the “reclusive” nature of the spider limits true bites. Of note, more bites had been reprted in Florida than recluses ever found in the area
