Spider bites are uncommon medical events, since there are limited number of spiders worldwide with fangs strong enough to pierce human skin, and most spiders bite humans only as a final defense when being crushed between skin and another object. Thus, most lesions attributed to spider bites are caused by some other etiology. The spiders that can cause medically significant bites include widow and false widow spiders (worldwide), recluse spiders (mostly North
and South America), Australian funnel web spiders (eastern coastal Australia) and Phoneutria spiders (Brazil). Acute spider bites most commonly result in a solitary papule, pustule, or wheal. Systemic symptoms can accompany envenomation of widow; funnel web, and Phoneutria spiders, and less often, those of recluse spiders.