(Click the link to comment and to vote – voting not working through email, sorry!)

An 8 year old boy caught a spider, placed it in a jar, and was showing it to his friend when he was bit on the hand. Initially he had minimal pain but now, 1 hour later, has significant hand and arm pain and he has vomited a few times. On physical exam, the wound site is a blanched rounded patch with central punctum, and palpation of extremity reveals muscle rigidity when compared to the other side.

Which of the following is true of this spider envenomation?