injuries poisoning
Spider Bites
Diagnosis of Spider Bites
Clinical evaluation Careful consideration of alternative diagnoses Spider bites are often falsely suspected by patients. Diagnosis is typically suspected based on history and physical signs, but confirmation is rare because it requires witnessed biting, identification of the spider (the spider is rarely recovered intact), and exclusion of other causes. In nonendemic areas, a brown spider bite should not be diagnosed without identifying the spider. Many patients incorrectly attribute much more common methicillin-resistantStaphylococcus aureus(MRSA) skin infections to brown recluse spider bites. Such infections should be excluded, as should other conditions that mimic spider bites (see table). Severe cases of latrodectism should be distinguished from acute abdomen, rabies, or tetanus. Spiders are identified by location and markings. Widow spiders live outdoors in protected spaces (eg, rock piles, firewood cords, hay bales, outhouses) and have a red or orange hourglass marking on the ventral abdomen. Brown spiders live indoors or in protected spaces (eg, in barns, attics, and wood piles; behind furniture; under baseboards) and have a fiddle- or violin-like marking on the dorsal cephalothorax, extending from the eyes to the abdomen. This marking may be difficult to recognize even in the intact spider. 