Most arachnids do not bite. Lactrodectus: widow spiders (black is worse), found outdoors, in garages, and in wood piles. Loxosceles: recluse spiders, found inside basements and dark places
S/S: local reactions are most common: papules, wheals, pustules, bite marks, tender nodule.
Spontaneous resolution within 10 days common. Systemic reactions less common. Widow: muscle pain, tremors, weakness, HA, n/v, shaking, generalized erythema, target lesion with punctum, tachycardia, hypotension. Recluse: sphingomyelnase; skin necrosis/ulceration, malaise, nausea, vomiting, fever, tachycardia, hypotension. Rare: acute hemolytic anemia, disseminated intravascular coagulopathy, rhabdomyolysis, myonecrosis, renal failure, coma, and death
Tx: remove living arthropods (mouthparts needed for ticks). Antihistamines, topical steroids, preventing reinfestation (education). Clean wound, ice/elevate, pain management; benzodiazepines, antivenom. For prevention use deet, wear long sleeved-pant clothing, mosquito nets, permethrin, frequent cleaning