Epidemiology: Black widow spiders, recognized by a red hourglass marking on a shiny black ventral abdomen, are most abundant in the southeastern United States. Other Latrodectus species are present in other temperate and subtropical parts of the world.

Pathogenesis: Female widow spiders produce a potent neurotoxin that binds irreversibly to presynaptic nerve terminals and causes release and depletion of acetylcholine and other neurotransmitters.

• Clinical features
  • Within 60 min, painful cramps spread from the bite site to large muscles of the extremities and trunk.
  • Extreme abdominal muscular rigidity and pain may mimic peritonitis, but the abdomen is nontender.
  • Other features are similar to that of acetylcholine overdose (e.g., excessive salivation, lacrimation, urination, and defecation; GI upset; and emesis).
  • Although pain may subside within the first 12 h, it can recur for weeks.
  • Respiratory arrest, cerebral hemorrhage, or cardiac failure may occur.