Widow spider envenomation in Adult
Widow spider venoms are all very similar and contain a neurotoxic component called alpha-latrotoxin that causes massive presynaptic release of most neurotransmitters including acetylcholine, dopamine, epinephrine, norepinephrine, and glutamate. The result is initial stimulation of neuromuscular transmissions followed by depletion of synaptic vesicles. Local tissue changes are minimal as the venom lacks locally active toxins capable of producing inflammation.
There are approximately 31 widow spiders that are highly poisonous and are of medical importance. Most notable are the North American female black widow spider (Latrodectus mactans) and the Australian female red-back spider (Latrodectus hasselti). The female black widow spider is shiny, black, and has the characteristic red hourglass marking on the abdomen. The female red-back spider is also black and often has a line of small red dots on the abdomen.
A bite from a widow spider is typically sharp and somewhat painful. As a result, the victim often sees the spider. Tiny fang marks with a local inflammatory reaction may be evident. Most of the time, symptoms do not progress beyond this local reaction. However, with significant envenomation, massive release of neurotransmitters results in neuromuscular symptoms that can become dramatic within 30-60 minutes. Severe, painful, and sustained muscular spasms, especially in the large muscle groups of the abdomen, thighs, and lower back, develop. Massive release of acetylcholine causes the "SLUDGE" syndrome (salivation, lacrimation, urination, defecation, gastrointestinal distress, emesis and bronchorrhea), and catecholamine crisis (hypertension, tachycardia, fasciculations, hyperthermia, and diaphoresis). Symptoms usually resolve over a 3-7 day period, and deaths are rare.
T63.311A – Toxic effect of venom of black widow spider, accidental, initial encounter
217666004 – Latrodectism
- CA-MRSA skin infection (presenting as an abscess or abscesses or furunculosis) is often mistaken for spider bites. Have a very high suspicion for CA-MRSA and discount the patient history of a spider bite if there is any clinical suspicion of CA-MRSA.
- Scorpion sting
- Centipede envenomation
- Contact dermatitis / contact dermatitis (pediatric)
- Hymenoptera stings (bee sting, wasp sting)
- Insect bites
- Medication-induced drug reactions such as Stevens-Johnson syndrome and toxic epidermal necrolysis
- Necrotizing fasciitis
- Pyoderma gangrenosum
- Skin infections caused by cutaneous anthrax, Streptococcus, sporotrichosis, herpes zoster (shingles), and herpes simplex virus (HSV)
- Acute coronary syndrome