Latrodectus moctons/ with the characteristic
ventral red hourglass. Reproduced with
permission from Knoop KJ, Stack LB, Storrow
AB, et al. The Atlas of Emergency Medicine.
3 rd ed. New York: McGraw-Hill Medical,
2009:505. Photo contributor: Lawrence B.
characteristics of the envenomed patient. In 20-25% of
for crotaline envenomation severity have been developed,
although most of these systems have limited utility in
clinical practice. Instead, the clinical effects of these
envenomations can be divided into 3 major categories:
minimal swelling and pain to severe edema, blistering,
ecchymosis, and necrosis. Hematologic effects can be
extreme after moderate to severe envenomations and
include thrombocytopenia, elevated coagulation studies
(prothrombin time and partial thromboplastin t ime), as
well as degradation of fibrinogen. Even with laboratory
evidence of severe coagulopathies, however, most patients
do not develop clinically significant hemorrhage.
Systemic effects are nonspecific; include abdominal pain,
vomiting, diaphoresis, tachycardia, and hypotension; and
may also be related to concomitant fear, anxiety, pain, or
In contrast with crotaline envenomations, patients
with significant elapid envenomations may initially
present with minimal symptoms. The neurologic
systemic symptoms that characterize North American
elapid envenomations are classically delayed for hours,
with reports of patients being asymptomatic up to 13
hours before developing ventilator-requiring r espiratory
failure. It is difficult to determine who with an elapid
exposure will develop symptoms of envenomation, as it
has been estimated that approximately 60% of those
bitten by a coral snake did not have an envenomation.
Alternatively, 15% of those with coral snake envenom
ations have no fang marks, and only 40% have any local
Thurman Rj, jones 10. Chapter 1 6. Environmental conditions. In: Knoop Kj, Stack LB, Storrow AB,
Thurman Rj, eds. The Atlas of Emergency Medicine. 3rd ed. New York: McGraw-Hill, 201 0 .
The clinical presentation of black widow spider bites is
also referred to as latrodectism. The key feature of this
syndrome is pain, which can be localized, radiating, or
referred. This pain is gradual, beginning upward of an
hour after the time of the bite, and is typically described
as being severe muscle cramping pain in the bitten
extremity, but especially with the North American black
widow spider can involve the abdominal muscles,
mimicking a surgical abdomen. Additional findings in
latrodectism include localized areas of diaphoresis, nau
sea, vomiting, restlessness, fasciculations, fear of death
(pavor mortis), and rarely priapism. The constellation of
symptoms called "facies latrodectismica" is also specific to
black widow spider envenomation and is a painful facial
grimace with associated conjunctivitis, blepharitis,
"Loxoscelism" is the term used to describe envenomation from recluse spiders and can be divided into
cutaneous and viscerocutaneous or systemic forms. Of
significant recluse spider envenomations, the cutaneous
form is the most commonly seen in North America. These
patients will initially have little to no pain at the bite site,
to ulceration and necrosis with surrounding erythema and
induration up to 7 days after the initial bite when an eschar
generally forms. This wound then slowly heals over weeks
to months. Systemic loxoscelism occurs 1-3 days after the
cific systemic symptoms such as fever, rash, weakness,
arthralgia, nausea, and vomiting. This autoimmune
hemolytic anemia can be accompanied by tluombocytope
nia and rhabdomyolysis and rarely progresses to renal
North American snakes rarely attack unprovoked, although
this provocation may be unintentional by the envenomed
patient. Most bites occur during warm months, as snakes
hibernate in the winter. They also more commonly occur
risk of being bitten by a venomous snake, and it has been
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