ARTHROPOD BITES AND STINGS. Chrisnel Jean, D.O March 9, 2006 EM Lecture Session. Hymenoptera: Most important venomous insect known to humans More fatalities result from stings by these insects. Three major subgroups: Apidae includes honeybee and bumblebee
Chrisnel Jean, D.O
March 9, 2006
EM Lecture Session
Most important venomous insect known to humans
More fatalities result from stings by these insects.
Three major subgroups:
Apidae includes honeybee and bumblebee
Vespidae includes yellow jackets, hornets and wasps
Most of all allergic reaction reported yearly occur from vespid stings.
Apids are usually docile, stinging only when provoked.
Female bee is capable of stinging only once. (Male bees have no stinger).
Vespidhave ability to perform multiple stings.Hymenoptera (WASPS, BEES, AND ANTS)
Severe local reaction may involve one or more neighboring joints.
If the sting involve the mouth or throat, it can produce airway obstruction.
Multiple stings (Africanized bees) can lead to systemic toxic reaction.
Symptoms may resemble anaphylaxis, but these pts can also develop N/V/D.
They may also have HA, fever, drowsiness, involuntary muscle spasms, edema without urticaria, and convulsions.
Complication Renal / Hepatic failure, DIC, and DeathHymenoptera Venom: Local Reaction Toxic Reaction
Wash the sting site with soap and water to decrease risk of infection.
Intermittently apply ice to the site to limit local reaction and delay absorption of venom.
Oral antihistamines and analgesic may limit discomfort, pruritis, and decrease local reaction.
If pts develop symptoms of anaphylaxis then most important agent to give is Epinepherine.
Epinepherine 0.3 to 0.5mg (0.3 to 0.5 mL of 1:1000 conc.) in adults and 0.01 mg/kg in children (never more than 0.3 mg) given IMHymenoptera Venom: Treatment
A Solenopsis xyloni major
worker surrounded by minor workers
Pustule can lead to localized necrosis scarring secondary infection.
Systemic reaction (urticaria / angioedema) can also occur.
local wound care.
Usual treatment for anaphylaxis should be initiated if there is evidence of systemic reaction.Ants (Formicidae)
L. reclusa(true brown recluse)
L. laeta (corner spider)
L. arizonica(Arizona brown spider) – produce majority of Loxosceles bites in the US.
Prefers warm and dry areas (abandon buildings / woodpiles, and cellars)
L. reclusa (true brown recluse)
One of the most common species found in the US.
Definitively diagnosing a brown recluse bite is difficult.
The necrotic wound that develop can resemble other unrelated arthropod species and medical disorder (i.e. Necrotizing Fascitis).Necrotic Arachnidism (Loxosceles)
5’ –ribonucleotide phosphohydrolase
Sphingomyelinase D (major enzyme responsible for necrosis.)
Necrotic wounds occur by way of neutrophil activation, platelet aggregation, and intravascular thrombosis.
Initially pts develop mild to severe pain several hrs after the bite
Erythema and blister formation
Bluish discoloration within the first 24 hrs
Lesion may become necrotic with eschar formation in 3 to 4 days.L. Reclusa (brown recluse)
Basic Chemistry tests
BUN / Creatinine
Supportive measure should be the initial goal (Analgesic / clean wound site).
Consider using antibiotics if any s/sx of infection develop.
Must have close follow – up with physician for serial evaluations of the wound.L. Reclusa (brown recluse)
The hair cannot penetrate human skin however can cause conjunctiva and cornea injury.
Pts who are handling tarantula and present with red eye must be evaluated via Slit-Lamp to identify hairs
Hairs that are identify must be surgically removed.
Initiate topical steroid tx to help control inflammation.
Initial bite are painful local erythema edema Local joint stiffness following nearby bites. (systemic sx are rare).Tarantulas
With in the pit vipers, the rattle distinguishes the rattlesnake from other crotaline snakes.
Pit is a heat sensor that guides strikes at warm-blooded prey or predators.Crotalinae (Pit Viper) Bites:
Causes the following:
determined on the presence of fang marks and a history consistent with exposure to a snake
**An elastic bandage / Penrose drain, rope, or piece of clothing wrapped above the bite. It’s applied with enough tension to restrict superficial venous / lymphatic flow while maintaining distal pulses and cap. refill. It retard venom absorption, increase local tissue injury but reduce the severity of systemic effects.
Mainstay of treatment for poisonous snakebites
Composed of heterologous antibodies derived from the serum of animal immunized with the appropriate snake venoms.
Bind and neutralize the venom molecules
Indication for antivenom tx:
All crotaline bites that show evidence of progressive signs and symptoms.
Pts with worsening of local injury (pain, ecchymosis, swelling)
Pts with lab errors (decr platelet count, incr coagulation time, decr fibrinogen)
Pts with systemic sx (unstable vitals / MS∆)Crotalinae (Pit Viper) Bites: Treatment
Vasopressor (maybe needed for ongoing hypot)
PRBC / FFP / Platelet may be needed if antivenom is not effective in stopping the bleeding that can occur.
Fasciotomy maybe needed if compartment syndrome occur secondary to venom spreading into the compartment.
Cultures / Antibiotics only needed if signs of infection develop.
Steroids should only be used for signs of allergic rxn or serum sickness (occur in 5% of pts after FabAV- fever / rash / arthralgias. Tx with prednisone 60mg/d for 1-2wk)Crotalinae (Pit Viper) Bites: Other medical Treatment:
Contain multiple toxin that produce different effect:
1. Neurotoxins in the venom bind to postsynaptic acetylcholine receptors and produce depolarizing neuromuscular blockade.
2. Some toxins from the venom poison cell membrane. Chief effect is on the heart producing arrhythmias and impaired contractility.
3. Third type of toxins contain enzyme that break down protein and connective tissue.
Some are monovalent, specific for a single species, but most are polyvalent, containing antibodies against several important or common cobra species in that country or region.
Should be considered experimental and can have high incidence of allergic rxn.
Should be started before the constricting band is loosened.
Should be initiated in pts with s/sx of systemic toxicity.
Reduces systemic toxicity but does not reduce local tissue damage and necrosis.Cobra Bite - Antivenom Treatment