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ARTHROPOD BITES AND STINGS Chrisnel Jean, D.O March 9, 2006 EM Lecture Session Slide 2 Hymenoptera (WASPS, BEES, AND ANTS) Hymenoptera: 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 Formicidae ants 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). Vespid have ability to perform multiple stings. Slide 3 Africanized honeybees Known as killer bees Now found in Texas, Arizona, California, and most of the temperate southeastern and southwestern states. Attack from these bees massive stinging resulting in multisystem damage and death from severe venom toxicity. Slide 4 Hymenoptera Venom Contain several components. Histamine is only a minor component within the venom. 50% of the venom consist of Melittin. Melittin is a known membrane-active polpeptide that can cause degranulation of basophils and mast cells. Yellow jackets venom is perhaps the most potent sensitizer. Slide 5 Hymenoptera Venom: Local Reaction Toxic Reaction Urticarial lesion contiguous with the sting site. 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 Death Slide 6 Hymenoptera Venom: Anaphylactic Reaction Can occur from a single sting or multiple stings. May range from mild to fatal and death within minutes. There is no correlation between the systemic reaction and the number of stings. Slide 7 Hymenoptera Venom: Delayed Reaction Delayed reaction appearing 5 14 days after the sting consists of serum sickness-like signs and symptoms. Pts can develop fever, malaise, HA, urticaria, lymphadenopathy, and polyarthritis. This reaction is believed to be immune complex-mediated. Slide 8 Hymenoptera Venom: Treatment Immediate removal of the bee stinger from the wound, is the important principle rather than the method of removal. 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 IM Slide 9 Hymenoptera Venom: Treatment Other treatment should include: Diphenhydramine 25 to 50 mg IV, IM or PO H2-receptor antagonists (ranitidine 50 mg IV) Methylprednisolone 125 mg Use Beta agonist nebulization if pt has evidence of bronchospasm IVF, oxygen, cardiac monitor, pulse ox. Persistent hypotension after multiple IVF bolus may require Dopamine or Epinepherine drip Slide 10 Hymenoptera Venom: Disposition Pts who develop severe systemic reactions should be admitted monitored for potential cardiac, bleeding, renal or neurologic complications. Skin tests and RASTs (radioallergosorbent test) are not reliable in determining which patients are at risk in developing future systemic reactions. Slide 11 Hymenoptera Venom: Disposition Every patient who has had a systemic reaction should be provided with an insect sting kit containing premeasured epinepherine and be carefully instructed in its use. The physician should stress that the patient must inject the epinepherine at the first sign of a systemic reaction. Slide 12 Ants (Formicidae) 5 known species of fire ants (Solenopsis) (S. aurea, S. geminata, S. xyloni, S. invicta, and S. richteri) Fire ants swarm when provoked and they may attack in numbers. Fire ants sting simultaneously in response to an alarm pheromone released A Solenopsis xyloni major worker surrounded by minor workers Slide 13 Ants (Formicidae) Fire ants sting result in a papule that becomes a sterile pustule in 6 to 24 hrs. Pustule can lead to localized necrosis scarring secondary infection. Systemic reaction (urticaria / angioedema) can also occur. Treatment includes: local wound care. Usual treatment for anaphylaxis should be initiated if there is evidence of systemic reaction. Slide 14 Spiders (Araneae) More than 34000 species of spiders worldwide Only few dozen produce medically significant envenomations in humans Refer to Table 194 3 for medically important spiders by geographic location. Slide 15 Necrotic Arachnidism (Loxosceles) Three species: 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). Slide 16 L. reclusa (true brown recluse) Brown recluse has a dark brown violin shape on the cephalothorax (the portion of the body to which the legs attach). The neck of the violin points backward toward the abdomen. However, what you should look at instead is the eye pattern of 6 eyes in pairs with a space separating the pairs. Most spiders have 8 eyes in 2 rows of 4. Slide 17 L. Reclusa (brown recluse) Venom includes multiple enzymes such as Hyaluronidase Alkaline phosphate 5 ribonucleotide phosphohydrolase Sphingomyelinase D (major enzyme responsible for necrosis.) Necrotic wounds occur by way of neutrophil activation, platelet aggregation, and intravascular thrombosis. Clinical Features: 1. Initially pts develop mild to severe pain several hrs after the bite 2. Erythema and blister formation 3. Bluish discoloration within the first 24 hrs 4. Lesion may become necrotic with eschar formation in 3 to 4 days. Slide 18 L. Reclusa (brown recluse): Systemic reaction Are rare in adults, however more common in children Occur in 24 72 hrs after the bite. Can lead to N/V, Fever/chills, arthralgias, hemolysis, thrombocytopenia, hemoglobinuria, and renal failure. DIC and Death are rare Slide 19 L. Reclusa (brown recluse) If a brown recluse bite is suspected, the following labs test should be perform: CBC Basic Chemistry tests BUN / Creatinine Coagulation Profile Treatment: 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. Slide 20 Hobo Spider (Tegenaria agrestis) Found in the Pacific northwest of the US They are aggressive because it bite with minor provocation. Live in moist dark areas (woodpiles/basements). They are brown with grey markings, have 7 14mm body length and 27 45mm leg span Slide 21 Hobo Spider (Tegenaria agrestis) Clinical Features: Present similar to that of brown recluse spider. Initial bite is painless delay presentation Induration may occur with surrounding erythema, followed by blistering, rupture, and necrosis. HA is the most common systemic symptom, but N/V and fatigue can occur. Aplastic anemia and death are rare complications. Slide 22 Hobo Spider (Tegenaria agrestis) Clinical Features: Slide 23 Hobo Spider (Tegenaria agrestis) Treatment: No diagnostic test for hobo spider envenomation. No proven treatment for local or systemic complications. Surgical resection with skin grafting may be necessary after the necrotizing process is completed. Slide 24 Widow Spiders (Latrodectus) Has a worldwide distribution In the US, the black widow is the most well known of the 5 Latrodectus species L. mactans, L. various, and L. hesperus are black L. geometricus are brown and L. bishopi are red. Found most often in woodpiles, basements, garages, and sheds. Slide 25 Widow Spiders (Latrodectus) L. mactans are the only species that have the classic hour glass-shaped (orange/red) marking. Slide 26 Widow Spiders (Latrodectus) Female spiders Large in size Body size = 1.5 cm Leg spans 4 -5 cm Bites can penetrate human skin. Become aggressive when protecting her web and eggs. Male spiders Smaller in size 1/3 the size of female Liter in color Bites cannot penetrate human skin. Slide 27 Widow Spiders (Latrodectus) Most bites occur between April and October and are usually seen on the hands and forearm. Inject a highly potent venom most active component is latrotoxin. Through a calcium mediated mechanism, latrotoxin cause the release of acetylcholine and norepinephrine from nerve terminals. Slide 28 Widow Spiders (Latrodectus) Clinical Features: Most bite site, initially feels like a pinprick then quickly cause increasing local pain that then involve the entire extremity. In 1/3 of cases the initial erythema evolves into a larger target lesion. The presence of the target lesion, severe pain and muscle spasm is pathognomonic for widow spider bites. Pts most commonly c/o muscle cramp like spasms in large muscle groups. Slide 29 Widow Spiders (Latrodectus) Clinical Features: Other s/sx: HA, nausea, diarrhea, diaphoresis, photophobia and dyspnea. May experience intermittent severe pain for 24+ hours Laboratory test to confirm Latrodectus bite is not available. Slide 30 Widow Spiders (Latrodectus) Treatment: Initial Tx: Support ABC. Clean the bite site. Use Opioids and benzodiazepines to control pain and muscle spasms. The most effective tx for severe envenomation are parental opioids and Latrodectus antivenom. Slide 31 Widow Spiders (Latrodectus) Treatment: Latrodectus antivenom: Cause rapid resolution of symptoms and significantly shorten the course of illness. When given properly, pt can often be d/c form ED after a short period of observation Produced in three countries: Anti Latrodectus antivenom available in Argentina Red-backed spider antivenom available in Australia Antivenin ( Latrodectus mactans ) available in U.S.A. (1-800-396-6250) Indications, amount, and route of administration vary according to product. Slide 32 Tarantulas Large hairy spiders Popular as pets Family Theraphosidae Hairs found on the abdomen and legs are use defensively Slide 33 Tarantulas When threaten, they may flick some of their hair. 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). Slide 34 Scorpions (Scorpionidae) World-wide distribution Highly toxic species are found in Middle East, India, North Africa, South America, Mexico, and Trinidad. In the US, only the Centruroides exilicauda (bark scorpion) possesses venom potent enough to cause systemic toxicity. Slide 35 Scorpions - Centruroides exilicauda Clinical features: Venom can open neuronal sodium channels and cause prolonged and excessive depolarization. Immediate onset of pain and parathesias in the stung extremity is noted and may become generalized. Slide 36 Scorpions - Centruroides exilicauda Clinical features: Severe Systemic cases after bite can lead to: Abnormal roving eye movements, blurred vision, pharyngeal muscle incoordination and drooling. Other s/sx: Restlessness, seizure like activity, N/V, tachycardia, and severe agitation. Symptoms can last 24 48hrs without anitvenom treatment. Cardiac dysfunction, pulmonary edema, pancreatitis, bleeding d/o, skin necrosis, and occasionally death can be seen with stings from Asian and African scorpions. Slide 37 Scorpions - Centruroides exilicauda Treatment: Initial treatment is supportive / analgesics. Centruroides-specific antivenom is only available in Arizona and is produce from goat serum. (production has been stop, only used in severe systemic toxicity cases). Scorpion antivenom directed against different species is now used and available in 10 other countries. Slide 38 Reptile Bites Approx 3 million bites and 150,000 deaths occur each year from venomous snakes in the world. Most bites occur in the warm summer months (snakes and victims are most active). In the US, mortality has improve from 25% to only Questions 1: The edema of snakebite usually does not involve the deep compartments or cause vascular compromise. Fasciotomy should therefore be undertaken only when __. a) findings of compartment syndrome are present b) massive edema is present c) the measured intracompartmental pressure is >repeat doses of antivenom and elevation have failed d) 30-40 mmHg e) Only a, b, d is correct Slide 62 Questions 2: Much of the toxicity of coral snake venom is due to its acetylcholine receptor blocking activity. Absorption and spread of the venom is rapid. Which one of these statement is false about the treatment or sign / symptoms of coral snakes bites is incorrect? a) Delayed: drowsiness, confusion, coma, euphoria, salivation, vomiting, seizures, paralysis and death in 8-24 hours. Progression to paralysis can occur rapidly once symptoms begin. b) Tourniquet application, incision and suction if seen within one hour. c) Antivenin is available for the eastern coral snake and may be lifesaving. d) Early signs: local weakness and paresthesias may begin within 15 minutes or be delayed several hours. Mydriasis, dysphagia, ataxia, slurred speech and myalgias begin within a few hours. e) Support respiration and treat seizures. Slide 63 Questions 3: Treatment for a brown recluse spider bite does not includes: a) cleaning the wound with soap and water and administering tetanus prophylaxis. b) local cold compresses, elevation of the affected extremity, and loose immobilization of the affected part. c) with severe ulceration, delayed excision and grafting may be necessary. d) amoxicillin 125-250 mg QID may be as effective as dapsone. Slide 64 Questions 4: Treatment of Hymenoptera stings includes all except: a) epinephrine subQ (0.01 mg/kg to a 0.5 mg max) and/or IM or IV diphenhydramine (1 mg/kg) for systemic reactions. Systemic corticosteroids. b) PO diphenhydramine, 4-5 mg/kg (75 mg max) QID, and perhaps prednisone 0.5-1.0 mg/kg/day for several days for severe local inflammation. c) washing (to minimize infection), rest, ice, and elevation. d) IV crystalloid and vasopressors (dopamine or epinephrine) for hypotension. e) Nebulized albuterol or other beta-2-specific agonist for bronchospasm; intubation, cricothyroidotomy, or jet ventilation may be required for severe cases or upper airway edema. f) All the above is true Slide 65 ANSWERS: 1. E 2. B 3. D 4. F