Arthropod Envenomation. Michael R. Loomis, DVM, MA, DACZM North Carolina Zoological Park

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1 Arthropod Envenomation Michael R. Loomis, DVM, MA, DACZM North Carolina Zoological Park

2 Hymenoptera Envenomation

3 Order Hymenoptera Family Vespidae- wasps Family Formicidae- ants Familt Mutillidae- velvet ants Family Apidae- bees

4 Stinger is a modified ovipositor

5 Bee and Wasp Venom Components Proteins, peptides and amines Phospholipase Histamine Bradykinin Acetylcholine Dopamine Seratonin Mast cell degranulating peptide Mastoparan Apitoxin 52% Melitten (potent antiinflammatory agent that increases production of cortisol) 10-12% Phospholipase A2 2-5% Aldolapin (blocks cyclooxygenase) 1-3% Hyuronidase 0.5-2% Histamine 1-2% Dopamine and noradrenaline 2% Protease-inhibitors Apamine increases cortisol production, mild neurotoxin

6 Ant Venom Components Fire ants- 95% alkaloid (Unique among ants) Most other ants, similar to bee and wasp venom Harvester ant venom contains a hemolysin

7 Venom Toxicity Family Common Name LD 50 (mg/kg) Apidae Honey bee 2.8 Mutillidae Velvet ant 71.0 Vespidae Paper wasp 2.4 Vespidae Yellowjacket 3.5 Formicidae Harvester ant 0.66 Formicidae Maricopa Harvester ant 0.12

8 Morbidity and Mortality Bees and Wasps In US, 9.3 million ant stings and 1 million stings of other Hymenoptera/year More deaths/year than any other type of envenomation Most deaths are the result of Anaphylaxis 17-56% produce local reactions 1-2% produce generalized reactions 5% seek medical care deaths from wasp and bee stings/year

9 Local Reactions Pain Edema which may extend 10 cm from sting +/- bleeding Pruritis Sensation of warmth due to vasodilation Nausea/vomiting

10 Generalized Reactions- Anaphylaxis Urticaria Confluent red rash Shortness of breath or wheezing Weakness, syncope Anxiety, confusion Chest pain Target organs (IgE-mediated allergic reaction) Skin- urticaris Respiratory System Bronchospasm Laryngospasm Vascular system Vasodilation Angioedema Twice as many anaphylactic reactions from wasps than bees Possible DIC

11 Generalized Reactions- Toxic Can result from 30 vespid stings or 200 honey bee stings Massive envenomations in adults results in > 15% mortality 20 honey bee stings/kg lethal for humans Melittin, phospholipase A2 and hyluronidase responsible for most toxic signs Vomiting Diarrhea Shock Hemoglobinuria Rhabdomyolysis Multiorgan failure

12 Generalized Reactions- Toxic Acute renal failure Acute tubular necrosis Direct nephrotoxic effects Interstitial nephritis from hypersensitivity reaction Pigment nephropathy (Rhabdoymolysis or intravascular hemolysis) Kounis syndrome (allergic myocardial ischemia and infarction) Inferior ST-segment elevation

13 deaths from fire ants Pathnpneumonic sterile pustules Little protein so anaphylaxis uncommon Can survive as many as 5000 stings Fire ants

14 Harvester Ants Maricopa harvester ant has the most toxic insect venom Single sting of harvester ant

15 Treatment- Generalized- Anaphylaxis Antihistamines Diphenhydramine Cimetadine (IV) if unresponsive to Diphenhydramine Bronchodilators Epinephrine Albuterol Theophylline Corticosteroids

16 Treatment- Local Remove stinger Diphrenhydramine Ice or cool pack Elevate extriminity

17 Centiped Envenomation

18 Class Chilopoda 3000 species Single pair of legs/body segment Predominately nocturnal Warm temperate and tropical regions Scolopendra most dangerous genus

19 Venom delivered by forcipuels, modified pair of legs behind the mandibles Venom components: 5-hydroxytryptamine hemolytic phospholipase A a cardiotoxic protein a cytolysin Unknown frequency of stings

20 Morbidity and Mortality Systemic reactions ECG changes suggestive of Ischimia Rhabdomyalysis Proteinuria Fatalities extremely rare 7 year old Phillipino girl stung by S. subspinipes 5 fatalities reported in U.S from

21 Symptoms and Signs of Envenomation Severe pain Local tissue swelling Redness Swollen, painful lymph nodes Headache Palpitations Nausea and/or vomiting Anxiety Local puritis

22 Treatment Systemic analgesics as needed Local injectable anesthetics (e.g. lidocaine) Update tetanus vaccination Monitor for local infection Symptomatic treatment for systemic signs

23 Milliped Envenomation

24 Class Diplopoda 7000 species 2 pairs of legs/body segment Do not have biting mouthparts or fangs

25 Morbidity and Mortality No documented deaths Secrete defensive irritating liquid from pores along sides Secretions contain Benzoquinones Aldehydes Hydrocyanic acid Phenols Terpenoids Nitroethylbenzenes

26 Signs and Symptoms Local erythema Mild edema Vessicles Rarely, cracked skin that may slough and heal Conjunctivitis

27 Treatment

28 Scorpion Envenomation

29 1500 species 50 species dangerous to humans Flattened, elongated body 1 pair of claws 4 pairs of legs Segmented tail with poisonous spike at end Most dangerous species belong to family Buthidae

30 Scorpions Known to be Lethal to Humans Genus Buthus Parabuthus Mesobuthus Buthotus Tityus Leiurus Androctonus Centruroides Geographical Location Mediterranean area Western and Southern Africa Throughout Asia Southern Africa and SE Asia Central and South America North Africa and Middle East North Africa to SE Asia SW U.S., Mexico, Central America, Caribbean

31 Frequency of Stings Occur in temperate and tropical regions (50 N to 50 S latitude) In ,231 reported stings in U.S. Only 1 of 30 species of scorpions in U.S. dangerous to humans (Centruroides)

32 Lethal Stings Most fatalities within 24 hours of sting from respiratory and/or cardiovascular failure < 1% Centuroides stings in adults are fatal 25% children under 5 die if not treated Mexico 1000 deaths /year U.S. 4 deaths in 11 years

33 Venom Contains multiple toxins and other compounds Neurotoxins -Glycosaminoglycans Cardiotoxins -Histamine Nephrotoxins s -Serotonin Hemolytic toxins -Tryptophan Phosphodiesterases -Cytokine releasers Phospholipases Hyaluronidases

34 Neurotoxins Most Potent toxin components Cause impairment in nerves, muscles and heart by altering ion channel permeability 2 classes Long-chain polypeptide Stabilizes sodium channels in open position causing prolonged firing of somatic, sympathetic and parasympathetic neurons Release of excessive neurotransmitters Short polyprptide Blocks potassium channels

35 Venom Toxicity SPECIES LD50 (mice) mg/kg Leiurus quinquestriatus (Middle East) 0.25 Androctonus crassicauda (Saudi Arabia) Centruroides noxius (Mexico 0.26 Tityus serrulatus (Brazil) 0.43 Centruroides sculpturatus (SW U.S.) 1.12 Mesobuthus eupeus (Iran) 1.45 Mouse LD50 of < 1.5mg/kg considered potentially lethal for humans

36 Signs and Symptoms Most common are: Mydriasis Nystagmus Hypersalivation Dysphagia Restlessness

37 Signs and Symptoms Sympathetic Override Tachycardia Hypertension Hyperthermia Pulmonary Edema Parasympathetic Symptoms Hypotension Bradycardia Salivation Lacrimation Urination Defecation Gastric Emptying

38 Signs and Symptoms Cranial Nerve Effects Roving or rotary eye movements Blurred vision Tongue fasciculations Loss of pharyngeal muscle control Somatic effects Restlessness Muscle jerking True seizures (Centruroides)

39 Treatment Local RX Negative-pressure extractor Ice bags (first 2 hours) Local wound care Immobilize affected body part below level of heart Calm the patient Lymphatic-venous compression wrap if medical RX is delayed Topical or local anesthetic Muscle relaxers for severe spasms =/- tetanus prophylaxis, antibiotics

40 Treatment Systemic Treatment ABC s O2 IV fluids Cardiac drugs as necessary Atropine (counters venom-induced parasympathetic effects)

41 Treatment Antivenom Treatment of choice

42 Spider Envenomation

43 Over 3000 Species of Spiders 98-99% of spider bites are harmless 4 Genera have produced lethal bites 3 additional genera are probably capable of producing lethal bites Symptoms can include: Necrotic wounds Systemic toxicity Death

44 Lethal Genera Atrax- Australian funnel-web spiders Latrodectes- Widow spiders Loxosceles- Recluse spiders Phoneutria- Wandering spiders

45 Potentially Lethal Genera Hadronyche- Australian funnel-web spiders Missulena- Mouse spiders Sicaritus- Six-eyed sand spider

46 Types of Venom Neurotoxic Widow spiders- Latrotoxins Australian funnel web and mouse spiders- open sodium channels Brazilian wondering spiders- attacks multiple types of ion channels, serotonin Necrotic venom Family Sciariidae recluse and six-eyed sand spiders. Produce dermonecrotic compound sphingomyelinase

47 Venom Delivery Two chelicerae, each with two segments, the fang and the basal portion. Fang penetrates the skin Basal portion includes all or part of the spider's venom glands, which can be squeezed under voluntary control by the spider to force venom out of the glands and into the wound

48 Widow spiders Genus Latrodectus Large geographical range Black widow spider

49 Widow spiders Genus Latrodectus Latrotoxins-cause release of acetylcholine Stimulates muscle contractions painful abdominal cramps interfering with respiration 5% death rate prior to development of antivenom 63 deaths in US from Katipo spider

50 Widow spiders Local pain may be followed by localized or generalized severe muscle cramps, abdominal pain, weakness, and tremor Large muscle groups (such as shoulder or back) are often affected, resulting in considerable pain. In severe cases, nausea, vomiting, fainting, dizziness, chest pain, and respiratory difficulties may follow. European black widow spider

51 Widow spiders In some cases, abdominal pain may mimic such conditions as appendicitis or gallbladder problems. Chest pain may be mistaken for a heart attack. Blood pressure and heart rate may be elevated. The elevation of blood pressure can lead to one of the most severe complications. Life-threatening reactions are generally seen only in small children and the elderly. Redback spider

52 Widow spiders Treatment Pain management (Narcotics may be required for severe pain) Muscle relaxants Antivenom in severe cases Black widow spider with egg case

53 Australian funnel-web spiders Genera Atrax and Hadronyche All are Australian except 1 species of Hadronyche from Chile Produce atracotoxins- very toxic to primates Sydney funnel-web spider, Atrax robustus

54 Australian funnel-web spiders Symptoms of systemic envenoming include: Tingling around the mouth and tongue Facial muscle twitching Nausea Vomiting Profuse sweating Salivation Shortness of breath. Sydney funnel-web spider

55 Australian funnel-web spiders Patients may rapidly develop: Agitation Confusion and coma associated with hypertension Metabolic acidosis Dialation of the pupils Generalized muscle twitching Pulmonary edema. Sydney funnel-web spider

56 Australian funnel-web spiders Death results from progressive hypotension or possibly raised intracranial pressure resulting from cerebral edema 13 deaths from A. robustus Hydronyche cerberea, Southern tree funnelweb spider

57 Australian funnel-web spiders Treatment: Supportive care Applying a pressure immobilization bandage Antivenom H. infensa, Toowoomba funnel-web spider

58 Mouse spiders Genus Missulena Similar venom to Australian funnel-web spiders

59 Brazilian wandering spider Genus Phoneutria Found throughout Central and South America Aggressive In addition to neurotoxins, venom contains serotonin

60 Brazilian wandering spider Symptoms from mild envenomation Pain Edema Hyperemia Sweating

61 Brazilian wandering spider Symptoms from severe envenomation Local pain Tachycardia Prostration Profuse sweating Poor peripheral profusion Muscle fasciculation Diarrhea Vomiting Priapism Pulmonary edema

62 Brazilian wandering spider Treatment Pain management Supportive care Antivenom Mechanical ventilation 2.3% of cases required antivenom in a series of 422 patients Deaths from bites have been drastically reduced since introduction of antivenom in 1996

63 Recluse spiders Genus Loxosceles Worldwide distribution, but most common in the new world Venom contains the dermonecrotic agent sphingomyelinase D Brown recluse spider

64 Recluse spiders Symptoms Severe pain at bite site after about four hours Severe itching Nausea Vomiting Fever Brown recluse spider Myalgias (muscle pain)

65 Recluse spiders Symptoms may progress to: Blistering (common) Necrosis (death) of skin and subcutaneous fat (less common) Severe destructive necrotic lesions with deep wide borders (rare) Brown recluse spider bite

66 Recluse spiders First Aide Apply ice to decrease pain and swelling. Elevate area if possible above the level of the heart. Wash the area thoroughly with cool water and mild soap. Avoid any strenuous activity because this can spread the spider's venom in the skin. Brown recluse spider bite Use acetaminophen for pain relief.

67 Recluse spiders Medical RX Tetanus immunization Pain medication Antibiotics if signs of infection are present in the wound Antihistamines such as diphrenhydramine (Benadryl) for itch relief Brown recluse spider

68 Recluse spiders May form a necrotising ulcers that destroys soft tissue and may take months and very rarely years to heal, leaving deep scars Damaged tissue may become gangrenous and eventually slough away Brown recluse spider bite

69 Recluse spiders Systemic effects Mild symptoms include nausea, vomiting, fever, rashes, and muscle and joint pain Rarely more severe symptoms occur including hemolysis, thrombocytopenia, and DIC Brown recluse spider

70 Recluse spiders Treatment Routine treatment should include elevation and immobilization of the affected limb, application of ice, local wound care, and tetanus prophylaxis In almost all cases, bites are self-limited and typically heal without any medical intervention Brown recluse spider

71 Recluse spiders An antivenom is available in South America Chilean recluse-systemic reactions in 15% of cases and fatalities in 3-4% Chilean recluse spider

72 Six-eyed sand spider Genus Sicaritus Found in southern hemisphere Same family as recluse spiders (Sicariidae) Considered by some as worlds most venomous spiders Death and loss of limbs reported

73 Other Spiders Causing Necrosis Hobo spider Yellow sac spider Hobo spider Yellow sac spider