Diferencia entre revisiones de «Brown recluse spider bite»
| Línea 1: | Línea 1: | ||
==Background== | ==Background== | ||
[[File:Loxosceles reclusa range.png|thumb|Brown recluse range (yellow area)]] | [[File:Loxosceles reclusa range.png|thumb|Brown recluse range (yellow area)]] | ||
[[File:Brown Recluse.jpg|thumb|Brown recluse]] | |||
*Brown violin shape on cephalothorax (fiddleback) | *Brown violin shape on cephalothorax (fiddleback) | ||
*In Southern midwestern US | *In Southern midwestern US | ||
Revisión del 00:05 12 mar 2015
Background
- Brown violin shape on cephalothorax (fiddleback)
- In Southern midwestern US
- Loxosceles family
Mechanism
- Venom contains variety of cytotoxic enzymes causing necrotic wound
Clinical Features
- Bite is initially painless
- Mild reaction
- Most common
- Mild erythematous lesion that later becomes firm and heals without scar
- Severe reaction
- Begins w/ mild-severe pain several hrs after bite accompanied by erythema and swelling
- Hemorrhagic blister then forms surrounded by vasoconstriction-induced blanched skin
- By day 3 or 4 hemorrhagic area may become ecchymotic
- Leads to "red, white, and blue" sign (erythema, blanching, ecchymosis)
- By end of first week ecchymotic area may become necrotic w/ eschar formation
- Systemic effects
- Rare
- Occur predominantly in children 24-72hr after the bite
- Include nausea/vomiting, fever, arthralgias, DIC, rhabdo, renal failure
Differential Diagnosis
Envenomations, bites and stings
- Hymenoptera stings (bees, wasps, ants)
- Mammalian bites
- Closed fist infection (Fight bite)
- Dog bite
- Marine toxins and envenomations
- Toxins (ciguatera, neurotoxic shellfish poisoning, paralytic shellfish poisoning, scombroid, tetrodotoxin
- Stingers (stingray injury)
- Venomous fish (catfish, zebrafish, scorpion fish, stonefish, cone shells, lionfish, sea urchins)
- Nematocysts (coral reef, fire coral, box jellyfish, sea wasp, portuguese man-of-war, sea anemones)
- Phylum porifera (sponges)
- Bites (alligator/crocodile, octopus, shark)
- Scorpion envenomation
- Reptile envenomation
- Spider bites
Workup
Management
- Local wound care
- Abx are indicated only if signs of infection exist; secondary infections are uncommon
- Although some texts recommend Dapsone, it has been shown to be of limited benefit and is associated with hemolysis in G6PD patients and als methemoglobinemia