injuries poisoning
Spider Bites
Symptoms and Signs of Spider Bites
 bites are most common in the US. Some bites are painless initially, but pain, which can be severe and involve the entire extremity, develops within 30 to 60 minutes in all cases. The bite area becomes erythematous and ecchymotic and may be pruritic. Generalized pruritus may also be present. A central bleb forms at the bite site, often surrounded by an irregular ecchymotic area (bull’s eye lesion). The lesion may mimic Pyoderma Gangrenosum . The central bleb becomes larger, fills with blood, ruptures, and leaves an ulcer. A black eschar forms over the ulcer and eventually sloughs. Most bites leave minimal residual scarring but some can leave a large tissue defect, which may involve muscle. Loxoscelism, a venom-induced systemic syndrome, may not be detected until 24 to 72 hours after the bite and is uncommon but more prevalent in children and adolescents. Systemic effects (eg, fever, chills, nausea, vomiting, arthralgias, myalgias, generalized rash, seizures, hypotension, disseminated intravascular coagulation, thrombocytopenia, hemolysis, renal failure) are responsible for all reported fatalities. Widow spiderbites usually cause an immediate, sharp, stinging sensation. The pain may be described as dull and numbing and may be disproportionate to the clinical signs. Within 1 hour after envenomation, there may be progression to persistent local pain, diaphoresis, erythema, and piloerection at the bite site. Sometimes remote and/or systemic symptoms develop. Widow spider envenomations are graded as mild, moderate, or severe. Mild: Pain restricted to the bite site, normal vital signs Moderate: Diaphoresis and piloerection in the area of the bite, cramping pain in large muscle groups of the trunk, normal vital signs Severe (also called latrodectism): Diaphoresis at a remote site; intense generalized cramping pain in large muscle groups of the trunk; hypertension and tachycardia; often headache, nausea, and vomiting Latrodectism, a systemic syndrome caused by neurotoxic venom components of widow spider bites, manifests as restlessness, anxiety, sweating, headache, dizziness, nausea, vomiting, hypertension, salivation, weakness, diffuse erythematous rash, pruritus, ptosis, eyelid and extremity edema, respiratory distress, increased skin temperature over the affected area, and cramping pain and muscular rigidity in the abdomen, shoulders, chest, and back. Abdominal pain may be severe and mimic acute surgical abdomen, rabies, or tetanus. Symptoms tend to resolve over 1 to 3 days, but residual spasms, paresthesias, agitation, and weakness can last weeks to months. Tarantulabites are extremely rare and nonvenomous with North or South American ("New World") tarantulas. However, agitation of the spider may cause it to throw needle-like hairs. The hairs act as foreign bodies in skin or eyes and can trigger mast cell degranulation and an anaphylactoid reaction (eg, urticaria, angioedema, bronchospasm, hypotension) in sensitized people, usually pet owners who handle the spider daily. Tarantula species native to non-American continents ("Old-World" tarantulas) are occasionally kept as pets. They are more aggressive than New World tarantulas, lack needle-like hairs, and can be venomous. 