![]() ![]() This is characterised by a central red swollen blister that is separated from a peripheral bluish region by a white zone of firm swelling. With more serious bites a “ bull's eye” wound may form. In self-healing wounds, the bite site gets no worse than being swollen and red. The dermatological features of these spider bites depend on the severity of the bite. Systemic symptoms are of more diagnostic value. In untreated cases, a rash may develop after several days. The skin around the site of the bite is red and two fang marks may be visible where the skin was penetrated. What are the dermatological features of a spider bite? Widow spider bite In severe cases, systemic conditions may occur, such as thrombocytopenia, disseminated intravascular coagulation, renal failure.In extreme cases, skin grafts may be necessary. The ulcer will heal over months and leave behind a scar.Eventually, a blister may form over a necrotic lesion which then sloughs to create an ulcerated wound (up to 10cm).Initial bite is painless but symptoms develop about 2–8 hours later, the area becomes painful and swollen.Affects cellular tissue and usually restricted to the area of the bite.More severely affected are children and older persons.Symptoms usually start about 1-3 hours after being bitten.Breathing difficulties, heart palpitations.Severe pain in the chest and abdomen (cramp-like pains).The severity of the symptoms depends on the species of the spider as the symptoms of bites from different species of Loxosceles can range from unremarkable (requiring no care), localised (usually self-healing), dermonecrotic (slow-healing ulcerated lesion requiring treatment), to systemic ( vascular, renal damage and sometimes life-threatening). The signs and symptoms from a bite from a spider with neurotoxic venom differ to those produced by a spider with cytotoxic venom. Age of the patient (small children and older persons are more adversely affected).The signs and symptoms of a spider bite depend on many factors, these include: What are the signs and symptoms of a spider bite? Spiders of the Latrodectus genus produce neurotoxic venom, while the violin spider and yellow sac spider produce cytotoxic venom. Web dwellers tend to have neurotoxic venom and non-web dwellers cytotoxic venom. The venom produced by spider bites is generally either neurotoxic or cytotoxic. Phoneutria (banana spider) is found in Central and South America.Ītrax and Hadronyche (funnel-web spider) are found in Australia. Tegenaria agrestis (hobo spider) and Cheiracanthium (yellow sac spider) are found in the United States. Loxosceles spp is found in South America, United States, Australia, and commonly in the tropics. Latrodectus spp (widow spiders) are found throughout the world and known by many different common names according to country. Which spiders bite and may be harmful to man? ![]()
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