#Spider bite skin

The pairs are arranged in a semi-circle with a space between each pair. Most spiders have eight eyes however, the brown recluse only has six eyes, arranged in pairs. The body size is 10-15 mm with a leg span of 25 mm. The size of the spider is not sex specific, and both female and male spiders are capable of medically relevant envenomation. The brown recluse spider is known for the violin-shaped marking on its cephalothorax, although this is not consistent across the species. The female black widow spider is the one capable of medically relevant envenomation for humans. The female spider is larger than the male counterpart, with a body size of approximately 10-15 mm and a leg span of 30-40 mm. The red coloring may be in the shape of an hourglass. The American black widow female spider is typically shiny black with red on the ventral aspect of the abdomen. This is particularly true for suspect brown recluse bites because other dermonecrotic wounds have been notoriously misidentified as a brown recluse bite, even in areas where the spider is not endemic. Clinical toxicology reports indicate that to identify a definite spider bite, clinical signs and symptoms must be present, apprehension of the spider at the time of the bite must occur, and the spider should be identified by an arachnologist. This can be difficult in light of undetected bites that may not be symptomatic for minutes to hours. Loxoscelism: If severe envenomation (i.e., systemic symptoms), then consider evaluation for hemolysis and rhabdomyolysis: complete blood count, electrolytes, BUN, creatinine, urinalysis, prothrombin time, partial thromboplastin time, INR, fibrinogen, D-dimer, urine myoglobin, and creatinine kinase.Ĭonfirming the diagnosis of a spider bite is dependent on clinical judgment as well as spider identification. What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results? A few considerations include: contact dermatitis, cellulitis with staphylococcal and streptococcal species, Lyme disease, sporotrichosis, ecthyma gangrenosum, anthrax, herpes simplex, herpes zoster, leukocytoclastic vasculitis, and, of course, bites by other spiders. The differential diagnosis of dermonecrotic lesions is rather extensive.

#Spider bite skin

Loxoscelism or necrotic arachnidism can be difficult to diagnose on skin findings alone. However, while patients with an acute abdomen often prefer to lie quite still, patients suffering from latrodectism are often agitated, hypertensive, and unable to find a comfortable position. Latrodectism can be confused with an acute abdomen secondary to the significant muscle cramping and abdominal rigidity that can occur with a black widow spider bite. Untreated, symptoms most often resolve within 48 hours.īrown recluse spider, Loxosceles reclusa public domain from What other disease/condition shares some of these symptoms? Pain and generalized muscle cramping tend to be hallmarks of latrodectism. Systemic signs and symptoms typically develop over the next 60 minutes and can include hypertension, muscle cramping, abdominal pain, agitation, diaphoresis, nausea, vomiting, fasciculations, seizures, priapism, and, very rarely, death. Other local signs and symptoms of latrodectism may include local diaphoresis, lymphangitis, and/or urticaria. A target lesion may appear that has pallor at the site of the bite with surrounding erythema. Latrodectus mactans (black widow spider) (Figure 1): The initial bite may go unnoticed, but most often is described as a sharp pinch with subsequent pain that develops over the next 30 minutes. Likewise, six species of brown recluse spiders are found in the United States, with Loxosceles reclusa the most prevalent.

There are five species of widow spiders in the United States, of which the Latrodectus mactans is the most common. In the United States, two medically important families of spiders exist: Theridiidae or widow spiders and Loxoscelidae or brown recluse spiders. OVERVIEW: What every practitioner needs to know Are you sure your patient has a spider bite? What are the typical findings for this disease?