Background: Necrotic arachnidism represents a common health problem and standard treatments are usually safe and effective.
Objective: The aim of this study was to review documented Loxosceles species spider envenomations and identify the natural history of affected patients.
Methods: A retrospective single-centre study included 52 patients with necrotic arachnidism hospitalized in the dermatology department between 1997 and 2004. We examined the relationship between the epidemiological, clinical and laboratory parameters and degree of lesion severity, length of hospitalization and time to complete healing.
Results: The bites occurred predominantly in rural areas, 67% between April and August. Only 35% of the patients sought medical care within 24 h post bite. Most bites were of the extremities (67%). Time to complete healing ranged from 14 days to more than 8 weeks (mean, 4.8 weeks). A marked relationship was found between age, comorbidities, lesion severity and time to complete healing (P < 0.01). Duration of hospitalization was significantly longer in patients with severe thigh lesions (P < 0.02).
Conclusions: Loxosceles species spider bites frequently induce necrotic, slowly healing ulcers on the fatty areas of the body. Early, appropriate systemic therapy may provide clinical benefit.