Cutaneous-hemolytic loxoscelism following brown recluse spider envenomation: new understandings

Abstract

Background: Brown recluse spider (BRS) (Loxosceles reclusa) envenomation can cause local dermonecrotic lesions, constitutional symptoms, and potentially fatal hemolysis (i.e., cutaneous-hemolytic loxoscelism). As the incidence of hemolysis is low and the spider habitat is limited, little is known regarding the clinical course of cutaneous-hemolytic loxoscelism.

Methods: We performed a retrospective observational study of patients following BRS envenomation over an eight-year period. Demographics, clinical course, laboratories, and interventions were assessed. Wilcoxon rank-sum tests and Pearson chi-square tests were used in the univariate analyses. Logistic regression assessed the independent contribution of symptoms in a multivariate analysis.

Results: Of the 97 patients, 40.2% (n = 39) developed hemolysis; the majority (66.7%) were 18 years old or younger. Univariate analysis revealed that constitutional symptoms were associated with hemolysis, but multivariate analysis showed only myalgia (aOR: 7.1; 95% CI: 2.2–22.7; p < .001) and malaise (aOR: 12.76; 95% CI: 1.4–119.9; p = .026) were independently associated with hemolysis. The median time to hemolysis onset was 1.0 days (IQR: 1.0–2.5) and all occurred within a week of envenomation. Hemolysis durations were longer in patients DAT positive for IGG antibodies (7.5 vs. 4.0 days; p = .042). Most (76.9%) of hemolyzing patients received blood. In patients with cutaneous-hemolytic loxoscelism, hematuria occurred in 32.4%, rhabdomyolysis occurred in 60.9%, and elevated transaminases with normal hepatic synthetic function occurred in 29.4% but all of these patients developed rhabdomyolysis. Hemolysis was both intravascular and extravascular. Complications (hyperkalemia, INR ≥2.0, metabolic acidosis requiring bicarbonate, hypotension requiring vasopressors, and hypoxia requiring intubation) occurred only in patients with profound hemolytic anemia (hemoglobin <4 g/dL); one patient died.

Conclusions: Constitutional symptoms occur in both cutaneous and cutaneous-hemolytic loxoscelism, although they occur more frequently in patients who develop hemolysis. Children may be at a higher risk of hemolysis after envenomation. Renal involvement (as evidenced by hematuria) and rhabdomyolysis may occur more frequently than has been previously reported. Hemolysis was both intravascular and extravascular.

Keywords:

• Loxoscelism
• envenomation
• brown recluse spider
• hemolysis

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Research reported in this publication was supported by the National Center for Advancing Translational Sciences of the National Institute of Health (NIH) under award number UL1TR002243. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.