Abstract
ObjectiveSystemic loxoscelism is a rare illness resulting from the bite of the recluse spider and, in its most severe form, can lead to widespread hemolysis, coagulopathy, and death. We aim to describe the clinical features and outcomes of the largest known cohort of individuals with moderate to severe loxoscelism.MethodsWe performed a retrospective, cross sectional study from January 1, 1995, to December 31, 2015, at a tertiary-care academic medical center, to determine individuals with clinical records consistent with moderate to severe loxoscelism. Age-, sex-, and race-matched controls were compared. Demographics, clinical characteristics, laboratory measures, and outcomes of individuals with loxoscelism are described. Case and control groups were compared with descriptive statistics and phenome-wide association study (PheWAS).ResultsDuring the time period, 57 individuals were identified as having moderate to severe loxoscelism. Of these, only 33% had an antecedent spider bite documented. Median age of individuals diagnosed with moderate to severe loxoscelism was 14 years old (IQR 9.0–24.0 years). PheWAS confirmed associations of systemic loxoscelism with 29 other phenotypes, e.g., rash, hemolytic anemia, and sepsis. Hemoglobin level dropped an average of 3.1 g/dL over an average of 2.0 days (IQR 2.0–6.0). Lactate dehydrogenase and total bilirubin levels were on average over two times their upper limit of normal values. Eighteen individuals of 32 tested had a positive direct antiglobulin (Coombs’) test. Mortality was 3.5% (2/57 individuals).ConclusionSystemic loxoscelism is a rare but devastating process with only a minority of patients recalling the toxic exposure; hemolysis reaches a peak at 2 days after admission, with some cases taking more than a week before recovery. In endemic areas, suspicion for systemic loxoscelism should be high in individuals, especially children and younger adults, presenting with a cutaneous ulcer and hemolysis or coagulopathy, even in the absence of a bite exposure history.
Highlights
Systemic loxoscelism is a constitutional illness resulting from the bite of spiders of the genus Loxosceles, which is distributed worldwide
Systemic loxoscelism is a rare but devastating process with only a minority of patients recalling the toxic exposure; hemolysis reaches a peak at 2 days after admission, with some cases taking more than a week before recovery
Suspicion for systemic loxoscelism should be high in individuals, especially children and younger adults, presenting with a cutaneous ulcer and hemolysis or coagulopathy, even in the absence of a bite exposure history
Summary
Systemic loxoscelism is a constitutional illness resulting from the bite of spiders of the genus Loxosceles, which is distributed worldwide. In parts of the United States, the Loxosceles reclusa, commonly referred to as the brown recluse spider, is endemic. Such bites commonly cause local necrosis, referred to as necrotic arachnoidism.[1] Systemic toxicity may occur and in its mild form consists of nausea, vomiting, fever, chills, or arthralgia. The underlying pathogenesis of systemic loxoscelism remains incompletely understood, but sphingomyelinase D, a component of the venom toxin, has been shown to have a central role in the process.[10,11,12] Recent literature suggests it causes both direct toxin-mediated hemolysis and complement-mediated erythrocyte destruction.[8, 11, 13] There is an indication that hemolysis may be partly immunemediated, given that a certain proportion of individuals reported in the literature have shown positive direct antiglobulin testing (DAT; Coombs’) for surface immunoglobulin G (IgG).[7]
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