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EDs Should Suspect Spider Bites with Certain Critical Hematologic Symptoms

NASHVILLE, TN – Brown recluse spiders rarely are seen or identified, and many patients bitten by them don’t even notice until symptoms appear hours later.

That doesn’t mean the arthropods who prefer more temperate climates aren’t dangerous. A new study published by PLOS One warns that their bites can create serious complications, especially in children.

Typically the spiders just leave a blistering skin lesion that can cause pain, but Vanderbilt University Medical Center reports that those bites, in rare circumstances, also can lead to systemic loxoscelism, which causes blood clotting disorders and hemolysis.

Researchers suggest that clinicians should suspect loxoscelism if patients live in areas of the Southeast or Midwest where the spiders are more common and, especially, if they are children. Brown recluse bites often aren’t noticed when they occur, the article adds, so that shouldn’t be used as rule-out information.

“Children are much more likely to develop this systemic syndrome,” explained senior author Jeremy Warner, MD, MS, a Vanderbilt hematologist. If the condition is especially severe, emergency physicians might have to admit patients for blood transfusions and supportive care, he added.

Warner also suggested that the risk might be greater than average for African-Americans.


To reach those conclusions, the study team conducted a retrospective, cross sectional study from January 1, 1995, to December 31, 2015, at Vanderbilt’s medical center, focusing on clinical records consistent with moderate to severe loxoscelism.

With 57 patients identified as having moderate to severe loxoscelism, results indicate that only 33% had actual documentation of a previous spider bite. Those affected had a median age of 14 years.

Compared to descriptive statistics and phenome-wide association study (PheWAS), loxoscelism was linked to 29 other phenotypes, such as rash, hemolytic anemia, and sepsis. In the patients, hemoglobin level decreased an average of 3.1 g/dL over an average of 2.0 days, while lactate dehydrogenase and total bilirubin levels rose an average of two times the upper limit of normal values. In addition, 18 of 32 patients tested had a positive direct antiglobulin – commonly referred as Coombs’ – test. Two of the patients died.

“Systemic loxoscelism is a rare but devastating process with only a minority of patients recalling the toxic exposure; hemolysis reaches a peak at two days after admission, with some cases taking more than a week before recovery,” study authors write. “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.”

“We were inspired to carry out this analysis after treating a patient with a particularly striking episode of hemolysis several days after a brown recluse spider bite,” Warner noted. “He lost literally half of his blood supply over the course of 24 hours but was ultimately OK.”