Two people bitten by brown recluse spiders developed a rare condition in which their immune system destroyed their red blood cells, according to a new case report.
In the first case, a 30-year-old man came to the hospital with nausea, vomiting, muscle aches and a painful injury to his left shoulder. In the other case, a 28-year-old woman presented with severe low back pain. They both had strange lesions. The man’s, on his left shoulder, was small and irregularly shaped, with a black, crusty patch on one side; the woman’s, on her upper back, was target-shaped and larger. Both were painful to the touch.
In both cases, the doctors noticed that the whites of the patients’ eyes were yellowish. The condition, called scleral jaundice, is caused by a buildup of a pigment called bilirubin in the blood, which occurs when red blood cells break down.
Based on blood tests, both patients were diagnosed with a condition called autoimmune hot hemolytic anemia – something that caused their immune system to destroy their red blood cells. In both cases, that something was systemic loxoscelism, a body-wide reaction to a bite from the venomous Loxosceles reclusa spider, otherwise known as the brown recluse.
Although brown recluse bites can be painless, the bite can become itchy, red, and inflamed soon after the bite, depending on the National Capital Poison Control Center (opens in a new tab) (CNPC). It may eventually become more painful, darker, and blister. A bite can also cause necrosis or death of the tissues around it and can eventually form a black scab-like area called an eschar. According to the NCPC, brown recluse bites are difficult to diagnose — doctors make the diagnosis based on the patient’s history and symptoms, if any.
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The patients in the report were treated with intravenous fluids and corticosteroids, which suppress the immune system. Both also received blood transfusions and eventually recovered enough to leave the hospital.
The man’s recovery was uncomplicated, the woman’s less so for reasons apparently unrelated to her spider bite. She was six weeks pregnant and miscarried, and also developed a brain condition called acute toxic metabolic encephalopathy while in hospital. This condition can also be caused by withdrawal from alcohol and drugs, and the woman had a history of drug abuse. But she eventually recovered enough to be discharged with oral corticosteroids.
Treatment has gone well for these patients: some people who develop autoimmune hemolytic anemia have to take a blood cancer drug with potentially serious side effects if corticosteroids don’t work, and some may even need removal of the spleen, according to the study.
The brown recluse spider, a small brownish or tan spider with a dark brown “violin-shaped” marking on its head, lives in several parts of the United States, but is most common in Texas, Missouri, and Illinois .
Most people shouldn’t lose sleep over worrying about brown recluse bites, as they are rare and 90% of them cause no major complications.
According to the study, children, as well as African Americans and Hispanics, are at greater risk of having systemic reactions. The American Association of Poison Centers reported (opens in a new tab) that in 2019, out of 802 reported brown recluse bites, only 24 people had major reactions and no fatalities were reported.
Brown recluse bites were described in a report published in the journal Hematology (opens in a new tab).