The Myth of the Brown Recluse Spider Bite

March 2, 2014 Animals, In The News Comments (2) 1913

Few things stick in my craw more than perpetuating bad information, particularly when it comes from a respected community of medical professionals and major media outlets. This weekend, the story broke of Ron Reese, a Tampa-area man who died of a necrotic wound on the back of his neck. Reese’s doctor diagnosed him with a bite from a brown recluse spider, and the media reported as much: “Man Dies From Brown Recluse Bite.”

My sympathies go to Mr. Reese and his family, of course, but the reason I’m posting is because Ron Reese was almost certainly NOT killed by a brown recluse spider. How can I say this? Because there are no brown recluse spiders in the Tampa area.

Rick Vetter is an entomologist at the University of California Riverside who has dedicated himself to fighting the myth of the brown recluse spider bite. See, each year multiple thousands of brown recluse spider bites are reported by medical authorities across the United States–but the vast majority of these diagnoses are almost certainly wrong, because they happen in places brown recluse spiders don’t exist.

The range of the brown recluse is quite limited, across a portion of the southern and central United States, between Texas and Georgia, north into Iowa and just passing into the Westernmost tip of the Florida panhandle, more than 400 miles by shortest overland route from Tampa Bay. Yet each year, hundreds of people are diagnosed with bites far outside of that range.

From 2000 to 2005, Vetter issued a “show me the spider” challenge, in which anyone encountering a brown recluse spider outside its identified range was invited to capture it and mail it to him for proper identification. You can see him present a brief portion of his results in this video. In short, a lot of people misidentified spiders, and the identified range of the brown recluse remains intact. The University of Florida, incidentally, picked up the challenge after Vetter got sick of receiving spiders in the mail.

Image: Wikimedia Commons

Image: Wikimedia Commons

Of course it’s not impossible to encounter an isolated recluse, or any other spider, outside it’s home range. Spiders can travel in shipping containers and vehicles, stow away aboard loads of produce, or hide out in a cardboard box before an interstate move. Black widows, which favor locations like attics, are somewhat famous for this. Recluses, however, are not known to be frequent travelers. They’re also not particularly aggressive or eager to bite.

The brown recluse is a fairly common spider within its range, and it is an unusual spider in that it tends to form colonies–so when you find one, you are likely to find many. Yet bites within the spider’s range are hardly epidemic, and most people who report confirmed interaction with the spiders come away unharmed. In one famous case, eight schoolchildren on a playground in Kansas collected more than 60 spiders, with their bare hands, and not one was bitten. In another, a Kansas family had been living in their home more than 5 years before they realized the spiders they seemed infested with were brown recluses. In six months, they collected more than 2,000 spiders, including some they found hiding in their clothes or crawling on them while they slept. Not once did anyone in the house suffer a bite.

In fact, there has never been a confirmed case of a fatal brown recluse bite; “confirmed” meaning the victim (or someone with the victim) saw the spider bite, captured that spider (either alive or dead), had the spider positively identified by an expert, and died as a result of the bite. It’s never happened*.

What does happen, quite frequently, is that a patient goes to the doctor with a particular type of necrotic wound, which a doctor diagnoses as a brown recluse bite. Trouble is, it’s impossible to diagnose the cause of such a wound simply by looking at it, and there are dozens of things more common than brown recluse spiders, from ticks to fungus to bacteria, that can cause identical wounds.

In 1998, the journal Missouri Medicine posted an article by Dr. Phillip Anderson, a physician who specialized in brown recluse bites (Missouri, you will note, is in the heart of brown recluse territory), disputing the widespread medical diagnosis of recluse bites. Wrote Dr. Anderson: “The entire loxoscelism [medical consequences of a recluse bite] literature is deficient in failing to produce the evidence that the bite of the Loxosceles reclusa [the brown recluse spider] was the cause of the illness reported.”

Dr. Anderson also questions the conventional wisdom around brown recluse toxicity, estimating that in confirmed bites, serious health risks resulted in only about one percent, and the vast majority of cases showed a safe recovery. To quote Vetter, “If [Anderson’s assertions] ruffle your feathers, then you really need to reconsider whether the source of your information has more experience that Phillip Anderson. That is very unlikely.”

In my own experience, most people you talk to believe they live in close proximity with brown recluse spiders, a good number believe they have encountered them, and a handful of people you know and regularly interact with probably believe they’ve been bitten. They may even have a doctor’s diagnosis to “confirm” their bite–and, again speaking from personal experience, people can be pretty intractable when you question a doctor’s knowledge about something.

But the fact is that brown recluse spiders are much less common than people believe, much less toxic than people believe, and much less aggressive than people believe. In most parts of the country, including Florida, the spiders don’t exist. If your doctor tells you you’ve been bitten by a brown recluse, he or she is probably wrong, and while the death of Ron Reese is a sad tragedy, it almost certainly was not at the fangs of a brown recluse spider.

* Similar circumstances surround the bite of the hobo spider, which in its range is widely accepted as having a medically dangerous bite. Experts are divided about the actual dangers of the hobo’s bite; my brother lived in Oregon for a time, and still gets angry with me when I question the conventional wisdom around hobo spiders.

2 Responses to :
The Myth of the Brown Recluse Spider Bite

  1. Andrew G. says:

    We have them in St. Pete – I do not know where you live. I’ve seen them and black widows / brown widows quite a few times.

    1. Andrew G. says:

      I forgot to add my friend was bitten by one about 5 years ago in Maderia Beach – the hospital also said it was a brown recluse . She has a nice divet left in her body from the encounter.

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