LLUMC emergency medicine - Arachnomania! - Sean Bush, MD

Venom ER


By Sean Bush, MD, FACEP

Black widow spiderPossibly the scariest thing about spider bites is the fact that doctors are often uncertain about the diagnosis; and once the diagnosis is made, even the experts disagree about what should be done. Fortunately, a spider bite is very rarely (if ever) fatal.No deaths in the United States have ever been reported from a confirmed spider bite. However, there is a lot of "arachnomania;" that is, craziness surrounding spiders! Spiders are often the subjects of urban legends--especially the brown recluse.

Photo: Dr. Bush holds a black widow spider.

The brown recluse spider

The wound following a brown recluse spider bite may look red around the edges with a rotten center, and systemic symptoms can sometimes develop over the whole body. However, it is difficult to distinguish a spider bite from wounds caused by other things just by looking at the wound. Doctors commonly misdiagnose unexplained wounds as brown recluse or other spider bites. Alarmingly, cutaneous anthrax, Lyme disease, cancer, and "flesh-eating bacteria" are just a few of the conditions that have been misdiagnosed as brown recluse spider bites. These medical mistakes can lead to delays in appropriate treatment and possibly to loss of life or limb.

Fortunately, there is a venom-detection kit in development that should make it easier to properly diagnose brown recluse spider bites. Meanwhile, if a spider ever bites you, put the spider into a container (if you can safely do so) and bring it to your physician. Your doctor may preserve the spider in alcohol and send it to an entomologist for identification. This may or may not help the physician treat your spider bite, but it might help us learn more about spider bites.

There is no specific therapy for recluse spider bites that is agreed upon by the experts, although many unusual therapies have been tried (such as hyperbaric oxygen, electric shock, and a leprosy medication). There is no commercially available antidote or antivenom in the United States for the bite of the brown recluse spider, although there is one being researched.

While there are no brown recluse spiders in the Inland Empire, there are desert recluses (which produce effects similar to that of the brown recluse). The range of the desert recluse in Southern California includes the high desert from Lancaster east through Victorville and through the Mojave Desert to Arizona. In the low deserts, it is found from the Yucca Valley area through the Colorado deserts south to Mexico.

The violin pattern that is often observed on the back of a brown recluse is faint or absent in the desert recluse. Therefore, the desert recluse is a rather nondescript brown spider with a leg span about the size of a quarter. This spider is found exclusively in arid lands. It spins a small, irregular web sometimes under a stone or log. As their name implies, recluse spiders are shy creatures that avoid human contact and are reluctant to bite.

The black widow spider

The black widow lives everywhere in the Inland Empire, particularly in garages and water meters. The female spider is a shiny, glossy black with a large round belly and delicate, hairless legs. There is usually a red or orange hourglass or spot on the underside of the abdomen. The smaller male black widow spider is not able to cause a noticeable bite. The black widow spider spins an irregular and low-lying cobweb.

Although there are millions of black widow spiders in the Inland Empire, only a few people come to the emergency department at Loma Linda each year complaining of bites. A bite doesn't produce a wound like the brown recluse, but instead produces painful muscle cramping starting in the area of the bite and spreading into the abdomen, back, and/or chest. The bite itself may not be particularly painful, and symptoms may take hours to develop. Severe abdominal pain may mimic a need for emergent abdominal surgery.

There is antivenom for black widow spider bites. However, there has been a death attributed to the antivenom (and only one recent death reported from a black widow spider bite). So most doctors opt to treat patients' symptoms after such spider bites with pain medications and sedatives.

Most people recover fully although certain conditions, such as pregnancy or heart disease, may increase the danger associated with a black widow spider bite.

Other spiders

There are other spiders in the Inland Empire that may capture your attention or bite you (or both)! For example, tarantulas are common in the late summer and early fall. While a tarantula bite is certainly not a pleasant experience, it is generally not dangerous.

Another common local spider is the green lynx spider, which appears about the size of a half-dollar coin and bright green with spiky legs. The female aggressively defends her egg case and may pounce on you from a rose bush, delivering a painful bite. She may even spit venom at you! However, the bite usually doesn't cause much more than a little pain and a lot of surprise.

There are also false black widow spiders locally, which look very similar to black widows except that they are dark brown rather than black. They do not have red markings. Symptoms similar to a mild black widow spider bite may follow the bite of a false black widow.

Jumping spiders, which are small and covered with black fuzz, are often seen in local homes on windowsills. They have iridescent green mandibles and excellent sight. The bite may cause a small wound, similar to a mild brown recluse bite.

A popular urban legend states that the "daddy longlegs" spider is one of the most poisonous spiders, but their fangs are too short to bite humans. There are no reported daddy longlegs bites in humans and toxicity studies have never been done. Therefore, this belief is not based on any available evidence.

There are many other spiders in this area that are capable of biting humans and sometimes causing a small wound. However, most of these wounds heal with simple wound care (i.e., cleaning the wound and keeping it from getting infected). Any concerning symptoms should prompt a visit to your doctor or the emergency room.

Sean P. Bush, MD, FACEP, is Professor of Emergency Medicine and an envenomation specialist at Loma Linda University Medical Center. To suggest topics for future columns, call (909) 558-4419.

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