How Long Does Spider Venom Stay In Your Body?
Spider venom reveals new secret: Once injected into a bite wound, venom of brown recluse spider causes unexpected reaction
- 1 Spider venom reveals new secret: Once injected into a bite wound, venom of brown recluse spider causes unexpected reaction
- 2 Spider-Man: 5 Weird Effects of Real Spider Bites
- 3 Spider Bites: Symptoms, Signs & Spider Bite Treatment
- 4 Dangerous Spider Species
- 5 What To Do About Spider Bites
- 6 When to Worry About Spider Bite Symptoms
- 7 For More Information
Venom of the brown recluse spider causes a reaction in the body that is different from what researchers previously thought, a discovery that could lead to development of new treatments for spider bites.
University of Arizona researchers led a team that has discovered that venom of spiders in the genus Loxosceles, which contains about 100 spider species including the brown recluse, produces a different chemical product in the human body than scientists believed.
The finding has implications for understanding how these spider bites affect humans and for the development of possible treatments for the bites.
One of few common spiders whose bites can have a seriously harmful effect on humans, the brown recluse has venom that contains a rare protein that can cause a blackened lesion at the site of a bite, or a much less common, but more dangerous, systemic reaction in humans.
«This is not a protein that is usually found in the venom of poisonous animals,» said Matthew Cordes, an associate professor in the UA’s department of chemistry and biochemistry and member of the UA BIO5 Institute who led the study, published today in the journal PLOS ONE.
The protein, once injected into a bite wound, attacks phospholipid molecules that are the major component of cell membranes. The protein acts to cleave off the head portion of the lipids, leaving behind, scientists long have assumed, a simple, linear, headless lipid molecule.
The research team has discovered that in the test tube, the venom protein causes lipids to bend into a ring structure upon the loss of the head portion, generating a cyclical chemical product that is very different than the linear molecule it was assumed to produce.
«The very first step of this whole process that leads to skin and tissue damage or systemic effects is not what we all thought it was,» Cordes said.
The lipid knocks off its own head by making a ring within itself, prompted by the protein from the spider venom, Cordes explained. «Part of the outcome of the reaction, the release of the head group, is the same. So initially scientists believed that this was all that was happening, then that became established in the literature.»
The research team includes Cordes; Vahe Bandarian, an associate professor also in the UA’s department of chemistry and biochemistry; and Greta Binford, an associate professor of biology at Lewis and Clark College in Portland, Ore. who, completed her doctorate and a postdoc at the UA.
Cordes, Bandarian and Daniel Lajoie, a PhD candidate in Cordes’s lab, tested venom from three species of brown recluse spiders from North and South America. Binford, an arachnologist who has traveled the world in search of the eight-legged creatures, collected the spiders, isolated their DNA and milked their venom, which was then frozen and shipped to the UA labs for analysis.
«We didn’t find what we thought we were going to find,» Cordes added. «We found something more interesting.»
The cyclical shape of the headless molecule means that it has different chemical properties than the linear headless lipid believed to be generated by the protein, Cordes explained. The biological effects of either molecule in human membranes or insects aren’t completely known, he said, but they are likely to be very different.
«We think it’s something about that ring product generated by this protein that activates the immune system,» Binford said.
«The properties of this cyclic molecule aren’t well-known yet, but knowing that it’s being produced by toxins in venoms might heighten interest,» Cordes said. «Knowing how the protein is actually working and making this cyclic molecule could also lead to better insights on how to inhibit that protein.»
For those who do have a reaction to the venom, the most common response is inflammation that after one to two days can develop into a dark lesion surrounding the bite site. The blackening, or necrosis, of the skin is dead skin cells, evidence of the immune system’s efforts to prevent spread of the toxin by preventing blood flow to the affected area.
«Our bodies are basically committing tissue suicide,» Binford said. «That can be very minor to pretty major, like losing a big chunk of skin. The only treatment in that case is usually to have a skin graft done by a plastic surgeon.»
About once every five years, Binford said, someone develops a serious systemic reaction to a brown recluse bite, which can be fatal.
«If it goes systemic, then it can cause destruction of blood cells and various other effects that can in extreme cases lead to death by kidney failure or renal failure,» Cordes said.
However, it is believed that the vast majority of brown recluse bites are so minor that they go unnoticed by those who were bitten.
It’s not known what determines the type or severity of reaction a person is likely to get when bitten by a brown recluse, Cordes said, «but what is known is that this protein is the main cause of it.»
«I think if we know how the toxin works, it opens a new door to understanding how the syndrome is initiated as well as the possibility of blocking that process.»
«The discovery of this product may be crucial in understanding what exactly is going on in the human reaction,» Binford said.
For the spider biologists and chemists, the work has just begun.
«These spiders have been around with this toxin for over 120 million years,» Binford said. «I want to understand the full set of variation present in a single spider and across the entire genus and the activity of this compound.»
«People think about the brown recluse with fear,» she added. «When I think about a brown recluse or any other spider, I think about how a single spider can have 1,000 chemicals in its venom and there are about 44,000 species, so tens of millions of unique compounds in spider venom that we’re in the process of discovering. We have a lot to learn about how these venom toxins work and potential for understanding new chemistry and developing new drugs or treatments.»
Understanding how brown recluse venom produces harmful effects in humans is particularly relevant in Arizona, a hotbed for these spiders, Cordes said: «There are more variant species of Loxosceles here than anywhere else in the United States.»
The UA-led study of brown recluse venom was supported initially by a pilot project award from the UA BIO5 Institute. Binford’s venom collections were supported by a National Science Foundation Career Award.
Materials provided by University of Arizona. Original written by Shelley Littin. Note: Content may be edited for style and length.
- Daniel M. Lajoie, Pamela A. Zobel-Thropp, Vlad K. Kumirov, Vahe Bandarian, Greta J. Binford, Matthew H. J. Cordes. Phospholipase D Toxins of Brown Spider Venom Convert Lysophosphatidylcholine and Sphingomyelin to Cyclic Phosphates. PLoS ONE, 2013; 8 (8): e72372 DOI: 10.1371/journal.pone.0072372
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Spider-Man: 5 Weird Effects of Real Spider Bites
Although Spider-Man got his superhero abilities from a spider bite, ordinary spider-bite victims may have to deal with spider-bite effects that have nothing to do with being able to scale walls and climb around on ceilings.
Some of the weirdest effects that spider venom may have on regular, nonsuperhero humans include unwanted erections, dead skin tissue that turns black, unusual rashes, dark pee and sweat so heavy it makes puddles on the floor.
However, it is important to remember that such unusual symptoms are extremely rare, and the vast majority of spider bites are harmless, or cause only mild irritation and itchiness. [In Photos: The Science of the Amazing Spider-Man 2]
In fact, spiders do not often bite people, and if they do, it is because they feel threatened. Black widow spiders and brown recluse spiders are the only two spider species in North America whose bites may sometimes result in symptoms more serious than minor local pain and swelling, according to Rick Vetter, a retired arachnologist at the University of California, Riverside.
Although hobo spiders, which are common in the Pacific Northwest, are also listed by the Centers for Disease Control and Prevention as one of the three types of spiders that can be toxic to people, some researchers have argued that hobo-spider venom may not be so toxic after all.
Here are some of the weirdest effects spider bites have had on people.
The Brazilian wandering spider’s venom contains a toxin whose unusual erection-inducing qualities have attracted the attention of the pharmaceutical industry. In 2007, researchers found that the bites of the Brazilian wandering spider can cause long and painful erections in human males, along with other symptoms. The effect happens because the spider’s venom raises the levels of nitric oxide, which is a chemical that increases blood flow.
Researchers have since tested the toxin that is responsible for this unusual effect, called PnTx2-6, in the hope of developing a potential new drug for erectile dysfunction.
The Brazilian wandering spider is large, with a body size reaching up to 2 inches (5 centimeters) and leg spans stretching 5 or 6 inches (13 to 15 cm). Although the creepy crawler’s size may make it look threatening, it is not aggressive and, like most spiders, will only attack when it feels threatened, experts say.
Although there have been cases of «necrotic arachnidism,» in which spider venom kills human tissue, such cases are extremely rare. In fact, researchers estimate that less than one case of dead human tissue is reported per 5,000 spider bites from verified spider specimens, and verification of spider bites is very rare, Dr. Scott Weinstein, a toxinologist at Women’s and Children’s Hospital in North Adelaide, South Australia, told Live Science. (Toxinology is the study of the venoms and poisons of plants, animals and microbes; it is different from toxicology, which is the study of chemicals and drugs as they affect the body.)
If a spider bite is «verified,» it means that there was actual evidence that a person was bitten by a particular kind of spider. The only spider in North America whose bites have been shown to kill human tissue in rare instances is the brown recluse spider, Vetter said.
When necrosis does occur, tissue may sometimes turn black as cells die. One such case was reported last year — a woman on vacation in Italy developed necrosis in her ear after being bitten by a brown recluse spider. Part of her ear turned black, and her doctor had to remove the dead tissue and restore it, using cartilage from the woman’s ribs.
Some people develop unpredictable skin reactions to spider bites. A 66-year-old patient in France developed a strange rash after being bitten by a spider, which the doctors suspected was likely a brown recluse spider, according to a report of his case. The man had pinhead-size bumps on his forearms, which later spread to other parts of his body.
The medical staff diagnosed the man with a condition called acute generalized exanthematous pustulosis (AGEP), which typically occurs in people taking antibiotics. Other reports have also linked AGEP to brown recluse spider bites, the researchers said. The man recovered in five days, after doctors treated him with oral corticosteroids.
Unusual blood disorders and dark pee
In the case of the man in France who developed the strange rash, the doctors also found that he had a blood disease called periarteritis nodosa (PAN), in which small arteries become swollen and damaged. The doctors linked his blood condition with the brown recluse bite, because previous reports had described conditions similar to PAN in animals injected with brown recluse spider venom.
In fact, blood disorders are some of the rare symptoms that occur in people who have been bitten by recluse spiders, Vetter wrote in one study. The brown recluse venom may cause red blood cells to burst and release their contents into plasma, in a process called hemolysis. As a result, anemia may develop and can last from four to seven days, he said.
These blood problems may lead to other symptoms, such as acute kidney injury and jaundice (yellowing of the skin), as the blood protein called hemoglobin breaks down. The waste products of the breakdown can build up in the blood, and turn the urine dark when they are then excreted.
Puddles of sweat
Some Australian widow spider bite victims have been found to sweat so much after getting bitten that their sweat formed puddles on the floor, Vetter reported in one study.
Excessive sweating is one of the symptoms that may result from the bites of certain spiders that affect the nervous system. The venom of the black widow, for instance, attacks nerves by blocking their signals to the muscles. This causes the muscles to contract repeatedly, which can be painful and stressful for the body.
Black widow spider bite victims may also experience other nerve-related symptoms, such as high blood pressure, restlessness and severe facial spasms.
Who gets these spider-bite symptoms?
Whether a spider bite affects a person only mildly or causes severe symptoms depends on a number of factors, such as the amount of the venom injected, and the size and age of the person who got bitten. Children and elderly people are particularly susceptible to extreme symptoms from toxic spider bites.
However, most people who get bitten are highly unlikely to experience these severe symptoms, researchers say.
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Spider Bites: Symptoms, Signs & Spider Bite Treatment
In truth, spiders are not intentionally harmful to humans. Most spider bites occur when humans accidentally trap or brush up against a spider and receive a defensive bite. On rare occasions, spiders may have a serious lapse in judgment and bite a human finger (or other body part) mistaking it for a caterpillar or other such prey. Even then, most spiders are too small and not capable of breaking the skin with their fangs, or their venom too weak to be dangerous to humans. Simply put — most spider bites are accidental, harmless and require no specific treatment.
Still, that is not enough to stop spiders from having a bad reputation. It is common for any unexplained skin irritation to be called a «spider bite.» In fact, most skin lesions and bite symptoms that are attributed to spiders are rarely actually due to a spider bite. Research has shown that 80 percent of presumed spider bites are actually bites from other insects, or due to skin infections such as MRSA (a resistant staph infection).
Yet, occasionally, a spider bite will cause real harm. Especially with larger spiders, the bite itself may be painful and cause injury. However, far more concerning is the spider’s venom, which can include necrotic agents or neurotoxins. Spider bites rarely transmit infectious diseases.
Most spider bites are less painful than a bee sting. Pain from non-venomous spider bites typically lasts for five to 60 minutes while pain from venomous spider bites frequently lasts for longer than 24 hours. The rate of a bacterial infection due to a spider bite is low (less than one percent).
The two spiders of greatest concern in the United States are the brown recluse and the black widow spiders, most commonly found in southern states. Both species prefer warm climates and dark, dry places. Typically, these are timid, non-aggressive spiders, often found in dry, littered, undisturbed areas such as closets, woodpiles and under sinks.
Dangerous Spider Species
Black Widow Spiders
Black widow spiders can be found throughout North America, but are most common in the southern and western areas of the United States. Male widows, like most spider species, are much smaller and generally less dangerous than the females. Widows tend to be non-aggressive, but this spider will bite if its web is disturbed or if it feels threatened, especially after laying eggs. The more dangerous female is a dark colored spider with a red hourglass shape on the underside of its abdomen. While the bite feels like a pinprick and at first may go unnoticed or seem rather minor, the black widow spider’s venom is reported to be 15 times stronger than that of a rattlesnake. Early on there may be slight swelling and faint red marks. Within a few hours, though, intense pain and stiffness begin. Other signs and spider bite symptoms include: chills, fever, muscle cramps, and gastrointestinal symptoms such as nausea, vomiting and severe abdominal pain. Typically, black widow bites are less common, but more severe than brown recluse bites. That said, no one in the United States has died from a black widow spider bite in more than 10 years.
Brown Recluse Spiders
The brown recluse spider, also known as the violin spider, is most commonly found in the south-central, mid-western and southern states of the United States. Most encounters with this spider occur from moving boxes or rooting about in closets, attics, garages or under beds where they may have nested. Brown recluse spiders typically take up residence in dry, warm and dark environments such as basements, woodpiles and closets. These spiders are brown in color with a characteristic dark violin-shaped (or fiddle-shaped) marking on its head. Whereas most spiders have eight eyes, brown recluses have six equal-sized eyes. These spiders will bite if they feel trapped, such as when a hand reaches into a box in the attic or a foot slides into a shoe that the spider has made its home. The bite produces a mild stinging, followed by local redness and intense pain within eight hours. A fluid-filled blister forms at the site and then sloughs off to leave a deep, enlarging ulcer. Systemic (or generalized) reactions from a brown recluse spider bite vary from having spider bite symptoms like a mild fever and rash to nausea and listlessness. Generally, brown recluse spider bites are reported much more frequently than black widow bites, but while the brown recluse bite may cause very significant local skin reactions, it is much more unusual for these spider bites to cause generalized symptoms. Since these bites can develop over the course of three or more hours while taking about three weeks to heal, it’s important to pay attention to someone who has been bitten throughout the process. Brown recluse venom has been known to cause severe allergic reactions in children and elderly adults, as well as those with preexisting medical conditions. Unfortunately, brown recluses are almost communal and can be sometimes be found in great numbers.
What To Do About Spider Bites
- If you suspect a spider has bitten you, try to bring it with you to the doctor so they can determine the best course of treatment based on the species.
- Clean the site of the spider bite well with soap and water.
- Apply a cool compress over the spider bite location (using a cloth dampened with cold water or filled with ice).
- If you suspect the bite is from a black widow or brown recluse spider, and the bite is on an extremity, elevate it.
- Consider tying a snug bandage above the bite and elevate the limb to help slow or halt the venom’s spread. Ensure that the bandage is not so tight that it cuts off circulation in your arm or leg.
- Adults can take aspirin or acetaminophen and antihistamines to relieve minor signs and spider bite symptoms (but use caution when giving aspirin to children or teenagers).
- Seek medical attention for any severe spider bite symptoms and signs , or if they continue to worsen for more than 24 hours.
When to Worry About Spider Bite Symptoms
If a local reaction continues to get worse for more than 24 hours, it may be time to seek medical attention. Look for redness spreading away from the bite, drainage from the bite, increase in pain, numbness/tingling, or a discoloration around the bite that looks like a halo or bull’s-eye. If generalized spider bite symptoms set in, be concerned. In very rare cases, there have been reports of spider bites (by spiders considered otherwise harmless) causing allergic reactions — including anaphylactic shock, a life-threatening condition (much like may result from the sting of a bee, or wasp in a highly allergic person).
For More Information
Contact a pest professional if you think you may be dealing with a spider infestation. To learn more about different types of spiders and the threats they pose to our health, check out our spider Pest Guide section or watch this Health Checks video on spider bites.
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