Posted : May 2014
Author : Agata Blaszczak-Boxe
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 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.
Dead tissue
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.
Weird rash
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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