Spider bites and risky remedies: the case of Corsica

Corsica is an island in the Mediterranean sea, between the coasts of France and Italy.
Ask any of its inhabitants, and they'll tell you it's the most beautiful place on Earth. Sure, islanders all over the world will often claim the same about their island, but it's hard to deny that Corsica is absolutely gorgeous: majestic mountains plunging into the azure sea, heavenly beaches and coves, sand dunes covered in wild flowers, snow-capped peaks shining under the blue sky, their slopes dotted with picturesque little villages... 

It is also a place blessed with an extreme scarcity of dangerous land animals. It doesn't have any venomous snakes or medically significant scorpions. Mosquito-borne yellow fever and malaria used to take their toll on Corsicans unlucky enough to work and live in swampy areas, but were eradicated during the twentieth century. While bilharzia, a deadly disease caused by a parasite carried by a freshwater snail, has been making a worrying comeback in the recent years, it is rare; as long as you stay out of shallow freshwater streams, you're safe.
All in all, the greatest danger about the island's terrestrial fauna is probably the risk of road collisions involving its many feral and free-roaming farm animals.

There is, however, one creature Corsicans treat with an almost superstitious fear, and never fail to depict as extremely dangerous and deadly. They have given it deliciously macabre nicknames such as "u malmignattu" (literally "the evil leech") or "a zinevra" (a word that also means "witch"). This infamous animal is Latrodectus tredecimguttatus, the Mediterranean black widow.

A zinevra, u malmignattu: Latrodectus tredecimguttatus, the Mediterranean black widow

Widespread in dry parts of Eurasia and North Africa, the Mediterranean black widow is very rare in mainland France, where it is restricted to a few dry steppe and dune localities. It is somewhat more common in Corsica, where it can be found in a wider range of habitats, including, sometimes, in gardens.
That spider has a medically significant venom, but also (like all widow spiders) a passive and non-confrontational nature; a black widow will not bite unless it gets pressed against the skin. In addition to that, it is also web-bound and does not tend to wander around. Bite incidents are, therefore, extremely rare: between 0 and 5 cases every year.

However, these accidents used to be a more common instance in the past, when people used to work the fields manually. Latrodectus tredecimguttatus likes to build its web at the base of grass tussocks or low, dense bushes, which exposes someone harvesting cereals, grapes or herbs by hand to a higher risk of accidentally putting their hand on one. Even in more recent times, manual agricultural tasks have been the chief cause of accidental Mediterranean black widow bites.

Historically, Mediterranean black widow bites typically happened during manual agricultural tasks, by grabbing bunches of stalks with bare hands and accidentally squishing a spider*

Of all Latrodectus species, L. tredecimguttatus is probably the best-known and most extensively studied from a clinical perspective: the first medical studies on this species are almost 200 year old!
Like all widow spiders, its venom mainly has neurotoxic effects. On a human, a bite can cause, alongside other, less common symptoms: intense to excruciating pain, painful muscle contractions, profuse sweating, rigidity in the abdomen, dyspnoea, heart rate anomalies, and hypertension. The average duration of the symptoms is 3 to 5 days, often with residual after-effects, particularly fatigue, persisting for several weeks after the bite.
A black widow bite is a harrowing, exhausting experience, but the victim almost always survives it. Even though the Mediterranean black widow is among the "deadliest" Latrodectus species, the survival rate of its bites is about 99.8%.
Fatalities exist, but they are extremely rare. They are generally caused by acute, fast-evolving heart complications, which have not, so far, been linked to identified pre-existing health factors (although people with heart conditions are, of course, considered more at risk). 

This very high survival rate is not exactly a recent improvement; it's not one of these situations where the introduction of antivenin turned previously frequent deaths into an anecdotal occurrence.The fatality rate was already low in pre-serum times: it is estimated that over 95% of the bitten subjects lived to tell the tale. The serum has helped make the survival rate even closer to 100%, and, more importantly, helps significantly lowering the duration and severity of the symptoms. However, the frequent antivenin shortages do not significantly increase the numbers of fatalities. It is, actually, quite rarely used to treat envenomations, because of the risk of adverse effects, although some authors argue that these are outweighed by its effectiveness in reducing the pain and duration of the symptoms.

As early as 1833, Dr. Cauro, a physician from Ajaccio (Corsica), had already noticed that bitten subjects left untreated generally survived, although they healed slowly, with lingering after-effects.

The bite of the Mediterranean black widow is, therefore, not typically deadly; fatalities directly induced by its venom are extremely rare, and already were before modern treatment protocols.
How, then, did the black widow gain such a sinister reputation? Why is it perceived as extremely deadly when it's not? Why are Corsicans, up to this day, so terrified of this spider? 

It surely has something to do, in part, with the absence of other dangerously venomous land animals in Corsica. On the mainland, the widow shares its habitat with vipers and medically significant scorpions, putting its relatively low dangerousness in perspective. Being one of the only medically significant species on the island, without any other, more dangerous animal to steal the spotlight, surely adds to its sinister aura.

It probably has even more to do with the excruciating effects of the bite, as the intense pain, muscle cramps, heart palpitations and exhaustion can understandably make the subject believe they're going to die.
In addition to that, a fairly common and intriguing effect of the venom is a state of abnormal anxiety and agitation, sometimes even resulting in visual hallucinations; even though their life is unlikely to be in danger, the patient becomes frantic, anxious, and convinced they're going to die. 

However, Cauro, in his thesis about black widow bites in Corsica (1833), reports what is probably the main reason for this scary reputation: a high proportion of people bitten by black widows did indeed die, although they were not killed by the bite.
If you were bitten by a black widow in eighteenth-nineteenth century Corsica, your life was in serious danger. Not because the bite was likely to kill you, but because villagers would try to cure you with their traditional "remedies".

Cauro describes two main types of traditional "cures" that were in use against black widow bites throughout Corsica in his time.
They were based on the false assumption that black widow venom killed by lowering the body temperature (further studies have demonstrated that it does not affect the body temperature in any way). Therefore, to combat its effects, the body had to be warmed up at all costs, which was generally achieved in two equally disturbing (and dangerous) ways.
The first way was to have the victim forcefully ingest colossal amounts of wine and spirit; as much as their body was physically able to take (and often more).
The second, and possibly even more terrifying method, was to lock up the victim in an unlit, but still hot, bread oven (again, as hot as their body could physically take, and often more) until the symptoms abated.
Of course, one can easily imagine how much deadlier than the venom these "cures" actually were. Cauro noted that they seemed to work to a certain extent, but, more often than not, actually killed the patient...

The dreaded black widow's reputation as a killer is wildly overstated, but a large part of it may be because the "cures" for its bites were much deadlier than the venom itself

 

How such extreme and dangerous "remedies" may have been perceived, at any point, as effective and necessary can seem puzzling.
When reading about it on paper, 200 years later, it's easy to judge them and wonder how these people could have been so stupid. However, they had their reasons, which are, unfortunately, the same reasons why many people across the world, nowadays, still cling to similarly ineffective traditional remedies. 

First, one has to consider the action bias, i.e. the strong instinctive reluctance humans feel towards inaction, particularly in emergency situations, even when the consequences of action are worse than those of inaction. A reluctance so strong, in fact, that action bias is still a problem in today's medical world: one famous case of this is the over-prescription of antibiotics, in situations where they are unnecessary or even counter-indicated, just because the patient wouldn't accept the idea of going back home without a prescription. 
It's hard to resist the urge to try something, anything, when you're watching someone you know and love going through the worst hours of their life, particularly if you believe they're going to die if nothing is done.
Add to this, in that specific case, that the victims themselves may also be in a state of anxiety and delirium that convinces them that death is certain and imminent, and you may get a situation where people are desperate to get shoved in ovens in order to "save their life".

An even more important factor at play was the false assumption that a black widow's bite will always be deadly if left untreated. Unfortunately, that false idea is not restricted to Corsica, nor is it a thing of the past: lots of people, everywhere on the planet, firmly believe it today, possibly even more than in ancient times (as Internet-borne misinformation and exaggeration about spiders is rife).

If one is firmly convinced that any bite from some venomous species will become deadly or life-threatening if nothing is done to stop the action of the venom, anything can be perceived as a potential remedy, regardless of its ineffectiveness or dangerousness.

Worse: as long as some subjects "treated" with it survive and heal, the "remedy" may be perceived as effective, and adopted as the go-to method in case of envenomation. The trust in the false remedy may persist even if the fatality rate among "treated" subjects is high: death and other adverse events, regardless of their cause (the venom or the "cure") are always blamed on the venom, while every patient who survives and heals is assumed to have been "saved" by the remedy, when they did in fact survive despite it.

There is no venomous species (except maybe a handful of incredibly toxic marine animals) whose bite or sting is fatal in 100% of untreated cases. In fact, the vast majority of "deadly" toxic animals only kill people in a fairly small proportion of envenomation cases.

Medically significant scorpion and spider envenomations, including those that can kill people, are actually rarely life-threatening to healthy individuals. Even species commonly portrayed as extremely dangerous and deadly, such as the Sydney funnel-web spider (Atrax robustus), the "banana spiders" (genus Phoneutria) or the "death stalker" scorpion (Leiurus quinquestriatus), life-threatening envenomation cases are actually a minority: only about 5% death stalker stings on children (even fewer on adults) and 0.5% of Phoneutria bites on humans are severe. While funnel-web spiders (Atracidae) have, by far, the highest rate of life-threatening bites in spiders, with as much as 20% of bites being severe, fatal cases were never the most common outcome and have always been very scarce (about 15 deaths between 1927 and 1980, none after 1980 thanks to the antivenin).

Even the most medically significant scorpions on the planet, such as species in the genus Buthus, do not frequently cause fatal envenomations

Even bites from very dangerous snakes such as the black mamba (Dendroaspis polylepis), which are often fatal if no antivenin can be administered, are not always life-threatening.
Sometimes, the animal simply doesn't inject enough venom to cause severe symptoms, or doesn't inject venom at all (which is known as a "dry bite"). It is estimated that in sub-Saharan Africa, between 10 and 50% of bites from venomous snake species are dry bites.
That leaves plenty of survivors that can wrongly believe a remedy they used was effective, when the outcome would have been the same without it.

Moreover, while many people believe all snakes and all scorpions are dangerous and potentially deadly, only 10 to 15% of the 3700+ known snake species are venomous, of which only 200 (5%!) can cause life-threatening human envenomations. Similarly, only 10% of all known scorpion species, and a puny 1% of all spider species, are medically significant.

That means an overwhelmingly vast majority of snake, spider and scorpion bite and stings do not result in any serious symptoms, simply because the culprit was not a medically significant species, and therefore cannot cause dangerous envenomations.
 

Scorpions are widely perceived as extremely dangerous creatures and lots of people believe any sting from any scorpion may be deadly, even though only one species out of ten is medically significant.

 

Even someone who is aware that not every species of spider, scorpion or snake is dangerous may still very often misidentify harmless (or at least not medically significant) species as more dangerous ones,  because the latter are generally much more famous.
For instance, because of their terrifying (and exaggerated) reputation, all brownish, nondescript spiders are frequently mistaken for recluse/violin spiders (genus Loxosceles).

Many harmless snakes, when cornered or grabbed, will try to fend off the attacker by striking and biting in a way that mimics more dangerous species. Someone who doesn't know much about snakes may be fooled by this bluff, and conclude the snake that just bit them was venomous when it wasn't.

 

These combined factors create plenty of situations where someone gets tagged by a snake, a scorpion or a spider, think they're going to die (or at least get very sick), and then, when they don't, believe it's something they did that "saved" them, when the actual reason is simply that their life was never in danger in the first place.
Which is how people end up thinking a "remedy" that actually does nothing or even harms them is a life-saver that should be used against venoms.

While the case of Corsica is among the most extreme examples, many other ineffective, and sometimes downright dangerous "remedies", were, and unfortunately still are, used to "treat" spider, scorpion or snake bites throughout the world. 

Hot oil*, cauterisation* (burning the bitten area!), soda*, petrol*, incisions*, tomato slices*, or even killing the animal and crushing its remains on the bite site*, are examples of ridiculous things people use, claim to be necessary, and even dare advise others to use on spider bites or scorpion stings!

In the best-case scenarios, these false "remedies" are simply useless, and do nothing.
In the worst cases, they do nothing about the venom AND cause infection, poisoning or tissue damage, turning what would have been a harmless, or at least more benign, envenomation, into a much more severe ordeal, whose consequences may drag on for much longer than they would have without "treatment".

Furthermore, these "remedies" are a significant problem in the medical management of serious bites, as they are sometimes so deeply ingrained in culture and traditions that people will preferably turn to them before or instead of appropriate medical attention, even when the latter is readily available. This results in delayed or inappropriate care, which does cause avoidable complications and even deaths, particularly in snakebite cases.

Of course, that doesn't mean every folk remedy is ineffective or harmful. We are not dismissing and ridiculing thousands of years of cumulated traditional medical knowledge, nor are we praising an alleged "superiority of modern Western medicine". Current medicine actually owes a lot to medical traditions and ancient knowledge from all over the world, because some traditional remedies do work. Countless modern medications are actually derived or directly extracted from substances that were, before that, used as traditional remedies.
For instance, quinine, the first efficient malaria treatment to be made commercially available (1820!), was originally extracted from the bark of trees in the genus Cinchona, which was used as a traditional remedy by the Quechua in the Andes.
The Madagascar periwinkle, Catharanthus roseus, was widely used against many diseases, most notably diabetes, in Africa, Asia and the Caribbean, before some of its compounds were found out to be literal life-savers against many forms of cancer (which sparked a famous controversy about theft of Indigenous Knowledge, as the plant extracts were patented by pharmaceutical companies without crediting or compensating the Indigenous People who sourced the plant and were the first to identify its therapeutic value).
Plantain (genus Plantago), a small herb widely used in Europe as a traditional treatment for insect bites, has demonstrated anti-inflammatory and analgesic properties.

The Madagascar periwinkle, Catharanthus roseus, is widely used as a traditional remedy in most tropical parts of the world, and actually holds some amazing medicinal properties against certain diseases, including some forms of cancer

Even the treatment actually advised by Cauro for black widow envenomations, opium, was originally used as traditional painkiller and narcotic in Asia before Europeans started using it. While it is not exactly a very safe medication, and opioids were eventually found not to be very effective against the pain induced by black widow venom, the simple fact that it helped moving away from ovens and forced binge drinking as a "treatment" probably saved many lives.

The issues with the problematic folk remedies used against bites and stings is not their "traditional" nature. It is how their alleged properties were found out: simply observing improvement in the patient's condition after administrating a "remedy" does not necessarily prove it works. 

The human body is not defenceless against threats to its health. As soon as something foreign, such as venom, enters it, the immune defences start fighting back. Sometimes, it's not enough, or it costs too much in terms of energy, and medication is required to supplement the natural defences or alleviate the symptoms. Sometimes, the body is not equipped at all to deal with it, or the attack is simply too massive, and even appropriate treatment is not enough to prevent a fatal outcome.

However, in most cases, the body eventually heals by itself, particularly if the envenomation was mild (or if there was none at all) regardless of whether the remedy helped or not. Therefore, simply observing improvement after administering a remedy is not enough to prove its effectiveness, as the person may simply be getting better because their system is fighting successfully on its own.

Swelling, one of the most common and visible trademarks of inflammation, is caused by an influx of fluid to the bitten area, so the immune system can do its job faster and easier. It's a sign that the body is fighting back.

Without comparison, it is therefore impossible to tell if the treatment actually helped or if the body just healed on its own. Thus, to prove the effectiveness of a suspected remedy, its performance has to be compared with how the same disease unfolds in patients who don't receive any treatment.
That's how Cauro demonstrated that patients who did not receive any treatment for their black widow bites had better prospects of survival than those who were "treated" with alcohol and ovens.
It's also how he found out that patients treated with opium suffered milder symptoms and recovered more quickly than those who weren't treated at all. It's only by comparing with what happens when nothing is done that one can determine if the remedy makes things significantly better or not.

That method is still the basic principle of modern pharmaceutical research: after it's demonstrated to be safe enough, the effectiveness of a potential medication against a disease is tested in comparison with a control group of (consenting and informed) patients who receive placebos. Of course, because the impact of the placebo effect² can be surprisingly high, the patient does not know if they receive a placebo or the actual medicine (they are informed about what the medicine is, what it does, and what are the risks, and also that they may or may not receive a placebo, though), nor does their doctor: that's why it's called a double-blind, placebo-controlled study.

Cauro did not invent that method himself; at his time, it was already the standard method in medical research. The one generally credited with the first known standardised placebo-controlled test is Dr. James Lind, who researched a remedy against scurvy on board of the ship Salisbury, in 1747, where he compared several groups treated with different remedies with a control group who simply received seawater, eventually discovering that citrus fruits effectively cured scurvy.
Of course, others, such as Ibn Sina (aka Avicenna) or Ambroise Paré, and who knows how many outside of the Western world, have come up before him with similar ideas of comparative tests, but Lind's test was the first recorded instance of one involving a control group treated with a placebo (seawater, which was known to be inactive against scurvy).

In 1747, lemons and oranges were found out to be a simple and effective remedy against scurvy, in what is currently the first known example of a placebo-controlled clinical trial

The main issue with most traditional remedies is that there is no confirmation that they have been tested in that way, which is the only way to objectively prove it is effective.
Most of them, just like the "cures" to black widow bites in Corsica, are simply based on improvement observed in some people treated that way (while dismissing the cases where the remedy doesn't work, by blaming the venom), and the (untested) assumption that things would have been worse if nothing had been done. 

In addition to that, the absence of testing for safety and toxicity is a major issue.
Just like venom, medication is treated by the body as a foreign element, and, no matter how "natural" it is, it always has a certain toxicity (everything does, even water, the question is never "toxic or not", it's always "how toxic"). The last thing you want, in a case of severe envenomation, is to further burden the body with additional poisoning or infection from a "cure" that doesn't help.
That's why the other major component of medical research, besides testing the effectiveness of medicines, is assessing their toxicity, and finding ways to mitigate it, in order to get the best possible balance between effectiveness and adverse effects.

In short, the effectiveness of a home or folk "remedy" is not proven in any way by:
- surviving the envenomation, or even not suffering any major symptoms
- noticing your condition somewhat improved after using it
- the fact that others have claimed they noticed the same thing
- the untested assumption that "things would have been worse without it"
- the fact that some friend or family member you love, trust and respect very much only swears by that remedy
- the fact that this remedy has been widely used for a long time in your community
- the fact that a random stranger on the internet (including a famous random stranger, or one that claims to have some medical qualifications) claims it works .

Some of these (particularly 2,3 and 6) can be evidence the remedy is somewhat effective, but it is not proof. 

The only valid proof is:
- Comparative tests conducted on a large enough number of subjects have proven the remedy works better and is safer than doing nothing at all.

These issues take a special importance when it comes to spider bites in particular, for one simple reason: spider bites are almost never a medical emergency.
Not only are actual spider bites uncommon (not the many cases of lesions randomly diagnosed as spider bites* when they actually have nothing to do with spiders at all), but fewer than one spider species out of 100 is medically significant (something between 300 and 400 species worldwide, out of more than 52000).
The vast majority of spider bites actually have very little effect on humans, including very young children and the elderly: just a local reaction, generally somewhere, in terms of severeness, between a mosquito bite and a wasp sting (with an extremely low risk of allergic reaction, unlike wasp and bee stings).
That means the main risk of complication with non-medically significant spider bites comes from infection; the best course of action in case of (real) spider bite is to disinfect the bite thoroughly, keep it clean and dry, avoid touching or scratching it, and seek medical attention in the unlikely case of any unusual symptoms (local or systemic¹) appearing.

On the other hand, applying anything non-sterile (such as a tomato slice, clay, soda, improperly prepared herbs, or even the crushed animal's corpse(!)*...) on the bite as a home remedy, or tampering with it (by squeezing, scratching, cutting, burning*...), will significantly increase the risk of infection, turning something that would have healed quickly and without any problem into a badly infected wound, which will take weeks and a heavy course of antibiotics to get better. Doing nothing at all is often a much safer option than doing the wrong thing.
Forget what your grandma, neighbour or random Facebook user told you: it's just not worth the risk.

Despite their sinister and largely undeserved reputation, most spider bites are actually less risky than the home "remedies" claimed to "cure" them

Don't be a fool. Don't play with your health. Most grandmas, neighbours, or random people on social media aren't arachnologists nor medical experts, so their advice about spider bites isn't worth a dime.
You would only trust an actual mechanic to fix your broken car engine; why trust hearsay or advice from a random unqualified person about your health?

If you still want to keep hurting yourself by burning or cutting spider bites* "to draw the venom out" because you firmly believe it works and won't be told otherwise, it's your right and responsibility. You've been warned.
Don't drag anyone else into it, though, and don't recommend your irresponsible practices as medical advice.

Finally, don't use your experience to argue against arachnologists that some harmless spider species "has a nasty bite" because a tomato slice* or hot oil* on the bite got it infected and nasty. The culprit wasn't the spider.  ⏹

Notes: 

*I have personally witnessed each of these ineffective and dangerous "remedies" being recommended at least once on social media, for spider bites, scorpion stings, and, unfortunately, snake bites (venomous snake bites are, on average, a much more serious and pressing medical emergency than spider bites or scorpion stings, so giving incorrect advice is even more irresponsible and likely to have disastrous consequences than with the latter).

*Sources marked with this symbol contain detailed images of extensive necrotic skin lesions, which may be disturbing to some readers

 *What you see in this image is not the result of intentional handling. It's simply a situation where the spider, agitated by the disturbance, raced towards my hand in an attempt to get away from the camera. Please do not try to replicate what you see in this photo. I am a trained professional, experienced in working with medically significant Arachnids and other venomous animals. Free and intentional handling of wild animals, particularly those capable of significantly harming humans, simply for the purpose of taking an impressive photo, is not something I do or condone.

Lingo:

¹Systemic symptoms: Symptoms of an envenomation or poisoning are described as "systemic" when they affect a general body function (for instance, the nervous, circulatory, or respiratory systems) or organs and body parts well away from the bite site, as opposed to local symptoms, which are restricted to the bite site and its immediate surroundings.
For instance, nerve pain, muscle spasms, heartbeat anomalies, hypertension, nausea, dizziness, anxiety and hallucinations are examples of systemic symptoms that can result from the bite of a widow spider (genus Latrodectus).

²Placebo effect: A clinical phenomenon where an inactive treatment, which should theoretically have no effect (such as a sugar tablet or a saline injection), still results in significant relief of some of the patient's symptoms. The main cause of the placebo effect seems to be the reassurance provided by the care and "treatment" received.

Except when the source is explicitly cited, the images illustrating this blog are mine and are not free to use without permission.

References:
† Rollard C., Chippaux J-P., Goyffon M., éd. La Fonction Venimeuse. Lavoisier Tec & Doc, Paris, 2015.  

References to web sources are integrated into the text of the article; the words in blue are clickable and will redirect you to the sources of the information.