Dangerous spiders in Europe: How worried should we really be?

If you were asked to name a place where venomous animals live, what comes to mind? Perhaps Australia, home to notorious snakes like the inland taipan (Oxyuranus microlepidotus), or terrifying creatures like the yellow scorpion (Tityus serrulatus) It may be Brazil, where it lives. But Europe is not known for its menacing fauna, so it will probably be lower on the list.

But in recent years, widely reported deaths from one particular spider have sparked fears of the tiny eight-legged creatures in southern Europe. The most recent known case occurred just this summer in the Italian city of Bari, where a 23-year-old man died from a suspected bite by the Mediterranean recluse spider, also known as the brown recluse or corner spider. Just a month ago, a 52-year-old police officer in Palermo died from the same cause.

Two of Europe’s most feared spiders

They like to stick their hands in every nook and cranny, and if you’re unlucky enough to walk through the Spanish countryside you’ll come across some of the country’s larger arachnids, such as the brown recluse spider (Macrothele calpeiana) or the wolf spider (Lycosa tarantula). . However, in the Mediterranean region, there are only two species of spiders whose bites are a medical concern. The European black widow spider (Latrodectus tredecimguttatus) and the Mediterranean recluse (Loxosceles rufescens).

Black widow spiders have always had the worst reputation, but there are no records of deaths caused by bites from the European variety. Moreover, this impressive animal is found in the countryside and is rarely encountered, as it builds irregular nests under the bark of trees and rocks. The neurotoxic effects of its venom on humans are well known. A complex cocktail of molecules, collectively known as latrotoxins, affect neurotransmission, cardiac and smooth muscle function, causing a syndrome called latrotoxin.

Recluse spiders, which usually have small, violin-shaped black spots on the cephalothorax, are a completely different matter. Although it can be found in the wild, today it can essentially be considered a commensal species. This means they tend to live in close proximity to humans, especially in homes, garages, and workplaces. They often find dark, dusty hiding places, such as behind or under large furniture, and can go unnoticed for long periods of time.

different kind of poison

Unlike the neurotoxins of black widow spiders, the venoms of spiders in the Hemitidae family, to which Mediterranean recluses belong, have necrotic effects, causing the death of body tissue. Among the many proteins in the venom is a phospholipase enzyme that breaks down cell membranes and causes blood vessels to burst. The two effects usually combine to cause a local reaction at the sting site, such as swelling, redness, and itching, for several weeks.

In a small number of cases, a necrotic lesion may develop in the central area of ​​the bite, where the tissue dies and eventually sloughs off, healing after several weeks.

This set of symptoms, called cutaneous loxocerism, usually does not have a major impact unless the bite occurs in a particularly sensitive area, such as the face. Additionally, necrotic progression is less common in European recluse spiders than in some Latin American spiders (L. reclusa and L. laeta). It is considered a serious public health problem in countries such as Chile, Argentina, and Peru.

However, in rare cases, the necrosis caused by a recluse spider bite can reach the underlying muscles, causing toxic shock syndrome, which includes symptoms such as fever, muscle pain, and joint pain. When caused by a Loxosceles bite, this is known as cutaneous visceral Loxosceles, a very rare condition that can lead to acute hemolysis (destruction of blood cells), kidney failure, shock, and ultimately death.

loxoceles of spain

L. rufescens is a species native to the Mediterranean region and has lived among humans for thousands of years. However, bites are extremely rare, and reliable official data on bites is extremely lacking. Even when more severe clinical reactions occur, patients are rarely able to see, let alone catch, the animal that bit them. This means that most diagnoses of loxoseliosis cannot be fully verified.

This difficulty is also highlighted by an interdisciplinary research group directed by the University of the Balearic Islands. In a paper published this year, researchers analyzed four recent cases of suspected recluse spider bites and another 12 recorded in Spain between 2005 and 2021.

To date, there have been no official deaths reported in Spain due to recluse spider bites. A recent case of death from the bite of a Mediterranean recluse in Italy remains a mystery. It could be a simple statistical anomaly or a series of clinical errors.

It’s also possible that, with the globalization of commerce and today’s high level of intercontinental travel, the Italian bite was caused by an American species of the genus Loxoceres that was accidentally brought to Europe.

This has happened several times with specimens of the much more dangerous genus Phonutria, including the famous Brazilian wandering spider, which can occasionally appear in fruits imported from South America. However, there is no official record of the existence of stable populations of the American recluse spider or phonutria in Europe.

Should I worry?

Arachnophobia is a widely held fear, fueled by horror movies, books, and sensational publications in the media. However, the reality is quite different: at least in Europe, the threat posed by any species of spider is almost negligible.

In Europe, 1,691 deaths were recorded in 23 years due to stings from wasps, wasps and wasps, but most of us are unaware of the smell of jam on our toast. Even if they come, they won’t run away to the hills.

The fact that the number of deaths from alleged spider bites during a similar period can be counted on one hand speaks to the reality of the situation.

There is little to worry about, as the Mediterranean recluse spider is not very aggressive and will usually only attack if directly disturbed. If you take precautions such as cleaning under the couch and behind the wardrobe from time to time and wearing gloves when moving such furniture, your chances of being bitten by a Loxoceres and ending up in the hospital are much less likely to be struck by lightning. It’s not that different from what you’re likely to encounter.

This article is republished from The Conversation under a Creative Commons license. Read the original article.