Spider bite: symptoms and treatments

Spider bites usually occur when provoked. Usually, their bites only cause a mild reaction, such as minor swelling, inflammation, or itching. On the other hand, some American spiders such as the Black Widow or the Tarantula can be fatal to humans.

What are the symptoms of a spider bite? In this article, we answer your questions about how to treat a spider bite and what to do in case of an allergy.

Do spiders bite?

Spiders are not insects. They are arthropods that are part of the arachnid family, like scorpions. “They have four pairs of legs and a body made up of two parts: the thorax and abdomen. They feed on other insects and trap their prey in webs obtained from the silk they secrete.

Spider bite

Although colloquially referred to as bites, spiders do not bite. They bite and thus inoculate their venom to their prey or their aggressors. “Their saliva is made up of enzymes distilled through their chelicerae, that is, their fangs.” When they bite a human, it’s usually to defend themselves.

“We have to distinguish between the spiders that are found in our homes in France, which give local and moderate reactions more readily, and the spiders with serious envenomation that we spot in South America or Australia”.

Among the dangerous spiders, we find:

  • Black Widows;
  • brown recluse spiders;
  • and tarantulas.

Symptoms of a spider bite

“Spider bites found in France generally give local and moderate, pruritic and fleeting reactions which require the application of an antiseptic to disinfect and the taking of an antihistamine to avoid itching”.

Appearance of lymphangitis

Poor disinfection can lead to lymphangitis, as with any blood-sucking insect bite. “It takes the form of a red streak going from the bite to, for example, an axillary hollow to the inguinal hollow with the appearance of lymph nodes and fever requiring antibiotic therapy and sometimes hospitalization”.

In general, the spider bite results in two close red dots, usually surrounded by a white border. The spider can bite several times.

“Depending on the species of spiders (especially those from South America), we can see the appearance of contact urticaria with stinging hairs”.

Acute exanthematous pustulosis, what is it?

Acute generalized exanthematous pustulosis (AGEP) is a rare disease characterized by an acute febrile rash. It is usually induced by drugs.

“Its occurrence following a spider bite has exceptionally been reported in the literature in the case of a spider bite of the genus Loxosceles, a family in which we also find the recluse spider (“Loxosceles reclusa”) or the violinist spider (“Loxosceles rufescens”)”.

Risk of allergy from a spider bite

“Strictly speaking, there is no real allergic reaction to spider bites, but rather non-specific inflammatory reactions in our French latitudes”.

On the other hand, there may be an allergic reaction to spider venom such as angioedema. The main symptom of angioedema is swelling:

  • Lips ;
  • of the language ;
  • around the eyes;
  • hands and feet.

These swellings are often associated with breathing difficulties.

The most dangerous species of spiders

The two most well-known dangerous spiders are the black widow spider and the segestria florentina.

The black Widow

The black widow spider, recognizable by the red dots on its abdomen, is extremely dangerous.

“It secretes a toxin causing intense muscle or abdominal pain with increased sweating. The skin lesions are rather discreet, but always precede neurological disorders”.

The Florentine Segestria

The Segestria florentina (or the Florentine Segestria) is a large black spider that lives in the crevices of the walls. It is recognizable by the green reflections of its chelicerae. It is mostly found in Mediterranean regions.

“His bite is painful and leaves both local inflammation and the mark of the hooks”.

In addition to the black widow spider and the Segestria Florentina, there are other species of spiders that are dangerous such as:

  • the cheiracanths;
  • the lycosis of Taranto;
  • the tarantula or the violin spider.

“These poisonous spiders cause an immediate reaction, an edema of the bitten area. It is then necessary to inject an anti-venom whose effectiveness is not optimal depending on the spider in question”.

When to consult for a spider bite?

It is important to consult a doctor when the following cases exceed the small local reaction:

  • Headache ;
  • nausea;
  • fever ;
  • muscle numbness;
  • stiffness in the joints;
  • dizziness.

“The doctor will first look for a trace of a bite on the body and then perform a blood test to identify the venom injected”. When possible, try to catch and identify it.

Treatment for spider bite

Treatment for spider bites depends on the type of spider.

In the case of minor bites, it is usually sufficient to disinfect the bite. Painkillers, antibiotics, and antihistamines may be given to counter allergic reactions.

If it is a dangerous spider, antivenom should be administered promptly.

Image Credit: Image by user18526052 on Freepik

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