Brown recluse spider bites in children and adults
I always thought of this as an esoteric topic, until a good friend of mine got a spider bite and I decided I should write about it.
Before I dive into the topic:
This spider, brown recluse, can be found in the southern part of North America – south of southeastern Nebraska, Southern Iowa, Illinois, Indiana Southwestern Ohio, central Texas, western Georgia and northern Kentucky. Other species of that spider can be found in the Mediterranean region but also distributed worldwide including in western Asia, parts of Europe, north Africa, Japan, Australia, the Pacific Islands and North America.
I have a different post about all the other bites that can be caused by annoying insects where I cover different bites and their complications. You can find it in the link here. I suggest you read it as the approach to insect bites and spider bites is quite similar.
Shall we get started?
What do we know about the brown recluse spider and when does it bite?
The scientific name for this spider is Loxosceles reclusa. As its name “reclusa” implies, this spider likes to isolate itself in undisturbed places. It has 3 pairs of eyes, whereas most spiders have 4 pairs of eyes.
This spider is also nicknamed “violin spider” because the mature Loxosceles reclusa, which is about 2-3cm in size, has markings on its back resembling the shape of a violin.
This spider tends to be more active during the end of spring and the beginning of the summer season, especially during the night, when it is able to hide in clothes and sheets (typically ones stored in the bottom of closets).
The Mediterranean recluse spider (Loxosceles rufescens), is a species of the Loxosceles spiders that originated in the Mediterranean region but is now distributed worldwide including in western Asia, parts of Europe, north Africa, Japan, Australia, the Pacific Islands and North America. It is almost indistinguishable from Loxosceles reclusa.
Do these bites hurt? Where in the body do they occur?
Usually, one does not feel the initial bite at all.
Most of the bites occur in the upper parts of the arms (see the first image), the chest or the inner parts of the thighs.
What can the brown recluse spider bite lead to?
This bite can lead to one of three different clinical presentations: a local skin reaction, a systemic reaction and/or an allergic reaction.
Local (skin) reactions to brown recluse spider bite
The skin reaction to a brown recluse spider bite includes a red rash surrounding the initial bite area that can spread. In about half the cases a black discolouration will also appear, and this indicates necrosis of the area. Many times, this is our sign that bite was caused by this spider.
Blistering, warmth, and a burning sensation may follow. The rash typically spreads and redness worsens within a few days, as seen in the second image.
Systemic reactions to brown recluse spider bite
This refers to any symptoms that the body may experience other than the skin reaction. It can include fever, shivers, vomiting, joint pain, hemolysis of red blood cells, kidney involvement and other complications.
These potential systemic reactions are the reason why it is important to monitor symptoms such as a change in the person’s urine colour (to a darker colour) and to consult with a physician if such changes occur.
Allergic reactions to brown recluse spider bite
Allergic reactions may include a rash, including urticaria or angioedema (swelling of the hands and feet) and more.
What exactly does this bite lead to – an inflammation, infection or allergic reaction?
Turns out the spider’s venom contains several toxins that cause these severe reactions described above. Secondary infections may occur at the site of the bite but these are not very common.
How can you determine whether a wound/bite was caused by a brown recluse spider?
This can be done in one of two ways:
a. If the person with the wound saw the spider – then it is easy and straight forward.
b. If the person does not recall seeing a spider treading on them then the physician ought to be familiar with the characteristic skin manifestations in order to make the diagnosis. Don’t forget, there are other skin diseases that may look similar, especially skin infections.
When the patient presents with a systemic rash/reaction, and does not recall any interaction with spiders, the diagnosis becomes even more challenging.
How are brown recluse spider wounds treated?
First of all, it is important to determine whether the wound was caused by a brown recluse spider bite and not to miss other possible causes for wounds such as skin infections.
The skin surrounding the bite needs to be cleaned properly with water and soap and the child/adult should be monitored.
There aren’t any other specific treatments or preventative management required.
If the child/adult are not vaccinated for tetanus, then they need to receive a tetanus vaccine as explained in the post here.
A couple more important thoughts:
Are antibiotics required? Similarly to other bites, bites caused by the brown recluse spider are not infectious and usually do not wind up developing into bacteria infections. Therefore, antibiotics are not needed. On the other hand, it is often quite difficult to distinguish between a bite and an infection and therefore many patients do end up receiving antibiotics.
Are steroids required? I tend to prescribe patients with a topical steroid. Systemic steroids are reserved for more complex cases including allergic reactions.
In summary, these bites are unpleasant, to say the least. They are often difficult to identify but the good news is that most of the time patients manage without any complications or the need for any specific treatment.
Just make sure not to miss a different, more dangerous, diagnosis that may only resemble a bite…
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