The brown recluse spider is a member of the arachnid Sicariidae family that uniquely has six eyes, instead of the eight eyes. Its genus is Loxosceles recluse. In addition to the recluse spider, the Sicariidae family also includes the six-eyed crab spiders, genus Sicarius, found in Central and South America, and South Africa.
The brown recluse spider was the very first group of spiders blamed for the disease called necrotic arachnidism. This disease is characterized by blisters and ulcers or necrosis (destruction) of the skin after being bitten by a spider. When it was specifically caused by recluse spider, it is called loxoscelism. The discovery of this disease can be credited to a Chilean physician in 1870s when he traced a strange lesion known as “gangrenous spot of Chile” to bites caused by brown recluse spider, Loxosceles laeta. Since then, recluse spiders and six-eyed crab spiders are considered harmful and venomous to human beings.
What does a brown recluse spider look like?
There are several species of Loxosceles reclusa or recluse spider. Eleven of them are native to the southwestern U.S while two others are from other countries. They are found in various locations from southern Wisconsin east to Ohio, and south to northern Florida and central Texas.
It is easy to identify adult brown recluse spiders because they have a distinct “violin” marking on their dorsal cephalothorax. They are sometimes called “fiddleback” spider. The adult recluse spider has a body with 10-12 mm length.
However, the violin-shaped mark is not always the identifying mark of a recluse spider. The young brown recluse spider does not develop the mark until its adult stage. Sometimes, there are also other spiders with markings that resemble a “violin”.
Is the recluse spider a biting spider? The brown recluse spider is not really aggressive but it bites when crashed or pressed. Its home are warm area of the house, firewood, storage boxes and clothing. It has a nocturnal hunting habit so it usually bite when the victim is soundly asleep.
The recluse spider’s bite
The bite of a recluse spider is venomous. It can cause tissue necrosis when the dermonecrotic factor appears to be phospholipase sphingomyelinase D disrupts the cell membranes. How the patient’s immunity respond to the foreign antigens in the spider’s bite can tell how severe the tissue necrosis will be. Here are the factors considered when identifying the degree of venom of the recluse spider:
- The amount of venom injected
- Host susceptibility
- The site where the venomous bite occurred
Many times, recluse bites go unnoticed. One reason for this is because the bite usually occurs at night and the symptom is simply a mild stinging sensation. However, some have significant envenomation symptoms include local itching (pruritis), pain, swelling, redness of the skin (erythema), induration, blisters and pustules. If within 48-96 hours, none of those symptoms appear, then there is unlikely any necrosis or envenomation.
Recluse bites can cause complications to the affected area. Areas with less subcutaneous fats are observed to have greater degree of complications.
- The eyelids and extremities are high risk for complications from recluse bite.
- BRS bites have also been associated with tissue necrosis like pseudoepitheliomatous hyperplasia, deep venous thrombosis and pyoderma gangrenosum.
- Fever and malaise are the primary symptoms.
- Systemic manifestations include headache, anorexia, joint pains, rashes, nausea, vomiting, abdominal and chest pains.
When the severity of the recluse bite is not immediately detected, other complications like acute renal failure secondary to hemoglobinuria, leukocytosis, leukopenia, thrombocytopenia, disseminated intravascular coagulation, convulsions, and coma can fatally affect the victim. These will be reflected in any abnormality in the leukocytosis as well as an elevated ESR.