Of the 20,000 species of spiders in the world, only two have been the cause of major tissue damage and death, namely the brown recluse (Loxosceles) and the black widow (Lactrodectus).1
The brown recluse is a medium sized spider as an adult, 8 mm to 15 mm in length. It is usually light brown in color and as a classic fiddle shape mark extending down is back. It can usually be found inhabiting dark, quiet places in the home, such as closets, garages, boxes, and attics. The brown recluse does not usually create webs, except for laying eggs, and roams for prey during the night.
Black widows are usually found in cool, damp areas, such as under rocks, inside mailboxes, in woodpiles, or around swimming pools. The adult female is approximately 2 cm long and is black with a red hourglass mark on its abdomen. The adult male is typically lighter in color with no red mark, and is much smaller than the female.2
The brown recluse bite may not cause any noticeable symptoms initially. The cytotoxic venom causes tissue changes.
After 1-3 hours, however, the bite may appear red, edematous and painful.
Within the next few hours, the bite may display the classic “red, white, and blue” sign. This bullseye is usually characterized by a blue center, caused by thrombosis, an area of pallor surrounding the bull’s-eye, caused by vasoconstriction, and an area of redness surrounding the pallor, caused by inflammation.1 The majority of cases do not cause significant signs or symptoms and resolve without medical care. However, more severe bites may take weeks to heal, even with medical care.3
The body’s immune system responds to the bite with release of inflammatory agents, which can lead to tissue necrosis and eschar development. After sloughing of the eschar, the wound may require surgical intervention with skin grafting.
Systemic symptoms are rare, but the patient will present with fever, headache, joint pain, gastrointestinal complaints, rash, and chest pain. Deaths occur as a result of acute renal failure, DIC and sepsis.1
The black widow bite is usually very painful, causing severe pain in the bitten extremity within minutes. The venom is a neurotoxin that causes presynaptic release of neurons and muscle cells.
Within one hour, symptoms of envenomation can appear including muscle spasms in the abdomen or trunk, nausea, vomiting, hypertension, tachycardia, headache, ptosis, diaphoresis, weakness, and respiratory difficulty.4 In the majority of cases, the effects resolve within a week.
Nursing Care & Treatment
Treatments for brown recluse bites vary in the literature. The most popular methods include interventions to improve skin integrity, prevent infection, and maintain circulation.1
Rest, ice and elevation has been shown to work for most patients. Other possible treatments include the use of dapsone, steroids, hyperbaric oxygen, and antibiotics. A tetanus booster should be given to the patient based on immunization history.
In one recent study, the use of nanocrystalline silver showed to be beneficial in brown recluse cases with faster healing, reduced inflammation, and less pain.5
Patients who have severe tissue damage, necrosis, or systemic effects will usually be admitted to the hospital. Those patients may need IV antibiotics, fluid and electrolyte replacement, and renal status monitoring.
Wound care may include surgical excision and grafting. Nurses must maintain good hand hygiene and frequently assess the patient for worsening condition.
In the field, black widow bites should be initially treated with application of ice to slow down the neurotoxin. Constrictive clothing and jewelry should be removed from the extremity. The patient’s ABCs should be monitored until transport to a hospital is accomplished.
For black widow bites, pain control is a major concern for the nurse. Opiates work well for pain relief and benzodiazepines are utilized for muscle cramping.6 Vital signs need to be monitored closely for signs of respiratory depression and hypertension. Some hospitals include calcium gluconate or calcium chloride in their protocol, but current research into the effectiveness of calcium is lacking.
Antivenin is used in cases of severe envenomation. One vial by slow IV infusion is the typical dose.
Because there is such a high rate of allergic reaction to the antivenin, the patient should be monitored closely.
Research has shown that when given correctly, patients who receive antivenin for severe cases have better outcomes than those who do not receive it.6
All patients who have been bitten by a black widow should be observed for at least 12 hours due to the risks of hypertension and muscle spasm. Any patient under the age of 14 and over the age of 65 should be hospitalized, as well as those with a history of hypertension.4
Prevention of subsequent bites should be addressed with the patient.
Because the brown recluse prefers dark, quiet areas, boxes and storage containers should be sealed shut. Clothes and shoes should be shaken out, especially if they have been stored on the floor.
Patients should use caution when reaching into dark spaces, especially basements, garages, and attics. Sticky traps can be placed in these areas to trap and kill spiders.3
When working in wooded areas, the incidence of spider bites can be reduced by wearing gloves. Spiders are reclusive creatures and will usually only bite when threatened. People need to become familiar to their surroundings, especially in areas where spiders tend to hide.
References for this article can be accessed here.
Stephanie Turner is associate professor of nursing at the University of Alabama.