Neurotoxic Arachnidism

In the United States, black (Latrodectus. mactans, L. various, L. Hesperus), red (L. bishopi), and brown (L. geometricus) widow spiders, in Australia and New Zealand, the red back (L. hasselti) widow spider, and in South and eastern Africa black (L. mactans, L. geometricus) widow spiders, attack people. The tarantula (L. tredecimguttatus) is also a member of this family.

Adult male (0.5 cm) and immature black widow spiders are more colorful than are adult females (1.0 cm). With the familiar red hour glass, females are mostly responsible for human bites. These eight-eyed creatures spin variably-sized webs close to the ground and in such varied sites as logs, shutters, windows, doors, dumps, barns, and sheds. In infested outdoor privies, spiders bite penises of seated men who disturb the web with a urine stream. Most often injury results when a human limb disturbs the web or a body part traps the spider against it.

Local effects, except for Latrodectus hasselti, are usually quite mild, ranging from a sharp pinprick to nothing, leaving a small pair of red marks, and occasionally yielding slight redness and swelling. Within an hour, dull cramping and often severe pain and numbness spread from bite to the entire torso; the syndrome begins to wane after three hours, but can last for days. Sometimes, a surgical abdomen is mimicked, but the lack of tenderness and distension, the history, and the muscle spasms allow the correct diagnosis. Other symptoms include tachycardia, headache, diaphoresis, salivation, weakness, fever, vomiting, backache, respiratory distress, priapism, impotence, urinary retention, anxiety, increased deep tendon reflexes, protein-uria, parasthesia, hypertension, fetal positioning, and burning; these changes usually end after several days, but can last for months. Complications include shock, convulsions, and cerebral hemorrhage, as well as respiratory, cardiac, or renal failure.

Local treatment includes cleansing the wound, tetanus vaccination if not administered within the past ten years, and an ice cube on the wound. If the patient is less than 16 or more than 60 years old, pregnant, suffering from chronic disease, or subject to one of the more severe symptoms listed in the previous paragraph, hospitalization and antivenin are recommended (52,53).

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