ENVENOMATIONS - Medicine for Mountaineering and Other Wilderness Activities - page 504

Thefemaleblackwidowtypicallyiscoalblackandhasaprominent,sphericalabdomen
that may be as large as one-half inch (1.25 cm) in diameter. This appearance is so distinct-
ive that finding the characteristic markings on the undersurface of the abdomen is rarely
necessary. The typical markings consist of red or orange figures that usually resemble an
hourglass but may be round, broken into two figures, or have some other configuration.
Markings of the same color but in varying patterns are sometimes present on the back, al-
though only the undersurface markings are considered characteristic. In some parts of the
U.S. Southwest black widow spiders have irregular white patches on their abdomens. Dif-
ferent species of Latrodectus in other countries have a similar appearance. (The male is
smaller, has a brown color, and is harmless.)
Blackwidowsweavecoarse,crudelyconstructedwebsindarkcorners,bothindoorsand
out. A number of the black widow bites reported in the medical literature in the first four
decades of the twentieth century were inflicted on male genitalia by spiders on the under-
side of outdoor toilet seats. However, this spider is timid and would rather run than attack
an intruder.
Forty to fifty years ago five to ten deaths a year resulted from black widow spider bites,
although they were limited almost entirely to small children or elderly individuals in poor
health.Recognitionandtreatmentofsuchbiteshaveimprovedsomuchthatdeathsarerare
within the United States. (Bites in children weighing thirty pounds or less would still have
a mortality of about 50 percent if untreated.) In healthy adults, black widow spider bites
cause painful muscle spasms and prostration for two to four days, but complete recovery
essentially always follows. Antivenom treatment usually is not recommended for adults.
The bite may feel like a pinprick, may produce a mild burning sensation, or may not be
noticed at all. Small puncture wounds, slight redness, or no visible marks may be found
at the site of the bite. Within about fifteen minutes, painful muscle cramps develop at the
point of the bite and rapidly spread to involve the entire body. The characteristic pattern of
spread is by continuity. From a bite on the forearm the cramps spread to the upper arm, to
the shoulder, and over the chest to involve the rest of the body, including the legs. The ab-
dominal muscles are characteristically rigid and hard, although the abdomen is not tender.
Weakness and tremors are also present.
Typically, a person who has been bitten is anxious and restless. A feeble pulse and
coldclammyskinsuggestshock.Laboredbreathing,slurredspeech,impairedcoordination,
mild stupor, and rare seizures (in children) suggest a disease involving the brain. Bitten
individuals are often covered with perspiration. Dizziness, nausea, and vomiting are com-
mon.Ifthe spider orits bite has notbeen observed, the signs andsymptoms may lead toan
erroneous diagnosis of an acute abdominal emergency.
Symptoms typically increase in severity for several hours, occasionally as long as
twenty-fourhours,andthengraduallysubside.Aftertwotothreedaysessentiallyallsymp-
toms have disappeared, although a few minor residua may persist for weeks or months.