Spiders in the United States are generally
harmless, with several exceptions. The most notable
are the black widow (Latrodectus mactans) and brown
recluse (Loxosceles reclusa, also found in South
America) spiders. Their bites are serious but rarely
fatal. Wandering spiders (Phoneutria species, found in
South America), funnel web spiders (Atrax species,
found in Australia), and more widely distributed
spiders of the Chiracanthium species may also cause
moderate to severe human reactions. Check current
MEDIC CD-ROM for management of specific
situations and venues.
The female black widow spider is usually
identified by the red hourglass-shaped spot on its belly
(fig. 5-2). Its bite causes a dull, numbing pain, which
gradually spreads from the region of the bite to the
muscles of the entire torso. The pain becomes severe,
and a board-like rigidity of the abdominal muscles is
Nausea, vomiting, headache, dizziness,
difficulty in breathing, edema, rash, hypertension, and
anxiety are frequently present. The bite site can be
very hard to locate (there is little or no swelling at the
site), and the victim may not be immediately aware of
having been bitten. The buttocks and genitalia should
be carefully examined for a bite site if the suspected
victim has recently used an outside latrine.
following first aid treatment steps are suggested:
1. Place ice over the bite to reduce pain.
2. Hospitalize victims who are under 16 or over 65
3. Be prepared to give antivenom in severe cases.
The brown recluse spider (fig. 5-2) is identified by
its violin-shaped marking. Its bite may initially go
unnoticed, but after several hours, a bleb develops over
the site, and rings of erythema begin to surround the
bleb. Other symptoms include skin rash, fever and
chills, nausea and vomiting, and pain. A progressively
enlarging necrotic (dead tissue) ulcerating lesion (with
a c r u s t y b l a c k s c a b ) e v e n t u a l l y d e v e l o p s .
Intravascular hemolysis (breakdown of the blood) is
most often seen in children and may be fatal.
Antivenom is not currently available.
Treatment for brown recluse spider bites includes
Debridement of lesion, followed by peroxide
cleansing and Burrows solution soaks
Application of polymyxin-bacitracin-neomycin
ointment and sterile dressing
Dapsone 50-100 mg twice a day is used to
promote healing in some cases, but only after
screening for G6PD deficiency.
antibiotics may be used to treat infection, and
steroids to reduce inflammation
NOTE: Glucose-6-phosphate dehydrogenase
(G6PD) deficiency is a common human
enzyme deficiency. A G6PD deficiency can
cause a harmful reaction to a number of
medications, including dapsone.
Based upon medical consultation, excision of
the lesion and optional commencement of
Centipedes can attain sizes of over one foot in
length! Their bite, though rare, leaves two tiny red
marks and causes redness and swelling. Severe pain,
swelling, and inflammation may follow, and there may
be headache, dizziness, vomiting, irregular pulse,
muscle spasm, and swollen lymph nodes.
long-term effects are usually seen. Treat discomfort
with acetaminophen, cool packs, and elevation of the
affected limb to heart level.
THE BLACK WIDOW SPIDER
A. TOP VIEW
Figure 5-2.Black widow and brown recluse spiders and