NAVMED P-5010-8 - Navy Medicine - U.S. Navy

8-46 CHAPTER 8. NAVY ENTOMOLOGY AND PEST CONTROL TECHNOLOGY 8-46
8-46. Common Venomous Arthropods
a. General. Injury produced by venomous
arthropods is more common than generally
realized. Millions of people in the United States
are affected by these arthropods each year.
About 25,000 of these envenomizations result in
severe injury and about 30 result in death. This
mortality contrasts markedly to the usual 14
deaths per year that are caused by poisonous
reptiles. Clinical manifestations associated with
envenomization include anaphylactic shock,
hemolysis, necrosis, paralysis, cardiopulmonary
dysfunction, allergenic asthma, and antigen
induced dermatologic manifestations.
b. Venoms. Venoms produced by
arthropods are mixtures of four toxic types:
vesicating (blister beetles), neurotoxic (black
widow spiders), cytolytic (brown recluse spider),
and hemolytic (horse flies).
c. Venomous Arthropods of Importance
(1) Centipedes. Centipedes are fast
moving, dorsoventrally flat, elongate arthropods
having one pair of legs per body segment. All
centipedes contain venom-producing glands that
are connected by tubes to claws that are modified
appendages on the first body segment. The
potential for these arthropods to inflict injury on
man is contingent on the size of the claw and its
ability to penetrate the skin. Injected venom
causes a considerable amount of pain, but rarely
death. When death occurs, it is believed to be a
result of an anaphylactic reaction. The wound
should be disinfected and a medical officer
consulted.
(2) Millipedes. These arthropods are
slow moving, rounded, elongated arthropods
with two pairs of legs per body segment. Many
millipedes exude a vesicating fluid and may
cause injury to persons handling them. Some
are capable of squirting vesicating venom some
distance and may cause severe injury to the eyes
as well as the skin.
(3) Scorpions. Scorpions are venomous
arachnids that rarely sting man, and then, only
when provoked. Although few species are deadly,
all stings should be considered dangerous because
of the hemolytic and neurotoxic venom properties.
The signs and symptoms associated with these
stings vary with species and may include tachypnea,
tachycardia, nausea, glycosuria, epigastric
pain and tenderness, excessive salivation, slurred
speech, tissue discoloration, and necrosis. The
ground scorpions have a predominantly hemolytic
toxin that is generally associated with swelling and
except in the young, old or debilitated, death is
uncommon. On the other hand, the venom of bark
scorpions has a dominant neurotoxin that does not
cause swelling and is more often associated with
death.
(4) Spiders. Spiders are venomous
arachnids and in most cases are considered to be
beneficial because they feed on other arthropods.
Bites of black or brown widow spiders (Latrodectus
mactans and Latrodectus geometricus
respectively), and the brown recluse spider,
Loxosceles reclusa, are serious and of considerable
medical importance. The venom of the Latrodectus
spp. is strongly neurotoxic, causing severe
symptoms of extreme pain, abdominal cramping,
profuse perspiration, respiratory duress, and
speech inhibition. Only 5 percent of untreated
cases are fatal. The venom of L. reclusa is
strongly hemolytic and vesicating, causing
progressive tissue necrosis.
(5) Blister Beetle. When these beetles
are touched, they exude a drop of vesicating fluid
through the membranes of the appendage joints.
The active ingredient of this fluid is cantharidin.
Upon dermal contact, this fluid causes formation
of serious blisters that eventually break, the
released fluids causing satellite blisters. Bacterial
secondary infection is common. Medical attention
for affected individuals is considered important.
(6) Hymenopterous Insects. Member
species of bees, wasps, yellow jackets, hornets,
and ants are high in number and are the most
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