Pediatric emergency medicine trisk 1807 1807
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can be prominent features of the inflammatory reaction, a common conundrum in
the ED is determining whether an insect bite has become infected. In our
experience, cellulitis, indicative of infection, is tender and tends to be firmer than
a simple inflammatory reaction.
Unfortunately, no specific treatment exists for insect bites. Antihistamines,
calamine lotion, or topical steroids have a limited or temporary effect. Prevention
through the prophylactic use of insect repellents and protective clothing offers the
best solution. Elimination of the biting insects by treatment of the homes with
insecticides or treatment of the infested animals is important.
For additional information about insect bites, see Chapter 67 Rash:
Vesiculobullous .
Tick Bites
Tick bites usually cause only local reactions. Erythema migrans is the
characteristic rash of Lyme disease and looks like large bull’s eye; the rash
generally appears 7 to 10 days post tick exposure but the range is 3 to 30 days and
is not always seen. Rarely, tick bites are associated with significant systemic
illness, including Rocky Mountain spotted fever (RMSF), tick paralysis, and
Lyme meningitis.
When ticks are removed, it is important not to leave fragments of the
mouthparts in the skin or to introduce body fluids containing infectious
organisms. Various methods have been recommended for removal of ticks from
the skin. The safest method is to use a blunt-curved forceps, tweezers, or fingers
protected by rubber gloves. The tick is grasped close to the skin surface and
pulled upward with a steady even force. The tick should not be squeezed,
crushed, or punctured. If mouthparts are left in the skin, they should be removed.
Spider Bites
Loxosceles reclusa , or the brown recluse spider ( Fig. 88.4 ), found most
commonly in the south central United States (from southeastern Nebraska
through Texas, east through southern Ohio and Georgia), is responsible for most
skin reactions caused by the bite of a spider. This spider is small, the body being
only 8 to 10 mm long, and bears a violin-shaped band over the dorsal
cephalothorax. The venom contains necrotizing, hemolytic, and spreading factors.
The initial symptoms include mild stinging and/or pruritus. A hemorrhagic
blister then appears, which can develop into a gangrenous eschar. Severe bites can
cause a generalized erythematous macular eruption, nausea, vomiting, chills,
malaise, muscle aches, and hemolysis. Treatment includes tetanus prophylaxis
and surgical removal of the necrotic area to prevent spread of the toxin.
