4-52
Parasitic Infections
Skin: Loiasis (loa loa)
MAJ Joseph Wilde, MC, USARIntroduction: A parasitic infection transferred to humans by the bite of blood-sucking tabanid flies (deer fly,
horse fly, or mangrove fly), found in damp, forested areas of West and Central Africa.
Subjective: Symptoms
Migrating sensations in the skin described as itching, tingling, pricking or creeping; recurrent temporary edema
of hands and upper extremities (Calabar swellings); painful irritation of the conjuctiva and eyelids.
Objective: Signs
Using Basic Tools: Recurrent swelling of the upper extremities; sighting of adult worms in the conjunctiva.
Using Advanced Tools: Lab: CBC for eosinophilia; peripheral thick blood smear for microfilaria (see Color
Plate Picture 31)
Assessment:
Differential Diagnosis
Gnathostomiasis – May also cause recurrent hand swelling; due to the ingestion of certain types of raw fish
Toxocariasis (Ocular and Visceral Larva Migrans)—Hepatomegaly, chronic abdominal pain, pneumonitis
Onchocerciasis—Subcutaneous nodules on head and shoulders; pigment changes; atrophy; edema of skin
Plan:
Treatment
Primary: Ivermectin 200 mcg/kg po x 1
Alternative: Diethylcarbamazine 2mg/kg tid after meals x 14 days; not available in US
Patient Education
Prevention: Personal protective measures against insect bites (Permethrin, DEET, insect netting, etc.).
Follow-up Actions
Evacuation/Consultant Criteria: Evacuation not usually indicated. Consult dermatology or infectious
disease as needed.
Skin: Myiasis
MAJ Joseph Wilde, MC, USARIntroduction: A parasitic infestation of the skin caused by the larvae of flies. Infestation can occur in any
open wound or exposed intact skin. The fly eggs are carried on the abdomen of mosquitoes, which then
deposit them on to human skin. Eggs then develop into larvae that burrow under the skin.
Subjective: Symptoms
Painful boils on exposed skin
Objective: Signs
Using Basic Tools: A localized group of furuncular (boil-like) lesions typically seen on the face, arms, legs, or
scalp, with a central punctum draining serosanguinous fluid. Close observation of the central punctum reveals
the posterior portion of a fly larva.
Assessment: Diagnose by clinical presentation.