Gnathostomiasis Diagnosis and Management

Clinical Presentation

The American College of Physicians recommends considering gnathostomiasis in patients with recurrent painful or pruritic subcutaneous nodules that migrate over time, typically appearing as ill-defined swellings under the skin, with an incubation period of approximately 7 days after exposure 1
The Centers for Disease Control and Prevention notes that the migration pattern of these nodules distinguishes gnathostomiasis from other causes of subcutaneous nodules, with nodules moving to different locations over days to weeks 1
The World Health Organization reports that the distribution of gnathostomiasis can affect both upper and lower extremities, unlike erythema nodosum which predominantly affects the anterior tibial areas 1, 2

The European Academy of Dermatology and Venereology states that erythema nodosum presents with tender, raised, red or violet nodules of 1-5 cm diameter that are typically bilateral and symmetrical on the anterior tibial areas, and does not migrate 3, 2
The Infectious Diseases Society of America notes that trichinellosis presents with facial and periorbital edema, urticarial rash, severe myalgia, and muscle weakness in the parenteral phase, preceded by gastrointestinal symptoms in the enteral phase 4, 1

The British Infection Association recommends that clinical diagnosis is usually sufficient based on the characteristic migratory pattern of subcutaneous nodules, and serology can be sent to the Swiss Tropical and Public Health Institute if confirmation is needed 1
The American Society of Tropical Medicine and Hygiene states that travel history is essential, as gnathostomiasis is endemic in Southeast Asia, particularly Thailand, and transmission occurs through consumption of raw or undercooked freshwater fish, poultry, or frogs 1
The National Institute of Allergy and Infectious Diseases notes that eosinophilia may be present on complete blood count 4

The World Health Organization recommends treating gnathostomiasis with ivermectin 200 μg/kg PO daily for 2 days with monitoring for relapse, and seeking expert advice 1
The Centers for Disease Control and Prevention states that albendazole 400 mg PO twice daily for 21 days can be used as an alternative, and treatment may need to be repeated if symptoms recur 1

The Infectious Diseases Society of America recommends follow-up to assess for relapse, as gnathostomiasis can recur after initial treatment, and watching for neurologic complications including meningitis, encephalitis, or myelitis 1

Erythema nodosum presents with bilateral, symmetrical, raised tender nodules on anterior tibial areas that do not migrate, distinguishing it from gnathostomiasis 5
Psoriatic arthritis with dactylitis is characterized by "sausage digit" swelling, psoriatic plaques, nail pitting, and morning stiffness, unlike the migratory nodules of gnathostomiasis 6, 7, 8
Tendinopathy presents with well-localized tenderness at tendon insertion sites and load-related pain, differing from the migratory pattern of gnathostomiasis 9

Meningitis and encephalitis are potential neurologic complications of gnathostomiasis, highlighting the importance of close monitoring 5