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DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/gnathostomiasis/.

Gnathostomiasis

[Gnathostoma hispidum][Gnathostoma spinigerum]

Hematoxylin and eosin (H&ampE) stained cross-section of Gnathostoma sp., taken from a subcutaneous nodule above the right breast of a patient, showing the esophagus. Note the presence of cuticular spines (arrow). Image courtesy of Diagnostix Pathology Laboratories LTD, Canossa Hospital, Hong Kong, China.

Hematoxylin and eosin (H&E) stained cross-section of Gnathostoma sp., taken from a subcutaneous nodule above the right breast of a patient, showing the esophagus. Note the presence of cuticular spines (arrow). Image courtesy of Diagnostix Pathology Laboratories LTD, Canossa Hospital, Hong Kong, China.


Another H&E-stained cross-section of Gnathostoma sp., taken of the same specimen in Figure A, showing the intestinal cells and characteristic large lateral chords (LC). Note the multinucleate intestinal cells and the presence of pigmented granular material in the intestinal cells.

Another H&E-stained cross-section of Gnathostoma sp., taken of the same specimen in above figure showing the intestinal cells and characteristic large lateral chords (LC). Note the multinucleate intestinal cells and the presence of pigmented granular material in the intestinal cells.

Causal Agent

The nematodes (roundworms) Gnathostoma spinigerum and Gnathostoma hispidum, which infect vertebrate animals. Human gnathostomiasis is due to migrating immature worms.


Life Cycle

Life cycle of Gnathostomiasis.

Adapted from a drawing provided by Dr. Sylvia Paz Díaz Camacho, Universidade Autónoma de Sinaloa, Mexico.

In the natural definitive host (pigs, cats, dogs, wild animals) the adult worms reside in a tumor which they induce in the gastric wall. They deposit eggs that are unembryonated when passed in the feces The number 1. Eggs become embryonated in water, and eggs release first-stage larvaeThe number 2. If ingested by a small crustacean (Cyclops, first intermediate host), the first-stage larvae develop into second-stage larvaeThe number 3. Following ingestion of the Cyclops by a fish, frog, or snake (second intermediate host), the second-stage larvae migrate into the flesh and develop into third-stage larvaeThe number 4. When the second intermediate host is ingested by a definitive host the third-stage larvae develop into adult parasites in the stomach wallThe number 5. Alternatively, the second intermediate host may be ingested by the paratenic host (animals such as birds, snakes, and frogs) in which the third-stage larvae do not develop further but remain infective to the next predatorThe number 6. Humans become infected by eating undercooked fish or poultry containing third-stage larvae, or reportedly by drinking water containing infective second-stage larvae in CyclopsThe number 7.

Geographic Distribution

Most human cases have been reported from Asia (especially Thailand and Japan) and Mexico.

Clinical Presentation

The clinical manifestations in human gnathostomiasis are caused by migration of the immature worms (L3s). Migration in the subcutaneous tissues causes intermittent, migratory, painful, pruritic swellings (cutaneous larva migrans). Migration to other tissues (visceral larva migrans), can result in cough, hematuria, and ocular involvement, with the most serious manifestations eosinophilic meningitis with myeloencephalitis. High eosinophilia is present.

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  • Page last reviewed November 29, 2013
  • Page last updated November 29, 2013
  • Content source: Global Health - Division of Parasitic Diseases and Malaria
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