UNIVERSIDAD AUTÓNOMA DE SINALOA

Ciclo Biológico de Gnathostoma

El ciclo biológico se completa en casi 100 días, cuando los segundos huéspedes intermediarios o paraténicos son ingeridos por los huéspedes definitivos, donde la larva L3A se transforma en parásito adulto (Fig. 31-2).


Fig. 31-2.- Ciclo Biológico de Gnathostoma

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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

  1. Eggs become embryonated in water, and eggs release first-stage larvae.
  2. If ingested by a small crustacean (Cyclops, first intermediate host), the first-stage larvae develop into second-stage larvae.
  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 larvae.
  4. When the second intermediate host is ingested by a definitive host, the third-stage larvae develop into adult parasites in the stomach wall.
  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 predator.
  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 Cyclops.

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Life cycle of Gnathostoma:
Adapted from a drawing provided by
Dra. Sylvia Páz Díaz Camacho, Universidad Autónoma de Sinaloa, Mexico.

Universidad Autónoma de Sinaloa, Facultad de Ciencias Químico Biológicas,
Unidad de Investigaciones en Salud Pública “Dra. Kaethe Willms”
Ave. de las Américas y Blvd. Universitarios, Ciudad Universitaria, C.P. 80100, Culiacán, Sinaloa, México,
Tel/Fax (667) 752-04-60.