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Crenosoma vulpis Homepage

            Common name: Fox lungworm

              Kingdom: Animalia

                Phylum: Nemathelminthes

                  Class: Nematoda

                    Order: Strongylida

                      Family: Crenosomatidae

                        Genus: Crenosoma

                          Species: vulpis

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Adult Parasite:

    The adult worm measures less than 16 mm long. The cuticle of the anterior end of the this worm is thrown into crenated folds as seen in this photomicrograph of a portion of the worm recovered by a tracheal wash.


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  • Foxes, wolves, raccoons and dogs (definitive).
  • Snails and slugs (intermediate).

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Life Cycle:

    The first stage-larva penetrates the intermediate host (a snail or slug). The larva molts twice and by 17 days post-infection becomes a third stage-larva. The third stage-larva remains in the snail's tissues until the snail is eaten by a definitive host. The third stage-larva makes its way to the lungs and develops to the adult stage in the bronchi and bronchioles. The female worm lays live first stage-larvae, which are carried up the trachea, are swallowed and pass out with the feces. The prepatent period is about 19 days.

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Site in host where adult parasite is found:

  • The bronchi and bronchioles

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Diagnostic Stage:

  • First stage-larva in the feces

Photomicrographs of L1 from tracheal wash

Common Diagnostic Test

Clinical Signs:
  • Rhinotracheitis
  • Bronchitis
  • Nasal discharge.


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University of Pennsylvania  2004

Comments or Questions please contact:  Dr. Nolan at: