Introduction

Hookworms are bursate worms in which the anterior end is bent 90 degrees putting the mouth on the side of a worm, instead of at the front. Hookworms live in the small intestine of their hosts. The lungworms, as the name suggests, live in the lungs (parenchyma or bronchi/trachea) of their host. Most are members of the Superfamily Metastrongyloidea and their L1 have a "kink" in their tail, however, Dictyocaulus spp. are bursate nematodes. The genus Strongyloides contains many species that are important parasites of neonatal animals. The small parasitic adult is a parthenogenic female that lives in the crypts of the small intestine. All species of this genus have one or more free-living generations.

Objectives Checklist

Be able to:

9 Recognize the typical lungworm L1 ("kinked" tail) and be able to identify to species (by host).

9 Recognize Dictyocaulus spp. L1 from cattle (larva with straight tail in fresh feces).

9 Recognize the eggs and L1 of Strongyloides spp.

9 Distinguish between and recognize the L1 of Strongyloides stercoralis, Ancylostoma sp., and Oslerus (Filaroides) sp. (or Aelurostrongylus sp. if from a cat) from the feces of dogs.

Lab Exercises

Lungworms

Dogs: Oslerus (Filaroides) osleri

Nodules at the bifurcation of the trachea.

Adult worms removed from a nodule.

Cats: Aelurostrongylus sp.

Sheep: Muellerius capillaris

Cattle: Dictyocaulus viviparous

Adult Dictyocaulus viviparous worms in the lung of a cow.

Click here to link to the Dictyocaulus viviparus life cycle.

Pigs: Metastongylus apri

Cross section of adult Metastrongylus apri worms in the bronchi of a pig's lung.

Strongyloides

Sheep: Strongyloides papillosus

Horse: Strongyloides westeri

Pigs: Strongyloides ransomi

Dogs: Strongyloides stercoralis

Third stage larva (L3)Strongyloides stercoralis

Note the long esophagus.

First stage Strongyloides stercoralis larva (L1).

Note the large genital promodium.

Click here to link to the Strongyloides stercoralis life cycle.

Primary Diagnostic Features of Nematode Larvae Found in Canine Larvae

	Ancylostoma caninum (L3)	Stongyloides stercoralis (L3)
sheath	present	absent
esophagus	bulbed and runs ~ 25% the length of the worm	straight and runs ~ 40- 50% the length of the worm
tail	straight	notched

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