Laboratory 4
ASCARIDS, OXYURIS, AND TRICHOCEPHALIDS
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| Ascaris suum This is the ascarid of swine. Note its size and shape. The male is smaller than the female and has a curved tail with spicules. |
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| Ascaris suum This slide shows the 3 lips at the anterior of the worm. (Focus up and down to see all 3.) |
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Card 4:3a
| Pig lung infected with Ascaris suum
Note the marked degree of hemorrhage in the lung, most of the air spaces are filled with blood. In addition, there is edema and cellular infiltration. |
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Card 4:3b
| All of the ascarids in this 1 gallon jar came from one foal. |  |
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| Parascaris equorum This is the ascarid of horses. Note its size and the 3 large lips at the anterior end. (three lips are a characteristic of all ascarids.) |
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| Parascaris equorum This slide shows the 3 lips (1 dorsal and 2 ventral). Focus up and down to see all three. |
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| Toxocara canis This is the common ascarid of dogs. Note the 3 lips (focus up and down to see all 3) and the cervical alae. The alae are clear cuticular flanges running along the lateral margins of the worm. They are similar in shape to those of Toxascaris leonina. |
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Card 4:7
| Toxascaris leonina The cervical alae of this ascarid of dogs and cats is similar to those of the dog ascarid T. canis. In both of these worms the alae merge gradually into the cuticle. In contrast, the alae of T. cati end abruptly. |
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| Toxocara canis and Toxascaris leonina Adult worms. T. canis is much larger, the males measure up to 10 cm and the females up to 18 cm long T. leonina males are up to 7 cm and the females are up to 10 cm. Recall the biological differences between the two species: Host(s), transmission options, larval migration (or not) and the resulting differences in pathogenesis. Are both equally significant in public health. |
Toxascaris leonina |
Toxocara canis |
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Card 4:9
| Toxocara canis The worms in this bottle were recovered from the 3 lb. puppy described in the case report. |
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| Toxocara cati These are the adults of the common ascarid of cats. Note that the cervical alae can be seen with the naked eye. |
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| Toxocara cati Note that the cervical alae of this ascarid terminate abruptly, unlike those of T. leonina the other ascarid of cats. Thus, ascarids that are expelled in the feces of cats can be easily distinguished. |
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Card 4:12
| Baylisascaris procyonis Adults from the small intestine of a raccoon. This worm lacks cervical alae. As has been pointed out in the lecture, this is an increasingly important parasite in veterinary public health. Although its larvae are not as prevalent in humans as those of T. canis, they are large and highly neurotropic, causing this species to be especially pathogenic. The larvae (not adults) occur in humans (and other mammals and birds) where they are one of several causative agents of "larval migrans". |
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Card 4:13
| Ascaridia galli Adult worms. This parasite occurs in the small intestine of chickens, turkeys, geese, and many wild birds (e.g. crows). Males 50 - 76 mm Females 72 - 116 mm |
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| Heterakis gallinarum These are adults. This is the most common caecal worm of ground-reared poultry. Note its size. The females are larger than the males. |
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| Oxyuris equi These are adults of the pinworm of horses. Formerly a very common parasite of the large intestine, its susceptibility to modern anthelmintics has all but eliminated this nematode from horses in this part of the country. Note the females have long thin tails (a characteristic of the family) while the males have a blunt tail with caudal alae and a single spicule. |
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| Trichinella spiralis This is a section of muscle from a Trichinella spiralis infected mouse in the acute phase. Observe the abundant inflammation. It is these larvae that cause the most characteristic symptoms of trichinosis. Trichinella spiralis is unique among the nematodes because the same individual serves as the definitive and intermediate host. |
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| Trichuris vulpis These are adult dog whipworms. Note the size and the long, thin anterior end (the "lash") and the short, thick posterior end (the "whip-handle") of the worm. Hence, the common name: "whipworm". |
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| Trichuris vulpis This museum specimen demonstrates an infection with the whipworm of dogs. Note that the thin anterior end is embedded in the mucosa, whereas the thick posterior end protrudes into the lumen. |
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Card 4:19
| Trichuris vulpis The egg of Trichuris sp. is brown in color, thick shelled, lemon-shaped, with a smooth surface and possesses a plug at each pole. It is unembryonated when passed in the feces. It measures 80 X 40 um. Note: Focus up and down to see the texture of the outer surface of the eggshell. |
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Card 4:20
| Capillaria spp. These nematodes are closely related to Trichuris, but they are small and slender. The posterior portion of the body is not conspicuously thicker than the anterior as in the case of the whipworms. Capillaria spp. occur in many species of birds, mammals and other vertebrates. In some species, larvae may occur in invertebrates as well. |
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| Capillaria aerophila The sides of this egg are usually parallel and the polar plugs tend to be asymmetrical. The easiest way to distinguish this egg from that of a whipworm is to examine the surface of the egg. Capillaria spp. eggs have a rough surface while Trichuris spp. eggs have a smooth surface. Note: Focus up and down to see the texture of the outer surface of the eggshell. |
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| Dioctophyma renale This nematode is one of the largest known and is found in the kidney of dogs and wild carnivores (especially fish eating carnivores, e.g. mink). It causes destruction of the kidney tissue until only a fibrous shell is left. Fortunately, only one kidney is usually parasitized. Note the very large size and its location (within the kidney). |
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Card 4:23
| Dioctophyma renale This slide shows the egg of the kidney worm of dogs and other carnivores. They are barrel shaped, thick shelled, pitted (except at the poles) and are unsegmented (unembryonated) when passed in the urine. |
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Card 4:24
| Review Question This slide under the microscope contains the product of a fecal exam on a young pup from Philadelphia which, some two weeks prior, had shown clinical signs of pneumonia, e.g., coughing, elevated respiratory rate, foamy nasal discharge, etc. A) Name the parasite(s) present on the slide. (Note : Please do not move the slide.) B) Which parasite(s) could have accounted for the pulmonary signs? |
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