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  • Clinical Parasitology Images: Gallery V (Click on images for an enlarged view)

    Capillaria spp egg

    Capillarids eggs differ from whipworms eggs by the following features: the shell wall has abberations, the eggs are slightly irregular in symetry, the color is light amber and the plugs are less prominent. These parasites are in many animal species and are found in the lungs, liver parenchyma, urinary bladder, nasal passages of dogs and other animals.

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    Oxyuris equi egg

    Eggs of Oxyuris quickly embryonate after leaving the adult female worm. The nematode is a pinworm of equids. The eggs have medium-thick shells with a prominent plug on one end. The single flattened side is characteristic of most pinworm eggs regardless of the host species.


    Spirurid eggs (Physaloptera spp)

    These eggs have medium-thick shell walls and contain a vermiform larva. The length of Physaloptera is usually about twice the width. This differs from Spirocerca lupi eggs which are much more than twice their width and very small in size. The adult worms are commonly found in the stomach of dogs and cats.

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    Spirocerca lupi egg

    These eggs are small, larvated and elongate with medium-thick shells. The adult worms are found in large fibrous nodules in the esophagus (occasionally the stomach) of dogs. The larval stages migrate upward from the stomach following the epiploic arteries and the dorsal aorta. Compare these eggs to those of Physaloptera spp. which are similar but much larger.

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    Ancylostoma sp. and Uncinaria sp eggs (hookworms)

    Strongylid eggs are unembryonated with thin shells and are characteristic of hookworms of dogs and cats. Eggs of all other strongyles and trichostrongyles are similar and usually cannot be differentiated to specific genera. The presence of this type egg in dog or cat feces is usually indicative of a hookworm infection.

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    Strongyloides westeri egg

    Larvated-thin-shelled in fresh uncontaminated feces is indicative of Strongyloides species. Strongyloides stages pass from the host in the form of larvated eggs (as shown here) or as rhabditiform first stage larvae. This egg is from a horse parasite in the small intestine and only parasitic females are known to exist.

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    Strongyloides canis infective third stage larvae

    Infective larave have a long esophagus, no protective sheath and dog and human forms have a notched tail. This is a dog parasite which is sometimes called S. stercoralis. It is passed in feces as a larval stage. Positive diagnosis is made from larval cultures of feces from suspect animals. The presence of a third stage larva with a long esophagus is indicative of infection.

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    Strongyloides canis and Ancylostoma caninum infective larvae

    Both nematodes are parasites of dogs and both may produce respiratiory complications that may be lethal to neonatal pups. Both also transmit larvae in mother's milk. There is some public health concern that these parasites might be transmissible to humans, however, direct evidence of regular or normal transmission is difficult to find. A relationship between human and dog infection is based on the similarities between adult females and infective larvae.


    Dictyocaulus viviparus larva (1st stage)

    This is a lungworm of cattle that is usually classified as a trichostrongyle instead of a metastrongyle. Similar nematodes are found in sheep, donkeys and horses. The first-stage larvae are diagnostic when found in fresh clean feces. The baermann procedure is used to find the larvae. Unlike most other lungworms these parasites have a direct life cycles and do not use intermediate hosts. Disemination on pasture sometimes involves the fungus Pilobus sp. The exploding fungal spores cast the larvae for long distances from the fecal pat. This is one of the few nematodes for which an effective vaccine has been developed, however, it is not availaible in the U.S.

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    Metastrongylus apri egg

    Metastrongylus apri is a parasite of pigs and the only lungworm of the superfamily Metastrongyloidea that passes in the host's feces as an embryonated egg. Dung beetles serve as intermediate hosts. Beetle larvae (grubs) ingest eggs while scavenging in feces and soil. The larval stages are then released from the eggs, develop to infective L3 larvae which accumulate in the beetles.