Laboratory 3
HOOKWORMS, LUNGWORMS AND STRONGYLOIDES
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| Ancylostoma caninum Whole worms. A fresh specimen of A. caninum is often colored red by the blood in its gut (the color fades on fixation in alcohol). Compare the size of these worms (10 to 16 mm) with the smaller U. stenocephala. |
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| Ancylostoma caninum Specimen showing the mouth capsule. Note the deep capsule (bent dorsally) and 3 pairs of teeth (3 on each side of the ventral margin). |
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| Ancylostoma caninum First-stage larva. Note the mouth tube, bulbed rhabditiform esophagus and straight tail (no genital rudiment is visible). |
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| Ancylostoma braziliense This hookworm occurs in both cats and dogs. It is endemic in the gulf coast states, but may be transported north in pets that travel with their owners. It is the major etiological agent of cutaneous larval migrans in humans in the United States. Note the deep mouth (buccal) capsule, which is bent dorsally, and the pair of large lateral teeth. |
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| Uncinaria stenocephala Whole worms. Note that these hookworms are smaller and thinner than A. caninum. Male 5 to 8.5 mm Female 7 to 12 mm |
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| Uncinaria stenocephala This adult worm is mounted to show the buccal capsule. Remember that this nematode is similar to A. caninum but instead of teeth there are cutting plates, one on each side of the ventral surface of the mouth. Because the head is bent to the dorsal side, the ventral surface appears to be the anterior end of the worm. |
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Card 3:9
| Bunostomum trigonocephalum Whole worms. This species occurs in sheep and is similar in size and appearance to the cattle hookworm (B. phlebotomum). Because there are other bursate nematodes in the small intestine of sheep and cattle, identification of the hookworms will depend on seeing the buccal capsule and cutting plates. Male 14 mm Female 24 mm |
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| Bunostomum trigonocephalum Specimen mounted to show the buccal capsule. Note the cutting plates seen on the ventral aspect of the mouth. |
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Card 3:11
| Oslerus (Filaroides) osleri L1 The first stage larvae of this lungworm can be found in the feces or tracheal washes of infected dogs. Note the kinked tail (A). |
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| Oslerus (Filaroides) osleri This slide is a cross-section of one of several nodules removed from the trachea of a dog. Note the accumulation of fibrous tissue around numerous nematodes (seen in cross-section). Numerous L1 can be seen within the uteri of the female worms. |
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Card 3:13
| Oslerus (Filaroides) osleri This is a preserved specimen of a trachea of a dog infected with O. osleri. Note the numerous wart-like nodules present at the bifurcation of the trachea and extending into the bronchi. |
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Oslerus (Filaroides) osleri
PATIENT: 1 1/2 year old male schnauzer.
HISTORY: During the last 2-3 weeks there was periodic respiratory distress, the dog would have labored breathing, become cyanotic, and pass out. Taken to 3 different veterinarians who diagnosed:
1) allergy 2) pneumonia 3) normal dog.
PHYSICAL EXAMINATION: Dog sits on front elbows abducted, "gasping for breath". During attacks the dog became cyanotic. Decreased lung sounds on the right side.
TENTATIVE DIAGNOSIS: 1) Diaphragmatic hernia, 2) Tension pneumothorax, 3) Allergy.
COURSE OF THERAPY:
DIAGNOSIS: Pneumothorax due to leakage of air from the trachea. Wall of trachea weakened due to Oslerus osleri infection.
NOTE: At the time this dog was seen there were no anthelmintics which were active against O. osleri. Today we have several effective drugs to kill this worm and one of them would have been used in this dog along with the surgery.
*This indicated that the dog had heartworm in addition to the Oslerus osleri infection.
BEFORE
AFTER
Card 3:15
| Muellerius capillaris This slide shows this lungworm in the lung of a goat. The worm is associated with small, nodular lung lesions which contain adult worms and larvae. |
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| Dictyocaulus viviparous Whole specimens. These nematodes occur in the bronchi of cattle. Note the large size (4 to 8 cm) and the white color (the intestine may show through as a dark line). |
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Card 3:18
| Metastrongylus apri Whole specimens. Note they are long (up to 6 cm), slender, white nematodes found in the bronchi of pigs. |
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| Metastrongylus apri This is an autopsy specimen from a pig infected with Metastrongylus apri. Note the presence of several worms (seen in cross-section) in the bronchi and the normal lung tissue surrounding the bronchi. |
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Card 3:22
| Strongyloides ransomi Adult females from the intestine of a pig. (see card3:23 for comparable image) |
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| Strongyloides stercoralis This is a parasitic (parthenogenic) female recovered from a mucosal scraping of the small intestine of a dog. Note the small size, and long esophagus. There are no males in the parasitic portion of the life-cycle. |
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| Strongyloides stercoralis This is a first-stage larva as passed in the feces. Note the rhabditiform esophagus, which is short (much less than 40% of the body) and distinctly bulbed, the short mouth capsule, and the large genital rudiment (GR). (The latter 2 characteristics distinguish these larvae from those of the hookworms.) Note also the simple pointed tail (this separates these larvae from lungworm L1). |
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| Strongyloides stercoralis Infective L3. these occur on the soil surface or in fecal cultures. L3 can sometimes be found in tracheal washes of an infected dog. Note the filariform esophagus which extends to 40% of the body length. Focus carefully and notice the notched tail. The length of the esophagus and the notch in the tail allow you to distinguish between the L3 and the L1. Living L3 are infectious for dogs, primates and humans. |
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Card 3:26
| Review Question These worms were some of the many removed from the small intestine of a 6 week old puppy that died of severe anemia. A. Identify the nematode (Genus and species). B. How did the puppy most likely acquire this infection? |
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