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Lab 2 Appendix: Bursate Nematodes, Strongyloides and Lungworms

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Introduction

Strongyle-type nematodes are bursate worms, meaning the males have a copulatory bursa at their posterior end which wraps around the female during mating. All these worms have "strongyle-type" eggs which have a thin shell, and an 8 to 16 cell morula visible inside (as they are passed in the feces).

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 and have "strongyle-type" eggs.

 

Objectives Checklist

Be able to do the following techniques:

9 McMaster egg count to determine the EPG.

9 Fecal Egg Count Reduction Test

Be able to identify the following:

9 A typical "strongyle-type" egg (in a dog or cat this indicates an infection with either Ancylostoma or Uncinaria).

9 Nematodirus spp. egg

9 Haemonchus Adult (Largest abomasal nematode)

9 Ostertagia Adult (abomasal nematode - middle in size)

9 Trichostrongylus Adult (Smallest abomasal nematode)

9 Ollulanus Adult (from stomach of a cat)

9 Strongylus vulgaris Adult

9 Large Strongyle Adult (generic, from horse)

9 Small Strongyle Adult (generic, from horse)

9 Ancylostoma caninum and A. tubaeforme (by size, location and host) 

 



Lab Exercises

Abomasal Nematodes of Sheep and Cattle

Estimate the number of strongyle type eggs per gram of sheep feces using the McMaster Egg counting method.

With the advent of multi-drug resistance in many of the GI nematodes of sheep and goats (and in some areas cattle) a fecal egg count is becoming a necessity in the management of ruminant herd health. Drug resistance can be defined by the Fecal Egg Count Reduction Test (FECRT) . This is just 2 fecal egg counts, one done before drug treatment and the other done post-treatment (the time post-treatment varies with drug used). A reduction of less than 85% indicates the worms are resistant to the drug used.

The following nematodes might be found in a sample of the abomasum's contents

Haemonchus     

Haemonchus
largest: 2-3 cm

 

Ostertagia Ostertagia
intermediate: ~1 cm
Trichostongylus

  

Trichostrongylus
smallest: less than 7mm long

(penny = 19mm)

 

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A. Haemonchus contortus

Common name of this worm is "Barber pole worm" because the white ovaries of the females wrap around the intestine, which, when full of blood gives the appearance of a barber pole. The male worm will have an asymmetrical dorsal ray (ie: the dorsal ray arises from one side of the mid-line). (See pg 19 of the text: Urquhart, et al.), however, you are not responsible for identifying this feature on the males, it is enough to know that the worm is a male and because of its size it probably is Haemonchus contortus.

The number of worms in a sheep or goat can qualitatively be estimated by the use of the FAMACHA eye chart (see DEMO) which measures the level of anemia in the animal. The greater the level of anemia, the greater the number of H. contortus.

Click here to link to the life cycle for Haemonchus contortus

 

Haemonchus vulvar flap In this worm the vulva is protected by a flap of the cuticle. Haemonchus copulatory bursa The dorsal ray of
the bursa emerges from the side of the bursa rather than along the mid-line as in other bursate worms.

 

B. Ostertagia sp.

Of the 3 nematodes found in the abomasum of sheep, this species is intermediate in size (about 1 cm long).

Ostertagia copulatory bursa

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C. Trichostrongylus axei

The smallest of the abomasal nematodes, less than 7mm long (hard to see with the naked eye).


Small Intestine Nematodes of Sheep and Cattle

A. Other Trichostongylus sp.

B.Cooperia sp.

Cooperia sp.

A small worm ~4-6 cm, a.k.a. "watch spring" worm because it may be tightly coiled.

 

The cuticle of the anterior end is slightly swollen (cephalic vesicle) and striated.

D. Nematodirus sp.   A long worm (about 1 to 2 cm). The spicules of the male extend past the bursa. The egg is twice as large as any other strongyle - type egg.


Stomach of Cats and Swine

 Ollulanus tricuspis   This small nematode (~1 mm) is ovoviviparous (gives birth to larva rather then eggs, the eggs hatch in the uterus) and transmission is via the vomit.

       Adult Female (1 mm)                                                                             Tail of female (3 cusps)

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Hookworms

Ancylostoma sp.

Ancylostoma caninum (L3) vs. Stongyloides stercoralis (L3)

 
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

hookworm Ancylostoma caninum

Anterior end of an adult worm showing the 3 pairs of ventral teeth. Note that the mouth is bent to the side of the worm.
(Ancylo= bent, stoma = mouth; therefore: hookworm)

 

hookworm (A. caninum) Bursa of an adult male A. caninum. hookworm (A. caninum) Adult A. caninum in a petri dish.

Click here to link to the Ancylostoma caninum life cycle.

Ancylostoma braziliense below:  anterior of adult worm (note the 2 pairs of teeth)

hookworm (A. braziliense)

Other Hookworms

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hookworm (U. stenocephala) Uncinaria stenocephala
Note the cutting plates instead of teeth.
ruminant hookworm (Bunostomum) Bunostomum sp.
Large hookworm found in sheep/cattle with cutting plates in the mouth capsule of the adult worm

 

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