Trichostrongyles 2 Flashcards
Name this condition and a parasite that can cause it.
“Bottle Jaw”
Submandibular edema. Commonly seen in cases of Haemonchus contortus infection.
What system can you use to gauge the severity of anemia in goats?
FAMACHA
What is premunition?
A state of resistance to chronic infection which is established when an acute infection becomes chronic and lasts as long as the infecting organisms stay in the body.
What are the two principles of selective therapy?
(Brewer keeps harping on this, so it’s probably totes important)
- Minimize the number of eggs in the environment and guard against clinical signs.
- Use drugs in such a way that we slow the spread of resistance.
Selective therapy relies on which two observations?
- Parasites are unevenly distributed (overdispersed). So, a small proportion of individuals shed the majority of the parasite eggs.
- Strongyle egg shedding is consistent over time. High egg shedders will remain high egg shedders.
You detect Haemonchus contortus in your goat population. You should probably just deworm all the goats, right?
If you do that, I’m going to have to beat you over the head with a FAMACHA chart.
Remember, we want to only treat the goats showing the most severe signs of anemia. By selectively treating, we keep some susceptibility genes in the population.
This goat is shedding eggs. Should you treat this goat?
He’s fine. Let him keep eating cans or whatever goats do.
This goat is shedding eggs. Should you treat this goat?
I’m surprised he’s still standing. TREAT IMMEDIATELY.
This goat’s probably fine, and I don’t want to spread anthelmintic resistance. Am I right?
Bro, do you even FAMACHA?
You should treat goats that score a 4 or 5 on this chart.
What test is this?
DrenchRite Assay
This is a larval development assay. It is used to test larval sensitivity to anthelmintics.
H. contortus is most resistant to which class of anthelmintics?
Benzimidazoles
By what percentage should an anthelmintic reduce FEC in order to be considered effective?
95%
True or False:
Self cure (purging of worms once the animal reaches a certain level of immune development) is consistent in Haemonchus infections, just like with ascarids.
FALSE
Whereas most animals tend to self-cure ascarids by 6 months, the phenomenon is not as consistent in Haemonchus infections.
This chart is trying to tell you something. Decode the crytpic symbols and tell me what it means.
Reduction in FEC against Haemonchus is inconsistent with Albendazole and Ivermectin (suggests resistance). Levamisole and moxidectin have better clearing rates.
If you’re going to cut your cocaine with an anthelmintic, which anthelmintic should you use?
Levamisole!
In which host do you typically find Ostertagia ostertagi?
Cattle
In which hosts do you typically find Telodorsagia?
Sheep
Goats
Camelids
Name the major species of stomach trichostrongyles.
- Haemonchus*
- Ostertagia*
- Telodorsagia*
- Trichostrongylus*
(Remember HOTT. As in: being able to recite the stomach worms is super HOTT and sexy)
Identify the species.
Ostertagia ostertagi
Note the annular striations near the mouth that give way to longitudinal striations along the body. Isn’t that pretty? Now, unless you carry a SEM in your back pocket for diagnostics, I suggest you not waste too much time on these features.
What color are adult Ostertagia inside the host?
Brown
What is the most important parasitic nematode of cattle?
Ostertagia ostertagi
Where do adult Ostertagia ostertagi live?
Abomasal lumen
What is the major difference between L3 migration in Ostertagia and Haemonchus?
- Haemonchus* enters BETWEEN the cells of the gastric glands.
- Ostertagia* enters INTO the gastric glands.
What is the prepatent period of Ostertagia?
3 weeks
What is being depicted here?
L4 Ostertagia developing within a gastric gland.
What is shown here?
Adult Ostertagia emerging from a gastric gland.
Adults emerge about 2 weeks after entering the gland.
That must have been a seriously lucky pathologist to capture that image. Go buy a lotto ticket.
What is a zymogen?
A zymogen is an enzyme that must be cleaved or activated in order to assume its enzymatic activity.
Example: Pepsinogen -> Pepsin
What do gastric parietal cells secrete?
What do gastric chief cells secrete?
HCl
Pepsinogen
Describe the pathogenesis that results from larval Ostertagia living in the gastric glands and damaging the parietal cells.
- Damage to parietal cells decreases production of stomach acid.
- Pepsinogen requires a low pH to be cleaved to pepsin. Without the acid production by the parietal cells, pepsinogen entering the stomach is not cleaved into the active form.
- Decreased pepsin results in decreased protein absorption for the animal.
- The high levels of inactive pepsinogen diffuse into the blood stream, which can be detected by bloodwork.
Pepsinogen in the bloodstream is a sign of what?
Generalized stomach damage.
Can be a sign of infection with Ostertagia, but not necessarily.
Name the lesion
“Cobblestone” or “Moroccan leather” lesion of the stomach
Characteristic of O. ostertagi
What eventually happens to the glands damaged by Ostertagia?
Glands are covered with undifferentiated epithelium.
Results in hyperplastic, non-functional gastric mucosa
What are the overall effects of a clinical Ostertagia infection?
Reduced weaning weights of calves
Reduced milk production
Reduced breeding efficiency
What age of animals are most susceptible to Ostertagia infections?
Calves and yearlings
These animals tend to develop high worm burdens and EPGs.
Adults develop immunity with repeated exposure.
Describe Type 1 ostertagiosis
- Infection without hypobiosis
- Large number of L3’s acquired in a short period
- Affects young animals during first grazing season
- Will see many strongyle-type eggs in fecal
- Bloodwork: elevated pepsinogen, hypoalbuminemia, possible anemia
Describe Type 2 ostertagiosis
- Mass emergence of L4’s from gastric glands in short period of time
- Sudden mass destruction of gastric glands
- Unlikely to find eggs in fecal
- Poorer prognosis than Type 1
What necropsy findings would you expect to find in an animal with ostertagiosis?
Abomasal lesions
Increased gastric pH
Type 1: many adults and eggs
Type 2: few adults and low fecal EPG
What is the name of the ruminant stomach hair worm?
Trichostryongylus axei
Of the ruminant stomach worms, which is the largest and which is the smallest?
Largest: Haemonchus contortus
Smallest: Trichostrongylus axei
Which species can Trichostrongylus infect?
Ruminants
Horses
What is a risk factor for horses in acquiring Trichostrongylus infections?
Co-grazing with ruminants
Describe the Trichostrongylus L3 penetration into the stomach mucosa
Between the gastric glands
Causes less damage than Ostertagia
If you see the classic “Moroccan leather” lesion in the abomasum of a cow, which parasites should be on your differential list?
- Trichostrongylus*
- Ostertagia*
If you necropsy a horse and find hyperemic gastritis, which parasite should be on your differential list?
Trichostrongylus axei
Note that Ostertagia does not infect horses.
What kinds of lesions result from a Trichostrongylus infection?
- Ulceration of stomach with hemorrhage and necrosis
- Hyperplastic, non-functional gastric mucosa
- Increased abomasal pH and mucosal permeability
- Ruminants: white, circular plaques on abomasal mucosa, similar to Ostertagia infections
- Horse: hyperemic gastritis with thickened glandular stomach
Tissue from a horse. Name the condition and a parasite that can cause it.
Hyperemic gastritis
Trichostrongylus axei
Farmer Joseph Roberts (“Joe Bob”) is a cattle rancher who recently inherited some horses. Not having a lot of pasture space, he decided to turn the horses out onto pasture with the cows.
After several months, the horses began to appear emaciated and were having watery stools (the Squirts, according to Joe Bob).
With Dr. Brewer’s voice echoing in your head, you remember to put parasites on your differential list. What parasite do you suspect?
Trichostrongylus axei
