Ascarids #4 Flashcards
What is the primary host of Heterakis gallinarum?
Poultry
Also found in pheasants, water fowl, and raptors
H. gallinarum is a carrier for a protozoan pathogen. Name this protozoan.
Histomonas
Identify this egg
Heterakis gallinarum
Note the ellipsoid shape, thick, smooth shell, and non-embryonated cell mass. Similar to Ascaridia eggs, but smaller.
Where are the alae located in Heterakis?
Caudally
Note that the alae are cranially-located in Toxocara, etc.
List a paratenic host for Heterakis
Earthworm
Where does adult Heterakis live in its bird host?
Cecum
What is the pre-patent period of Heterakis?
1 month
Identify these structures on the caudal end of this adult male Heterakis
A) Spicule
B) Cloaca
C) Pre-anal sucker
Note that this species is non-bursate
In which definitive hosts might you find Ascaridia galli?
Ducks, geese, chickens, turkeys
Where are the alae found in adult Ascaridia?
Caudally
Identify these eggs
Eggs Ascaridia galli
Note their barrel shape. Larger in size than Heterakis eggs.
Which organism can serve as a paratenic host for Ascaridia larvae?
Earthworm
What is the pre-patent period of Ascaridia galli infections?
30-50 days
What are the potential results of heavy Ascaridia galli infections?
Fatal intestinal blockage, rupture
Identify the treatment and control measures you might use against Ascaridia galli
Drugs:
Ivermectin, levamisole, fenbendazole
Control:
Sanitation to limit the number of eggs in the environment
What kind of life cycle does Anisakis simplex have?
Indirect
Note that most ascarids have a direct life cycle. Anisakis is unique in this respect.
What is the definitive host for Anisakis simplex?
Marine mammals (dolphins, etc.)
What is the intermediate host of Anisakis simplex?
Crustacean
How do humans become infected with Anisakis simplex, and what kind of hosts are humans to this parasite?
Eating undercooked fish.
Paratenic host.
How does Anisakis simplex cause disease in human hosts?
Bowel perforations
Eosinophilic granulomas
Allergic reactions (urticaria, anaphylaxis)
What is the name of the horse pinworm?
Oxuris equi
How many lips do pinworms have?
3
Closely related to ascarids
What kind of life cycle does Oxyuris equi have?
Direct
You would normally find adult Oxyuris worms in what age of horses?
Weanlings, yearlings, and adolescents.
Uncommon to find adult worms in adult horses.
How do Oxyuris equi infections occur in the equine host?
Ingestion of a larvated egg.
This usually occurs during grooming activities.
Where do adult Oxyuris reside in the equine host?
Large intestine
True or False:
Male Oxyuris worms possess a caudal bursa
FALSE
Identify this structure in this adult worm and name the species.
Esophageal bulb
Oxyuris equi
(this structure is characteristic for the species)
Where do adult female Oxyuris equi lay their eggs?
Exit the host via the anus and glue their eggs to the perineal area. The females die after this event.
How long does it take the L3 larva of Oxyuris to develop within the egg? (I.e. how long does it take for the egg to become infective?)
4-5 days
How long is the pre-patent period in Oxyuris equi infections?
5 months
What is the pathology associated with Oxyuris equi infections?
Large numbers of L4 larvae browsing on the gut mucosa can cause inflammation and abdominal discomfort.
Eggs attached to the perineum cause intense anal pruritis
How do you detect Oxyuris equi infections?
Use cellophane tape to detect eggs around the perineum.
You might be able to find eggs in a fecal float, but this is unlikely (recall that females crawl out of the anus to lay their eggs)
Identify this egg
Egg of Oxyuris equi
Look for the elongated shape, smooth shell, and flattened edge on one side (lower left in this picture). May or may not have a mucoid plug.
Name the species and identify the structures pointed to by the arrows.
Oxuris equi
Mucoid plug (top right)
Flattened side (bottom right)
Which drugs would you use to treat equine pinworm infections?
Macrocyclic lactones, benzimidazoles.
Pyrantel to a lesser extent.
How would you treat and control equine pinworm infections?
Wash the perineum to remove eggs (this also helps with the intense anal pruritis).
Clean stalls and destroy bedding.
Treat with anthelmentics (macrocyclic lactones and benzimidazoles)
Name the mouse pinworm
Syphacia obvelata
Name the pinworms that can infect rats
- Syphacia muris*
- Aspicularis* sp.
Name the pinworms that can infect hamsters and gerbils
- Syphacia obvelata*
- Syphacia muris*
- Aspicularis* sp.
What are the potential consequences of heavy rodent pinworm infections?
Anal pruritis leading to self-mutilation at tail end
Rectal prolapse
Sticky stools
How do you detect rodent pinworm infections?
Just like with equine pinworms, use tape to detect eggs in the perianal region.
Identify the species
Syphacia muris
Note the characteristic banana shape. Just like other pinworms, the egg has a distinct flattened edge.
Identify the general class of worms that these eggs come from.
Pinworm.
In this case, these are reptile pinworms.
What is the name of the human (and other ape) pinworm?
Enterobius vermicularis
Which of the pinworms are zoonotic?
None of ‘em.
Contrary to popular belief, you cannot get pinworms from your dog.
(But maybe tell your kids to wash their hands after scratching their backsides).
