Lecture 14- Gastrointestinal Parasites of Poultry

What type of parasite is Ascaridia galli?

An ascarid parasite of poultry

What are the morphological characteristics of Ascaridia galli?

Stout worms with three lips and sexually dimorphic

Where do adult Ascaridia galli worms reside in poultry?

in the small intestine

What type of lifecycle does Ascaridia galli have?

a direct lifecycle

How do poultry become infected with Ascaridia galli?

By ingesting larvated eggs.

Does Ascaridia galli undergo tracheal or somatic migration?

No, it does not.

What pathology is caused by Ascaridia galli?

Penetration and inflammation of the duodenal mucosa, and possible intestinal impaction in severe infections.

Which age group of birds is most susceptible to Ascaridia galli?

Young birds, as they develop age-acquired immunity by three months of age.

What are the clinical signs of Ascaridia galli infection?

Weakness, marked emaciation, and decreased egg production.

Where do adult Heterakis gallinarum worms reside in poultry?

In the cecum

What are the morphological characteristics of Heterakis gallinarum?

Stout worms with two lips and sexually dimorphic

What type of lifecycle does Heterakis gallinarum have?

Direct and facultative indirect lifecycle

What serves as a paratenic host for Heterakis gallinarum?

Earthworms

What disease does Heterakis gallinarum vector in turkeys?

"Blackhead" (enterohepatitis) caused by Histomonas meleagridis

How does Histomonas meleagridis remain viable in the environment?

It remains protected within Heterakis gallinarum eggs

What pathology is caused by Heterakis gallinarum?

Marked thickening of the cecal mucosa

How does Heterakis isolonche pathology differ from Heterakis gallinarum?

H. isolonche causes nodular typhlitis, caseous lesions, diarrhea, wasting, and death.

How are Ascaridia and Heterakis infections diagnosed?

By recovering eggs on fecal flotation

What is the morphology of Ascaridia and Heterakis eggs?

Thick-shelled with a single cell

How do Ascaridia galli and Heterakis gallinarum eggs differ in size?

- Heterakis gallinarum: 65‐80 x 35‐45 μm

- Ascaridia galli: 73‐92 x 45‐57 μm

Are Ascaridia and Heterakis eggs immediately infective?

No, they must develop to the infective stage in the environment.

What biologic feature do Ascaridia galli and Heterakis gallinarum share with other ascarid-type nematodes?

Eggs require environmental development before becoming infective

Where do adult Capillaria parasites reside in poultry?

In the intestine, esophagus, or crop

What are the morphological characteristics of Capillaria spp.?

Stout body with an elongate, whip-like esophagus

What type of lifecycle does Capillaria spp. have?

Direct and facultative indirect lifecycle.

What organisms serve as paratenic or potential intermediate hosts for Capillaria spp.?

Earthworms

How does pathology of Capillaria spp. vary based on infection site?

Intestinal species: Emaciation, hemorrhagic diarrhea

Crop & esophagus: Hyperplasia, croupous inflammation

What clinical signs are associated with Capillaria spp. infections?

Dysrexia, emaciation, and death

In what type of poultry management systems is Capillaria spp. a significant concern?

Deep litter poultry houses and range yards where hyper-contamination is likely

Where do adult Syngamus trachea parasites reside in poultry and wild birds?

In the trachea

What are the morphological characteristics of Syngamus trachea?

Medium-sized, bright red worms, permanently in copula

What type of lifecycle does Syngamus trachea have?

Direct and facultative indirect lifecycle

How are Syngamus trachea eggs expelled from the host?

Eggs are coughed up and discharged from the host

Why is the Syngamus trachea larval stage vulnerable?

Larvae are highly susceptible to adverse environmental conditions.

What role do earthworms play in Syngamus trachea transmission?

They serve as important paratenic hosts and may enhance infectivity in susceptible birds

What migration pathway do ingested Syngamus trachea larvae follow?

They undergo tracheal migration and reproduce in larger bronchi and trachea

What pathology is associated with Syngamus trachea migration?

Lung migration leads to ecchymoses, edema, and lobar pneumonia.

What is the hallmark clinical sign of Syngamus trachea infection?

"Gape" behavior—open mouth breathing, dyspnea, and asphyxia due to mucus accumulation.

What are severe consequences of Syngamus trachea infection?

Emaciation and death

Where do adult Spiruid nematodes reside in poultry?

In the gizzard, proventriculus, esophagus, etc.

What type of lifecycle do Spiruid nematodes have?

Obligate indirect lifecycle

What are the intermediate hosts for Spiruid nematodes?

Orthoptera (grasshoppers, crickets) and Coleoptera (beetles).

How does the pathology of Spiruid nematodes vary based on the site of infection?

Intestinal species: Emaciation, hemorrhagic diarrhea.

Mild infections: Often unremarkable.

Which birds are most susceptible to Spiruid nematode infections?

Younger birds

How are Spiruid nematode eggs diagnosed?

Recovered on fecal flotation or centrifugal sedimentation.

What are the three distinct egg morphologies associated with Spiruid nematodes?

1. Strongyle-type eggs: Thin-shelled morula, 70‐90 x 45 μm.

2. Capillarid-type eggs: Polar plugs, 50‐60 x 35‐40 μm.

3. Spiruid-type eggs: Thick shell, colorless, with larvae, 35‐50 x 25‐35 μm.

What is the key to preventing parasitic infections in poultry?

Avoidance of hyper-contaminated environments.

How does raising birds in confinement off the ground help prevent infections?

It isolates birds from infective parasite stages.

Why is parasite control challenging in backyard poultry environments?

Due to the presence of paratenic/intermediate hosts and lack of prophylactic deworming.

What management strategy helps with parasite control by segregating birds by age?

The "All in, All out" system, which allows for standardized treatment regimens.

What is important to consider when selecting anthelmintics for poultry?

Cost-effectiveness and withdrawal periods prior to slaughter