Poultry nematodes

List the nematodes of poultry

• Syngamus trachea

• Capillaria spp.

• Trichostrongylus tenuis

• Ascaridia galli

• Heterakis gallinarum

What are the features of Syngamus trachea?

• Poultry gape worm

• Hookworm

• Affects chickens, gamebirds, turkeys etc.

• Wild bird reservoir

Larger female, smaller male attached

Where in the bird is syngamus trachea adult found?

Trachea, permanently paired (male worm constantly fertilising eggs & embedded within female —> M smaller than female = “Y” shaped)

How does the disease of syngamus trachea present?

Mechanical blockage of trachea:

• Asphyxia

• Coughing

• Gasping

What are the characteristics of Syngamus trachea eggs?

• Characteristically shaped mucoid eggs (thickening at either end)

• 80µm

• L3 develops in egg

• Passed in faeces

How do birds get infected with syngamus trachea?

Ingestion of:

• L3 in egg

• Hatched L3

• L3 in transport/paratenic host —> earthworm (not an intermediate host as not essential)

Describe the lifecycle of Syngamus trachea

• L3 ingested

• Migrates from small intestine, enters blood stream

• Larvae reach lung via pulmonary capillaries

• Migrate through alveoli to trachea

• Adults develop in trachea & attach there, males & females in copula

What is the PPP of Syngamus trachea?

18-20 days

What are the general features of capillaria?

• Three species

• Direct & indirect life cycles.

  • Direct —> bigger threat to indoor (lots of birds, close prox.)

  • Indirect —> bigger threat to outdoor

What are the morphological features of capillaria?

Very thin (capillary-like) worms

1-5cm long

Where in the bird is Capillaria found?

Upper digestive tract (crop, oesophagus) or small intestine

What are the morphological features of a Capillaria spp egg?

• Lemon shaped —> similar to trichurius spp. egg

• Barrel with two mucoid plugs

• 50-70µ

What is the infective stage of capillaria?

L1 (develops in egg)

What is the intermediate host of Capillaria (those with indirect lifcycle)?

Earthworm

• Birds infected by ingesting earthworm

What is the PPP of Capillaria?

3-4 weeks

Describe the direct lifecycle of Capillaria

Describe the pathogenesis of Capillaria

• Highly pathogenic

• Head of worm buried deep in mucosa leading to diphtheritic inflammation → sloughing of the mucosa followed by haemorrage

What are the clinical signs of Capillaria in birds?

• Inappetence

• Weight loss

• Decreased egg production

What bird is most affected by Trichostrongylus tenuis?

Red grouse (game bird)

Where in the bird are Trichostrongylus tenuis found?

Caeca

What is the infective stage of Trichostrongylus tenuis

L3

What are the morphological features of Trichostrongylus tenuis egg?

80-100

Typical trichostrongyle egg

What is the pathogenesis of Trichostrongylus tenuis?

Adults burrow into caecal mucosa

• Localised flattening

• Bleeding

What are the clinical signs of Trichostrongylus tenuis in birds?

Reduced body condition and weight

Explain the lifecycle of T. tenuis

• Larvae ingested when grouse feeding on heather (larvae wrapped round)

• Larvae move to caeca

• Adults reproduce

• Eggs passed in caecal droppings

• Eggs hatch inside caecal dropping and develop into L3

• L3 dispersed and wrap round heather shoots

What are the poultry ascarid species?

• Ascaridia galli

• Heterakis gallinarum

How does the size and location differ between Ascaridia galli & Heterakis gallnarum?

• Ascaridia galli —> small intestine, large (12cm)

• Heterakis gallinarum —> caeca, small (1.5cm)

What are the morphological features of the poultry ascarid eggs?

Eggs indistinguishable between them

• Thickened wall

• Undifferentiated mass inside

• Larva develops within egg

What is the infective stage of poultry ascarids?

L2/L3 in egg

Do poultry ascarids migrate?

No —> all development within GI tract

(Most other ascarids migrate)

Describe the pathogenicity of poultry ascarids

• Low pathogenicity

• BUT Heterakis gallinarum vector for highly pathogenic protozoan —> Histomonas meleagridis

What parasites are significant in housed birds? What are the risks?

Parasites with direct lifecycles

• Most have resistant eggs (Ascaridia, Heterakis and Capillaria) so can be infected from prev. batch

How do you control poultry nematodes in housed birds?

• Biosecurity —> prevent intro in new batches

• Use of anthelmintics in feed

  • BZs —> flubendazole

What parasites are significant in outdoor reared birds or birds maintained oudoors? What are the risks?

Parasites w/ direct AND indirect lifecycles important

• Resistant eggs & intermediate / transport hosts —> parasite stages persist in environment

• Wild birds important source of infection

How do you control poultry nematodes in outdoor reared birds or birds maintained outdoors?

• Biosecurity —> prevent introduction of nematodes with new batches of birds

• Use of BZs in feed —> flubendazole

• Rotate pens between batches of birds

  • e.g. don’t use same pen for different batches of game birds when rearing them

What birds are Histomonas meleagridis highly pathogenic for?

Turkey poults

What does Histomonas meleagridis cause?

• 'blackhead’ (wattle goes black)

• Severe entero-hepatitis

• High levels of mortality

What are the morpholoigcal features of Histomonas meleagridis

Amoeboid protozoan with single flagellum

Describe the pathogenesis of Histomonas meleagridis?

• Trophozoites in caecum erode caecal epithelium

• Invade liver causing necrosis & typical (pathognomic) saucer-like lesions

What are the clinical signs of Histomonas meleagridis?

• Depression

• Ruffled feathers

• Sulphur yellow faeces

• Cyanosis of wattle & comb —> blackhead

How is Histomonas meleagridis transmitted?

• Transmitted in larvated eggs of Heterakis gallinarum

• H. gallinarum in caeca & Histomonas also in caeca.

• H. gallinarum worm ingests Histomonas —> migrate to uterus of female H. gallinarum

• Incorporated into the H. gallinarum egg

• Only transmitted in larvated egg

How do you control Histomonas?

• Biosecurity

• Drug for it withdrawn

• Control Hetarakis infection

  • Flubendazole

  • Don't use same pens for different batches

  • If get rid of heterakis = control of histomonas

• Chickens asymptomatic carriers —> don't rear turkeys on ground prev., used for chickens

What are the features of Spironucleosis (Hexamita) meleagridis?

• Direct transmission.

• Young game birds

• Causes watery bright yellow D+.

• No tx —> prevent by all in/all out, mix age groups, rotate pens.

What are the general features of Trichomonas gallinae?

• Direct transmission.

• Oral canker, cheesy yellow material around beak.

• URT of finches, pigeons, birds of prey