Exam 2 - Lecture 14

Question 1

Important Nematode Parasites in Poultry Production

Answer 1

• Impact of parasitism in poultry production largely a factor:
  -For backyard flocks
  -Natural “organic” range‐fed operations

-Parasites in agribusiness are controlled by:
-Confinement breeding limiting contact w/ infective stages in soil/environment
-Prophylactic use of anthelmintics
-“All in all out” production segregates animals by age class, reduces risk

-Parasites of particular interest:
-Ascaridia galli
-Heterakis gallinarium
-Capillaria spp.
-Syngamus trachea
-Spiruid nematodes

Question 2

Ascaridia galli - Poultry Roundworm

Answer 2

-Ascarid parasites of poultry:
-Stout worms w/ 3 lips
-Sexually dimorphic
-Adult worms live in small intestine

-Direct lifecycle:
-Ingestion of larvated eggs
-Develop in intestine
-No tracheal/somatic migration

-Pathology from penetration & inflammation in duodenal mucosa:
-Impaction in severe infections

-Young birds most susceptible to disease:
-Age acquired immunity
- > 3 months of age

-Clinically affected birds weak, markedly emaciated

-Decreased egg production

Question 3

Heterakis gallinarum - Poultry Cecal worm

Answer 3

-Adult parasites living in the cecum of poultry:
-Stout worms w/ 2 lips
-Sexually dimorphic

-Direct & Facultative Indirect lifecycle
-Earthworm as paratenic host

-Vectors “Blackhead” (enterohepatitis) in turkeys:
-Histomonas meleagridis, protozoan parasite remains viable/protected in egg

-Pathology marked thickening of cecal mucosa

-Contrast w/ H. isolonche”
-Nodular typhlitis, casesous lesions, diarrhea, wasting & death

Question 4

Heterakis gallinarum - Poultry Cecal worm - Diagnosis

Answer 4

-Ascaridia/Heterakis eggs readily recovered on fecal flotation:
-Similar morphology
-Thick shell, single cell

-Slight differences in size:
-Heterakis 65‐80 x 35‐45μm
-Ascaridia 73‐92 x 45‐57μm

-Not immediately infective:
-Must undergo development to infective stage in the environment

-Similar biologic feature in common with all Ascarid‐type nematode parasites

Question 5

Capillaria spp.

Answer 5

-Adult parasites living in the intestine, esophagus, or crop of poultry:
-Stout body w/ elongate whip‐like esophagus

-Direct & Facultative Indirect lifecycle:
-Earthworm as paratenic host
-Perhaps Intermediate host

-Pathology, etiology based on site of infection:
-Emaciation, hemorrhagic diarrhea w/ intestinal species
-Hyperplasia of crop & esophagus
-Croupous inflammation
-Dysrexia, emaciation & death

-Important in deep litter poultry houses, range yards where hyper‐contamination is likely

Question 6

Syngamus trachea - Gape Worm

Answer 6

-Strongylate parasites living in the trachea of poultry & wild birds:
-Medium size worms,
-Bright red coloration
-Permanently in copula

-Direct & Facultative Indirect lifecycle:
-Eggs coughed up, discharged from host
-Larvae highly susceptible to adverse environmental conditions
-Earthworm important paratenic host, may enhance infectivity to susceptible birds
-Ingested larvae undergo tracheal migration
-Reproduction in larger bronchi and trachea

-Migration through lung associated with ecchymoses, edema, lobar pneumonia

-Clinically apparent “gape” behavior: open mouth, dyspnea & asphyxia from accumulated mucous in mouth

-Emaciation and death

Question 7

Spiruid Nematodes

Answer 7

-Adult parasites living in the gizzard, proventriculus, esophagus, etc.

-Obligate indirect lifecycle: Orthoptera/Coleoptera as intermediate host

-Pathology & etiology based on site of infection:
-Emaciation, hemorrhagic diarrhea w/ intestinal species
-Mild infections are unremarkable

-Disease susceptibility in younger birds

Question 8

Spiruid Nematodes - Diagnosis

Answer 8

-Eggs readily recovered on fecal flotation

-Centrifugal sedimentation may also be efficient

-Distinctive morphology:
-Strongyle‐type eggs; thin shelled morula and 70‐90 x 45μm
-Capillarid‐type eggs: polar plugs and 50‐60 x 35‐40μm
-Spiruid‐type eggs: thick shell, colorless, w/ larvae and 35‐50 x 25‐35μm

Question 9

Treatment & Prevention of Parasitisms in Poultry Production

Answer 9

-Prevention based on avoidance of hyper‐contaminated environments

-Birds raised in confinement & off ground are isolated from infective parasite stages

-Difficult to achieve reasonable parasite control in backyard environments w/out prophylactic deworming: especially parasites that use paratenic/intermediate hosts

-Segregate by age group:
-All in All out” allows for standardized treatment regimens

-Wide selection of cost effective anthelmintic choices:
-Must pay attention to withdrawal periods prior to slaughter