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Lab 2: Measuring Parasite Eggs, Fecal Flotation, Ascarids

Terms in this set (30)

All ascarids have 3 prominent lips.

Toxocara canis: Dog large roundworm
Host: canines
Site of infection: Adult in SI, juveniles migrate extensively
Distribution: throughout the world, very common
Lifecycle:
-Eggs + L3 ingested (eggs are infective in 2-4 weeks under ideal conditions)
PPP=3-4 weeks
-L3 hatches and migrates to liver, then lung via blood
Option 1: Mature dogs (>6 months old)
-Somatic migration of L3s dissemination via peripheral circulation to tissues where they encyst
-Pregnant bitch
-Option 1A:
--Transplacental migration of L3s to fetal liver
--neonatal pup lungs
--tracheal migration of L3s which then migrate up the bronchial tree
--Pharynx (L3s swallowed)
--Stomach (L3-L4)
--Small intestine (L4-Adults)
-Option 1B:
--Migration of L3s to mammary glands
--L3s ingested by suckling pups
--Pharynx (L3s swallowed)
--Stomach (L3-L4)
--Small intestine (L4-Adults)
Option 2:
-Puppy <5 weeks old
-tracheal migration of L3s which then migrate up the bronchial tree
-Pharynx (L3s swallowed)
-Stomach (L3-L4)
-Small intestine (L4-Adults)
Option 3:
-Mouse (paratenic host)
-somatic migration of L3s dissemination via peripheral circulation to tissues where they encyst
-dog eats mouse, larvae released
-L3s->L4->adults in the intestine of the canine host

Pathogenesis/Clinical Signs: Migrating juvenile worms
-Respiratory disease
--2-3 day old pups
--transplacental transmission
-Heavy infection of worms in small intestines
--Nursing and weaned pups
--pot-bellied pups
--tender abdomens often due to bloating
--pups will frequently whimper and cry

Adult dogs less susceptible:
-Intestinal infection with T. canis is rare in adult togs (may not be as rare as previously thought)
-Puppies spontaneously purge intestinal infections as they mature and develop immunity to T. canis

Identification: Patent infections
-Eggs in flotations
-Adults at necropsy or in vomitus
Identification: Prepatent infections
-clinical signs and age

Eggs:
-85-90 by 75 micrometers
-thick pitted outer wall
-dark
-single cell that is developing
-subspherical

Adults:
-12.7 cm (5 inches)
-lanceolate cervical alae
-prominent 3 lips

Toxocara cati: Large roundworm of cats
Hosts: Felines
Site of infection: Adults in SI, juveniles migrate extensively
Distribution: common throughout the world
Lifecycle:
-Egg+L3 ingested
-L3s hatches and invades stomach of host
Option 1: mouse (PH)
-somatic migration migrate to and encyst in body tissues)
-cat eats mouse and L3s released
-L3s enter wall of stomach or intestine
-develop into reproducing males and females
Option 2: Cat (definitive host)
Option 2A: L3s tracheal migration migrate to liver, lungs, bronchi, trachea, pharynx, stomach and small intestines
-L3s enter wall of stomach or intestine
-develop into reproducing males and females
Option 2B: Cat (DH)
L3s somatic migration dissemination to tissues where they encyst
-pregnant queen
-migration of L3s to mammary gland
L3s ingested by suckling kittens, enter mucosa of stomach
-mature to reproducing males and females

Transmission: Ingestion of infective eggs
-no age-related immunity
-all age cats susceptible
No prenatal infections
Transmammary infections-yes but not activated by suckling like T. canis
-ingestion of paratenic hosts important
PPP 2 months

Pathogenesis and Disease:
-Respiratory signs in newborn kittens are absent (no transplacental transmission)
-Nursing kittens may obtain heavy infections from transmammary transmissions if queen is infected during preganancy
-Clinical signs may include abdominal distension and distress and chronic ill thrift

Identification: Patent infections
-Eggs in flotations
-adults at necropsy or in vomitus
Identification: Prepatent infections-clinical signs and age

Eggs: 65-75 micrometers
-thick pitted outer wall
-dark
-single cell that is developing
-elliptical
Adults: 7.5 cm (3 inches)
-arrow-shaped cervical alae
-3 prominent lips