Lecture Quiz 4 - Exam 2 - Nematodes - Ascaridida

Front 1

What are some key features of Ascaridida?

Back 1

1. Have 3 large lips
2. May have 2 alae (wings) on sides of worm

Front 2

What are the superfamilies of Ascaridida?

Back 2

1. Cosmoceroidea: Probstmayria vivipara

2. Heterakoidea: Heterakis gallinarum and Ascaridia galli

3. Ascaridoidea: the ascarids

Front 3

Describe the Superfamily Cosmocercoidea: Probstmayria vivipara.

Back 3

Minute pinworm

Permanent parasites of equines: in lower GI tract - asymptomatic

Structure: 2-3 mm with long filamentous tail in both sexes

Front 4

What is the life cycle of Probstmayria vivipara?

Back 4

L1 develop into infective L3 in utero --> fecal contamination of food/water --> ingestion

Autoinfection: females produces L3 that develop into adult in same host

Front 5

Describe Superfamily Heterakoidea: Heterakis gallinarum.

Back 5

Common name: cecal worm

Most common worm in domestic poultry

Mainly as vector of a protozoan pathogen, Histomonas

Structure: Adults = 1/2 in long; 3 lips/caudal alae (males do NOT have bursa, but DO have spicules); Eggs = ellipsoid, medium sized, thick, smooth shell and non-embryonated

Front 6

What is the life cycle of Heterakis gallinarum?

Back 6

Adults in ceca --> eggs passed in feces (infective larva develops WITHIN the egg) --> bird ingests egg with larva (earthworm can be paratenic host) --> larva hatches from egg in gizzard --> mucosal migration (?) --> ceca

Front 7

Describe Superfamily Heterakoidea: Ascaridia galli.

Back 7

In ducks, geese, chickens and turkeys (fairly common)

Adults: whitish-yellow, 3-4 inches long, 3 lips and caudal alae

Eggs: larger than Heterakis, more barrel-shaped walls and thick shell, not as hardy as most ascarid eggs (survives 3 months)

Front 8

What is the life cycle of Ascaridia galli?

Back 8

Adults in SI lay eggs (non-embryonated egg in fresh feces and infective larva develops WITHIN egg) --> feces --> ingest egg or paratenic host --> larvae hatch and undergo mucosal migration --> return to lumen and develop to adults

Front 9

What are clinical signs associated with larval migration and with adults?

Back 9

Clinical signs mainly in 1-3 month old birds

Larval migration: possible hemorrhage, mucosal ulceration

Adults: anorexia, lethargy, weight loss, diarrhea; if heavy infection = potentially fatal with intestinal blockage or rupture

Front 10

Describe, in general, Superfamily Ascaridoidea.

Back 10

1. Direct life cycles
2. Non-embryonated egg shed in feces
3. Infective larva develops INSIDE egg
4. Infection acquired by ingestion of egg (eggs very resistant and can persist in environment for years)

Front 11

What are the Genus species of the Superfamily Ascaridoidea?

Back 11

Dogs/cats: Toxocara canis/cati; Toxascaris leonina

Horses: Parascaris equorum

Swine: Ascaris suum

Cattle: Neoascaris (Toxocara) vitulorum

Front 12

Describe Toxocara canis.

Back 12

Common dog roundworm

Adults: large, robust worms (11-20 cm long); 3 lips; long, narrow CERVICAL alae; posterior = males DO NOT have a bursa

Eggs: round or elliptical; shell = thick, rough, pitted, yellowish brown; contents = single cell (dark brown-black, granular and non-segmented; almost fills ENTIRE shell)

Front 13

What is the life cycle of Toxocara canis?

Back 13

Adults in SI --> eggs (lots) in feces --> Infective larva develops WITHIN egg --> egg with larva ingested --> larva hatches in duodenum

(Young hosts: liver-lung-tracheal migration; Older hosts: liver-lung-somatic migration)

Front 14

Describe the Liver-lung-tracheal migration for Toxocara canis.

Back 14

In hosts less than 12 weeks old:

Larvae --> gut wall --> liver via hepatic portal vein or lymphatics --> hepatic vein --> heart --> lungs --> alveolar capillaries --> alveoli --> coughed up and swallowed

Front 15

Describe the Liver-lung-somatic migration for Toxocara canis.

Back 15

For hosts older than 12 weeks old:

At alveoli --> stay in bloodstream --> skeletal muscle/kidneys/+/- liver/brain --> hypobiotic; granulomas develop around larvae and survive 1 year = dead end for most larvae

Front 16

Describe prenatal transplacental transmission of Toxocara canis in pregnant bitches. (most common route of infection)

Back 16

Prenatal transplacental transmission: hypobiotic larvae activated in last trimester

Enter uterine circulation, cross placenta --> fetal liver +/- lungs; Larvae complete migration after birth (liver --> lung --> trachea --> SI)

Front 17

Describe lactogenic transmission of Toxocara canis in pregnant bitches.

Back 17

Hypobiotic larvae activated in late gestation and early lactation --> migrate to mammary glands --> pups ingest larvae in colostrum and milk --> ingested larvae mature in SI

Front 18

What is the epidemiology of Toxocara canis?

Back 18

Adults survive 4 months; pups expel most worms by 6 mos of age

Eggs infective in 2 weeks or more in environment; eggs are very hardy and resist environmental extremes; killed by direct sunlight and heat

Front 19

What are some lesions in Toxocara canis infection?

Back 19

Due to larval migrations:

Lungs: petechial/ecchymotic hemorrhages

Granulomas in viscera (most noticeable beneath capsule of kidney)

Due to adults in GI tract: mild catarrhal enteritis

Front 20

Describe Toxocara cati.

Back 20

Common roundworm of wild and domestic felids = arrowhead worm

Adults: have PROMINENT arrow-shaped cervical alae

Eggs: similar to Toxocara canis but smaller

Front 21

What is the life cycle of Toxocara cati?

Back 21

Adults in SI produce eggs --> infective larva develops in egg in environment (4 weeks) --> egg with larva ingested --> larva hatches and enters gut mucosa --> liver --> lungs: tracheal or somatic migration

Front 22

Describe the larval tracheal migration for Toxocara cati.

Back 22

Ingested eggs --> larvae --> usually undergo tracheal migration regardless of cat's age --> larvae coughed up and swallowed --> brief mucosal --> mature to adults in SI

Adults expelled in feces or vomit before kittens 6-7 months old

Front 23

Describe larval somatic migration of Toxocara cati.

Back 23

--> lungs, stay in blood --> carried to organs (mainly skeletal muscle) and becomes encapsulated hypobiotic larvae

Females: hypobiotic larvae activated in late pregnancy and early lactation; NO transplacental transmission

Front 24

Clinical signs of Toxocara cati infections.

Back 24

Potbelly, ill thrift, emaciation, dullness, dull hair coat, possible sneezing, coughing, intermittent diarrhea, vomiting

Front 25

Describe Toxascaris leonina.

Back 25

Infects both dogs and cats of all ages

Not as prevalent as Toxocara

Adults: slightly smaller than Toxocara; long, narrow cervical alae

Eggs: oval to ellipsoidal; shell is smooth, thick and colorless; eggs contains a single cell - occupies only part of shell; non-segmented, granular and yellowish

Front 26

What is the life cycle of Toxascaris leonina?

Back 26

Adults in SI --> non-embryonated eggs --> eggs passed in feces --> infective larva develops within egg in 6-10 days --> egg with larva is ingested --> larvae --> mucosal migration in gut wall --> emerge --> develop to adults

Front 27

What is special about Toxascaris leonina life cycle?

Back 27

No liver-lung-tracheal migration
No liver-lung-somatic migration
No hypobiotic larvae
No transplacental transmission
No lactogenic transmission

Front 28

What is the epidemiology of Toxascaris?

Back 28

Eggs are very resistant to environment: females prolific egg layers

Reservoir of infection: paratenic hosts with arrested larvae

NO transplacental or transmammary transmission

Front 29

Describe Parascaris equorum.

Back 29

Equine large roundworm or ascarid

Females prolific egg-layers

Eggs survive for years in environment: killed by hot, dry conditions and exposure to sunlight; horses don't need to be on pasture for infection

Adults: large stout worms (6-8 inches long); off-white; 3 large lips at anterior end; no bursa on males; no alae

Eggs: round to ellipsoidal; thick rust-brown pitted shell; sticky albuminous surface

Front 30

What is the life cycle of Parascaris equorum?

Back 30

Adults in SI --> eggs --> infective larva in egg --> ingestion of egg --> larva released from egg in SI --> liver-lung-tracheal migration --> coughed up --> swallowed --> adults in SI

Front 31

What are the clinical signs of larvae in lungs of Parascaris equorum?

Back 31

1. Verminous pneumonia = "summer cold"

2. Signs: fever, cough, increased respiratory rate, nasal discharge, and possible relapse after antibiotics

Front 32

What are the clinical signs and lesions of adults in the SI of Parascaris equorum?

Back 32

Catarrhal enteritis
Pot-bellied appearance
Rough hair-coat
Poor growth or weight gain
Decreased appetite
Colic
Diarrhea, constipation, flatulence and pale, fetid feces
Gut motility increased/decreased
Intussusception
Bowel obstruction or impaction: worms "plug up" intestine = rupture

Front 33

What is the epidemiology of Parascaris equorum?

Back 33

Most common in suckling or weanling foals

Transmission from foal to foal

Rarely see infection in mature horses

Front 34

What are possible post-treatment complications of Parascaris equorum?

Back 34

Obstruction or rupture of SI: due to heavy infection, use of anthelmintic that paralyzes or causes rapid kill

Front 35

What is the sanitation process of Parascaris equorum?

Back 35

1. Remove feces, bedding from stalls weekly
2. Steam or pressure clean stalls: NO disinfectant effective against eggs
3. Wash mare before foaling

Front 36

Describe Toxocara (Neoascaris) vitulorum.

Back 36

Cattle ascarid or roundworm

Front 37

What is the life cycle of Toxocara vitulorum?

Back 37

Egg ingested by young calves --> liver-lung-trachea to SI --> larvae develop into adults

Egg ingested by older claves --> liver-lung-somatic migration --> hypobiotic in tissues

Front 38

What are the clinical signs of Toxocara vitulorum?

Back 38

Signs caused by less than or = to 70 worms

Very foul-smelling diarrhea; colic; emaciation and death can occur

Front 39

Describe Ascaris suum.

Back 39

Large roundworm of swine (+/- humans)

Most economically important swine parasite

Adults: large, 8-12 inces; off-white to cream colored; 3 lips around mouth

Eggs: yellow-brown, rust; oval with thick shell; rough, albuminous outer coating with prominent projections; single cell inside

Front 40

What is the life cycle of Ascaris suum?

Back 40

Adults in SI --> non-embryonated eggs in fresh feces, infective larva develops inside egg --> egg with infective larva ingested --> larva undergoes liver-blood-lung migration --> coughed up --> swallowed --> mature to adults in SI

Front 41

What is the epidemiology of Ascaris suum?

Back 41

Transmission via eggs very effective
Females prolific egg layers (2 million/day)
Eggs very hardy - survive in soil for years
Eggs sticky: fomites important in transmission

Front 42

What are clinical signs and lesions of Ascaris suum?

Back 42

Occur mainly in young animals

Larval migration in liver: focal hemorrhage; hypersensitivity to larvae --> inflammation --> hepatic interstitial fibrosis

Larval migration from lung capillaries --> alveoli --> verminous pneumonia: petechial hemorrhages in lungs, hypersensitivity to larvae develops (dry cough, shallow, rapid breathing, "thumps")

Adults: catarrhal enteritis; stunted; pot-bellied

Front 43

Describe Baylisascaris procyonis.

Back 43

Raccoon roundworm
Adults and eggs similar to Toxocara
Infection acquired by ingestion of egg containing infective larva
Larvae undergo liver-lung-tracheal migration

Front 44

What are Visceral Larva Migrans?

Back 44

Prolonged somatic migration of larval parasites in an abnormal host

Most commonly caused by Toxocara canis in humans

Front 45

What are Ocular Larval Migrans?

Back 45

Prolonged somatic migration of larval parasites in an abnormal host

Cause unilateral inner eye lesion similar to retino-blastoma

Front 46

What are Neural Larva Migrans?

Back 46

Most often caused by Baylisascaris

Acute eosinophilic meningoencephalitis

Weakness, ataxia, irritability, seizures altered mental status, stupor, coma