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46 Cards in this Set
- Front
- Back
What are some key features of Ascaridida?
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1. Have 3 large lips
2. May have 2 alae (wings) on sides of worm |
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What are the superfamilies of Ascaridida?
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1. Cosmoceroidea: Probstmayria vivipara
2. Heterakoidea: Heterakis gallinarum and Ascaridia galli 3. Ascaridoidea: the ascarids |
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Describe the Superfamily Cosmocercoidea: Probstmayria vivipara.
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Minute pinworm
Permanent parasites of equines: in lower GI tract - asymptomatic Structure: 2-3 mm with long filamentous tail in both sexes |
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What is the life cycle of Probstmayria vivipara?
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L1 develop into infective L3 in utero --> fecal contamination of food/water --> ingestion
Autoinfection: females produces L3 that develop into adult in same host |
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Describe Superfamily Heterakoidea: Heterakis gallinarum.
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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 |
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What is the life cycle of Heterakis gallinarum?
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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
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Describe Superfamily Heterakoidea: Ascaridia galli.
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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) |
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What is the life cycle of Ascaridia galli?
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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
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What are clinical signs associated with larval migration and with adults?
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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 |
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Describe, in general, Superfamily Ascaridoidea.
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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) |
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What are the Genus species of the Superfamily Ascaridoidea?
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Dogs/cats: Toxocara canis/cati; Toxascaris leonina
Horses: Parascaris equorum Swine: Ascaris suum Cattle: Neoascaris (Toxocara) vitulorum |
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Describe Toxocara canis.
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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) |
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What is the life cycle of Toxocara canis?
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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) |
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Describe the Liver-lung-tracheal migration for Toxocara canis.
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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 |
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Describe the Liver-lung-somatic migration for Toxocara canis.
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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 |
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Describe prenatal transplacental transmission of Toxocara canis in pregnant bitches. (most common route of infection)
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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) |
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Describe lactogenic transmission of Toxocara canis in pregnant bitches.
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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
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What is the epidemiology of Toxocara canis?
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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 |
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What are some lesions in Toxocara canis infection?
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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 |
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Describe Toxocara cati.
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Common roundworm of wild and domestic felids = arrowhead worm
Adults: have PROMINENT arrow-shaped cervical alae Eggs: similar to Toxocara canis but smaller |
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What is the life cycle of Toxocara cati?
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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
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Describe the larval tracheal migration for Toxocara cati.
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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 |
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Describe larval somatic migration of Toxocara cati.
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--> 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 |
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Clinical signs of Toxocara cati infections.
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Potbelly, ill thrift, emaciation, dullness, dull hair coat, possible sneezing, coughing, intermittent diarrhea, vomiting
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Describe Toxascaris leonina.
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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 |
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What is the life cycle of Toxascaris leonina?
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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
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What is special about Toxascaris leonina life cycle?
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No liver-lung-tracheal migration
No liver-lung-somatic migration No hypobiotic larvae No transplacental transmission No lactogenic transmission |
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What is the epidemiology of Toxascaris?
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Eggs are very resistant to environment: females prolific egg layers
Reservoir of infection: paratenic hosts with arrested larvae NO transplacental or transmammary transmission |
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Describe Parascaris equorum.
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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 |
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What is the life cycle of Parascaris equorum?
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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
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What are the clinical signs of larvae in lungs of Parascaris equorum?
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1. Verminous pneumonia = "summer cold"
2. Signs: fever, cough, increased respiratory rate, nasal discharge, and possible relapse after antibiotics |
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What are the clinical signs and lesions of adults in the SI of Parascaris equorum?
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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 |
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What is the epidemiology of Parascaris equorum?
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Most common in suckling or weanling foals
Transmission from foal to foal Rarely see infection in mature horses |
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What are possible post-treatment complications of Parascaris equorum?
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Obstruction or rupture of SI: due to heavy infection, use of anthelmintic that paralyzes or causes rapid kill
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What is the sanitation process of Parascaris equorum?
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1. Remove feces, bedding from stalls weekly
2. Steam or pressure clean stalls: NO disinfectant effective against eggs 3. Wash mare before foaling |
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Describe Toxocara (Neoascaris) vitulorum.
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Cattle ascarid or roundworm
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What is the life cycle of Toxocara vitulorum?
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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 |
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What are the clinical signs of Toxocara vitulorum?
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Signs caused by less than or = to 70 worms
Very foul-smelling diarrhea; colic; emaciation and death can occur |
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Describe Ascaris suum.
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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 |
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What is the life cycle of Ascaris suum?
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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
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What is the epidemiology of Ascaris suum?
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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 |
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What are clinical signs and lesions of Ascaris suum?
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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 |
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Describe Baylisascaris procyonis.
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Raccoon roundworm
Adults and eggs similar to Toxocara Infection acquired by ingestion of egg containing infective larva Larvae undergo liver-lung-tracheal migration |
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What are Visceral Larva Migrans?
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Prolonged somatic migration of larval parasites in an abnormal host
Most commonly caused by Toxocara canis in humans |
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What are Ocular Larval Migrans?
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Prolonged somatic migration of larval parasites in an abnormal host
Cause unilateral inner eye lesion similar to retino-blastoma |
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What are Neural Larva Migrans?
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Most often caused by Baylisascaris
Acute eosinophilic meningoencephalitis Weakness, ataxia, irritability, seizures altered mental status, stupor, coma |