Lecture 8 2/8/24 Flashcards
What are the general characteristics of Ascaroidea?
-large, stout worms
-in the small intestine
-three conspicuous anterior end lips
What are the characteristics of Ascaroidea eggs?
-eggs have a thick albuminous shell
-long persistence in environment
-shell is sticky and allows eggs to stick to surfaces
-eggs shed in feces unembryonated and must embryonate to become infectious
What are the characteristics of the Ascarid lifecycle?
-typically direct
-may use paratenic hosts
-migrate to liver, heart, lungs, etc.
-disease mostly in young animals
-older animals may shed without disease
What are the characteristics of Ascaris suum?
-DH is swine
-male is 15-28 cm
-female is 25-40 cm
-eggs are 50-75x40-50 um
-PPP is 7-9 weeks
What is the pathogenesis associated with adult Ascaris suum?
-interference with nutrition
-can block intestine
What is the pathogenesis associated with A. suum larval liver migration?
-mechanical damage
-hypersensitivity and “milk spots”
-liver condemnations
What is the pathogenesis associated with A. suum larval lung migration?
-mechanical damage
-allergic inflammation
What pulmonary pathology leads to the clinical signs of Ascaris suum?
-inflammatory reaction
-pulmonary tissue destruction/hemorrhage
-infiltration of eosinophils
-collagen production
-fibrosis
What are the clinical signs associated with Ascaris suum?
-poor doer
-diarrhea
-resp. signs/cough
-mechanical destruction of small intestine/impaction
-icterus
-perforated intestine and death
-condemnation of liver
What is the human health concern associated with Ascaris suum?
can fully develop within the human
Which parasiticide cannot be used against roundworms?
praziquantel
What are the characteristics of Parascaris spp.?
-DH is horses/equidae
-males are 15-28 cm
-females are 18-50 cm
-eggs are 90-100 um
-PPP is 12 weeks
Which type of migration is more severe with Parascaris spp., lung or liver?
lung migration
What is the pathogenesis associated with adult Parascaris spp.?
-enteritis
-perforation of the gut
-intestinal blockage
What is the pathogenesis associated with larval Parascaris spp.?
-liver spots
-lung disease:
–eosinophilic lung disease
–permanent scarring
What are the clinical signs associated with Parascaris spp.?
-resp. disease with fever, cough, and nasal discharge
-lethargy
-rough hair coat
-poor weight gain
-decreased performance
-diarrhea
-colic
-pot-belly
What are the steps for prevention of Parascaris?
-wash mares before foaling
-feed young animals from containers
-do not graze foals with weanlings
-do not graze foals on pasture contaminated by previous foals
What are the characteristics of Parascaris treatment regimen?
-begin treatment in foals by 2 months
-repeat treatment every 2 months until foals are 6 months of age and FEC is neg.
What are the characteristics of Parascaris infection and age?
-seen mostly in foals and yearlings
-not clinically significant in adults
-rarely significant numbers in mature horses
What are the characteristics of Ascarid impaction?
-may be a consequence of therapeutic deworming in young horses
-using a paralytic drug can paralyze all the worms and lead to impaction
-need to do partial treatments to clear out worms
Is there a human health concern associated with Parascaris spp.?
no
What are the general characteristics of Toxocara canis?
-DH is dogs and wild canidae
-possible paratenic hosts
-males are 4-10 cm
-females are 5-18 cm
-eggs are 90x75 um
What are the general characteristics of Toxocara cati?
-DH is cats and wild felidae
-males are 3-7 cm
-females are 4-12 cm
-eggs are 65-75 um
What are the general characteristics of Toxascaris spp.?
-very short maturation period
-mice as paratenic host
-DH is cats and dogs
-males are 2-7 cm
-females are 2-10 cm
-eggs are 75-85x60-75 um
What are the characteristics of the Toxocara canis life cycle?
-eggs are ingested
-larvae migrate through liver, lungs, and small intestine
-larvae can arrest in tissues and reactivate during pregnancy
What are the characteristics of transplacental and transmammary transmission in Toxocara canis?
transplacental:
-arrested larvae in bitch migrate into puppy after 42nd day
-found in liver and lungs of puppies
transmammary:
-not significant
How is Toxocara canis diagnosed?
fecal float
What are the clinical signs associated with Toxocara canis?
-resp. signs
-diarrhea and vomiting
-pot belly
-unthrifty/failure to gain weight
-poor hair coat
-abdominal pain/crying out
Which animals contribute the most to environmental Toxocara canis contamination?
animals less than 6 months of age
How can transplacental transmission of Toxocara canis be prevented?
treatment of mother with fenbendazole or ivermectin prior to birth and through lactation
What are the characteristics of visceral larva migrans?
-humans are accidental host
-larvae in liver, brain or skeletal muscle
-potential for larvae to enter retina and cause ocular larval migrans
Which parasites are agents of visceral and ocular larval migrans?
-Toxocara canis
-Toxocara cati
-Baylisascaris procyonis
What are the characteristics of transplacental and transmammary transmission of Toxocara cati?
transmammary:
-only occurs with acute infection of the queen
transplacental:
-does not occur
How can the adult Toxocara cati worm be identified?
significant size; looks like cobra head
How can the Toxascaris egg be identified?
-clear internal cytoplasm
-cross-linked “cable” around outside of egg
What are the characteristics of Baylisascaris procyonis?
-important zoonotic disease
-DH is raccoon and potentially dogs
-males 9-11 cm
-females 20-22 cm
-eggs 70x60 um with golden brown cytoplasm
What are the characteristics of neurologic larva migrans caused by Baylisascaris?
-larvae go to brain of non-raccoons
-larvae continue to grow, causing mechanical and inflammatory damage
-helps facilitate transmission by making prey more accessible to raccoon
What are the general characteristics of the superfamily Oxyuroidea?
-medium-sized with slender, sharp-pointed tails
-no buccal capsule
-conspicuous muscular bulb on posterior end of esophagus
-live in posterior large intestine
-thin-shelled, asymmetrical eggs
-direct lifecycle with no migration
What are the characteristics of Oxyuris spp.?
-DH is horse/equidae
-males 9-12 mm
-females 3-6 cm
-egg 80-100x40-50 um
-PPP 5 months
Why are Oxyuris species not typically found in the feces?
-female protrudes to lay eggs at night
-eggs adhere to peritoneum
-horse scratches eggs off into environment
What are the characteristics of the Oxyuris lifecycle?
-adults in cecum and colon
-females travel to rectum and out anus to deposit egg packets on perianal skin
-infective larvae develop in 2-5 days
-ingested eggs hatch in small intestine to produce larvae
-fourth-stage larvae attach to intestine wall
What is the main method used to diagnose Oxyuris equi?
scotch tape along the perianal skin stuck to a slide
What are the characteristics of Enterobius spp.?
-DH is people
-adults 8-13 mm
-PPP 15-43 days
-eggs 55 um
-cannot be transmitted from dogs or cats; dogs and cats DO NOT have pinworms
