Parasitology 5: Nematodes 4 Flashcards
Ascaridida is part of which phylum?
Nematoda
What is a basic way to describe Ascaridida?
Big
Robust
GI tract
Ascaridida name that is used in clinic?
ROUND worms
-large, stout-bodied
-bigger than most other nematodes
-highly successful parasites in all vertebrate classes
-Ascaridids in domestic animals have DIRECT life cycle
Ascarids look like what food?
Spaghetti
What life cycle do Ascarids have?
DIRECT life cycle (definitive host)
What part of the small intestine do Ascarids live?
Lumen
-5-40cm
-they feed on lumen contents, host fluids
-do NOT attach
-Female prolific
How would describe Ascarids eggs?
Thick wall
ONE cell
Round
What is the life cycle of Ascarids?
Eggs pass through feces
-unembryonated, thick shell
-highly resistant to environmental conditions
-disinfectants largely ineffective, may survive years
Development to infective stage (egg with L3): 2-4 weeks
Egg is NOT infective until it is fully EMBRYONATED
The infective larva does NOT hatch until eggs swallowed by a host
Infective stage of Ascarids?
Embryonic egg
(NOT L3)
How do diagnosis Ascarids?
Eggs in feces
Patent infections not usually hard to detect
What is the patent infection in Ascarids?
young foals
How is the Ascarids life complicated?
Some species go straight to the intestine after ingestation by host and developto adults
Some, including important mammalian species, have larval migratory phase in definitive host
What is the equine Ascarids - life cycle
parascaris equorum and parascaris univalens
Eggs passed in manure
Larvae hatch in intestine, penetrate wall
Hepatotracheal migration
-carried to LIVER in blood
-enter hepatic portal system
-reach lungs about 1 week PI
-coughed up and swallowed
-return to small intestine
PPP about 3 months
Clinical importance of Parascaris Ascrids in Equine?
Common in young horses
low worm burden may be subclinical
Adults in small intestine
-competition with host nutrients
-poor condition, rough hair coat, pot belly
-very heavy infection can lead to perforation or impaction
Larvae in lungs (heavy infection)
-mechanical and inflammatory damage
-nasal discharge
Do adult horses transfer Ascarids to young horses?
NO
What is seen in all animals with Ascarids infection?
Distended bellies
Parascaris summary the equine ascarids?
patent?
difference from strongylid nematodes?
Patent infections occur in foals and young horses (<2-3 years)
Immunity develops, adults rarely have patent infections
Adults don’t play a role in parasite transmission
Different from strongylid nematodes, where even adults animals have some worms in GI tract
Ascarids in small animals names?
Toxcara found in small animals SI worldwide
Dogs: T. canis
Cats: T. cati
They are also other genus of Ascarids in small animals
Toxascaris leonina
What is the life cycle of Toxocara canis?
-Eggs passed in feces of infected animals
-Take at least 3-4 weeks in environment to become infective
-Can survive long periods if protected from desiccation
MORE COMPLEX than parascaris
Adult t.canis in SI
–>eggs contaminating one cell in feces
–> eggs containing infective larvae in soil
–>with somatic or hepatotracheal migrations
Somatic:
Infective larvae, arrested in tissues of bitch-> larvae in lungs of pups (enters in utero during last 3 weeks of pregnancy)-> Pups born, larvae mature, patent at 3 weeks post-partum OR Larvae shed in milk, ingested by pups
What is the summary of the life cycle of Toxocara canis?
What is a good summary of Hepatotracheal migration and Somatic migration?
What is Hepatotracheal migration probability with toxocara canis?
High at birth, decreses after 2 motns (PP:4-5 weeks)
What is the difference between equine and dogs Ascarids life cycle?
Horses do NOT go through Somatic migration
What are the transmission of Toxocara canis life cycle?
Ingestion of infective eggs
Transplacental
Transmammary infection
Paratenic hosts
What is the clinical importance of Toxocara canis?
Most clinical signs seen in puppies
Low burdensL no or few signs
Moderate to heavy burdens
-diarrhea/constipation
-colic and pot belly
-vomiting (worms can be seen)
-poor hair coat
-intestinal obstruction
-pneumonia
How do you diagnosis Toxocara Canis?
Patent infections
–Fecal exam
Somatic reservoir (Can be dormant phase resurfacing)
What are the big 3 canine nematodes?
Hookworms
Roundworms
Whipworms
Toxocara Cati is different that Toxocara canis life cycle how?
Transmammary transmission occurs but NO transplacental
Somatic reservoir appears to be less important
Longer PPP
Toxocara Public health importance
Larvae can migrate in humans as in other vertebrates
Most infections asympotomatic
Clinical diseases syndromes
-OCULAR larva migrans: in the eye
-visceral larva migrans: larva anywhere
What other species may be expected with Adcaridida?
Pigs (zoonotic): ascaris suum
Racoons (zoonotic): Baylisascaris procyonis
Humans: Ascaris lumbricoides
Cattle: toxocara vitulorum
Poultry and other birds, reptiles, fish
