Parasitology - Exam 1 Lecture 10 (ascarids) Flashcards
Discuss ascarids - the basics
- Very common
- large nematodes
- adults live in smallk intestine
- some species are zoonotic
- ## huge reproductive potential and eggs survive in envionrment for months
What ascarids infect the different species
- Toxocara canis –> dogs
- Toxocara cati: cats
- Toxocara leonina –> in dogs and cats and zooo animals
- ## Baylisascaris procyonis in racoons
Illustrate the different different parasites and the organs in wgich they infect
Discuss the Toxocara canis life cycle
- Adult worms in intestines mate and produce eggs whch are pooped inot the enuivornment
- Larva develops within the egg to the infectious L3. NOTE THAT THIS OCCURS IN THE ENVIORNMENT
- Dog ingests larvated egg
- Larvae hatches out in intestine and enters the blood stream:
- some somatic migration –> encysts in tissues
- some take tracheal route –> back to intestine to mature and produce eggs –> NOTE THAT THIS OCCURS IN THE HOST ANIMAL
Discuss thr Toxocar canis life cycle
-
somatic migration can occur in any malmallian host (mouse, rabit, humans, etc)
- becomes a paratenic host whre the parasite arrests in the infective larval stage but does not develop further –> waits for the paratenic hiost to be eaten by the definitive host - a dog can become infected by eating a paratenic host that contains Toxocar canis arrested by larvae
- ingestion of L3 from tissues results in patent infection in dogs
When considering Toxocara Canis, discuss the transmission
Four ways in which a dog can be infected:
1) ingest a larvated egg from the enivornment
2) eats an infected paratenic host
3) Transplacental transmission –> arrested L3 in the tissues of the dam are reactivated and migrate to the placenta during pregnancy > infects pups in utero
4) Transmammary transmission –> arrested L3 in the tissues of the dam are reacivated and migrate to the mammary gland > ingested by pups in the milk
Again, when consideirng toxicara canis, discuss the transmision routes
Transplacental transmission:
- larvae migrate thorugh lungs of thr pups
- Cause damage and inflammation
- Rare but the most commonly fatal route
Transmammary transmision:
- larva ingested by pups> go straught to the small intestine and develop into adults
Now, discuss the transmision and life cycle of toxocara canis
Discuss the opathologic effects of toxocar canis
- severity of clinical signs depend on hoist factors and worm burden
- Adult worms in the intestinal tract
- Smal numbers of intestinal worms: mild mucoidn enteritis, mild diahhrea, often asymptomatic
- **Large numbers of intestinal worms:* obstruction or rupture of intestine, blockage of bile or pnacreatic ducts
Discuss the clinicasl signs of toxocar canis
- pathogenic primarily in puppies, adults tend to be asymtpomatic
- **adult worms ** in the inestine –> live worms in feces or vomtius
- **larval worms ** mirgrating thorugh the lungs
- ## General ill thrft
Discuss the diagnsois of toxocara canis
- Fecal floats to identiofy the eggs
- fecal antigen tests
- young puppies - presum,toive because of clinical history of dam and kennel
Discuss the life cycle of toxocara cati
Different toxocar canis in dogs in that 1) very few undergo somatic migration in cats –> encysts in tissues 2) **almost all ** take tracheal route –> back to intestine to mature and produce eggs
Discuss the transmission routes for Toxocara cati
Three ways in which a cat can be infected:
1) ingests a larvated eggs from the eniuvonrment
2) Eat an infected paratenic host –> THIS IS THE MAJOR TRANSMISSION ROUTE FOR TOXOCAR CATI
3) Transmammary transmision is possoible but ONLY if the queen is infected during lacrtation
TRANSPLACENTAL TRANSMISSION DOES NOT OCCUR
DISCUSS THE DIAGNOSIS FOR TOXOCAR CATI
Same as Toxocara canis
fecal floats to identify the eggs
Discuss the species known as toxocaris Leonina and its life cycle
The main differences between this and that of Toxocar cati are that 1) takes less than 1 week for infectious L3 to develop in the egg –> NOTE that thiss occurs in the envornment. Next, 2) Larvae hatches out in the inestine and **molts L4 > L5, adult; also, it does not migrate in dogs and cats ** NOTEthat this occurs in dogs and cats
discuss the basics of Toxocaris leonina transmission
- Two ways in which an animnal can be infected:
- 1) Ingest a **larvated egg ** from the enivonrment
- 2) Eat an infected paratenic host –> this is the majior transmision route
transmammary and transplacental transmission does not occur
Discuss Bayliascaris
Baykliascaris is an important zoonotic nematode
Definitive host: racoon
Life cyclke: same as Toxocara canis –> it undergoes somatic migrauion in any mammal
Larva are muych larger than T. Canis, grow as they migrate and wander aggresivekly
why are toxocara canis and abylisacascaris considered to be important zoonotic pathogens/
Toxocara canis and Bayliasacris are important zoonotic pathogens
- ## These parasites cause **visceral larval ligrans (VLM) ** and ocular larval migrans (OLM) in humans
Discuss viceral larval migrans
- usually seen in children under 5 years old
- Damage is due to the L3 larvae migrating through the tisssues and the iummune response trying to stop them
- ## Symptoms vary from asymptomatic to very severe –> can have cardiac, pulmonary, neurologic involvement, dpendsing on where the larvae migrate
Discuss ocular larval migrans
Eosinophilic granuloma surroundsng in the larva in the retina –> can be mistaken for retinoblastoma
Discuss control and prevent human inection in terms of ascarids
- Treat pets –> deworm regualry (prevent transmission from dams to puppies; prevent puppies from shedding eggs)
- Reduce envionmentakl contamination: recue umber of stray dogs
educate clients
Discuss dog and puppy treatment in relation to ascarids
Anthelmintic arsenal:
- pyrantel maoate
- piperazine
- fenbendaz\ole
- macrocycli lactones
Treat puppies eery two weks starting at tweks old until 3 months old:
- pyrantel pamoate –> labeled for use in puppies 2 weeks and olde; treat dams at the same time
Piperazine and fenbendazole in puppies > 6 weeks old
Again, discuss the treatment for dogs and puppies when considering Ascarids
Treat kactating dams to prevent transpacental and transmammary transmission –> both options are off label
1) **fenbendazole __> daily from day 42 of gestation until 14 days after whelping **
2) High dose ivermectin –> not recommended by manufacturer
