Exam 1 Flashcards
What will happen if an animal swallows an ascarid egg that contains a single cell
Egg will be shed in feces, host not infected because egg has not developed yet to larvated infective stage. Egg will develop in environment until it reaches larvated infective stage and will infect the next animal to consume the egg
What is the cycle of events (all possibilities) if a dog (or other D.H.) ingests an infective larvated egg (T. cani)
Larva(e) will hatch and penetrate mucosa of small intestine and then undergo tracheal or somatic migration.
Tracheal migration: larvae burrow through walls of S.I. to enter portal circulation –> arrive in liver –> hepatic parenchyma to cd. vena cava –> lungs –> alveoli and molt –> bronchial tree –> trachea –> pharynx –> swallowed –> molt twice and mature in S.I.
Somatic migration: larvae burrow through walls of S.I. –> enter portal circulation –> arrive in liver –> hepatic parenchyma to cd. vena cava –> return to hearth via pulmonary vv. –> scattered through body via system circulation –> encyst in various tissues
Does tracheal migration occur in the I.H.
NOOOOO
Name 2 ways in which encysted larvae of T. cani (in the mother) can infect puppies and kittens
transplacental and transmammary infection
Can encysted larvae within an I.H. infect its young via transplacental/transmammary routes
Nope
How can a D.H. become infected with T. cani if it does not ingest an egg directly from its environment
Consuming an infected I.H. or paratenic host that has encysted larvae
Describe the typical cycle of events if a paratenic host ingests infective larvated eggs of T. cani and the paratenic host is then ingested by a D.H.
Larvae hatch and undergo somatic migration and encyst in tissue of paratenic host. Once P.H. is consumed, encysted larvae hatch and undergo mucosal migration (burrow into stomach wall and molt twice and re-enter lumen –> small intestine and molt to adults)
Will larvae of T. canis undergo somatic migration if encysted inside a paratenic host that then becomes eaten by a D.H.
No, will not undergo somatic migration again. Will undergo mucosal migration
Describe the events that occur in transplacental transmission (T. cani)
What is the PPP of T. cani in the puppies?
After 42 days of pregnancy, encysted larvae in the bitch migrate via umbilicus to infect unborn pups. larvae reside in liver until after birth and then undergo tracheal migration
PPP 21 days
Describe the events that occur in transmammary transmission (T. cani)
What is the PPP of T. cani in the puppies?
After 42 days of pregnancy, encysted larvae in bitch migrate to mammary tissue and are transmitted in milk. Larvae undergo mucosal migration in puppies
PPP 21 days
Which mode of migration is most common for T. cani in puppies? In older dogs?
tracheal migration in puppies/somatic in older dogs
rule of thumb is younger the dog = tracheal, older = somatic
T/F: encysted larvae within a host can be killed without harm to the host
False
What are the treatment options for Ascarids (available meds), dogs vs cats
dogs: fenbendazole SID for 3 days, Febantel PO, Milbemycin oxime PO, Moxidectin topical, Pyrantel PO,
cats: Emodepside topical, Febantel PO, Milbemycin oxime PO, Moxidectin topical, Pyrantel PO, Selamectin topical
With which medications can you reduce transmammary and/or transplacental transmissions in an infected bitch
Fenbendazole, Ivermectin (SC/PO)
T/F: Transplacental transmission can happen with T. cati in a cat, Transmammary transmission can happen with T. cati in a cat.
False, True
How would you distinguish the difference between an adult T. cati worm and an adult T. canis/Toxascaris sp. worm
T. cati have wide cervical alae (“arrowhead worm”)
T. canis & Toxascaris sp. have narrow cervical alae
Can T. cati eggs be distinguished from T. canis eggs
What about T. canis/T. cati from Toxascaris leonina
No
T. leonina has a thin and smooth outer wall with a waxy-wavy internal membrane
If there is no somatic migration, can there be transplacental/transmamamry migration
No
What mode of migration do Toxascaris leonina undergo once an infective larvated egg is ingested by a paratenic host that is then ingested by a D.H.
Mucosal migration
What are the ways in which Toxocariasis can manifest
Visceral larva migrans, ocular larva migrans, covert toxocariasis
What causes the symptoms of toxocariasis
Body’s inflammatory reaction, hepatitis common sign in children.
Why are raccoons not considered paratenic hosts for Baylisascaris procyonis
What kind of host are raccoons then
Adult raccoons can’t be infected by ingesting an infective larvated egg. They must ingest encysted larvae from tissues of I.H.
Intermediate Hosts
What kind of migration do B. procyonis larvae undergo when an infective larvated egg is consumed by a non-raccoon animal
Somatic migration: penetrate walls of S.I. to enter portal circulation to liver (hepatic parenchyma) to cd. vena cava to heart to lungs back to heart via pulmonary vv. and are then disseminated through body
How can you tell Baylisascaris eggs from Toxocara eggs (T. canis)
B . procyonis eggs slightly smaller, are darker in color (reddish brown) and have a rough coated outer shell
T. canis has a thick pitted shell and lighter in color
True/False: Ancylostoma species/Hookworms are the only worms that undergo the leak back phenomenom
true
Give the common name for each of these worms
Toxocara, Ancylostoma, Cyclophyllidea, Pseudophyllidea, Trichuris,
Roundworms, Hookworms, Tapeworms, Whipworms
Describe the different possibilities for infection of Ancylostoma caninum
Infective larvae in environment are either ingested by host or penetrate the skin. If ingested, larvae can undergo either mucosal migration or somatic migration. Arrested larvae from somatic migration can undergo transmammary transmission after being reactivated or udnergo tracheal migration (leak back). Larvae that undergo percutaneous transmission undergo tracheal migration.
4 routes of infection of Ancylostoma caninum
1) ingestion of infective larvae
2) percutaenous transmission
3) Transmammary transmission
4) Leak back phenomenon
True/False: hookworms can undergo transplacental migration
False
Which routes of migration are possible for ancylostoma caninum after leak back has started
tracheal or somatic migration
True/False: A. tubaeforme undergo transmammary transmition, but not transplacental transmission in cats
Fale, they do not undergo either one
do you find larvated eggs of hookworms in feces of infected animals
Noot
Can animals infected with hookworms die before the worms reach patency
Yes in small/young animals with large worm burdens
Can dogs/cats be ifnected with anylostoma spp. after ingesting eggs
No, the infective stage begins once larvae leave the eggs
Which species penetrate human skin, common name for disease?
A. caninum and A. braziliense, plumber’s itch
Is the genus strongyloides included in the superfamily strongyloidea? if not, then what superfamily
No, rhabditoidea
Why is strongyloides sp. considered a rhabditiform
anterior end is arranged in a corpus, isthmus, and bulb
Describe the 2 different life cycles of rhabditiform larvae
larvae can molt 4 times to become free living males/females or motl twice and become infective filariform larvae (can penetrate skin and undergo tracheal migration)
How can you diagnose strongyloides sp. infection
Baermann exam using fresh feces
Which order of worms, Cyclophyllidea or Pseudophyllidea have a bothria? Proglottids? Scolex?
Pseudophyllidea, both, cyclophyllidea
T/F: each proglottid contains either a male or female reproductive organ, but not both
Fale, it contains both
Proglottids at the distal end of the worm only contains _____
Eggs
What is the other name for mature proglottids? What happens when they reach this stage of development?
Gravid proglottids. Break off from worm and are shed in feces
T/F: cyclophyllidea lay eggs
False, they do not
Mature Cyclophyllidea eggs contain a 1st stage larvae called a _____ surrounded by 2 membranes. This stage is passed immediately infective/uninfective for the intermmediate host
Hexacanth embryo, infective
Within the I.H., the hexacanth embryo forms a _____
metacestode
Name the differnt metacestodes of Cyclophyllidea
Cysticercoid ( Dipylidium caninum & Mesocestoides spp.)
Cysticercus (Taenia spp.)
Strobilocercus (Taenia taeniaeformis)
Coenurus ( Taenia spp.)
Hydatid ( Echinococcus granulosus)
Alveolar Hydatid ( Echinococcus multilocularis)
Tetrathyridia (Mesocestoides spp.)
Which tapeworm species has proglottids that bulge outwards and what causes this bulging?
Dipylidium caninum “double pore tapeworm”, each segment has 2 genital pores
What kind of life cycle does D. caninum have? At which point does this tapeworm become infective for the D.H.? The hexacanth embryo forms a _____ inside the ______ .What is the PPP of this worm?
One egg = ______ = _____ tape worm(s)
Indirect, when the I.H. (flea) becomes an adult, cysticercoid, flea. 2-3 weeks
one cysticercoid, 1 worm
Which 2 taeniae spp. are the most common in dogs and cats
Taenia pisiformis and Taenia taeniaformis
What kind of netacestode does T. pisiformis have? T. taeniaeformis?
Cysticercus
Strobilocercus
how many worm(s) form from a strobilocercus
one
Which metacestode contains more scolices, hydatid cyst or coenurus
hydatid cyst (hundreds to thousands vs dozens
T/F, generally taenids usually are non-pathological to the I.H and are pathologic to the D.H
False, they are actually pathogenic to I.H. and not to D.H.
What will happen if a dog/cat ingests a taenia type egg
nothing, the I.H. containing the infective stage of the taenia spp. needs to be ingested
2 most common tapes for dogs?
T. pisiformis and D. caninum
2 most common tapes for cats?
T. taeniformis and D. caninum
What are the I.H.’s for E. multilocularis
mice and voles
Are humans considered an I.H. or D.H. for Echinococcus multilocularis
I.H.
How can you tell the difference between E. multilocularis eggs and Taenia spp. eggs
you can not. Only way to confirm diagnosis is to find a cyst and then use serological tests to confirm