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
How to tell D. caninum from Taenia spp.
D. caninum has egg packets vs taenia type eggs, D. caninum has more rounded bodys egments due to 2 genital pores, Taenia spp. has rectangular body segments
Describe the life cycle for Mesocestoides spp.
Has 2 I.H. before maturing in D.H.
eggs ingested by oribatid mite (larvae become free living) or dung beetle (become cysticercoid)
Then one of these I.H.’s are ingested by an amphibian, reptile, bird, mammal and become tetrathyridium which serve as the 2nd I.H.
Dogs and cats can serve as 2nd I.H. or as D>H>
What is a tetrathyridia
Infective stage of mesocestoides spp. that will infect the D.H.
Does Diphyllobothrium latum have a genital pore or uterine pore
uterine pore, “lays” eggs
How many suckers/hooks are found on the scolex of diphyllobrothrium
0
What is a majore morphological trait of diphyllobotrhium eggs
operculated
What do you call the larva that hatches from a diphyllobothrium egg
What needs to happen for the egg to hatch
coracidium
egg must reach water
Describe the life cycle of Diphyllobothrium
Eggs laid in the intestines and are shed in feces. If egg reaches water, then a coracidium will hatch from the egg. The coracidium is then ingested by a crustacean intermediate host (a copepod) and then turns into a procercoid. Crustacean then consumed by a fish and the procercoid develops into a plerocercoid in the fish musculature. D.H. is infected once it consumes a fish containing a plerocercoid
What kind of worms do you use fecal sedimentation for
flukes and false tapeworms
What can you do to treat Diphyllobothrium infection in dogs and cats. Is this FDA approved?
Praziquantel 2.5 - 7.5 mg/kg PO, not approved (off label)
T/F:Flukes contain both male and female reproductive organs
T
Does Alaria sp. have 1 intermediate host or 2?
2
In which genus of Trematode involves a mesocercariae life stage
Alaria
Describe the life cycle of Alaria sp.
Operculated eggs shed, if in water then a miracidium will hatch from each egg and turn into miracidia (able to swim) and penetrate a snail (1st I.H.), miracidia develop into cercariae inside the snail, cercariae exit snail and penetrate tadpoles and develop into mesocercariae, P.H. eaten by D.H. and mesocercariae migrate to lungs to get into small intestines and develop into adults
Which part of the life cycle of Alaria sp. causes more pathology in the D.H., adults in living in the S.I. vs Migration from Stomach to Lungs to S.I.
Migration causes more pathology - destruction of lung tissue
How do you recover Alaria sp. eggs? What is a defining characteristic of an Alaria sp. egg?
Sedimentation exam, operculated and large
Is Alaria sp. zoonotic?
YES, can be fatal due to pulmonary hemorrhage from migrating mesocercariae
Which parasite is responsible for Salmon Poisoning Complex
Neorickettsia sp. inside trematode Nanophyetus salmincola
Where can Nanophyetus salmincola be found
anywhere that has the 1st I.H. around (oxytrema silicula)
What is one way to distinguish an egg from Alaria sp. from Nanophyetus salmincola
Alaria egg much larger, Nanophyetus is small and yellow/brown. Both are operculated
How can you recover eggs from Nanophyetus salmincola
Sedimentation exam
Zoonotic potential for Nanophyetus salmincola
Not zoonotic
What is unique about the morphology of adult Heterobilharzia americana
Females live inside the gynecophoric groove of the males.
Where does the majority of development occur for Heterobilharzia americana. What is unique about the eggs of this fluke?
Inside the liver of D.H.
Eggs are motile and migrate through mesenteric vv. to serosal surface of intestines into the lumen of the intestines
What is a classical clinical sign of Heterobilharzia americana
Hypercalcemia
How can you recover eggs of Heterobilharzia americana
Sedimentation exam
Which parasite is responsible for Lizard Poisoning (hint affects cats)
Platynosomum fastosum aka Feline Liver Fluke
What makes the life cycle of Platynosomum fastosum unique amongst Flukes
the 1st I.H. (LAND snail) INGESTS the egg (not penetrated by it)
How do cats become infected by P. fastosum
Ingesting the 2nd I.H. (lizard)
Is P. fastosum zoonotic
Naw bae
Is this statement correct: Cystoisospora shed eggs
No, should be oocysts
What is the diagnostic stage of Cystoisospora sp.?
unsporulated oocyst
How many sporozoites are released from each Cystoisospora oocyst
8
Describe the life cycle of Cystoisospora sp.
Unsporulated oocyst is shed into environment, sporulates in environment over several days (becomes infective) and now contains 2 sporocysts with each sporocyst containing 4 sporozoites. Each sporozoite penetrates a separate epithelial cell in intestinal tract. Each sporozoite develops into a schizont and undergoes asexual reproduction (schizogony) to form merozoites. Merozoites burst out of epithelial cell and invade other epithelial cells to form schizonts to undergo further schizogony. After a certain number of schizogony cycles, a final merozoite enters another epithelial cell and develops into either a male or female gametocyte. Male gametocytes burst out of epithelial cell to penetrate epithelial cells containing a female gametocyte to form a zygote. Zygote becomes walled in, forming an unsporulated oocyst which destroys the host cell and is released to be shed in the feces
What will happen if an unsporulated oocyst of Cystoisospora is ingested by an animal
NOTHINGGG
What 2 genera cause coccidiosis
Cystoisospora and Eimeria
What is the difference between Cystoisospora sporulated oocysts and Eimeria sporulated oocysts
Cystoisospora: sporulated oocyst has 2 sporocysts, each containing 4 sporozoites
Eimeria: sporulated oocyst has 4 sporocysts, with each containing 2 sporozoites
What is the PPP of Cystoisospora
few days, less than 2 weeks
What is unique about the Cystoisospora spp. that infect cats
Can involve rodent P.H. where the (mouse) ingests an oocyst that forms a cyst (zoite) that can infect the cat when the cat ingests the infected P.H. (mouse). Zoite undergoes schizogony to form gametocytes and zygotes –> oocyst
Can also skip P.H. altogether and have cat ingest sporulated oocyst
Typically, do Cystoisospora cause disease in adults? Why or why not?
No because adults have most likely been exposed previously and built up an immunity to coccidia and are able to fight off severe infection to rpevent coccidiosis
Which drugs are FDA approved for Coccidiosis
None
What can you use off-label to treat Coccidiosis
Sulfadimethoxine - Albon or Ponazuril - Marquis
Which of these protozoa are considered a primary disease entity Cystoisospora spp. or Sarcocystis spp.
Sarcocystis spp.
What is different between the Sarcocystis spp. life cycle and Cystoisospora spp. life cycle
Gametogony occurs in D.H., D.H. are infected by ingesting I.H (rodent/herbivore), oocysts do not sporulate until ingested by the D.H., D.H. sheds sporocysts that are infective for I.H.
T/F: Sarcocystis spp. is pathogenic in D.H.
False
What treatment options are available for Sarcocystis infection
None
What organism causes the most important multisystemic protozoan disease in North America
Toxoplasma gondii
What are the definitive hosts for T. gondii
Cats only
What are the 2 different life cycles of T. gondii
Enteroepithelial (intestinal) cycle only in cats and the Extraintestinal (systemic) cycle in P.H. and D.H. (cats)
Describe the life cycle of T. gondii for enteroepithelial life cycle and extraintestinal life cycle
Enteroepithelial: Ingestion of sporulated oocyst by cat or P.H. (which can be a cat), sporozoites are released and penetrate intestinal epithelium to enter systemic circulation, spread to various tissues and develop into tachyzoites that rapidly divide and spread to other cells causing destruction of host cells (clinical toxoplasmosis), tachyzoites may develop into bradyzoites after a period of time which divide slowly (chronic stage/carrier stage) which can turn back into tachyzoites later and begin to divide and spread rapidly again
Extraintestinal: Paratenic host or another cat ingests sporulated oocyst, sporozoites infiltrate various tissues and become tachyzoites/bradyzoites. When the D.H. ingests infected tissues containing tachyzoites/bradyzoites (bradyzoites revert to tachyzoites after being ingested) penetrate intestinal epithelium and disseminate throughout the body and can become bradyzoites as well. Possible for tachyzoite/bradyzoite to undergo schizogony and gametogony
Can Enteroepithelial development of T. gondii occur in rodents?
No, only in cats
Infection of T. gondii occurs more commonly when A) cats ingest sporulated oocyst or B) ingest rodent tissues containing bradyzoites
B
What is unique about oocyst shedding of T. gondii?
Schizogony and gametogony are limited in duration as cats only shed oocysts for 1-2 weeks
How can kittens (too young to ingest tissues containing bradyzoites) be infected by T. gondii?
Transplacental or transmammary transmissions of Tachyzoites. Extraintestinal invasion can occur after being infected as well as enteroepithelial (which leads to shedding of oocysts)
What are the ways a cat can be infected by T. gondii
Ingestion of bradyzoites in P.H., Ingestion of sporulated oocysts, transplacental, transmammary,
Which developmental life cycles of T. gondii can only be found in cats
Schizonts, gametocytes, and oocysts
Which form of infection, Enteroepithelial or Extraintestinal, is more pathological
Extraintestinal
Which body systems are affected by toxoplasmosis
Neuromuscular, respiratory, cardiac, reproductive, ocular
Toxoplasmosis aka “The Great Imitator”
How can you diagnose Toxoplasmosis
Identify oocysts in fecal exam, serological testing for systemic disease (of limited value as you do not know if cat has been recently exposed), IgG and IgM titer tests (IgM means there was a recent infection, IgG means exposure was at least 2-4 weeks ago)
How can you differentiate T. gondii oocysts from Cystoisospora oocysts?
T. gondii oocysts are much smaller (4x smaller)
What drugs are available to treat toxoplasmosis that are FDA approved
none
How can humans be infected by T. gondii
ingestion of undercooked infected meat containing bradyzoites, ingestion of sporulated oocysts from cat feces contamination, organ/blood transfusions containing brady/tachyzoites, transplacental, ingestion of unpasteurized goat milk
True/False: if a woman has an AB titer prior to pregnancy, then the fetus is likely protected if mother is exposed during pregnancy
True
How can a fetus be infected transplacentally
If the mother does not have antibodies to T. gondii and is infected shortly before or during pregnancy
Match the Giardia assemblage to the host: A, B, C, D, F
A & B: Humans, cats, dogs
C & D: Dogs
F: Cats
What kind of life cycle does Giardia spp. have?
What is the PPP?
Direct, 6-8 days (1 week)
Describe the life cycle of Giardia spp.
Ingestion of cyst, trophozoites excyst and attach to intestinal epithelium and undergo binary fission. Move to lower intestines and secrete proteins inside vacuoles around trophozoite surface to form a coat (turn into cysts) and are shed in feces and are immediately infective
How can you diagnose Giardia infection
Can find trophozoites on direct smear of fresh feces, Zinc Sulfate flotation with centrifugation and Lugol’s Iodine stain for cyst recovery, K9 fecal ELISA test
Is the snap test for antibodies or antigens for Giardia? Is the snap test high sensitivity or specificity? What does this tell you about chances for a false positive?
Antigens, sensitivity, no false positives because all the true negatives will test negative
What is your best chance at detecting Giardia in a fecal
Since excretion of Giardia cysts is intermittent, best way to increase chances of finding them is to check fecal multiple times (conduct fecal floats or snap test 3 days in a row)
What treatments are approved by the FDA for Giardia
None
What can you use to treat Giardia, is it on label or off label? What is the critical last step of Giardia treatment?
Fenbendazole, Drontal Plus (contains a fenbendazole precursor - Febantel) , Metronidazole
Bathe animals on last day of treatment to remove infective cysts from coat.
If you have a puppy with diarrhea and you suspect Giardia infection and give metronidazole w/o conducting any diagnostic tests and see diarrhea subside, does that mean that dog had giardia and that it was successfully treated?
Not necessarily, diarrhea could have been due to something else (Giardia does not always cause diarrhea), metronidazole has anti-inflammatory properties and effective for stopping diarrhea so (will firm stool regardless of cause of diarrhea). Pet can also still be infected with Giardia (only diarrhea was treated successfully)
What breed of cats is most commonly associated with Tritrichomonas foetus
Bengal cats
True/False: T, foetus has a life cycle that does not include a cyst stage
True
How is T. foetus transmitted? What other parasite shares this mode of transmission?
Direct fecal-oral contamination with trophozoite (true fecal-oral route), Giardia
Which parasite causes more severe clinical signs: Giardia spp. or Tritrichomonas foetus?
T. foetus
Best way to diagnose T. foetus
Fecal culture and PCR
What is the only known effective treatment for T. foetus infection? Is it FDA approved?
Ronidazole, not approved
Is T. foetus considered zoonotic?
Nope (unless you have aids)
Which of these worms infects cats: Trichuris vulpis, Trichuris campanula, Trichuris serrata
T. campanula, T. serrata
What FDA drugs are approved for Trichuris spp. for dogs
Fenbendazole, Milbemycin Oxime, Moxidectin
Is T. vulpis considered zoonotic
Nope
Which worms/parasites can be treated with Fenbendazole
Trichuris spp., Spirocerca lupi, Physaloptera sp., Ancylostoma spp., Toxocara spp. (dogs only), Baylisascaris procyonis, Strongyloides sp. (off label), taenia spp. (dogs only), Mesocestoides spp. (twice the normal dose 2x day), Heterobilharzia americana, Platynosum fastosum, Giardia sp.,
Which worms/parasites can be treated with Milbemycin oxime
Trichuris spp., Spirocerca lupi, Ancylostoma spp., Toxocara spp.
Which worms/parasites can be treated with Moxidectin
Toxocara spp.,Baylisascaris procyonis, Ancylostoma spp., Trichuris spp.,
Which worms/parasites can be treated with Praziquantel
Tapeworms (D. caninum, Taenia spp., Echinococcus spp., Mesocestoide spp.) False Tapeworms ( Diphylobothrium latum.), Flukes (Alaria spp., Nanophyetus salmincola, Heterobilharzia salmincola, Platynosum fastosum,
Which worms/parasites can be treated with Pyrantel Pamoate
Physaloptera sp., Toxocara spp., Baylisascaris procyonis, Ancylostoma spp.,
Which worms/parasites can be treated with Ivermectin
Physaloptera sp, Toxocara spp (off label)., Baylisascaris procyonis, Ancylostoma spp., Strongyloides sp.,
Which worms/parasites can be treated with Sulfadimethoxine (Albon)
Cystoisospora sp.,
