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155 Cards in this Set
- Front
- Back
What are the major groups of parasites (hint...there are 3)?
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Worms (helminths)
Protozoa Arthropods |
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What are the major parasitic helminth groups of veterinary interest?
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Nematodes (roundworms)
Digenes (flukes) Cestodes (tapeworms) Also acanthocephala, pentastomes |
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A relationship in which one of the participants either harms or lives at the expense of the other is...
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...my first marriage! Wait...I'm in my first marriage! Seriously, it's PARASITISM
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A relationship in which one of the participants benefits without affecting the other is...
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...commensalism
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A relationship which is mutually beneficial to both participants is known as...
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...mutualism
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What factors distinguish a parasite from a predator?
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Size and time of association
(parasites are usually much smaller than their host and have a longer association with them) |
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An organism that can exist on its own or through parasitism is known as a(n) ___________ parasite.
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facultative parasite
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An organism that can only exist via parasitism is known as a(n) _________________ parasite.
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obligate parasite
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A host in which a parasite is incapable of completing its life cycle is a(n) ___________ host.
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Aberrant host
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An abnormal host in which a parasite can complete its development is a(n) _____________ host.
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Accidental (incidental) host
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T or F:
Aberrant hosts are always dead-end hosts. |
True.
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T or F:
Aberrant hosts are not dead-end hosts. |
False! They can be dead-end (parasite can complete development but fails to find a portal of exit)
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Which host contains the sexual stages of a parasite?
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Definitive host
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T or F:
Paratenic hosts are synonymous with intermediate hosts. |
False! Parasite development occurs within an intermediate host but NO DEVELOPMENT occurs in a paratenic host
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Which life cycle strategy describes a parasite that only requires one host to complete its life cycle?
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Direct (monoxenous) parasite
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In which host type does no parasitic development occur?
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Paratenic (transport) hosts
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Which life cycle strategy describes a parasite that requires more than one host to complete its life cycle?
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Indirect (heteroxenous) parasite
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Latin for egg layer is...
Latin for live bearers is... |
oviparous
viviparous |
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Embryos in "eggs" with no maternal nutrition; larvae born alive describes...
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...ovoviviparity
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a parasite of a parasite is called...
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...a hyperparasite (I tried to find a witty answer for this one but came up short)
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A parasite that can have many definitive hosts has ________ host specificity. Conversely, a parasite with only one definitive host has _______ host specificity.
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Broad/narrow host specificity
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A wild animal that harbors parasitic infection before transmission to domestic animals is a __________ host.
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Reservoir host
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Resistance to parasitic infection that is established after an acute infection has become chronic is known as_____________.
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Premunition
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What is another name for developmental arrest?
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Hypobiosis
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What is a nematode family that undergoes hypobiosis? Why would it do such a thing?
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Strongyles
strategy - "overwinters" as L4 in host; allows for lots of infective larvae in the spring (lambing time)! |
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T or F:
Nematodes are second only to the insects in terms of diversity. |
True, yo!
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Generically characterize nematodes in terms of their:
sexes morphological elaboration "skeleton" |
dioceious sexes
morphological elaboration around openings hydrostatic skeleton |
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Which letter(s) denote the Leaf Crown?
Which denote the Alae? How 'bout the vesicles? |
Leaf Crown - B
Alae - E Cephalic Vesicle - A Cervical Vesicle - C |
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What is nematode-induced tissue damage proportional to (and it is NOT the number of parasites)?
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The mouth size
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What are these doodads? Is this a male or female?
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Male!
A = spicules B = copulatory bursa |
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What helmenthic GI structure is often used as an initial screener for identification?
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Esophagus shape
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Let's do some matching...
Embryonated egg Unembryonated egg Embryonating egg |
Embryonated egg - C
Unembryonated egg - B Embryonating egg - A |
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Fill in the blanks for nematode development:
egg-->__-->__-->__-->__-->adult |
egg>L1>L2>L->L3>L4>adult
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Another name for a nematode molt is...
What is shed in the molt? |
ecdysis
Cuticle is shed |
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T or F:
Adult strongyles cause the most damage to the host. |
False! Larval migrans (L3/L4) do the most damage.
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What are three signs seen in a helminth infection?
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Impaired weight gain
Impaired food conversion Reduced fitness |
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What are the 6 orders of nematoda that are of veterinary importance?
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Rhabditida
Strongylida Ascaridida Oxyurida Spirurida Enoplodida |
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Which group are the pinworms in?
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Oxyurids
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Oxyurids are also known as...
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pinworms!
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What order do the hookworms and hairworms share?
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Strongylida
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Which worms are in the order Strongylida (there are 3 main groups)?
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Hairworms (trichostrongyloidea)
Hookworms (ancylostomatidae) Strongyles (strongylidae) |
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In which order are the lungworms found?
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Strongylida
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Big-ass roundworms are better known as...
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Ascarids
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Which nematode order uses invertebrates as vectors and intermediate hosts?
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Spirurida (spirurids and filarial worms)
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Heartworms are found within which nematode order?
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Spirurida
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Aw snap! Grampa got trichinosis! Tell him which nematode order trichinella is found in?
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Enoplodida
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What kind of nematode is depicted here?
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Pinworm (Oxyuridae)
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Which region of the GI tract do oxyurids (pinworms) inhabit?
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Lower intestine
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What is unique about pinworms?
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Only nematode that migrates out of the host to lay eggs (lays them around uranus); also pretty much the ONLY nematode with the entire life cycle within the GI tract
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How long does it take eggs from Oxyuris equi to become infective? How long is the prepatency time?
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4-5d before eggs are embryonate and infectious
Prepatency time (time b4 adults lay eggs) is ~5months |
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How is Oxyuris equi treated?
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Ivermectin or pyrantel
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Besides horses, what are other important hosts for pinworm infection?
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Rabbits
lab rodents |
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ID this nematode, fool!
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Oxyurid (pin worm)
Check the esophageal bulb and long clear tail |
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What is the MOST IMPORTANT genus in Trichostrongylidae (hair worms)? What do they infect in the NW?
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Haemonchus infects sheep, cattle, goats, and llamas
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Which nematode family (not order) is responsible for parasitic gastroenteritis?
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Hairworms (trichostrongylidae)
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What are some characteristics of hairworms (trichostrongylidae)?
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Small
Absent (or reduced) leaf crowns Absent (or reduced) buccal capsule Well-developed bursa |
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Which larval stage is ingested in the hairworm (trichostrongylid) life cycle?
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L3
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T or F:
Trichostrongylid (hairworm) hyperinfection is not an issue in free-range cattle. |
True! Confinement causes hyperinfection.
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The "spring rise" or increased concentration of fecal eggs per gram is an example of what parasite strategy?
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Hypobiosis
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Which genera of trichostrongylidae are the most important to veterinary medicine?
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Haemonchus
Ostertagia Trichostrongylus Nematodirus |
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Do barber pole worms (Haemonchus spp.) have a long or short prepatency period?
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Short (2-3 wks)
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About how long do Haemonchus larvae remain infective in the pasture?
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Up to 6 months
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Where do Haemonchus infections usually manifest in ruminants?
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Abomasum
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What structures give Haemonchus the "barber pole" appearance?
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White gonads twisted around blood-containing gut
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How do Haemonchus (barber pole worms) cause so much tissue damage (hint - it is something to do with their mouth)?
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SMALL mouth but has a lancet that slices away tissue
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What are some signs of trichostrongyle infection?
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Edema (bottlejaw)
Anemia Lethargy Weight loss and death |
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What is the parasitic "wonder drug"?
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Ivermectin
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What are some management practices that will cause parasite resistance?
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Treating all animals at once
Treating frequently Underdosing Treating when few larvae on pasture Treating then moving to clean pasture |
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What are two systems used to prevent parasite resistance?
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Drenchrite system
FAMACHA system (form of selective treatment) |
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T or F:
Treating the 33% most affected individuals of the herd is more effective than treating the entire herd for parasites. |
True!
Since 20-30% of the animals harbor most of the worms, this kills the virulent worms AND prevents resistance! |
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T or F:
Killing organisms in refugia is an important aspect of reducing antihelmenthic resistance. |
False!
Organisms in refugia shouldn't be killed as they increase genetic diversity and reduce resistance. |
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How do sheep become infected with Haemonchus?
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Eat larvae with grass
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What is the most important strongyle of cattle?
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Ostertagia ostertagia
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What is the most important strongyle of sheep and goats?
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Teladorsagia spp.
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How does Ostertagia ostertagia cause disease in cattle?
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Encysted larvae cause disease (tissue reactions to worm = hyperplastic response and inflammation)
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Why does Ostertagia cause disease in young and adult cattle (or why/when are young and adult cattle susceptible to disease)?
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Young - immunological naive
Adult - if experiencing stress (pregnancy, shipping, etc), hypobiotic larvae emerge |
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What is the proportion of the parasite population that is not selected by drug treatment?
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In refuga population
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T or F:
Trichostrongylus spp.only infect the small intestine. |
False!
MOST infect the small intestine but T. axei infects the abomasum. |
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Which of the Trichostrongylus spp. co-infects sheep and cattle? Where does the infection occur?
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T. axei; infects the abomasum
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Which of the trichostrongyles has a ridiculously large egg?
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Nematodirus
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What is unique about Nematodirus among the rest of the trichostrongyles?
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Nematodirus has a ginormous egg; hatches as an L3
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A state of resistance to infection that is established after an acute parasitic infection has become chronic and persists throughout the life of the organism is known as....
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...PREMUNITION
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Which family of Strongylida comprises the hookworms?
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Ancylostomatidae
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Which region of the GI to hookworms parasitize? What are common hosts?
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small intestine of dogs, cats, sheep, cattle, humans
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What are some morphological characteristics of ancylostomitidae?
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HOOKED DORSALLY
Big teeth! Presence of spicules on male posterior No leaf crowns |
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What is the key genus of the hookworms?
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Ancylostoma
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Which hookworms are key parasites of dogs? Of cats?
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Ancylostoma caninum (dogs)
Uncinaria stenocephala (cats and dogs) A. tubaeformae (cats) |
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Which hookworms are key parasites of sheep? Of cattle?
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Bunostonum trigonocephalum (sheep)
B. phlebotomum (cattle) |
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What are some transmission strategies used by hookworms?
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transmammary
transplacental transdermal oral ingestion (direct and by paratenic host) |
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Regarding Ancylostoma caninum, what is the route taken by L3 larvae after transdermal transmission?
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skin > circulation > lungs > alveoli > trachea > swallowed by host > to GI
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T or F:
Ancylostoma caninum undergo arrested development in the muscle as L4 larvae. |
False! They arrest at L3
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What pathologies are common with Ancylostomatid infection?
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Anemia
weakness, poor growth Malena emaciation pale gums dull haircoat death |
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What is the treatment protocol for hookworm infections in dogs?
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Ivermectin + pyrantel
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Which of the two common hookworms of dogs is the most pathogenic? Why is the other one not as pathogenic?
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Ancylostoma caninum (most pathogenic)
Uncinaria stenocephala (least pathogenic due to lack of teeth; does less damage) |
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T or F:
Infection with Uncinaria stenocephala frequently occurs transdermally. |
False! It is usually oral!
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T or F:
Infection by Bunostomum spp. (hookworm) in sheep and cattle frequently occurs transdermally. |
True! Rarely orally
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Which family of Strongylida comprises the "large strongyles"?
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Family Strongylidae
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What are the 3 most important species of large strongyles in horses?
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Strongylus vulgaris
S. endatus S. equinus |
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T or F:
Strongylus vulgaris has similarities to Nematodirus in that it is ingested as an L3. |
True!
Nearly all Strongylids are ingested at the L3 stage. However, Nematodirus HATCHES as L3 while S. vulgaris hatches as L1. |
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Describe the migration of S. vulgaris after ingestion.
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1. Ingestion
2. Penetrates duodenal submucosal arteries and molts to L4 3. L4 migrate to cranial mesenteric a. 4. develop 3-4 mos. into L5 5. return to intestinal wall via arteries (cecum and large int) 6. nodules form and rupture, releasing adults into intestinal lumen |
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T or F:
Strongylus vulgaris has a very short prepatency period. |
FALSE
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Contrast Strongylus vulgaris and S. edentatus in terms of migration of L3.
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S. vulgaris - L3 migrates to cranial mesenteric a.
S. edentatus - L3 migrates to liver |
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What circulatory lesion is closely associated with Strongylus vulgaris?
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Verminous arteritis
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Which group is known as the "small strongyles"?
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Cyathostomes
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What are the main morphological differences between the large and small strongyles?
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Large strongyles have large, well developed buccal capsules and attach to mucosa
Small strongyles have smaller buccal capsules and do not attach to the mucosa |
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What is (currently) the most important internal parasite of horses?
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Chathostomes (small strongyles of the horse)
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Compare/contrast the general life cycle of small and large strongyles in the horse.
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Both are released as eggs, hatch into L1 and are ingested as L3. However, small strongyles don't migrate farther than the wall of the intestine.
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What event creates the clinical signs associated with cyathostomatitis?
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simultaneous emergence of encysted L4 from the intestinal wall
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Which has the longer prepatency, small or large strongyles?
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large strongyles
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When are the highest periods of risk from cyathostomatitis?
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spring and fall
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When should animals be treated to prevent heavy pasture contamination of cyathostomes?
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early in the grazing season (spring and early summer)
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T or F:
Small strongyles and large strongyles can both be effectively diagnosed by fecal egg counts. |
False!
Large strongyles can but not small due to encysted (hypobiotic) larvae |
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What can be used to treat small strongyles?
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Not a lot:
Fenbendazole is best but has resistance issues Moxidectin works OK Vitamin I and Pyrantel - don't even bother! |
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Which group of strongyles infects cattle, sheep, and goats in the tropics?
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Oesophagostomum spp.
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Which worm is the "nodule worm"?
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Oesophagostomum
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What is the superior technique for counting trichostrongylid eggs?
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McMaster's technique
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Which is also known as a rhabditid? Strongyles or strongyloids?
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Strongyloids
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T or F:
Nearly all rhabditids are parasitic |
False! Only one genus is! Strongyloides
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What is an interesting feature of the strongyloid life cycle?
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It can be entirely free-living, entirely parasitic, or a mixture of the two
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T or F:
All strongyloid (rhabditid) larvae are capable of transdermal penetration. |
False.
Only the filariform larvae |
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T or F:
Both Ancylostomes (hookworms) and Strongyloids (rhabditids) undergo a tracheal migration after transdermal penetration. |
True!
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T or F:
The only Ancylostome (hookworm) adults found in the intestinal lumen are female. |
False!
This describes the Strongyloids (rhabditids) |
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What are the two main ways that rhabditids (strongyloids) infect their host?
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Transdermal penetration
Autoinfection (larval penetration of intestinal mucosa after hatching in lumen) |
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What are the four major species of rhabditids and what species does each infect?
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Strongyloides westeri – horses
S. stercoralis – dogs, humans S. ransomi – swine S. papillosus – ruminants, rabbits |
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Which antihelmenthics are effective against Strongyloides (rhabditids)?
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Vitamin I (Ivermectin)
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Why are lungworms called lungworms?
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If you have to ask, you'll never know. DUH! Because the adults infect the LUNGS!
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T or F:
Lungworms are a superfamily of order Strongylida. |
True
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What is the major lungworm of cattle? Which larval form is ingested?
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Dictyocaulus viviparus; L3 is ingested
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How are Dictyocaulus larvae spread?
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Via pilobolus fungi
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T or F:
Cattle lungworm infection is diagnosed by identification of eggs in feces. |
False!
Larvae (L1) are found in the feces; need to use Baermann funnel test |
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How is Dictyocaulus treated?
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Most antihelmenthics work well
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How does the life cycle of the sheep lungworm Muellerius capillaries differ from dictyocaulus?
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Uses slugs/snails as intermediate host
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How does the life cycle of the swine lungworm Metastrongylus differ from dictyocaulus?
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Uses earthworms as intermediate host
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T or F:
Cats commonly contract lungworms by eating the intermediate hosts of Aelurostrongylus abstrusus. |
False!
Slugs/snails are the intermediate hosts and mice/voles are the PARATENIC hosts |
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What is unique about the life cycle the dog lungworm, Filaroides?
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L1 larvae are INFECTIVE
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What are the hosts of Oesophagostomum spp? (circle the letter of your choice)
A .Cattle and sheep B. Cattle, sheep, pigs C. Cattle only D. Sheep only |
B. Cattle, sheep, pigs (also goats)
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What stage/s are parasitic in Strongyloides spp. infections?
i.e., what stages would you find inside/infecting the host? |
All stages except that adult is only female
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What is the cause of cutaneous larval migrans in humans?
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Hookworm
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What is premonition?
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When an acutely parasitized organism develops a degree of resistance after the parasitism becomes chronic
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What is the diagnostic stage of lung worms and where would you find this stage?
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Baermann technique, fecal float, tracheal wash/sputum
has eggs or L1 |
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What are some morphological characteristics of Ascaridae?
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3 lips
large and white roundworms no bursa on males they make your butt look ugly |
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T or F:
Ascarids have infectious eggs. |
True! They hatch as L2 or L3 after egg is ingested.
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Why are ascarids tough to get rid of?
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Sticky eggs
Eggs are tough to kill (thick shell) Larvae develop to L2 or L3 in eggs |
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T or F:
Ascarids undergo tracheal migration. |
True! Even though they don't penetrate the skin (a la Rhabditids or Ancylostomids), they undergo tracheal migration after penetrating the intestinal mucosa
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What lesions are caused by Ascirus suum that will condemn pig livers? How are these lesions formed?
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Milk spot liver from ascarid larval migrans
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T or F:
Normal ascarid infection does not manifest with anemia. |
True! Ascarids eat the host food, not the host!
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What is the ascarid that infects humans? Horses?
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Ascaris lumbroides
A. equorum |
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T or F:
Older horses are immune to Ascaris infection. |
True! Once they are >2yo, they have immunity.
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What are some management strategies that can prevent ascarid infection in foals?
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pick up manure
feed off the ground use ivermectin/pyrantel for adult roundworms deworm all horses stabled together at once (???) |
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Ascarid infection of which domestic animal may have acetone (fruity) breath as a sign?
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Cattle infected by Toxocara vitulorum
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Which ascarid is a zoonotic agent? How is it most likely transmitted?
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Bayliascaris procyon (raccoon ascarid) transmitted via direct infection of dogs
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T or F:
Toxascaris leonina exhibits no tracheal migration in either dogs or cats. |
True!
Larvae are eaten either directly or within paratenic host (rodent), undergo period of histotrophy, then enter intestinal lumen. |
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Yuk! Your damn cat puked a worm on my shoes! What kind of worm is it likely to be?
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Toxocara cati
Frequently vomited; have arrowhead cephalic region |
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These ascarids are parasites of marine mammals and birds...
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Survey says....
ANISAKIDAE |
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What are the intermediate hosts of anisakids? What is the definitive host? What is a dead-end host?
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Intermediate - crustaceans and fish
Definitive - sea mammals and birds Dead-end - Humans |