Parasitology In-Class Questions
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80 Terms
For the purpose of this class, what is our definition of a parasite?
An organism that is metabolically depedent and survives at the measureable expense of another organism.
3 multiple choice options
How do hookworms cause disease in their host?
Suck blood voraciously and cause varying degrees of anemia.
3 multiple choice options
A 10-day-old puppy presented at a clinic with pale mucous membranes, marked weakness, and bloody diarrhea. A presumptive diagnosis of hookworm infection was made although the subsequent fecal examination was negative. What is the most likely explanation for a negative fecal exam?
Sexually immature worms are voracious blood suckers and not yet passing eggs
3 multiple choice options
This 6-month old canine was presented at your clinic with pale mucous membranes and an associated packed cell volume of 24%. The presumptive diagnosis was hookworm anemia. What is the clinical interpretation for this case?
Acute disease
3 multiple choice options
How is a Paratenic host different than an Intermediate host?
It is a host where the larval parasite does not undergo any development
3 multiple choice options
These eggs were found on the fecal flotation of a 15 week old puppy. They measure approximately 60 x 40 µm. What is your diagnosis?
Ancylostoma caninum
3 multiple choice options
These eggs were found on the fecal flotation of a 2 week old puppy. They measure approximately 60 x 40um. How was the puppy infected?
Ingestion of infective larvae in mother's milk.
3 multiple choice options
These eggs were found on a fecal flotation of a 9-week-old Miniature Schnauzer puppy presenting for its vaccinations and an initial physical examination. They measure approximately 85µm in diameter. What is the diagnosis?
Toxocara canis
3 multiple choice options
These eggs were found on a fecal flotation of a 9-week-old Miniature Schnauzer puppy presenting for its vaccinations and an initial physical examination. They measure approximately 85µm in diameter. How was the puppy infected?
Transplacental transmission of infective larvae in the mother's tissues
3 multiple choice options
Why is it recommended to deworm puppies with presumed Toxocarasis at 2, 4, 6 and 8 weeks of age?
Immature worms do not complete sexual maturation, reproduce, and contaminate the environment.
3 multiple choice options
A 12-week-old puppy presents with pot-bellied appearance, and hair coat with dried vomit and diarrhea. A presumptive diagnosis of Toxocara canis is made. How does this parasite cause disease?
Mechanical damage in the lungs leads to pneumonia, irritation in the gut leads to ADR, vomiting and diarrhea.
3 multiple choice options
A 14-week-old Yorkshire Terrier presented with a cough of a 3 days duration and fluid diarrhea. Larvae observed on Baermann fecal exam. What is your diagnosis?
Strongyloides stercoralis
3 multiple choice options
A 2-year-old Domestic Shorthair feline presents at your clinic. The owner frantically reports that her cat has recently exhibited coughing-gagging behavior. Her cat vomited up robust worms like these. What is your diagnosis?
Toxocara cati
3 multiple choice options
What are these red worms found at necropsy in the fibrous nodules in the aorta of a dog from St. Kitt's?
Spirocerca lupi
3 multiple choice options
These eggs were found on the fecal flotation of a 5-year-old mixed breed hound. They measure approximately 90x40µm. What clinical signs are characteristically associated with dogs experiencing disease produced by this parasite?
Fluid diarrhea with mucous and low sodium/high potassium ratio
3 multiple choice options
Why are clinical signs associated with Trichuris infection in dogs often referred to as "Pseudo-Addison's Disease"?
Both diseases are characterized by electrolyte imbalance with low sodium/high potassium ratio.
3 multiple choice options
A puppy presents with cough and diarrhea. Lab work supports a diagnosis of Strongyloides. How does the lifecycle biology facilitate production of significant disease?
Parasitic females accumulate significant worm burdens by autoinfection.
3 multiple choice options
What label is used to describe the clinical condition affecting the boy's right eye in the picture? (Opaque blue eye)
Ocular larval migrans
3 multiple choice options
Physaloptera sp. is a worm found in the stomach of dogs and cats associated with gastritis. How are these animals infected?
Ingestion of a grasshopper (Order Orthoptera) serving as intermediate host
3 multiple choice options
An adult female Rottweiler presents at the clinic with a history of intermittent vomiting, watery brown diarrhea with mucus and red flecks of blood. Blood chemistry indicates electrolyte imbalance with low sodium and high potassium. What parasite should be high on the differential diagnosis?
Trichuris vulpis
3 multiple choice options
The eggs in the accompanying image measure approximately 65µm. What parasitic species are they likely to be confused with?
Trichuris vulpis
3 multiple choice options
This aneurysm in the cranial mesenteric was associated with the necropsy of a 6-month-old foal. What is your diagnosis?
Strongylus vulgaris
3 multiple choice options
What are the red worms seen in this fecal sample from a 2-year-old mare?
Immature small strongyles worms that have recently emerged from the colonic wall
3 multiple choice options
Identify the parasites encysted in the colonic wall of this recently necropsied foal?
Small Strongyles
3 multiple choice options
A 20-week-old foal presents at your clinic with severe impaction colic. Large robust worms were encountered during the emergency surgery to remove the impaction. What is your diagnosis?
Parascaris equorum
3 multiple choice options
What are the clinical signs associated with Type I Ostertagiasis?
Profuse watery diarrhea from damage to the gastric glands and mucosa, large worm burdens, and positive fecal exam.
3 multiple choice options
What are the characteristic clinical signs associated with Type 2 Ostertagiasis?
Profuse watery diarrhea and damage to gastric glands from mass emergence of hypobiotic larvae and negative fecal examinations
3 multiple choice options
A 2-year-old heifer is presented for necropsy. She has stunted growth with 3 week histroy of poor appetite, unthriftyness and diarrhea. The abomasum is edematous with small umbilicated nodules 1-2mm in diameter (cobblestone or Moroccan leather appearance). Other younger "2nd season on pasture cows" show similar signs and have diarrhea too. What parasite is involved?
Ostertagia ostertagi
3 multiple choice options
The sheep in this flock were effectively treated during the season (Jun-Nov) each time their FAMACHA score was ≥ 3. Which portion of the flock was infected with the greatest % of worms in refugia?
Gray circle
2 multiple choice options
The sheep in this flock were effectively treated during the season (Jun-Nov) each time their FAMACHA score was ≥ 3. Which portion of the flock was infected with the least % of worms in refugia?
Blue and orange circles
1 multiple choice option
Trichinella infections have been historically identified with consumption of poorly cooked pork. What recent trend has been influential with decreased risk of human infection?
Total confinement-based production systems and reduced exposure to infective parasites have resulted in a safe food commodity
3 multiple choice options
What is meant by maximizing refugia in the context of preventing the emergence of drug resistance in a population of parasites?
Parasitic worms that are not subjected to drug selection pressure and able to reproduce freely
3 multiple choice options
Larvae that look like this were found on a Baermann exam of a fecal sample from a yorkie presenting with a chronic cough aggravated by cold air. What are they?
First stage larvae from Filaroides sp.
3 multiple choice options
A 2-year-old poodle mix presents with a chronic dry cough. The owner believes it is worse on mornings when the air is cooler. Larvae that look like these were found on the fecal examination. What are they?
Filaroides sp.
2 multiple choice options
An 8-week-old Cocker mix presents with a chronic cough. Larvae that look like these found on the fecal examination. How was the puppy infected?
Ingestion of regurgitated content from mother
3 multiple choice options
A 2-year-old poodle mix presents with a chronic dry cough. The owner believes it is worse on mornings when the air is cooler. Bronchoscopy reveals nodules in the trachea and bronchi that looks like this. What parasite is implicated?
Filaroides osleri
3 multiple choice options
The eggs in the accompanying image were seen on the fecal flotation of a beagle with occasional sneezing. The eggs measure approximately 65µm. What is the diagnosis?
Capillaria (Eucoleus) bohemi
3 multiple choice options
What is the most important factor driving transmission of Canine Heartworm Disease?
The occurence of microfilaremic hosts in the area
3 multiple choice options
The organism in the accompanying image was seen on the blood examination of a 3-year-old mixed breed canine with dyspnea and exercise intolerance. It is approximately 300µm in length. What is the diagnosis?
Dirofilaria immitis
3 multiple choice options
What is the most likely post-treatment complication in a dog following the successful elimination of heartworms with appropriate chemotherapy?
Thromboembolism
3 multiple choice options
Canine heartworm disease (CHWD) is prevented by the monthly administration of prophylactic drugs classified as macrocyclic lactones (Ivermectin, Milbemycin, and Moxidectin). What is the best explanation for how these drugs prevent CHWD?
The drugs kill all infective larvae acquired in the 30-day period prior to the monthly treatment
3 multiple choice options
A patient is identified as CHW positive with a reputable antigen detection assay. Which population tested is associated with the highest positive predictive value?
Dogs receiving prophylaxis but showing clinical signs suggestive of CHWD
3 multiple choice options
What role do microfilariae play in the heartworm lifecycle?
They are embryonic stage larvae and must develop in mosquitoes before becoming infective to canine hosts
3 multiple choice options
Why is it appropriate to check for microfilariae following diagnosis of Canine Heartworm infection with antigen detection?
Killing microfilariae in the blood can lead to anaphylactic shock when the dog is placed on a preventive compound
3 multiple choice options
Microfilariae that look like these (300µm long) were found in the blood of an adult beagle. What is their clinical significance?
They are embryonic stage larvae and must develop in mosquitoes before they are infective to canine hosts.
3 multiple choice options
Are cats a competent reservoir for maintaining heartworm in other canine and feline host populations?
No, heartworm in cats are primarily single sex infections and rarely microfilaremic
3 multiple choice options
How many feeding opportunities are required for Dermacentor to complete its lifecycle?
Three
3 multiple choice options
Among 3 host tick species, which stage is more likely to be associated with transmission of an infectious disease?
Nymph
3 multiple choice options
Why is duration of tick feeding time a critical variable for explaining the likelihood of infectious disease transmission?
Ticks feedings and or > 72 hours demonstrate the highest probability of transmission
3 multiple choice options
This dog with a petechial rash on the abdomen presumptively indentified as RMSF was presented for spay at a rural health clinic. What tick vector is the likely culprit?
Dermacentor varriabilis
3 multiple choice options
A backyard chicken is presented for laying less eggs than normal and listless behavior. Tiny blackish brown specks are seen moving around the hen's vent. What is your best guess?
Ornithonyssus sylviarum (Northern Fowl Mite)
3 multiple choice options
A dog presents with an erythematous "red" mange showing hair loss around the eyes and boney projections of the body. What parasite mite should be high on your differential?
Demodex canis
3 multiple choice options
A 10-year-old female/spayed Scottish Terrier presents with excessive flaking dermatitis. A parasite was isolated off of the dog, what is it?
Cheyletiella spp.
3 multiple choice options
These organisms were observed emerging from a lesion on the withers of a horse imported from Argentina, commonly referred to as screwworms. What is their proper scientific name?
Cochliomyia hominivorax
3 multiple choice options
Flies that look like this pinned specimen were seen buzzing around the legs and throat of the pastured horses at the DVTC. What stage(s) is parasitic?
Larval stages in stomach
3 multiple choice options
Flies that look like this resting specimen were seen buzzing around the pastured horses at the DVTC. What stage is parasitic?
Adult flies buzzing the horses
3 multiple choice options
Eggs that look like this were found on the fecal flotation of a beagle with persistent flea infestation. How was the beagle infected?
Ingestion of a metacestode in infected vertebrate intermediate host
3 multiple choice options
How do people and other mammalian intermediate hosts acquire the disease "hydatidosis" produced by the tapeworm Echinoccous granulosis?
Ingestion of eggs passed in the feces of an infected canine
3 multiple choice options
Will Dr. Faulkner become infected with the "hydatid tapeworm" if he ate this cyst dissected from a GSMNP Elk at necropsy?
No, he will be neither a DH or IH from eating the cysts, and it is really disgusting and he will likely get sick/nauseous.
2 multiple choice options
Will Dr. Faulkner become infected with the "hydatid tapeworm" if he accidentally ingests these eggs vectored in the fur of his pet dog?
Yes, he will likely have the cyst growing in him and be a source of infection (intermediate host) for dogs that feed on his dead body.
3 multiple choice options
Why doesn't ivermectin work for treating tapeworms?
Tapeworm parasites do not have glutamate-gated chloride channels or GABA receptors
3 multiple choice options
Why doesn't Moxidectin work for treating tapeworms?
Tapeworm parasites do not have glutamate-gated chloride channels or GABA receptors
3 multiple choice options
But it was stated that Quest Plus is good for equine tapeworms, why is it effective?
It's a combo product formulated with a macrocyclic lactone (moxidectin) and praziquantel
3 multiple choice options
How is the intermediate host for a tapeworm species infected?
By ingestion of eggs passed in the feces of an infected host
3 multiple choice options
Neurocysticercosis is an significant zoonotic disease resulting from infection with the Pork Tapeworm (Taenia solium). How do humans acquire the disease?
Ingestion of pork tapeworm eggs by the fecal oral route
3 multiple choice options
What tapeworm of horses is associated with a x26 times risk of colic?
Anoplocephala perfoliata
3 multiple choice options
What trematode parasite is known as the "Salmon Poisoning Fluke"?
Nanophytes
3 multiple choice options
Eggs that look like this were found on a fecal flotation of a dog presenting with hemorrhagic enteritis and other signs similar to canine parvovirus. What etiologic agent is responsible for the clinical signs?
Neorickettsia helminthoeca
3 multiple choice options
This worm was found in the small intestine of a pig raised on a pastured wood-lot in Bell County, Kentucky. What is it?
Thorny-headed worm (Macroacanthorynchus hirudinaceus)
3 multiple choice options
Penny is a rehomed beagle bred and adopted from a USDA supplier of lab animal subjects. These structures about 15 micrometers were observed on a recent flotation examination. What parasite is involved?
Giardia sp.
3 multiple choice options
How was Penny (the beagle) infected?
Ingestion of infective cysts in the environment
3 multiple choice options
Should owners be worried about zoonotic transmission of Penny's giardia?
All of the above
3 multiple choice options
A cattle producer has requested services to investigate an apparent pattern of infertility in his 15 to 18 month old heifers. The animals were bred by AI and covered with a neighbor's "new" Angus bull. What parasitic differential should be at the top of the list?
Bovine Trichomoniasis
3 multiple choice options
A cattle producer has requested services to investigate an apparent pattern of infertility in his 15 to 18 month old heifers. The animals were bred by AI and covered with a neighbor's "new" Angus bull. What diagnostic strategy will you recommend?
Culture and PCR examination of semen sample from AI straw and neighbor's bull.
3 multiple choice options
A 2-week-old calf is presented that is dehydrated and almost emaciated from weight loss. She has a 1-week history of watery, foamy diarrhea and exhibits tenesmus during examination. The calf is the only sick one in a mixed group of calves that range from 3 weeks to 2 months of age. What is the diagnosis?
Cryptosporidiosis
3 multiple choice options
A female veterinarian is pregnant and her physician tests her serologically for toxoplasmosis. Her IgM titer is negative, but her IgG titer is positive. What is the most appropriate interpretation for these results?
Both mother and baby are safe
3 multiple choice options
A herd of ewes has had an abortion storm in which 80% of animals are affected. All stages of gestation are affected, and lambs that are born are very weak. On the placentas, cotyledons have white foci of necrosis. Which one of the following choices is the primary differential diagnosis?
Toxoplasma gondii
3 multiple choice options
A client visiting your practice is pregnant. She has been advised to surrender her cat because of the risk of Toxoplasmosis. What do you advise?
Clean the litterbox daily as a precaution to remove oocysts. Cook meat well, and wash fruits and vegetables.
3 multiple choice options
These oocysts, measuring 10µm, were found on the fecal flotation of a sneezing kitten. What is the public health significance of this finding?
The oocysts are likely Toxoplasma gondii and have zoonotic potential when sporulated
3 multiple choice options
A 6-year-old cat recently presented icteric with pale mucous membranes and dehydrated. The owner reported that the cat had gone missing for the last couple of days. What parasite should be high on your differential diagnosis?
Cytauxzoon felis
3 multiple choice options
