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VetTech Parasitology
Diagnostic Parasitology for Veterinary Technicians
| Question | Answer |
|---|---|
| Name the 5 types of symbiotic relationships: | predator-prey, phoresis, mutualism, commensalism, parasitism. |
| Describe the phoresis relationship: | When the smaller member is mechanically carried about by the larger member. ex: Bacterium |
| Describe the commensalism relationship: | An association where one symbiont benefits and the other neither benefits nor is harmed. |
| What is the difference between parasitiasis and parasitosis? | Parasitiasis = parasite is present on or within the host and potentially pathogenic but host DOES NOT exhibit outward clinical signs of disease. Parasitosis = parasite is present and host DOES exhibit obvious signs of parasitism. |
| What is an incidental parasite? | A parasite found in a host that it does not normally live in. Ex: D. immitus (canine heartworm) in a human. |
| What is the difference between a definitive host and an intermediate hose? | Definitive = harbors adult, sexual or mature stages of a parasite Intermediate = harbors larval, juvenile or asexual stages of a parasite. |
| What is a zoonosis? | Any disease or parasite that is transmissible from animals to humans. |
| List the categories in the Linnaean classification scheme: | Kingdom, Phylum, Class, Order, Family Genus, Species Mnemonically: King Phillip Came Over For Good Spaghetti |
| Name the 5 Eukaryota kingdoms: | Plantae, Animalia, Protista, Monera, Fungi |
| The term: Metazoan means: | Multi-cellular organisms. |
| What is the difference between oviparous and ovoviviparous? | Oviparous: Eggs produced by this type contain a single-cell stage Ovoviviparous: Eggs produced by this type contain a first-stage larva within the eggshell |
| A nematode is also known as a: | Roundworm |
| A trematode is also known as a: | Fluke |
| A cestode is also known as a: | Tapeworm |
| Describe an ascaroid type egg: | An egg with a single-cell stage within the eggshell. Round, thick, visible membrane with one cell inside. |
| Describe a trichostrongyle type egg: | An egg with a morula stage within the eggshell - i.e. many cells resulting from division of a fertilized ovum. Oval, thin, visible cell wall. |
| Describe a spiruroid type egg: | An egg containing a first-stage larva within the eggshell. Oval, thick walled membrane. |
| Describe a trichinelloid type egg: | An egg with a single-cell stage within the eggshell. Oval shaped with two "polar plugs" at the end. |
| Describe the external morphology of a nematode (roundworm): | Covered by a thin cuticle formed by it's hypodermis. Expansions seen at the anterior end are called cervical alae; posterior of some males is called the copulatory bursa used during mating. Spindle-shaped Muscles line the body cavity and help it move. |
| Describe the life-cycle of a nematode (roundworm): | Adult makes single-cell egg > cells divide to morula > evolves to tadpole > develops to 1st-stage in eggshell > Larva hatches, molts, develops to 2nd-stage > 3rd-stage infective larva. In definitive host, 4th & 5th stage > migrates & matures > mates |
| This parasite is often referred to as "spaghetti-like" in appearance. | Adult ascarid: T. canis, T. cati (Toxocara) |
| What is a vermifuge? | Anthelmintic that paralyzes a parasite so it passes via feces (ex. pyrantel) |
| Give examples of zoonotic nematodes: | Physaloptera (stomach worms), Toxocara canis, Baylisascaris procyonis (racoon), Ancylostoma (hookworm), Strongyloides stercoralis (threadworm), Dirofilarioa immitus (heartworm) |
| Define an Obligatory parasite: | A parasite that’s not capable of leading a free-living existence; it must be associated with a host to survive. |
| What is the Baermann technique? | Used primarily to recover lungworm larvae from feces. Warm water stimulates larvae to move out of the fecal sample for observation. |
| What is the modified Knott technique? | Used to identify the presence of microfilaria and to distinguish between D. immitis and A. reconditum based on unique characteristics of each. |
| What characteristics of feces should be recorded? | consistency, color, blood, mucus, age, gross parasites |
| When is fecal sedimentation primarily used? | To detect eggs or cysts whose specific gravity are too high to float or when a flotation solution may severely distort the egg/cyst |
| What is the best method for identifying trophozoites in feces? | Fecal smear diluted w/physiologic saline. Watching the unique movement and shape can help positively identify which protozoan is present. |
| How should parasite specimens be shipped to the lab? | In 70% ethyl alcohol or 10% formalin to render it noninfectious. Jars should be sealed tightly to prevent leaks and ample padding included to prevent breakage/damage. |
| What is the Baermann technique used for? | Recovering roundworm larvae from feces/soil/animal tissues. Warm water is placed over top of the sample and coaxes the larvae out into the water which can be collected and examined. |
| What is the primary disadvantage of the direct smear technique? | The sample size is very small and may not include any parasites unless they are present in very large numbers. |
| If lungworms are suspected, which diagnostic technique should be used and why? | Baermann technique because lungworms rely on fecal transmission for their larvae/eggs. They are coughed up, swallowed and passed through GI. |
| How is a skin scraping performed? | w/a No. 10 scalpel blade held perpendicular to the skin. The scraping area should be 6 - 8cm squared. Debris on the blade is spread in a drop of mineral oil on a microscope slide for examination. |
| Which flotation medium is best for concentrating cystic stages of Giardia? | Zinc sulfate solution |
| What is the least desirable flotation solution and why? | Saturated sodium chloride. It can corrode the microscope. |
| The process of development that takes place within a coccidian oocysts is called: | Sporulation |
| The best way to identify Tritrichomonas foetus is via what method? | Washings from the predilection sites and examination of the sediment. |
| Describe the Thelazia species of nematodes: | Those that live within the conjunctival sac and surface of the eye. |
| The term euryxenous means: | A parasite with a large host range (not exclusive to one species) |
| The kingdom: Animalia includes which parasites? | Platyhelminths(flatworms), trematodes(flukes), cestodes (tapeworms), nematodes(roundworms), acanthocephalans, annelids(leeches), arthropods(jointed insects). |
| The kingdom: Protista includes which parasites? | Protozoans (unicellular organisms) |
| Name some procedures used to estimate the total number of parasites per gram of feces: | Stoll, modified Wisconsin, McMaster |
| What is the best technique for observing motile trophozoites (Giardia). | Fecal direct smear diluted with physiologic saline |
| Describe the characteristics of Tritrichomonas foetus: | Pear shaped, 10-25um long w/sail-like, undulating membrane and 3 rapidly moving, whip-like anterior flagella. |
| An acaricide is used primarily for: | Killing mites and ticks |
| An anthelmintic is used primarily for: | killing roundworms, tapeworms, flukes and thorny-headed worms |
| List the various Phyla within the Protista kingdom. | Sarcomastigophorans = Flagellated, ameboid Ciliophoran = ciliated Apicomplexans = coccidia, malarial organisms & piroplasms |
| Name some of the most important flagellate parasites: | Leishmania, Trypanosoma, Trichomonas, Histomonas, Giardia |
| What are the Amoebae and Ciliate's two forms? | trophozoite and resistant cyst |
| Why are ciliates unique among other protozoans? | They contain two types of nuclei (macro and micronucleus) |
| Where are apicomplexans primarily found in domesticated animals? | The epithelium of the intestines, within blood cells & within cells of the reticuloendothelial system. |
| Describe the characteristics of apicomplexans: | Banana-shaped, non-visible internal locomotory organelles, move via undulation |
| Which solutions are considered the best for recovering Giardia cysts? | Zinc sulfate and Sheather sugar solution |
| What is the best protocol for diagnosing Giardia infection? | immunodiagnostic tests in conjunction w/fecal flotation |
| Describe the characteristics of Entamoeba histolytica's trophozoite form: | Single spherical nucleus w/tiny pinpoint center (endosome) |
| An intestinal coccidian of cats is: | Toxoplasma gondii |
| What is a hemoprotozoan? | A protozoan found circulating in the peripheral blood |
| How is Leishmania transmitted? | Blood-feeding arthropods (phlebotomine sand flies) |
| What apicomplexan is also called the "canine piroplasm"? | Babesia canis - a pear-shaped parasite which can be found within the RBCs of canines if bitten by infected ticks. |
| What is different about the Hepatozoon species when compared to other malaria-like parasites? | Hepatozoon are spread by the ingestion of an arthropod vs. a bite FROM and arthropod. |
| Protozoan Parasites that infect the GI tract include: | Giardia, Entamoeba histolytica, Balantidium coli, Cystoisospora (Coccidia), Toxoplasma gondii, Cryptosporidium |
| Protozoan Parasites that infect the Blood & Circulatory system include: | Trypanosoma cruzi, Leishmania, Babesia canis, Cytauxzoon felis, Hepatozoon canis/ameicanum |
| The two most common species of coccidia in cattle are: | Eimeria bovis = oval w/opening, 20 x 28um Eimeria zuernii = spherical, no opening, 15-22um x 13- 18um |
| Which parasite type infects the circulatory system, nervous system, urogenital and blood of horses? | Apicomplexans |
| What is the intermediate host of Haemoproteus species in wild birds? | Culicoides species |
| This parasite has the largest coccidian oocysts and usually causes asymptomatic infections in horses: | Eimeria leuckarti |
| Which parasite and its intermediate host should be reported to state and federal authorities upon diagnosis? | Babesia bigemina |
| A motile parasite with a single nucleus and an endosome found in a direct smear sample of diarrhea from a chimpanzee could be diagnosed as: | Entamoeba histolytica |
| How is coccidia diagnosed in birds? | Histopathologic examination of the small intestine |
| The characteristics of Giardia can be described as: | Pear-shaped w/flagella and two "eyes" (nuclei) |
| What organism causes avian malaria? | Plasmodium |
| Cryptosporidium species are what type of parasite? | Coccidian |
| What flagellate infects the bloodstram of humans and canines and uses the reduviid insect as an intermediate host? | Trypanosoma cruzi |
| Differentiate the characteristics of the Eimeria species oocysts in rabbits: | E. irresidua = smooth, light yellow wall w/wide micropyle, no polar granules or residuum, ovioid sporocysts. E. magna = dark yellow-brown w/wide micropyle w/o cap E. nedua = smooth, light-pink wall w/micropyle & residuum |
| Describe the characteristics of Cytauxzoon felis: | "Bejeweled ring" within stained RBCs. Spread by ticks. Symptoms: fever, icterus, anemia, dehydration, death |
| "Onion skin" tissue cysts found in skeletal muscle of dogs is known as: | Hepatozoon americanum |
| The most commonly diagnosed clinical condition in puppies and kittens (coccidiosis) is caused by which parasite species? | Cystoisospora species |
| This parasite can be round, ameboid or pear-shaped. 4 organisms joining give the affect of a "Maltese Cross" | Theileria equi and Babesia caballi |
| A non-pathogenic coccidian found in the kidneys of wild/lab rats is: | Klossiella muris |
| Equine protozoal myeloencephalitis, aka: | Sarcocystis neurona |
| Where would you find the "zig-zag" Gongylonema pulchrum parasite? | In the esophagus of ruminants and occasionally pigs and horses. |
| Bovine Trichostrongyle-type eggs can be described as: | Oval, thin-shelled eggs containing a morula w/4 or more cells. |
| The _____ species have the largest eggs in the Trichostrongyle family of parasites. | Nematodirus and Marshallagia |
| The intestinal threadworm of cattle is: | Strongyloides papillosus |
| Commonly called whip-worms and infect the cecum and colon of ruminants and swine | Trichuris species |
| What are the most common anthelmintics used to treat whipworms? | benzimidazoles, probenzimidazoles and ivermectin |
| The most common symptom of this ruminant parasite species is coughing. | Dictyocaulus species - lungworm |
| Which technique is used to identify lungworm infections in ruminants? | Baermann |
| Largest of the equine nematodes found in the small intestine of young foals. | Parascaris equorum |
| Associated w/thrombi in the anterior mesenteric artery of horses | Strongylus vulgaris |
| This parasite species is unique in that parasitic males do not exist. | Strongyloides |
| This parasite is often observed protruding from the anus of horses | Oxyuris equi |
| "Summer sores" in horses can be caused by: | The larave of Habronema species |
| Definitive diagnosis of trichostrongyles can be made only by: | Fecal culture and larval identification |
| Describe the characteristics of the Ascaris suum eggs found in a fecal flotation of a swine: | Oval, golden brown, thick shell w/projections giving it a lumpy/bumpy appearance |
| Humans that eat raw or undercooked pork may become infected with this parasite if it exists in the musculature of swine | Trichinella spiralis |
| Often referred to as the "rat pinworm" | Syphacia muris |
| After examining the vomitus of a cat diagnosed with chronic vomiting, you may find this parasite | Ollulanus tricuspis - has 3 major tail cusps at tip of tail |
| Which parasite's larval stage produces large nodules in the wall of the large intestine of swine? | Oesophagostomum dentatum |
| The largest parasitic nematode infecting domestic animals is: | Dioctophyma renale (giant kidney worm) |
| The scientific name for the swine kidney worm is: | Stephanurus dentatus |
| Nematode of dogs & cats found in nodules in the esophagus and stomach | Spirocerca lupi |
| Often associated with the formation of large, thickened, fibrous nodules in the stomach mucosa of horses | Draschia megastoma |
| This blood feeding parasite often found attached to the stomach of dogs and cats causes vomiting, anorexia, & dark tarry stools | Physaloptera species |
| The ruminant skin worm: Stephanofilaria stilesi is transmitted by the bite of which intermediate host? | Haematobia irritans (horn fly) |
| The intermediate host of the swine lungworm (matastrongylus elongatus) is what? | The earthworm |
| What is the best preventative measure against infection of bovines by Strongyloides papillosus? | Pasture rotation w/non-ruminants |
| Feline lungworm with an 'S' shaped bend which lives in the bronchioles and alveolar ducts: | Aelurostrongylus abstrusus |
| What are proglottids? | Identical, segmented compartments that comprise the tapeworm's ribbon-like body |
| Describe the characteristics of a true tapeworm: | long, segmented, flat; anterior end has a scolex (head) w/acetabula (suckers) or Rostellum (anchor) for attachment. No mouth, food absorbed through tegument (body wall). Neck+ strobila (body) just below scolex. M&F organs in each segment. |
| Describe the 4 different types of eggs found in the gravid proglottids of tapeworms: | Pyriform apparatus = Egg w/3 coverings; innermost is pear-shaped |Dipylidium = contains multiple hexacanths in 1 egg |Taenia = egg w/wide shell, thick outer covering, 6-hooked hexacanth |Pseudophyllidean = operculum on one end; 6-hooked hexacanths |
| What does digenetic mean? | "Two beginnings" - referring to a life cycle with alternation of generations, one parasitic and the other free-living |
| What are the physiological differences between a true tapeworm and a pseudotapeworm? | At the scolex (head), instead of acetabula (suckers) a pseudotapeworm has two slit-like organelles (bothria). Their eggs are operculated (have a 'lid') |
| What are the two subclasses of Cestoda? | Eucestoda = true tapeworm Cotyloda = pseudotapeworm |
| What are Psocids? | Primitive insects associated w/vegitation. They are the intermediate hosts of Thysanosoma actinoides. |
| Cattle are the intermediate hosts for this human tapeworm: | Taenia saginata "beef measles" |
| Which tapeworm is also called the "cucumber seed" tapeworm or double-pored tapeworm and why? | Dipylidium caninum = its shed gravid proglottids that can be found on feces, bedding, pet fur resemble seeds |
| What is the typical treatment for Dipylidium Caninum? | Praziquantel or epsiprantel. All pets in household must be treated for both fleas and tapeworms. |
| How is definitive diagnosis of Echinococcus species infection best achieved? | Identification of adult tapeworms taken from the intestinal tract. Purging the feces and collecting them from the final clear mucus is usually only done if infection STRONGLY suspected. |
| The proglottid of this organism has a centrally located rosette shaped uterus and uterine pore through which eggs are released: | Diphyllobothrium species |
| What life state is described as an invaginated scolex inside of a fluid-filled vesicle? | Cysticercus |
| How do dogs and cats become infected with the Spirometra species of tapeworms? | Ingestion of an infected fish or frog |
| What's the intermediate host of Moniezia benedini? | Oribatid grain mites |
| This pseudotapeworm absorbs vitamin B12 from the host causing pernicious anemia: | Diphyllobothrium species |
| What is the life cycle for Taenia pisiformis? | Rabbit ingests hexacanth embryos - develop to cysticercus stage - Dog ingests rabbit - cyticercus matures to adult |
| What is unusual about taenia saginata as it relates to the Taenia species? | It has an unarmed scolex |
| This equine tapeworm has prominent lappets behind each of its 4 suckers | Anoplocephala perfoliata |
| A metacestode is: | the larval stage of a tapeworm, found in an intermediate host |
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AmySichta
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