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Parasit - Lab Quiz 1-1

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dslemeraldcity's version from 2016-09-02 08:28

Definitions

Question Answer
Define Parasitea. An organism that lives in or on another organism of a different species b. Metabolically dependent on the host during part or all of its life c. Usually harmful to the host
Define Parasitisma. A kind of symbiotic relationship between two different species of organism b. One (the parasite) is metabolically dependent on the other (the host) c. Can go from essentially harmless (commensal) to highly virulent
Define Facultative parasiteAn organism that is capable of living either a free or parasitic existence (like a fly. Just using the faculties!)
Define EndoparasiteA parasite that lives mainly inside the body of its host (e.g., hookworms).
Define EctoparasiteA parasite that lives mainly on the surface of its host (e.g., fleas, ticks & lice).
Define HelminthsRoundworms or nematodes (e.g., ascarids) & flatworms (e.g., tapeworms or cestodes) & flukes or trematodes.
Define ProtozoansSingle-celled, eukaryotic organisms (e.g., amoebae).
Define ArthropodsOrganisms w/ exoskeletons (made of chitin) & jointed appendages (e.g., insects, arachnids, mites).
Define PseudoparasiteAn object (e.g., pollen) or nonparasitic organism (e.g., grain mite) that is mistaken for a “true” parasite.
Define HostA living organism in or on which a parasite subsists, develops and/or reproduces
Define Definitive hostAn obligatory host in which a parasite develops to sexual maturity.
Define Intermediate hostAn obligatory host in the life cycle of a parasite in which immature or asexual stages undergo essential development and/or proliferation before transmission to the definitive host (e.g., mosquito).
Define Mechanical vectorA nonessential host which passively carries infective parasite stages on its body; source of parasite contamination (e.g., boot, syringe).
Define Biological vectorUsually an arthropod (e.g., face fly); may be an intermediate host or a mechanical vector.
Define Paratenic (or Transport) hostA nonessential host, (e.g., rodents, roach), in the life cycle of a parasite capable of harboring & maintaining immature stages; parasites undergo no development or proliferation w/in these hosts, but are merely carried w/in the body until consumed by the proper definitive host.
Define Reservoir hostA population of infected hosts which serve as a potential source of infxn for other species of susceptible domestic animals or humans (e.g., wild [feral] animals).
Define Infective stageDevelopmental stage of the parasite capable of initiating a new infxn w/in another host (e.g., eggs, oocysts, larvae).
Define Direct life cycleTransmission of parasitic infxn from 1 host to another w/o the requirement of an intermediate host; 1-host life cycle.
Define Indirect life cycleTransmission of parasitic infxn from 1 host animal to another through 1 or more essential intermediate hosts; multi-host life cycle.
Define Pre-patent periodThe time between ingestion & invasions of infective stages of a helminth parasite in its definitive host until eggs or larvae are 1st produced (e.g., the time between ingestion of infective L3 nematode larvae until the appearance of eggs in the feces).
Define Patent periodThe life-span of the adult parasite in the host.
Define InfxnEstablishment of a parasite w/in a host, w/ or w/o development of clinical signs; generally, endoparasites infect their hosts (e.g., nematodes, cestodes & flukes).
Define InfestationEstablishment of a parasite on the surface of their host, w/ or w/o development of clinical signs. Ectoparasites infest their hosts (e.g., insects & arachnids).
Define DiseaseClinical manifestations of infxn or infestation.
Define Acute diseaseClinical infxn by parasites characterized by rapid onset, large parasite numbers & usually dramatic clinical signs (e.g., anemia, death).
Define Chronic diseaseClinical infxn by parasites characterized by slow debilitation, small to moderate parasite numbers, & clinical signs are usually slow in developing.
Define Subclinical infxnParasite infxn in which no clinical signs are manifested, however, evidence of parasitism may be detected by decreased growth, loss of production, etc. Many herd health parasitic problems are related to subclinical infxns.
How do parasites injure their hosts?They feed on blood, lymph, exudate or solid tissues; compete w/ the host for nutrition; they cause mechanical obstruction; they may produce pressure atrophy; destroy host cells by growing in them; they may produce toxic substances; they may produce host allergic rxns; they may promote the neoplastic transformation of cells; they may be biological vectors or intermediate hosts; contribute to decreasing the host’s immune system.
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Protozoa in General

Question Answer
Protozoa are __cellular, __karyotic organismsUnicellular, eukaryotic (have true nucleus)
What are the 2 life stages of protozoa?Trophozoite & cyst
Describe the trophozoite life stageMotile feeding form – very fragile & may be free-living or the infective stage (depending on the protozoan)
Describe the cyst life stageResistant, resting, but infective stage – may be multinuclear
What are some ways in which a trophozoite can be motile?1. Flagella (Trichomonads, Giardia) 2. Cilia (Balantidium) 3. Pseudopods: (Means “false feet” - Temporary extensions of cytoplasm) (Amoebae) 4. Undulating membranes (Trypanosomes, trochomonads), 5. Subpellicular microtubules
Describe the mode of feeding Protozoa utilize1. Protozoans obtain nutrition from endogenous or exogenous sources
The 3 asexual ways protozoa reproduce are...Binary fission
Budding
Multiple fission or Schizogony (a form of asexual reproduction characteristic of certain protozoa, including sporozoa, in which daughter cells are produced by multiple fission of the nucleus of the parasite (schizont) followed by segmentation of the cytoplasm to form separate masses around each smaller nucleus.)
What are the 2 sexual ways that protozoa reproduce?Conjugation ( temporary fusion of cells w/ nuclear exchange – newly formed organisms then divide by binary fission) & syngamy (union or fusion of sexually distinct gametes to form a zygote [or oocyst] )
What is a direct life cycle?Single host w/ no required intermediate host
What is an indirect life cycleObligatory multi-host life cycle requiring an intermediate host, or biological vector
A paratenic host is a ___ carrierActive
A mechanical vector is a ___ carrierPassive
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Protozoa - Tritrichomonas foetus

Question Answer
What host does Tritrichomonas foetus infect & what condition does it cause?CATTLE! & Bovine Trichomoniasis
What is the route of transmission for tritrichomonas foetus?Venereal (sexual), Reportable! Direct!
What are the host(s)/types of host(s) for tritrichomonas foetus?Definitive host: male & female bovids. No intermediate host.
What type of life cycle does tritrichomonas foetus have? How is it transmitted?DIRECT life cycle, it is venereal (sexual) transmission through coitus
Once in the body, where does tritrichomonas foetus like to live?MALE bull - preputial cavity. FEMALE cow - vagina, uterus, & oviducts
How does tritrichomonas foetus reproduce?Longitudinal Binary Fission
Pathology of tritrichomonas foetus?MALE- not much happening. FEMALE- severe endometritis (incld nodular lymphoid inflammation), periglandular fibrosis w/ mild to severe salpingitis → CAN CAUSE ABORTIONS
Clinical signs of tritrichomonas foetus?MALE- asymptomatic. FEMALE- EARLY ABORTION!! 3-4mo. Also might have varying degrees of vaginitis, cervicitis, salpingitis, & placentitis. Often endometritis w/ purulent discharge that may lead to sterility – infected cows are often restlessness
Diagnosis of tritrichomonas foetus?Recovery of organisms from.... MALE- preputial washing or scraping. FEMALE- smears from the placental fluid, aborted fetal abomasal contents, or the uterus or vagina
What should you never use to treat food animals bc of its carcinogenic association in humans?Metronidazole
Treatments following infection of Tritrichomonas foetus?Bulls: infected should NOT be used as breeding animals → prognosis for clearing of the chronically infected is guarded (treatment involves intensive flushing of prepucial cavity with 6 confirmed negative culture before returning to breeding) Cows: vaccine is currently available = TrichGuardTM for cows (previously infected should be artificially inseminated for at least 2 years following diagnosis with sexual rest of the cow for 2-6 months)
Describe the life stages of Tritrichomonas foetusTrophozoite stage, NO CYST STAGE!
Describe the appearance of the trophozoite stage of tritrichomonas foetusPyriform (rounded anterior end & pointed posterior end), 3 anterior flagella, 1 recurrent flagellum w/ undulating membrane
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Protozoa - Trichomonas gallinae

Question Answer
What condition does trichomonas gallinae cause?Avian Trichomoniasis - “Cankor” in most birds, “Frounce” in raptors
What is the route of transmission for trichomonas gallinae?DIRECT Transmission via FECAL-ORAL, crop-milk to young, or raptor eating infected birds
What are the host(s)/types of host(s) for trichomonas gallinae?BIRDS Definitive host- domestic pigeons, chickens (rare), turkeys, pheasants, doves, & raptors. Intermediate host- NONE
What type of life cycle does trichomonas gallinae have? How is it transmitted?1. DIRECT Transmission
2. Adults to squabs in crop milk of pigeons
3. Fecal-oral Contamination
4. Cloacal drinking
5. Can survive in water with organic matter, food, and bedding
6. Direct bill to bill contact during bird courtship
7. Birds of prey eating infected birds
Clinical signs of trichomonas gallinae?Usually affects young birds, adults often asymptomatic. Weight loss, ruffled feathers, difficulty breathing, mucoid nasal exudate, mouth may contain greenish fluid w/ lesions progressing from yellowish, circumscribed areas in the upper digestive tract to caseous nodules
How do you diagnose trichomonas gallinae?1. Location of lesion & and isolation of organism in those lesions
2. Can be found in saliva or smears of the cheese-like necrotic lesions
3. Samples must be collected within 48 hours of bird’s death
How do you treat Trichomonas gallinae?metronidazole in non-food birds, knodazole or enheptin
Describe the life stages of trichomonas gallinae?Trophozoite stage, NO CYST STAGE!
Describe the appearance of the trophozoite stage of trichomonas gallinae4 anterior flagella (instead of 3 like foetus, but otherwise the same, like shape & undulating membrane etc)
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Protozoa - Histomonas meleagridis

Question Answer
What condition does histomonas meleagridis cause?Histomoniasis/ BLACK HEAD DISEASE
What are the host(s)/types of host(s) for histomonas meleagridis?Definitive host: turkeys, chickens, & other gallinaceous birds. Paratenic (transport) host: Heterakis gallinarum (cecal worm)
What are the host(s)/types of host(s) for histomonas meleagridis?Definitive host: turkeys, chickens, & other gallinaceous birds. Paratenic (transport) host: Heterakis gallinarum (cecal worm)
What type of life cycle does histomonas meleagridis have? Explain.DIRECT, but unique, bc it is a pleomorphic protozoan (shape depends on where it is in the body). AMOEBOID STAGE- found in cecum, & after hepatic invasion. TRANSITIONAL FORM- present in intestinal lumen (NO CYST STAGE)
What is the route of transmission for histomonas meleagridis?Fecal-oral, Direct, but Unique. Earthworms or Nematodes (Heterakis gallinarum) serve as a (paratenic hosts) that the bird (definitive host) ingests. The Heterakis eggs (cecal worm eggs) containing the Histomonas passes through into the bird's feces. Through fecal-oral transmission, the ingested Heterakis eggs that contained the Histomonas that was in the feces is now passed once again, but now the egg can hatch in the cecum where the Histomonas is finally liberated. The flagellated form of the Histomonas develops here in the cecal lumen. When this form gets exposed to outside temperatures, it dies rapidly as a result without the protection of the nematode's egg shell.
How is histomonas meleagridis transmitted?Infxn occurs when direct host (chicken) eats the eggs of the cecal worm, which carry histomonas inside of them. This is bc histomonas uses the parasetic host to survive outside. Adult cecal worms in the host ingest Histomonas, which then pass into the worm eggs w/in the DH, allowing Histomonas to “hitch a ride” to the outside world in the resistant nematode egg shell
Pathology of histomonas meleagridis?Causative agent of blackhead disease (economic importance). (Principal lesions are in the cecum & liver.) Cecum-(pinpoint lesions in the cecum may enlarge to involve the entire mucosa & cause exudation of foul-smelling cecal plugs + perforation, leading to peritonitis & adhesions). Liver- (liver lesions have elevated margins w/ depressed centers; lesions may be small & numerous, causing a mottled appearance)
Clinical signs of histomonas meleagridis?(Turkeys most severely affected- Chickens less so) Ruffled feathers with hanging wings & tail. (Characteristic yellow droppings & black discoloration of the skin on the head (reason why its sometimes called "Blackhead") (associated with 2⁰ bact. infxns (E. coli & C. novyi)))
How do you diagnose histomonas meleagridis?1. Based on clinical signs and presence of liver and cecal lesions 2. ELISA and PCR can confirm diagnosis
Describe the appearance of histomonas meleagridis1. Pleomorphic (the ability to alter their shape or size in response to environmental conditions) 2. Amoeboid Form (a. Found in the intestinal lumen (1 or 2 flagella)
b. In tissues it is found singly or in clusters (Flagellum is absent) )
3. Transitional Forms
(a. May be present in the lumen
b. Enclosed in a dense membrane
c. Both lumen and intestinal forms die rapidly when exposed to outside temperature)
4. No evidence of a cyst stage (a. Has been produced experimentally in tissue culture)
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