Protozoans Flashcards
Name 4 different types of organelles of locomotion seen in Protozoans
- Flagella
- Cilia
- Pseudopods
- Undulating ridges, subpelliccular microtubules
Name 5 different modes of Protozoan reproduction
Most reproduction is asexual 1. Binary fission 2. Multiple fission, schizogony 3 budding 4. Conjugation
- Gametogony = sexual
Autotrophic
Ability to produce its own nutrients
Heterotrophic
Organism that must obtain its food
Holozoic
A heterotroph that ingests via mouth
Saprozoic
A heterotroph that absorbs nutrients through cell membrane
What is the classification of Protozoans
Kingdom Protista Subkingdom Protozoa Phylum : Sarcomastigophora Apicoomplexa Ciliophora Microspora
What Phylum under the Kingdom Protista does Giardia belong to?
Phylum Sarcomastigophora
In what two forms does Giardia exist?
- Trophozoite
2. Cyst
Discuss the morphology of trophozoites
Adhesive disk, 2 nuclei, 8 flagella
Pear shaped , flat dorsoventrally
Which giardia form is infective
Cyst
Discuss the morphology of a Giardia cyst
Oval, thick walled, refractile wall
Nuclei is less prominent than in trophozoites and occupy one end of the cyst
Describe the two forms of giardia.
Cyst = infective, 4 nuclei, oval and thick wall; found in formed feces
Trophozoite = motile, bilateral symmetry, flattened dorsoventrally, pear shaped,8 flagella, 2 nuclei, found in diarrhea
What kind of lifecycle does Giardia have?
Direct,no IH
Giardia lifecycle
- Cyst stage ingested - can survive in food/water for several months
- Excystation in duodenum
- attach via adhesive disks to microvilli of epi cells in SI - Trophozoites replicate via longitudinal binary fission
- Encyst meant in lower gi tract
5 infective cysts passed in feces
Pre-patent period = 1 wk
What are the clinical signs of Giardiasis?
Chronic infections
Intermittent diarrhea - loose and mucous, no blood
Majority asymptomatic
How can you dx giardia?
FF - to find cyst
Direct smear- find motile trophozoite
Elisa - if this is positive then we should be sent cysts on a fecal float
What preparation technique in a fecal will keep nuclei intact
Using zinc sulfate with iodine dye
What Phylum do Trichomonads belong to?
Phylum Sarcomastigophora
Trichomonads
How do they move? 2 ways
What is their supportive structure?
How do they reproduce?
What is the name of the form taken during extreme conditions?
Flagella, undulating membrane
Axostyle - which is similar to ventral groove in giardia
Longitudinal binary fission
Pseudocysts
What causes Bovine Genital Trichomonosis and Veneral Disease?
Tritrichomonas foetus - sexually transmitted
How does Bovine Trichomonosis affect birth in cattle?
Embryonic death and abortion
How do you dx trichomoniasis?
Preputial wash - sample from fornix and glans penis of bull
Or uterine/vaginal smears, placental fluid
PCR tells you species, differentiate infections from non infectious
Culture organism
What is large bowel disease?
feline trichomoniasis causes by
Tritrichomonas blagburni
What clinical signs are seen with feline trichomoniasis?
Chronic diarrhea
Flatulent
Irritated anus
Fecal incontinence
How is Feline Trichomoniasiis transmitted
Transmission is unknown
What are some unique features of feline trichomoniasis?
Chronic diarrhea
Ave 9months age of onset
Diarrhea may relapse
Spontaneous resolution
What protozoan is a member of the Family Trypanosomaidae
Trypanosome cruzi
What is a parasite of all classes of vertebrates, majority transmitted by blood feeding invertebrates, but dont cause disease
Trypanosomes - Protozoans
What are the two general shapes of trypanosomes?
Elongated cell bodies with single flagella OR rounded cell body, short flagella
Trypomastigote
Stages of trypanosome
- elongated cell body
- single flagellum
- blood stage
- kinetoplast at cell posterior
Promastigote
Stages of trypanosome
- elongated cell body
- single flagellum
- mainly insect vector
- kinetoplast at cell anterior
Epimastigote
Stages of trypanosome
- elongated cell body
- single flagellum
- some species
- kinetoplast between nucleus and anterior
Amastigote
Stages of trypanosome
- rounded cell body
- short flagellum if present at all
- some species
What is the vector of American Trypanosomiasis/ Chagas Dz – Trypanosoma cruzi
Resuviid bug
What two stages of trypanosomes are seen in Trypanosoma cruzi?
Trypomastigote in circulating blood
And
Amastigote pseudocyts, in neural cells of muscles
What is the infective state of Trypanosoma cruzi?
Metacyclic trypomastigote
what is the life cycle of Trypanosoma cruzi?
IH = Reduviid bug DH = dogs, humans
Reservoir hosts = cats, opossums, armadillos, raccoons, rads
- IH Redivide bug bites DH, Metacyclic trypomastigotes = Infective stage passed in feces and enters wound
- Trypomastigotes enter circulation and then cells of spleen, lymphs, muscles, liver
- Transform into amastigote stage - replicate via binary fission forming pseudocysts
- Cells rapture and trypomastigotes released into circulation or can reinfect the cell
- Trypomastigotes get picked up IH and become epimastigotes via binary fission
- Metacyclic tryptomastigotes apear in rectum and passed via feces
What animal is affected by American Trypanosomiasis?
Dogs via Trypanosome cruzi
Mainly sporting dogs, working dogs
What are the features of American Trypanosomiasis Acute Dz
Trypanosoma cruzi
Trypomastigotes in circulation
- myocarditis
- pale mm
- lethargy
- hepatomegaly
- splenomegaly
What are the features of American Trypanosomiasis Chronic Dz
Trypanosoma cruzi
No circulating trypomastigotes
- dilated heart
- arrrhythmia
- lethargy
- resp difficulties
- anemia
How can Trypanosoma cruzi be dx?
Serological testing
Blood smear
Xenodiagnosis
What are the characteristics of Phylum Apicomplexa?
Distinct nucleus
Movement = subpellicular tubules
Apioccal complex
Name 2 orders under Phylum Apicomplexa
Order Eucoccidiia
Order Piroplasmida
Name the two Genera under Order Eucoccidiia that we studied
Genera Eimeria
Genera Cystoisospora
Both of these are considered coccidia which are part of Sporozoea due to producing a resistant spore-like cyst stage
Name 4 characteristics of Cystoisospora and Eimeria
- Stenoxenous = host specificity, species specific
- Site specificity = depending on species but usually
SI or LI, rarely liver or kidney - Monoxenous = parasitism of one host, DH
-Direct life cycle, no IH
What species are affected by Cytoisospora?
Dogs, cats
Pigs
Humans - severe in AIDS patients
What species are affected by Eimeria?
Bird, cattle, small ruminants
Horses, rabbits rodents
Pigs
What type of reproduction do Eimeria and Cystoisospora have?
Asexual = sporogony, schizogony (merogony) = multiple fission
Sexual = gametogony
What is the infective stage of Cystoisospora Eimeria
Coccidian
Both have sporuated oocyts = infective stage
Describe the life cycle of Cystoisospora and Eimeria
- Sporolated oocyst = sporocyst ingested by host
- Sporozoites excyst from sporocyst
- Attach epithelial cells as trophozoite
- Schizogony occurs within schizont = asexual reproduction
- Merozoites form gametocytes
- Gametogogny between macrogametocyte (female) and microgametocytes (male)
- Zygote to Oocyst, oocytes released in feces
- Oocytes undergoes sporogony = asexual reproduction in the environment
- Sporocyst formed in environment = infective stage
What is the outcome of Sporogony for Cystoisospora
Within one oocyst 2 sporocysts produced
Inside each sporocyst = 4 sporozoites
What is the outcome of Sporogony for Eimeria
After sporogony, within one oocyst = 4 sporocysts
Inside each sporocyst = 2 sporozoites
How is coccidia trasmitted?
Sporulated oocyst from contaminated food, water, bedding, or litter
What are the two common causes of calf coccidiosis?
What are three characteristics of this dz?
Eimeria bovis and Eimeria zuernii
Resistant oocysts
Development in terminal ileum and colon
Intracellullar
Which calf coccidiosis is easier to dx? And why?
What reproductive stage causes most damage?
What is the major damage?
Eimeria bovis
- oocytes present when dz begins
- Gametogony causes majority of damage.
- causes mucosal damage
What calf coccidiosis is more severe?
What reproductive phase causes most damage?
How many phases does this dz have?
Eimeria zuernii
- schizogony produces most damage
- characterized by bloody diarrhea
- acute phase = death common and mucosa destroyed
- chronic phase blood loss abates diarrhea persists
Which coccidia studied is not zoonotic
What are its clinical signs
Cystoisospora
Occasional diarrhea, death
Enteritis,colitis, weight loss, dehydration
What are common paratinic hosts of Cystoisospora
Mice, rats, hamsters, other vertebrate
Which 3 parasites belong to Phylum Apicomplexa, and are considered related to Coccidians?
Cryptosporidium
Toxoplasma gondii
Sarcocystis
What is the habitat of Cryptosporidium?
Intestines - microvillus border, intracelluar
What is the infective stage of Cryptosporidium?
Sporulated oocyst - containing 4 sporozoites
Thick resistant cyst wall
How is Cryptosporidium transmitted?
- direct contact with infective oocyst
- mucosal scrapings or tissue homogenates
- contamination - food or equipment
- water
**low infective doses, oocysts are small have significant resistance
What water processing methods are effective against Cryptosporidium?
Reverse osmosis Distilled Filtered using filter Steaming hot tea/coffee Pasteurized Canned/bottled soda
What parasite is characterized by yellow, profuse watery diarrhea in young calves?
Cryptosporidiosis
Lifecycle of Cryptosporidi
Exogenous
1. Sporulated oocyst (sporocyst) with 4 sporozoites
released from infected host
Endogenous
- Sporocyst ingested
- Sporozoite - trophozoite – undergoes schizogony = asexual reproduction
- Schizont release merozoites that can either reinfect host or differentiate to macro + microgametocytes
- Gametogony occuse = sexual reproduction
- Zygote formed, then oocyst with 4 sporozoites
- Oocyst can either remain in host or be released as sporocyst
Aka sporogony occurs in the host
Which member of Phylum Apicomplexa has a Felidae definitive host and IH encompassing virtually all mammals including humans
Toxoplasmosis
What are the two forms of transmission for Toxoplasmosis
Acquired – via infective oocyst in feces or undercooked/raw food
Congenital- transplacental transmission
What are the two stages of toxoplasma gondi?
Where are they found?
What are their grouped/surrounded phases called?
Tachyzoites = rapidly dividing, in liver, lungs, spleen, lymph nodes
-pseudocyst = group of tachyzoites, NOT surrouded by cyst wall
Bradyzoites = slowly dividing, found in brain, heart, skeletal muscle, eye
-cyst = group of bradyzoites surrounded by resistant cyst wall
what are the 3 ways the DH can acquire toxoplasma gondii
DH = Felids
- Sporulated oocyst from feces of other cats
- Tachyzoite - congenital - through placenta
- Bradyzoite - encysted in IH
What is the only way an IH can acquire Toxoplasma gondii
IH = mosts mammals
Infected by sporulated oocyst
Discuss the lifecycle of Toxoplasma gondii
- Cat ingests either sporulated oocyst, or ingests IH infected with bradyzoite, or congenital via placenta
- Schizogonoy and gametogony occurs in intestines
- Oocysts in feces
What stage of Toxoplasma gondii crosses placenta and affects fetus?
Tachyzoite
Discuss the life cycle of Toxoplasma gondii in the IH
- IH ingested sporulated oocyst
- Tachyzoites develop in any cell except RBC
- Immunity develops
- Bradyzoites develop cysts in host tissue
- cycle may reinitiate after decline of immunity cycle
How to dx Toxoplasma gondii?
FF
Serological examination
Histology
PCR
When does a cat shed Toxoplasma gondii?
No confirmed oocyst shedding in clinically ill cats – only shed once
Relapse can happen but often with immunosuppressed animals or concurrent infection with Isospora felis
Who are the carriers of Bovine Genetil Trichomonosis?
Bulls are chronic carriers and a symptomatic
How does the DH of Sarcocystis become infected? The IH?
DH = carnivores/predator ingests sarcocyst = tissue cysts in IH
IH: herbivores/prey infected when grazing or ingest contaminated food/water with sporocyst
What does a Sarcocystis sporocyst look like?
4 long projections with residual body at the base
Describe the life cycle of Sarcocystis
- DH ingests prey tissue w/ sarcocyst
- Merozoites released
- gametogony in DH intestine
- Sporogony
- Sporocysts released in feces
- Sporocyst ingested by IH via grazing or contaminated food/water
- Schizogony = Schizonts forms in endothelial cells of BV of brain, liver, kidney
- Sarcocyst in IH skeletal and cardiac muscle await DH ingestion
What causes Dalmeny Disease in cattle?
Sarcocystis cruzi
What animal is a true intermediate host for Sarcocystis bertrami, S. Fayeri, S. Equicanis
Horse
What is the outcome of infection of Sarcocystis neurona to the horse?
In this case the horse is an aberrant host
- Equine Protozoal Myeloencephalitis
Causes CNS dz as schizonts develop in neural cells and destroy them
Sarcocyst do not deveop
How to dx Sarcosporidiosis
FF
Schizont in IH, sarcocysts via biopsy/necropsy
Western blot
PCR
What parasite is characterized by piroplasm invasive stages?
Cytauxzoon felis
Phylum Apicomplexa
Order Piroplasmida
Cytauzxoon felis
DH
IH/vector
Reservoir host
DH: domestic cats
IH/vector = Dermacentor variabilis and Amblyomma americanum = ticks
Reservoir host = N. American bobcat
Discuss lifecycle of Cytauxzoon felis
- Tick feeds on infected host = ingests piroplasm in erythrocyte
- Piroplasm travel to salivary gland of tick = asexual reproduction
- Infected tick feeds on DH - cats
- In cat – Piroplasm to schizont = schizogony occurs in macrophages
- In cat - merozoites released when macrophages rupture.
- Merozoite released when macrophage ruptures
- Enter erythrocyte and develop into piroplasms.
Transstadial trasmission
Occurs in ticks that carry Cytauxzoon felis = pick up pathogen at a young stage and carries as it molts into adult
What phase of Cytauxzoon felis is most destructive?
Schizogenous phase - macrophages infected w/ schizonts block blood vessels, multi- organ failure
DX Cytauxzoon felis
Blood smears
PCR
Biopsy/necropsy
Visceral organs histiocytes
Which member of Phylum Apicomplexa is known for the predator-prey relationship in its host
Sarcocystis spp
What clinical signs of Bovine Genital Trichomonosis is seen in cows?
Vaginitis Cervicitis Endometriosis Pyometra Mucopurulent discharge