PA8: Intro to protozoa Flashcards
(26 cards)
Define protozoa.
Single-celled eukaryotes with complex subcellular organisation that can have direct/indirect/arthropod-borne lifecycles & can be extra/intracellular.
What is the sporozoite stage?
Infective stage of protozoa able to survive environmental conditions outside the host.
What is the trophozoite stage?
The proliferative stage within the host.
What are the 4 subtypes of protozoa?
Rhizopod
Cilliate
Flagellate
Sporozoan
What are the characteristics of rhizopods?
Similar to amoeba
Amorphous
Movement using pseudopodia
Extracellular
Direct lifecycle
Feed by phagocytosis
Asexual reproduction by binary fission
Trophozoite & cyst forms
Characteristics of ciliates
Movement using cilia
Extracellular
Direct lifecycle
Feed on particulate matter using specialised invaginations in cell membrane
Trophozoite & cyst forms
Asexual reproduction by binary fission + sexual reproduction by conjugation between mating types
Characteristics of flagellates
Movement using 1-5 flagellae
Most are extracellular, some are intracellular in macrophages
Trophozoite & cyst form
Asexual reproduction
Intake of soluble nutrients through cell membrane for feeding
Characteristics of sporozoan protozoa
No obvious means of locomotion
Mostly intracellular
Direct & indirect lifecycles
Asexual reproduction (schizogony) & sexual reproduction (fusion of gametes to make an oocyst).
Characteristics of monoxenous protozoa
Lifecycle completed in a single host
Alternate between trophozoite & cyst
Oocysts are environmentally-resistant & can survive outside of the host
Found in body systems with easy access to outside
Found where there is high stocking density
How are monoxenous protozoa controlled?
Decreased stocking density
Decrease contamination of environment by cysts
Improve environmental hygiene
State examples of extracellular monoxenous protozoa.
Entamaoeba
Balantidium
Giardia
Trichomonas
Trichomonas foetus
Trypanosoma equiperdum
State examples of intracellular monoxenous protozoa.
Eimeria spp.
Isospora spp.
Cryptosporidium spp.
Characteristics of Entamaoeba.
Rhizopod
Affects dogs (esp. puppies)
Trophozoite found in gut
Cysts passed in faeces & infectious
Characteristics of Balantidium.
Ciliate
Zoonotic
Affects pigs
Trophozoite in gut
Cysts passed in faeces & infectious
Only cause disease in very large infestations
Characteristics of Giardia
Flagellate
Severe disease in young cats & dogs
Trophozoite in gut
Cysts passed in faeces & infectious
Spread via water in wild animal reservoirs
Characteristics of Trichomonas
Flagellate
Severe disease in birds
Oesophageal & intestinal forms
Pigeons get infected by water contaminated with crop milk
Characteristics of Trichomonas foetus
Flagellate
In vagina/prepuce of cattle
If protozoa migrates to the uterus, it causes abortion
Must prevent infected animals from breeding
Characteristics of Trypanosoma equiperdum
Flagellate
Cause of venereally-transmitted dourine in horses & donkeys
Results in infertility
Notifiable UK parasite
Prevent infected animals from breeding
Characteristics of Eimeria spp.
Coccidian protozoa, subclass of sporozoan
Found in gut
1 sporulated oocyst has 4 sporocytes & each sporocyte has 2 sporozoites –> 8 sporozoite per sporulated oocyst
Causes coccidiosis
Common in intensive poultry units & commercially-farmed rabbits, seasonal in lambs & calves
Host & site specific
Characteristics of Isospora spp.
Coccidian protozoa, subclass of sporozoan
1 oocyst has 2 sporocytes & each sporocyte has 4 sporozoites –> 8 sporozoites per oocyst
Mostly infects dogs, cats, pigs
Found in gut except for pigs who have extraintestinal stages (in liver, spleen)
Rodents act as reservoirs
Usually non-pathogenic
Characteristics of cryptosporidium spp.
Coccidian protozoa, subclass of sporozoan
Wide host range (mostly young animals)
What causes poultry caecal coccidiosis?
Eimeria tenella
How is poultry coccidiosis controlled?
Good hygiene
Use of medicated feeds
Treatment of affected birds
Attenuated live vaccine given in drinking water/feed
What type of sheep does ovine coccidiosis affect?
Unweaned lambs aged 4-8 weeks
