Protozoa Flashcards

From WikiVet English
Jump to navigation Jump to search
Infectious agents and parasitesWikiBugs Banner.png
PROTOZOA
WIKIBUGS FLASHCARDS


Toxoplasma gondii - Ke Hu and John Murray

Protozoa

Question Answer Article
What are the four different ways protozoa can move?
  • Cilia
  • Flagellum
  • Pseduopodia
  • Gliding
Link to Answer Article
How do protozoa reproduce?
  • By binary fission
  • By schizogony
  • By sporogony
  • By gametogeny
Link to Answer Article
Briefly summarise the life cycle of protozoa
  • The infectious sporozoite are released from the oocyst invading epithelial tissue
  • The nucleus of the sporozoites divides forming a schizont which contains merozoites (schizogony)
  • Schizont ruptures releasing merozoites which form micro and macrogamonts in the epithelial tissue (gametogeny)
  • Microgamonts penetrate the macrogamont forming the zygote
  • The zygote forms the oocyst which is passed in the faeces
  • Sporulation occurs which makes the oocyst infectious
Link to Answer Article

Coccidia

Question Answer Article
What is the transmission and life cycle of Eimeria species?
  • Direct transmission
  • Faecal-oral route
Link to Answer Article
What is the transmission and life cycle of Isospora species?
  • Usually direct transmission by the faecal-oral route
  • Some species use facultative intermediate hosts forming tissue cysts
    • Transmission is then by the faecal-oral or route or via ingestion of the intermediate host
Link to Answer Article
How long is the prepatent period of poultry Eimeria species?
  • 1 week
  • Sporulation takes 2-3 days
Link to Answer Article
Name the malabsorptive Eimeria species
  • E. maxima
  • E. acervulina
  • E. mitis
  • E. praecox
Link to Answer Article
Name the haemorrhagic Eimeria species
  • E. necatrix
  • E. brunetti
  • E. tenella
Link to Answer Article
Which area of the gastrointestinal tract does E. acervulina, E. maxima, E. tenella and E. necatrix affect and what kind of lesions are produced?
  • E. acervulina affects the proximal gut forming white ladder lesions
  • E. maxima affects the mid-gut producing a pink exudate
  • E. tenella affects the ceaca forming a core of dark, haemorrhagic blood
  • E. necatrix affects the mid-gut forming salt and pepper leions
Link to Answer Article
What are the two main Eimeria species which affect cattle and what is the prepatent period?
  • E. zuernii
  • E. bovis
  • 2-3 week prepatent period
Link to Answer Article
What are the two significant Eimeria species which affect sheep and what is the prepatent period?
  • E. ovinoidalis
  • E. crandalis
  • 2 week prepatent period
Link to Answer Article
What is the most significant species of Isospora which affects pigs and what the prepatent period?
  • I. suis
  • 1 week prepatent period
Link to Answer Article
Which parts of the gastrointestinal tract do the Eimeria species which affects rabbits inhabit?
  • 2 inhabit the caecum
  • 1 inhabits the bile duct epithelium (E. steidae)
Link to Answer Article

Cryptosporidia

Question Answer Article
What is the main species of Cryptosporidium which infects humans and domestic animals?
  • C. parvum
Link to Answer Article
True or False: In Cryptosporidium infections unsporulated oocysts are passed in the faeces
  • False
  • Sporulated oocysts are passed in the faeces
Link to Answer Article
How are Cryptosporidium infections passed between hosts?
  • Direct faecal-oral transmission
  • Water-bourne infections
  • Autoinfection can also occur
Link to Answer Article
How are Cryptosporidium infections prevented?
  • Isolate and quarantine brought in calves
  • Good hygiene and adequate disinfection of calf pens
  • Goog hygiene of humans working and visiting farms
  • Halofuginone and other drug treatments
Link to Answer Article

Giardia

Question Answer Article
What is the key points of the life cycle and prepatent period of Giardia?
  • Simple life cycle
  • Direct life cycle
  • Reproduce by binary fission
  • 5-6 day prepatent period
Link to Answer Article
How do both people and animals become infected by Giardia?
  • Water bourne transmission
  • Direct faecal-oral transmission
Link to Answer Article
How would you diagnose a Giardia infection?
  • The cysts are heavy and do not float well in saturated sodium chloride solution
  • Cysts excretion is intermittent so faeces need to be collected and sampled over 3 days
  • Cyst antigen can be detected in faeces by an immunoassay
Link to Answer Article

Piroplasmida

Question Answer Article
True or False: Both trans-stadial and trans-ovarian transmission can occur in Babesia species
  • True
Link to Answer Article
What are the recognisable features of small Babesia species and give an example
  • Peripheral nucleus
  • Obtuse angle
  • B. divergens
Link to Answer Article
What are the recognisable features of large Babesia species and give an example
  • Central nucleus
  • Acute angle
  • B. major
Link to Answer Article
What are the predisposing features to Babesia infection?
  • Susceptible animals introduced into an infected area
  • Infected ticks introduced into a clean area
  • Infected cattle introduced into an area with clean ticks
  • Temporary reduction in the tick population decreasing the transmission rate (causing enzootic instability)
  • Infected are transported or stressed in other ways, e.g. parturition
Link to Answer Article
What are the different vectors for Babesia species?
  • Ixodes ricinus for B. divergens
  • Haemaphysalis for B. major
  • Boophilus for B. bovis and B. bigemina
  • Dermacentor and Rhipicephalus for B. canis
Link to Answer Article
What species are the natural vectors for Cytauxzoon?
  • Ticks
Link to Answer Article
Where do schizonts of Cytauxzoon felis develop?
  • In macrophages
Link to Answer Article
What is the main condition caused by Theileria parva?
  • East Coast Fever
Link to Answer Article
What is the main condition caused by Theileria parva and what is the intermediate host?
  • East Coast Fever
  • Rhipicephalus appendiculatus
Link to Answer Article
What is the pathogenesis of Theileria parva infections?
  • Proliferation in the lymphoblasts
  • Proliferation in the local lymph node followed by spread throughout the body
  • Lymphocyte depletion
Link to Answer Article
What are the clinical signs of Theileria parva infection?
  • Pyrexia
  • Enlarged local lymph node
  • Loss of condition
Link to Answer Article

Tissue Cyst Forming Coccidia

Question Answer Article
What are the two main species of Neospora of veterinary interest and which animals do they affect?
  • N. caninum
    • Dogs
  • N. hughesi
    • Horses
Link to Answer Article
How long is the prepatent period of Neospora?
  • 5 days
Link to Answer Article
What are the clinical signs of Neospora infections in dogs?
  • Ascending paralysis
  • Sudden collapse due to myocarditis
  • Muscle wasting
Link to Answer Article
What are the clinical signs of Neospora infections in cattle?
  • Abortion
  • Encephalomyelitis
  • Paresis
Link to Answer Article
What are the clinical signs of Neospora infections in horses?
  • Myeloencephalitis
Link to Answer Article
How many intermediate and final hosts does Sarcocystis have?
  • One final host
  • One intermediate host
Link to Answer Article
True or False: Sarcocystis infections are mainly asymptomatic
  • True
Link to Answer Article
What is Equine protozoal myeloencephalitis?
  • Necrotising encephalomyelitis affecting the grey and white matter of the CNS
  • Caused by S. neurona
  • Causes spinal cord dysfunction leading to ataxia and paralysis
Link to Answer Article
What is the most pathogenic species of Toxoplasma?
  • T. gondii
Link to Answer Article
True or False: The life cycle of Toxoplasma is direct
  • False
  • The life cycle is complex
  • Described as facultatively heterozygous
Link to Answer Article
Describe the acute phase of Toxoplasma infections
  • Asexual reproduction in the cell by endodyogeny (budding) producing 8-16 tachyzoites
  • Tachyzoites are released when host cell bursts
  • Haematogenous spread as more cells are infected
  • Infection continues until the animal develops immunity (around 2 weeks) at which point the infection enters the chronic phase
Link to Answer Article
Describe the chronic phase of Toxoplasma infections
  • Slow growing intracellular bradyzoites become walled off forming infective cysts
  • Bradyzoites are protected from the host immune response (whereas extracellular tachyzoites are killed)
  • Cysts remain viable for months to years in muscle and nervous tissue
  • If immunity is suppressed the infection can revert to the acute form
Link to Answer Article
How can Toxoplasma infections be prevented?
  • ELISA to check for seropositive cats
  • Humans can avoid oocyst ingestion
  • Humans can avoid tissue cyst ingestion
  • Sheep can be vaccinated or given medicated feed
Link to Answer Article

Tropical Protozoa

Question Answer Article
What species transmits Leishmania?
  • Sandflies
  • Phlebotomus spp. in the Old World
  • Lutzomyia spp. in the New World
Link to Answer Article
Which cells are Leishmania species intracellular parasites of?
  • Macrophages
Link to Answer Article

Other Important Protozoa