Protozoans

Question 1

general features of the phyla protozoans

Answer 1

all unicellular
organelles of locomotion - cilia, flagella
most free living

Question 2

Apicomplexa general characteristics

Answer 2

aka sporozoa
obligate intracellular parasites
complex life cycles
many important pathogens

Question 3

Apicomplexans

Answer 3

1. coccidians- enterico parasites
2. coccidians - tissue parasites
3. blood parasites

Question 4

Coccidians - enteric species

Answer 4

Order Eimeriida

• Eimeria
• Isospora

Question 5

merogony

Answer 5

endogenous asexual reproduction in tissues (mucosal cells)
• Result : merozoites in schizont in cell. Schizont bursts from cell to release merozoite
asexual

Question 6

Gamogony

Answer 6

• formation of zygote by syngamy (union of cells- cf. fertilization)
  • Result is zygote in oocyst in host cell. Oocyst released from cell

Question 7

Sporogony

Answer 7

– reproduction from zygote in oocyst • Result: sporozoites in oocyst

Question 8

life cycle

Answer 8

Question 9

distinguishing eimeria and Isospora by oocyte

Answer 9

Question 10

explain the self limiting infection and coccidians

Answer 10

• in immunocompetent host, infection is self limiting

= cures without treatment.

Question 11

self-limiting disease

Answer 11

features

• clinical signs (eg diarrhoea) last for a while days to weeks
• parasites completely cleared after infection ( infection has an end-point)
• host refractory (immune) to re-infection by only that species

Question 12

Enteric coccidians

Answer 12

Isospora and Eimeria

• highly host specific
• each host has many species - usually hosts carry EITHER Eimeria spp. or Isospora ssp.
• nearly all enteric
• site in gut differs

Question 13

coccidiosis disease of intensive husbandry

Answer 13

clean the environment and faceces

Question 14

chicken coccidiosis

Answer 14

8 species of Eimeria
- species occur in different parts of the intestinal tract
- variable pathology, pathogenicity, mortality, morbidity
eg Eimeria tenella
- found in caeca where it causes hemorrhagic caecal coccidiosis

Question 15

cryptosporidium

Answer 15

Cryptosporidium causes significant morbidity & some mortality in immuno-
compromised hosts
Human-human transmission Zoonotic- wide range of domestic and wild hosts
- water borne
- cryptosporidiosis
- many different species
- significant zoonosis
- Diarrhoea in humans - self limiting in most cases
- transient disease
- disease of overcrowding

Question 16

list the three groups of tissue coccidians

Answer 16

• Toxoplasma gondii • Neospora• Sarcocystis

Question 17

typical coccidian life cycle

Answer 17

Question 18

characteristic of tissue coccidian life cycles

Answer 18

similar to enteric coccidians

• but add: life cycle split over two hosts
• Definitive host- gamogony (at least) occurs- in inestines
• Intermediate host - merogony in tissue sites

Question 19

Toxoplasma gondii general + life cycle

Answer 19

long known as tissue cyst in wide range of animals
only recognised as a parasite of cats ( as def. host) recently
Benign infections- except in immune suppression, pregnancy
– New infection during 3rd trimester can lead to death of foetus (sheep goats humans)

Question 20

Neospora

Answer 20

Definite host = canids
• Gamogony and oocyst formation
• Hindlimb paralysis in pups
• IH- cattle, horse– Major cause of abortion in cattle– California USD35 million loss due to abortion

Question 21

sarcocystis

Answer 21

muscle cyst in wide range of mammals

Question 22

explain the haemosporidians

Answer 22

• Malaria- Plasmodium
• Haemoproteus, Leucocytozoon-birds, reptiles
• Piroplasms

Question 23

explain the two piroplasms

Answer 23

babesia and theileria

Question 24

types of tick fevers (guessing its important)

Answer 24

Question 25

life cycle of babesia in host

Answer 25

Question 26

life cycle of babesia is host

Answer 26