Parasites (Yr 3)

Question 1

what is Babesia spp. transmitted by?

Answer 1

ticks

Question 2

what is specific about the location Babesia spp. are found in the body?

Answer 2

intra-erythrocytic

Question 3

what tick transmits Babesia divergens?

Answer 3

Ixodes ricinus

Question 4

what is the lifecycle of Babesia spp. starting with the merozoites in the red blood cells?

Answer 4

merozoites divide by asexual binary fission in RBC
tick ingests and infected RBCs
multiplication and sexual reproduction occurs in the tick
Babesia then disseminates into the ovaries creating infected larvae
larvae then feed on next host where sporogony occurs in the salivary gland
sporozoites are injected into the host with the tick saliva
sporozoites invade the RBCs and begin to divide

Question 5

what disease is caused by Babesia divergens?

Answer 5

babesiosis (redwater)

Question 6

what are the clinical signs of babesiosis?

Answer 6

pyrexia
haemoglobinuria
haemolytic anaemia
diarrhoea which becomes constipation

Question 7

how long after infection with Babesia divergens do cattle begin to show clinical signs?

Answer 7

2 weeks

Question 8

what time of year is babesiosis seen?

Answer 8

summer (May-November) this is when ticks are active and herds are out at pasture

Question 9

can animals develop immunity to babesiosis?

Answer 9

calves up to 9 months are resistant to disease but can become infected and gain immunity
hence you want to expose youngstock to this infection if they will encounter it in later life

Question 10

how does Babesia divergens represent an example of endemic stability?

Answer 10

the host, disease agent and vector can all coexist without disease when youngstock are exposed to the infection it allows cycling of infection between the cattle and ticks

Question 11

when does the endemic stability of Babesia divergens breakdown?

Answer 11

buying in naive stock
introducing partial tick control
removing ticks from pastures

Question 12

how can Babesia divergens be diagnosed?

Answer 12

clinical signs, history, season
giemsa stained blood smears (identify merozoites in RBCs)
PCR

Question 13

how is babesiosis treated?

Answer 13

imidocarb
(blood transfusion in very anaemic animals)

Question 14

what are the apicomplexan protozoan parasites of importance in farm species?

Answer 14

Cryptosporidium spp.
Babesia spp.
Toxoplasma spp.
Neospora spp.

Question 15

what host does Cryptosporidium parvum affect?

Answer 15

very low host specificity (even zoonotic)

Question 16

where is Cryptosporidium spp. found within the body?

Answer 16

microvillous border of epithelial cells lining alimentary and respiratory tracts
intracellular but extracytoplasmic (just covered by the cell membrane)

Question 17

how does the lifecycle of Cryptosporidium spp. differ from other protozoa affecting livestock?

Answer 17

it has a direct lifecycle (there is no intermediate host)

Question 18

what are the two ways Cryptosporidium spp. infection can occur?

Answer 18

ingestion of infected faeces
auto-infection from current oocysts

Question 19

what is the lifecycle of Cryptosporidium spp. starting with the oocysts in faeces?

Answer 19

oocyst within faces ingested
sporozoite attach to epithelial cells
microvilli fuse and expand around the sporozoite (enters trophozoite stage)
merogony occurs to produce 4-8 merozoites which then infect new epithelial cells
this occurs again and then the merizoites form microgamonts (females) and macrogamonts (males) which then mate sexually
sporulated oocysts are produced that are either thin or thick walled
thin walled oocyst hatch for autoinfection
thick walled oocyst passed in faeces

Question 20

what is the pathogenesis of Cryptosporidium spp.?

Answer 20

causes enteritis, villous atrophy, crypt hyperplasia and loss of mature epithelial cells leading to malabsorption and diarrhoea

Question 21

how long after infection do animals with Cryptosporidium spp. start to show clinical signs?

Answer 21

3-7 days (coincides with oocyst shedding)

Question 22

what age are animals effected by Cryptosporidium spp.?

Answer 22

0-6 weeks old

Question 23

what are the clinical signs of Cryptosporidium spp.?

Answer 23

watery, non-bloody diarrhoea
dehydration
inappetence
GI pain/discomfort

Question 24

how is Cryptosporidium spp. diagnosed?

Answer 24

clinical signs
oocysts stain in faeces (ZN stain)
snap tests