Parasites (Yr 3) Flashcards
what is Babesia spp. transmitted by?
ticks
what is specific about the location Babesia spp. are found in the body?
intra-erythrocytic
what tick transmits Babesia divergens?
Ixodes ricinus
what is the lifecycle of Babesia spp. starting with the merozoites in the red blood cells?
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
what disease is caused by Babesia divergens?
babesiosis (redwater)
what are the clinical signs of babesiosis?
pyrexia
haemoglobinuria
haemolytic anaemia
diarrhoea which becomes constipation
how long after infection with Babesia divergens do cattle begin to show clinical signs?
2 weeks
what time of year is babesiosis seen?
summer (May-November) this is when ticks are active and herds are out at pasture
can animals develop immunity to babesiosis?
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
how does Babesia divergens represent an example of endemic stability?
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
when does the endemic stability of Babesia divergens breakdown?
buying in naive stock
introducing partial tick control
removing ticks from pastures
how can Babesia divergens be diagnosed?
clinical signs, history, season
giemsa stained blood smears (identify merozoites in RBCs)
PCR
how is babesiosis treated?
imidocarb
(blood transfusion in very anaemic animals)
what are the apicomplexan protozoan parasites of importance in farm species?
Cryptosporidium spp.
Babesia spp.
Toxoplasma spp.
Neospora spp.
what host does Cryptosporidium parvum affect?
very low host specificity (even zoonotic)
where is Cryptosporidium spp. found within the body?
microvillous border of epithelial cells lining alimentary and respiratory tracts
intracellular but extracytoplasmic (just covered by the cell membrane)
how does the lifecycle of Cryptosporidium spp. differ from other protozoa affecting livestock?
it has a direct lifecycle (there is no intermediate host)
what are the two ways Cryptosporidium spp. infection can occur?
ingestion of infected faeces
auto-infection from current oocysts
what is the lifecycle of Cryptosporidium spp. starting with the oocysts in faeces?
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
what is the pathogenesis of Cryptosporidium spp.?
causes enteritis, villous atrophy, crypt hyperplasia and loss of mature epithelial cells leading to malabsorption and diarrhoea
how long after infection do animals with Cryptosporidium spp. start to show clinical signs?
3-7 days (coincides with oocyst shedding)
what age are animals effected by Cryptosporidium spp.?
0-6 weeks old
what are the clinical signs of Cryptosporidium spp.?
watery, non-bloody diarrhoea
dehydration
inappetence
GI pain/discomfort
how is Cryptosporidium spp. diagnosed?
clinical signs
oocysts stain in faeces (ZN stain)
snap tests
