Eimeria Flashcards
How does diffetent poultry systems affect parasites?
Boilers, Layer replacment, Layers-
Commercial flocks with thousands of birds, very tight margins, high biosecurity
Free range-
As above, but additional risks from wild birds
Hobby-
Small numbers often free range, less biosecurity
Which system of poultry is more likely to be exposed to parasites?
Free range- more likely to be exposed to parasites in environment, soil, wild birds can be reservoirs
What different families of parasites can affect poultry?
Nematodes
Ectoparasites
Protozoa
How many species of Eimeria are there in chickens and turkeys?
Chickens- 7
Turkeys- 2
When is eimeria disease most likely seen?
When the conditions for parasite survival are optimal
Under intesification, facilitating spread by faeco-oral
Warm, moist conditions- enabling rapid and successful sporulation
What are the three general stages of coccidiosis (eimeria) life cycle?
Sporulation
Infection and schizogony
Gametogony- sexual division
This is a sketch of a stage within Eimeria spp
What stage is it and describe what the arrows are pointing to?
Infective stage- sporulated oocyst
Top arrow- Oocyst
Middle arrow- sporocyst
Bottom arrow- sporozoite
Each sporulated oocyst has 4 sporocysts- each of which has 2 sporozoites
Describe the life cycle of Eimeria (Eimeria tenella)
- Unsporulated oocyst passed in faeces of bird- undergoes sporogony- sporulated oocyst
- The sporulated oocyst is ingested- wall of oocyst/sporocyst ruptures and sporozoite infect epithelial cells of caecum
- Sporozoite asexually reproduces into schizont
- Shizont causes rupture of cell and releases (now) merozoites
- Repeats infection and asexual reproduction- secondary schizogony
- Gameteogony occurs- producing macrogamete (F) or microgamete (M)
- Fertilisation occurs forming Zygote
- Zygote becomes unsporulated ooccyst
PPP- 5-7 days
Self-limiting infection
What are the following life cycle stages?
(top right is two- above and below)
What are the influcencing factors on epidemiology of Coccidiosis?
Parasite- survical of oocysts in environment, low numbers persist in housing as impractival to completely remove
Host- naieve, susceptible young
Immunity- good immunity follows natural infection
Environmental conditions- intensive husbandry, can provide ideal conditions
What causes disease to occur?
Rapid rise in oocysts- ideal conditions
Population of susceptible birds
Disease at 3-6 weeks of age
How is Coccidiosis diagnosed?
Clinical signs:
Diarrhoea, live listless, death
PM Exam-
Appearance of parasite stages- schizonts, merozoites
Drop in FCR- subclinical infections
Describe the pathogenesis of Coccidiosis?
Severity of disease related to paeasite density- high levels of exposure results in more severe disease
Damage to epithelial cells
Heavy infections- haemorrhage- depends on species
Lighter infections- impairs absorptive capacity of gut
How are drugs used to control coccidiosis?
Prophylaxis- Ionophores
Broilers- aim to eliminate disease and optimise growth
Life time in feed from hatching to withdrawal
Layers- aim to allow immunity to develop
Step down programmes, drug of low efficacy
Treatment- Toltrazuril
Other then use of drugs for prophylaxis and treatment how can coccidiosis be controlled?
Hygiene
Adjunct to control by drugs not sufficient alone
Vaccination
Strong immunity- species specific
Live attenuated- precocious strains
What species of parasite cause Coccidiosis in Mammals?
Eimeria and Isospora spp
Young animals- cattle, sheep, pigs, rabbits
Similar life-cycle characteristics
Isospora- 2 sporocysts each with 4 sporozoites
Pathogenic and non-pathogenic species
How does mammalian coccidiosis affect sheep and how is it diagnosed?
Disease in young lambs
10 species- 2 are most pathogenic:
E. crandalis
E. ovinodalis
Caecum and colon infected
Clinical signs- diarrhoea, dehydration, abdominal pain, anorexia
Diagnosis- history, clinical signs, oocytes in faeces
How does coccidiosis affect cattle?
Usually under 1 yo
20 species 2 most pathogenic
E. zuernii, E. bovis
Housed, older animals
Caecum and colon
Clinical signs- dysentry, diarrhoea, dehydration, sulphonamides, monesin, decoquinate
Diagnosis- same as sheep- history, clinical signs, oocysts in faces
How does coccidiosis affect pigs?
Very young piglets
Isospora suis- infect SI- 2 sporocysts with 4 sporozoites
High morbidity, low mortality
Diagnosis dificuly- PM
Prophylaxis of sows to reduce contamination of environment
How does coccidiosis affect rabbits?
E. stiedae
Wasting, diarrhoea, jaundice
Epithelium of bile ducts- enlarged liver, white nodules
Diagnosis- PM, Oocysts in faeces
Treatment/prophylacis
What ectoparasites are important in poultry?
Mites
Lice- pediculosis
What burrowing and non-burrowing mites affect chickens?
What two lice families affect lice?
Burrowing mites-
Knemidocoptes spp
Non-burrowing mites-
Dermanyssus gallinae
Ornithonyssus sylvarum
Lice-
Menacanthus spp and Lipeurus spp
