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[[Coccidiosis - Poultry]]
 
[[Coccidiosis - Poultry]]
'''Pathogenesis'''
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*7 important ''Eimeria'' species
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*4 malabsorptive species
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**''Eimeria acervulina'' which is moderately pathogenic
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**''Eimeria maxima'' which is moderately pathogenic
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**''Eimeria mitis'' which has low pathogenicity
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**''Eimeria praecox'' which has low pathogenicity
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*3 haemorrhagic species
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**''Eimeria tenella''
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**''Eimeria necatrix''
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**''Eimeria brunetti''
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**All highly pathogenic
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**Form large sub-epithelial second generation schizonts at the base of intestinal crypts
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**Deep eruptions form when cells rupture to release merozoites
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**Destruction of crypt stem cells and marked haemorrhage
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**Blood stained faeces
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**High morbidity and high mortality
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'''Diagnosis'''
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*Post-mortem diagnosis of lesion severity
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**Region of intestine affected
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**Appearance of lesion
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**Presence or absence of haemorrhage
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**Size of schizonts and oocysts found in mucosal scrapings
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*''Eimeria acervulina''
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**Proximal gut
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**Thickening of walls
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**'White ladder lesions' produced by dense foci of gamonts and oocysts
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**Watery exudate
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*''Eimeria maxima''
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**Mid-gut
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**Thickening of walls
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**Pink exudate
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*''Eimeria tenella''
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**Swollen [[Caecum - Anatomy & Physiology|caeca]]
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**Thickening of wall
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**Dark colouring containing a core of necrotic tissue and blood
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*Lesion scoring is the best method of diagnosing the severity of the lesions and therefore the causative ''Eimeria'' species
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*''Eimeria necatrix''
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**Mid-gut
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**Ballooning of wall
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**White spots and petechiae forming 'salt and pepper' lesions
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**Haemorrhage into lumen
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'''Immunity'''
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*Different ''Eimeria'' species produce different levels of protective immunity
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**''E.maxima'' -> ''E.brunetti'' and ''E.acervulina'' -> ''E.tenella'' and ''E.necatrix''
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*There is no cross immunity between species
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*There is very little passive immunity
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*Evokes a cell-mediated response
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*All ages of poultry are susceptible
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'''Epidemiology'''
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*Oocysts are ubiquitous and robust
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**Able to survive several months to years
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*It is impossible to keep buildings free from infection
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**Chicks become infected by pecking the ground shortly after being placed in the poultry house
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*Biotic potential is enormous
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**Generation time is short
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**Massive infections can build up rapidly
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*Immunity develops relatively slowly
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**With high stocking densities the situation is explosive
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'''Control'''
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*Chemical
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**Intensive poultry production is largely dependent on the use of anticoccidial drugs
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**For more information see [[Anti-Protozoal Drugs|here]]
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*[[Vaccines - WikiBlood|Vaccines]]
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**Paracox
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***Multivalent attenuated [[Vaccines - WikiBlood#What antigen(s) do we use in the vaccine?|live vaccine]] for replacement layers and broilers
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***Contains 7 live strains of ''Eimeria''
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***Lack the most pathogenic life cycle stage making the prepatent period shorter
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***Known as '''precocious''' strains
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***Chicks [[Vaccines - WikiBlood|vaccinated]] on a single occasion when 1-9 days old through oocyst suspension in the feed or water
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***[[Vaccines - WikiBlood|Vaccinated]] birds have sub-optimal growth rates so is not used for broilers
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**Paracox 5
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***Contains 5 strains of the most pathogenic ''Eimeria''
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***Used for broilers
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***Sprayed onto the first feed offered to new batches of chicks
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*Integrated control
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**Careful management is needed so in-feed prophylaxis and [[Vaccines - WikiBlood|vaccination]] do not fail
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**Remove litter and thoroughly clean houses in between crops
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***Optimum turn-around time is 10 days
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**Use the lowest stocking density which is compatible with economic production
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**Water bowls, roofs and walls should be well maintained to prevent litter becoming damp
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**Stress factors should be avoided and adequate nutrition provided
      
==Other Avian Coccidia==
 
==Other Avian Coccidia==
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