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| − | | + | #REDIRECT[[:Category:Coccidia]] |
| − | [[Coccidiosis]]
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| − | | |
| − | ==Introduction==
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| − | [[Image:Coccidia.jpg|thumb|right|150px|Coccidia - Joel Mills]]
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| − | ''The following refers specifically to the life cycle of Coccidia spp.''
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| − | *The '''oocyst''' is the resistant stage in the environment
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| − | | |
| − | *The infective '''sporozoite''' is released from the oocyst
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| − | | |
| − | *Inside the host, the sporozoites invade the intestinal epithelial tissue
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| − | **Sporozoites feed and grow
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| − | | |
| − | *As the sporozoite grows the nucleus divides forming a '''schizont'''
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| − | | |
| − | *The schizont contains numerous elongated '''merozoites'''
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| − | | |
| − | *The formation of merozoites is the first asexual reproductive stage called '''schizogony'''
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| − | | |
| − | *The schizont ruptures releasing the merozoites which also invade the epithelial cells
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| − | | |
| − | *Another generation of schizonts form which is the beginning of the sexual phase of reproduction called '''gametogony'''
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| − | | |
| − | *The merozoites form male '''microgamonts''' or female '''macrogamonts'''
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| − | **Collectively known as gamonts or gametocytes
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| − | | |
| − | *The microgamonts released from the microgametocyte penetrate and fertilise the macrogamont (which is contained within the macrogametocyte)
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| − | | |
| − | *Gametogony forms the '''zygote'''
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| − | **Surrounded by a cyst wall
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| − | **Forms the '''oocyst'''
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| − | | |
| − | *The oocyst is passed in the faeces and is unsporulated
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| − | | |
| − | *The oocyst becomes sporulated in the second asexual reproductive phase called '''sporogony'''
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| − | | |
| − | *Once the oocyst is sporulated it is infective
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| − | [[Eimeria spp.|''Eimeria'' spp.]]
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| − | [[Isospora spp.|''Isospora'' spp.]]
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| − | ==Coccidia of Poultry==
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| − | [[Image:Buff orpington.jpg|thumb|right|150px|Buff orpington - nabrown RVC]]
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| − | [[Image:Eimeria Sporulated.jpg|thumb|right|150px|Sporulated ''Eimeria'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
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| − | *Direct life cycle
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| − | *1 week prepatent period
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| − | | |
| − | *After oocysts are ingested, sporozoites are released which penetrate the intestinal epithelium
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| − | | |
| − | *2 asexual phases of multiplication called schizogony occur followed by a phase of sexual multiplication called gametogony
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| − | | |
| − | *Zygote develops into an oocyst which is then shed in the faeces
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| − | **Oocyst measures 20-30μm
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| − | | |
| − | *For each oocyst ingested, thousands are shed
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| − | | |
| − | *Life cycle is '''self-limiting'''
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| − | **Organisms from a single infection go through the sequence of developmental stages synchronously
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| − | **Organisms leave the body simultaneously as oocysts
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| − | | |
| − | *Oocysts are only infective once they have sporulated
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| − | **Sporulation requires warmth, moisture and oxygen
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| − | **Takes 2-3 days in broiler houses
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| − | | |
| − | *Oocysts contain 4 sporocysts each with 2 sporozoites
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| − | | |
| − | '''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
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| − | ==Other Avian Coccidia==
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| − | ===Coccidia of Turkeys===
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| − | *5 ''Eimeria'' species
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| − | **2 important pathogenically
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| − | *''Eimeria'' in [[Caecum - Anatomy & Physiology|caeca]] causes petechial haemorrhages and caseous [[Caecum - Anatomy & Physiology|caecal]] cores
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| − | *''Eimeria'' in the anterior and mid-intestine causes necrotic enteritis and petechial haemorrhages
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| − | *Causes watery [[Intestine Diarrhoea - Pathology|diarrhoea]] in young poults and some mortality
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| − | ===Coccidia of Geese===
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| − | *3 ''Eimeria'' species
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| − | *2 intestinal species causing macroscopic lesions in [[Urinary System - Anatomy & Physiology#The Kidney|kidney tubules]]
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| − | **Oocysts carried in urine and pass out with faeces
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| − | *Renal species cause severe disease in goslings
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| − | **Depression, emaciation, [[Intestine Diarrhoea - Pathology|diarrhoea]] and sometimes death
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| − | ===Coccidia of Ducks===
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| − | [[Image:Crested duck.jpg|thumb|right|150px|Crested duck - nabrown RVC]]
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| − | *Several ''Eimeria'' species
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| − | *Another coccidia species which produces 8 sporozoites but these are not enclosed in a sporocyst
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| − | | |
| − | *Causes severe enteritis and mortality in ducklings
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| − | **Haemorrhages and pale focal lesions in [[Small Intestine - Anatomy & Physiology|small intestine]]
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| − | ===Coccidia of Game Birds===
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| − | *3 main species
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| − | *[[Caecum - Anatomy & Physiology|Caecal]] species most pathogenic causing white [[Caecum - Anatomy & Physiology|caecal]] cores
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| − | ==Coccidia of Cattle==
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| − | [[Image:Coccidia ruminant.jpg|thumb|right|150px|''Eimeria'' sp. of ruminants - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
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| − | [[Image:Coccidia oocyst ruminant.jpg|thumb|right|150px|Coccidia oocyst from ruminant faeces - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
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| − | *Many species affect cattle
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| − | *Cattle under a year old are usually infected sporadically
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| − | *2-3 week prepatent period
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| − | *''Eimeria bovis''
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| − | **Endogenous stages in central lacteal of villi and epithelial cells of [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]]
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| − | **Causes [[Intestine Diarrhoea - Pathology|diarrhoea]] and enteritis
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| − | **Oocysts are 28x20μm
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| − | **Moderately pathogenic
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| − | *''Eimeria zuernii''
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| − | **Endogenous stages in connective tissue of lamina propria of the lower [[Small Intestine - Anatomy & Physiology|small intestine]] and in the epithelial cells of the [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]]
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| − | **More pathogenic than ''Eimeria bovis''
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| − | **Causes blood stained dysentery, tenesmus and sloughed mucosa
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| − | **Oocysts are spherical and measure 16μm
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| − | *Mainly occurs in calves in poor conditions and bought-in calves
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| − | **Also occurs in suckler calves turned out in spring
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| − | *''Eimeria alabamensis'' associated with [[Intestine Diarrhoea - Pathology|diarrhoea]] in calves after spring turnout
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| − | *[[Materno-fetal immunity - WikiBlood#Passive transfer via colostrum|Passive immunity]] is sufficient during the neonatal period
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| − | *Can be concurrent with cryptosporidium, viral and bacterial agents
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| − | '''Diagnosis'''
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| − | *History, clinical signs, [[Intestine Diarrhoea - Pathology|diarrhoea]] (often with blood) and a decrease in weight gain
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| − | *Post-mortem
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| − | **Diffuse inflammation and thickening of [[Caecum - Anatomy & Physiology|caecal]] mucosa (and sometimes [[Ileum - Anatomy & Physiology|ileal]] and [[Colon - Anatomy & Physiology|colonic]] mucosa)
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| − | **Masses of gamonts and oocysts in scrapings
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| − | *High faecal oocyst count
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| − | **However, healthy animals can pass millions of oocysts from mixed species infections which have no pathogenic significance
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| − | **Animals may die before oocysts are shed
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| − | '''Control'''
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| − | *Improve husbandry
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| − | **Improve sanitation
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| − | **Increase bedding
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| − | **Raise food and water troughs to avoid faecal contamination
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| − | *Preventative in-feed medication
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| − | **E.g. Decoquinate
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| − | *Injectable antiprotozoals may limit oocyst production but animals should still be moved to a clean environment
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| − | **E.g. Sulphamethoxypyridazine
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| − | ==Coccidia of Sheep==
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| − | [[Image:Isospora felis sporulated.jpg|thumb|right|150px|''Isospora felis'' sporulated - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
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| − | [[Image:Isospora felis unsporulated.jpg|thumb|right|150px|''Isospora felis'' unsporulated - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
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| − | *11 different Coccidia species although only two are of clinical significance
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| − | **Giant schizonts visible as white spots
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| − | *''Eimeria ovinoidalis''
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| − | **Highly pathogenic
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| − | **[[Intestine Diarrhoea - Pathology|Diarrhoea]]
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| − | **Parasitises the [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]]
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| − | *''Eimeria crandalis''
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| − | **Varying pathogenicity
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| − | **Scours, grey, foul-smelling faeces
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| − | **Parasitises the [[Small Intestine - Anatomy & Physiology|small intestine]], [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]]
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| − | *2 week prepatent period
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| − | *Disease frequently seen in lambs under 6 months old
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| − | **More often in twins and triplets when single lambs
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| − | *Oocyts from ewes (immune carriers) accumulate in poorly managed litter or around feed and water troughs
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| − | *Lambs born early in the year amplify the parasite problem increasing the parasite risk to lambs born later in the year
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| − | *Affected lambs may die before oocysts are found in the faeces
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| − | **Post-mortem diagnosis difficult
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| − | *Different species of ''Eimeria'' occurs in sheep and goats
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| − | *Infection may be coincident with ''Neospora'' or ''Cryptosporidium'' infections
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| − | **Mixed infections complicate the diagnosis as oocyst differentiation is difficult
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| − | *Other non-pathogenic species can cause papillomatous mucosal growths
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| − | '''Control'''
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| − | *Improve husbandry
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| − | **Avoid overcrowding
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| − | **Decrease stress
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| − | *Improve hygiene by dagging ewes
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| − | *Avoid mixing lambs of different ages
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| − | *Preventative measures include creep feeding lambs with decoquinate or oral dosing with diclazuril when lambs are 4-6 weeks
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| − | **A second dose can be given after 3 weeks
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| − | ==Coccidia of Goats==
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| − | [[Image:Goats.jpg|thumb|right|150px|Goats - nabrown RVC]] | |
| − | [[Image:Eimeria leukarti horse.jpg|thumb|right|150px|''Eimeria leukarti'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
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| − | [[Image:Isospora suis oocyst.jpg|thumb|right|150px|''Isospora suis'' oocyst from pig faeces - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
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| − | [[Image:Isospora canis.jpg|thumb|right|150px|''Isospora canis'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
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| − | [[Image:Coccidia.jpg|thumb|right|150px|Coccidia in Cat Faeces - Joel Mills]]
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| − | [[Image:Isospora felis.jpg|thumb|right|150px|''Isospora felis'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
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| − | *Many ''Eimeria'' species
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| − | *2 ''Eimeria'' are pathogenic
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| − | **Cause [[Intestine Diarrhoea - Pathology|diarrhoea]] and a decreased growth rate
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| − | *Different species of ''Eimeria'' occurs in sheep and goats
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| − | ==Coccidia of Horses==
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| − | *Only one atypical ''Eimeria''
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| − | *Forms large subepithelial gametocytes in villi
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| − | *Large, dark coloured oocysts
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| − | **Approximately 12μm
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| − | *Occasionally causes [[Intestine Diarrhoea - Pathology|diarrhoea]]
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| − | *''Besnoitia bennetti'' in [[Respiratory Parasitic Infections - Pathology#Besnoitia bennetti|larynx]] of horses
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| − | ==Coccidia of Pigs==
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| − | *Many species of ''Eimeria'' and ''Isospora''
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| − | *Only ''Isospora suis'' is of clinical pathogenic importance
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| − | *Causes sporadic, serious and sometimes fatal disease in unweaned piglets
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| − | **Causes profuse [[Intestine Diarrhoea - Pathology|diarrhoea]]
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| − | *Very short 1 week prepatent period
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| − | *[[Intestine Diarrhoea - Pathology|Diarrhoea]] starts before oocysts are shed in faeces
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| − | **Ante-mortem diagnosis is difficult
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| − | *Death usually occurs after parasites have left the host
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| − | **Post-mortem diagnosis difficult
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| − | **''Isospora'' infections are '''self-limiting'''
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| − | ==Coccidia of Dogs==
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| − | *2 common and 2 less common ''Isospora'' species
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| − | *Occasionally can cause disease
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| − | *Little pathogenicity
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| − | *Even if faecal oocyst count is high, other causes of [[Intestine Diarrhoea - Pathology|diarrhoea]] should be looked for
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| − | *''Hepatozoon americanum'' and subclinical ''H. canis'' in [[Bones Hyperplastic and Neoplastic - Pathology#Hepatozoon|periosteal bone formation]]
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| − | **Both are Tick borne diseases
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| − | ***''H. canis'' – ''Rhipicephalus sanguineus''
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| − | ***Ticks become infected by ingesting a blood meal containing macrophages and [[Neutrophils - WikiBlood|neutrophils]] infected with the parasite gamonts -> sexual replication in the gut of the tick -> oocysts containing infective sporozoites -> dogs ingest the tick schizogony occurs in numerous tissues
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| − | ==Coccidia of Cats==
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| − | *2 common ''Isospora'' species with little clinical significance
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| − | | |
| − | *Oocysts in faeces have to be distinguised from those of ''Toxoplasma'' (smaller) and ''Sarcocytis'' (sporulated or naked sporocyts in faeces)
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| − | ==Coccidia of Rabbits==
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| − | *3 pathogenic ''Eimeria'' species
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| − | **2 in the [[Caecum - Anatomy & Physiology|caecum]]
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| − | **1 in the bile duct
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| − | *''Eimeria steidae''
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| − | **Parasitises the bile duct epithelium
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| − | **Travels via the bile duct to the [[Liver - Anatomy & Physiology|liver]] where it forms large white nodules
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| − | **Oocysts travel in the bile and are passed out in the faeces
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| − | **Causes ascites, [[Intestine Diarrhoea - Pathology|diarrhoea]], weight loss and polyuria
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| − | *Serious disease of both pet and farmed rabbits
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| − | *Treatment is by administration of drugs in drinking water
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| − | **E.g. Toltrazuril
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| − | | |
| − | *Hygiene is the best method of prevention to prevent sporocysts from sporulating
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| − | | |
| − | *Medicated feed can be used in commercial units
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| − | **E.g. Rabenidine
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| − | ==[[Protozoa Flashcards - Wikibugs#Coccidia|Coccidia Flashcards]]==
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| − | [[Category:Coccidia]]
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