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| + | #REDIRECT[[:Category:Tissue Cyst Forming Coccidia]] |
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| − | |linkpage =Parasites
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| − | |linktext =PARASITES
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| − | |sublink1=Protozoa
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| − | |subtext1=PROTOZOA
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| − | <br>
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| − | ==Toxoplasma==
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| − | [[Image:Toxoplasma Life Cycle.jpg|thumb|right|150px|Toxoplasma Life Cycle Diagram - Dennis Jacobs & Mark Fox RVC]] | |
| − | *1 major pathogenic species called ''Toxoplasma gondii''
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| − | *Causes disease in a wide range of animal species including humans
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| − | *Important cause of abortion in sheep
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| − | *Zoonotic
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| − | **Can cause abortion
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| − | **Can cause congenitally aquired defects
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| − | *Forms a sporulated oocyst which is only 10μm
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| − | **Contains 2 sporocysts with 4 sporozoites
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| − | *Transmission through ingesting the intermediate host or via the faecal-oral route
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| − | '''Life Cycle'''
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| − | *Complex
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| − | *Usually indirect
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| − | **Reffered to as '''facultatively heterxenous'''
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| − | **Intermediate host is not essential for completion of the life cycle
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| − | *Gametogeny (sexual stage) is host specific for felids
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| − | *Any warm blooded animal can act as a facultative intermediate host
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| − | **Asexual reproduction occurs in the intermediate host forming tissue cysts
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| − | **Intermediate host swallows sporulated oocysts or tissue cysts
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| − | **Can be transferred between intermediate hosts by carnivorism
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| − | '''Pathogenesis'''
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| − | *Toxoplasma can cause [[Pancreas Inflammatory - Pathology#Acute haemorrhagic pancreatitis|acute interstitial pancreatitis]] in systemic toxoplasmosis
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| − | *''T. gondii'' in [[Respiratory Parasitic Infections - Pathology#Toxoplasmosis|pneumonia]]
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| − | *''Toxoplasma gondii'' causes [[Muscles Inflammatory - Pathology#Protozoa|myositis]]
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| − | ==Sarcocystis==
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| − | *Most infections are asymptomatic
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| − | *Heavy infections are causes of chronic wasting in large animals, hide sondemnation and downgrading of carcasses
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| − | *''Sarcocystis'' should be differentiated from other tissue-cyst forming coccidia
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| − | *There are many species of ''Sarcocystis''
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| − | *Sporulated oocyst has 2 sporocysts containing 4 sporozoites
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| − | **Naked oocyst usually seen in faeces as the oocyst wall is very delicate
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| − | *Indirect life cycle
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| − | *Life cycle alternates between the final and the obligatory intermediate host
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| − | *Only one final and one intermediate host
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| − | ==Neospora==
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| − | *2 main species
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| − | **''Neospora caninum'' in the dog
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| − | **''Neospora hughesi'' in the horse
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| − | *Sporulated oocysts measuring just 10μm
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| − | *Oocyst contains 2 sporocysts with 4 sporozoites
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| − | *Route of transmission not fully understood
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| − | *Often misdiagnosed as ''Toxoplasma gondii''
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| − | **''Sarcocystis'' cysts have thicker walls
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| − | *Infection diagnosed by IFAT, ELISA or PCR
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| − | **Identification of lesions and organisms in tissue using immunohistochemical staining
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| − | **Eliminate other causes of abortion first
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| − | '''Life cycle'''
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| − | *Life cycle similar to ''Toxoplasma gondii''
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| − | *Limited range of warm-blooded intermediate hosts
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| − | **Asexual reproduction occurs in intermediate host forming tissue cysts
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| − | *Host range of sexual stage is unknown for ''N.caninum''
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| − | **Intermediate host for ''N.hughesi'' is the horse, but the definitive host is unknown
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| − | *Final host
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| − | **Dogs pass oocysts
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| − | **Role not fully understood in pathogenesis
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| − | **5 day prepatent period
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| − | **Other wild canids may also act as final definitive hosts
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| − | *Intermediate host
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| − | **Mostly cattle
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| − | **Natural infection has been documented in other herbivores
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| − | *Transmission
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| − | **Transplacental infection occurs in all intermediate hosts and in the canine final host
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| − | ***Transplacental can occur in '''successive pregnancies'''
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| − | **In cattle, vertical transmission occurs
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| − | ***Post-natal infection occurs but is less common
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| − | '''Pathogenesis'''
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| − | *Dogs
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| − | **Occurs mainly in puppies
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| − | **Causes ascending paralysis, especially of hind limbs, with muscle wasting
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| − | **Causes sudden collapse due to myocarditis
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| − | **More than puppy in a litter may be affected, although this may not occur simultaneously
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| − | **Successive litters affected
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| − | *Cattle
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| − | **Commenest cause of infectious abortion in dairy cattle
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| − | **Congenitally infected calves can have encephalomyelitis and paresis
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| − | **Abortion usually occurs between 5-7 months of gestation but can occur as early as 3 months
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| − | **No other clinical signs in the cow
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| − | **Repeat abortions possible in same cow (persistently infected)
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| − | *Horses
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| − | **Myeloencephalitis
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| − | **Transplacental infection occurs
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| − | **Disease only diagnosed in USA
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| − | '''Prevention and Control'''
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| − | *Do not allow dogs access to calving cows, placental membranes and aborted or dead calves
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| − | *Do not allow dogs to defecate in cattle feeding areas
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| − | *Identify and cull seropositive cattle, or do not breed from them or their progeny
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| − | *Select seronegative cattle for breeding
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| − | *Vaccinate
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| − | **Only in the USA
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| − | **Neoguard or Intervet
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| − | **Killed protozoal vaccine for healthy, preganant cows
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| − | **Dosed in first 3 weeks of pregnancy and then every 3-4 weeks during gestation
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| − | **Revaccination with 2 doses during each subsequent pregnancy
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