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Tissue cyst-forming coccidia (view source)
Revision as of 09:20, 17 November 2008
, 09:20, 17 November 2008no edit summary
*Oocyst contains 2 sporocysts with 4 sporozoites
*Oocyst contains 2 sporocysts with 4 sporozoites
*Route of transmission not fully understood
*Often misdiagnosed as ''Toxoplasma gondii''
**''Sarcocystis'' cysts have thicker walls
*Infection diagnosed by IFAT, ELISA or PCR
**Identification of lesions and organisms in tissue using immunohistochemical staining
**Eliminate other causes of abortion first
'''Life cycle'''
*Life cycle similar to ''Toxoplasma gondii''
*Life cycle similar to ''Toxoplasma gondii''
**Intermediate host for ''N.hughesi'' is the horse, but the definitive host is unknown
**Intermediate host for ''N.hughesi'' is the horse, but the definitive host is unknown
*Route of transmission not fully understood
*Final host
**Dogs pass oocysts
**Role not fully understood in pathogenesis
**5 day prepatent period
**Other wild canids may also act as final definitive hosts
*Intermediate host
**Mostly cattle
**Natural infection has been documented in other herbivores
*Transmission
**Transplacental infection occurs in all intermediate hosts and in the canine final host
***Transplacental can occur in '''successive pregnancies'''
**In cattle, vertical transmission occurs
***Post-natal infection occurs but is less common
'''Pathogenesis'''
*Dogs
**Occurs mainly in puppies
**Causes ascending paralysis, especially of hind limbs, with muscle wasting
**Causes sudden collapse due to myocarditis
**More than puppy in a litter may be affected, although this may not occur simultaneously
**Successive litters affected
*Cattle
**Commenest cause of infectious abortion in dairy cattle
**Congenitally infected calves can have encephalomyelitis and paresis
**Abortion usually occurs between 5-7 months of gestation but can occur as early as 3 months
**No other clinical signs in the cow
**Repeat abortions possible in same cow (persistently infected)
*Horses
**Myeloencephalitis
**Transplacental infection occurs
**Disease only diagnosed in USA
'''Prevention and Control'''