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New page: {{unfinished}} {{toplink |linkpage =Viruses |linktext =VIRUSES |sublink1=Retroviridae |subtext1=RETROVIRIDAE |pagetype =Bugs }} <br> ====Pathogenesis==== *Primary replication in '''lung ...
{{unfinished}}
{{toplink
|linkpage =Viruses
|linktext =VIRUSES
|sublink1=Retroviridae
|subtext1=RETROVIRIDAE
|pagetype =Bugs
}}
<br>
====Pathogenesis====
*Primary replication in '''lung macrophages'''
*These then carry infection to '''brain, lung, udder and/or joints'''
*T cells react: '''Type IV immune complex disease'''
*Target organs become chronically inflamed after 2-6 years
*Visna:
**Inflammation results in '''demyelination''' with '''subacute meningitis''' around ventricles and choroid plexus
**'''Posterior paresis''' progresses for up to a year until sheep can no longer stand
*Maedi:
**Alveolar septa become infiltrated by lymphocytes and macrophages
**Smooth muscle hypertrophy
**PM: lungs are heavy, rubbery and do not collapse
*All result in loss of condition
*Infected animals remain antibody and virus positive
====Epidemiology====
*Transfer via '''aerosol, milk or colostrum'''
*Increased risk in '''winter housing'''
====Diagnosis====
*Clinical signs
*Serology: '''AGDT'''/'''ELISA''' for '''antibody'''
====Control====
*Seropositive and progeny must be removed from flock
*Farm can be re-accredited after 2 years of clear tests
{{toplink
|linkpage =Viruses
|linktext =VIRUSES
|sublink1=Retroviridae
|subtext1=RETROVIRIDAE
|pagetype =Bugs
}}
<br>
====Pathogenesis====
*Primary replication in '''lung macrophages'''
*These then carry infection to '''brain, lung, udder and/or joints'''
*T cells react: '''Type IV immune complex disease'''
*Target organs become chronically inflamed after 2-6 years
*Visna:
**Inflammation results in '''demyelination''' with '''subacute meningitis''' around ventricles and choroid plexus
**'''Posterior paresis''' progresses for up to a year until sheep can no longer stand
*Maedi:
**Alveolar septa become infiltrated by lymphocytes and macrophages
**Smooth muscle hypertrophy
**PM: lungs are heavy, rubbery and do not collapse
*All result in loss of condition
*Infected animals remain antibody and virus positive
====Epidemiology====
*Transfer via '''aerosol, milk or colostrum'''
*Increased risk in '''winter housing'''
====Diagnosis====
*Clinical signs
*Serology: '''AGDT'''/'''ELISA''' for '''antibody'''
====Control====
*Seropositive and progeny must be removed from flock
*Farm can be re-accredited after 2 years of clear tests