1. RobertGracia
Psittacine BeakandFeatherDisease iscausedbyavirusknownas a Circovirus.Thisvirusisa
single strandedDNA virusthatencodesforsevenproteinsandcontainsmultiplevariants. Sincethese
variantsdiffergeneticallytestingforthe disease mustinclude teststhatare specifictoeach variantor
teststhat detecta commonmarkerbetweenall the knownvariants,suchasa PCR assay.
The virusis spreadfrominfectedbirdsviafeces,cropsecretions,andskinandfeatherdander.
Transmissionof the virusisthoughttooccur byboth horizontal andvertical transmission,the former
vectorbeingof more importance.Itisbelievedthe virusentersitsnew hostby eitherbeingingestedor
inhaled.Once inside the hostthe virustravelstodifferenttissueswhere itcanreplicate andincrease in
number.Many tissuescanbe infectedbyviral infiltration,suchas the Bursa of Fabricus,crop, thymus,
intestine,esophagus,feathers,integument,andinleukocytes. The viruscausescomplicationswiththe
epidermisandvariouscomponentsthatinteractatthe integumentlevelwhichcausesfeatherdysplasia,
featherloss,andhemorrhage. Damage tothe epidermisof the beakcausedbythe viruscauses
overgrowthandeventuallylossof structural integrity. Necrosisof tissuethatshare immune system
importance suchas the Bursa of Fabricus,thymus,andleukocytes,cause immune suppressionand
predisposesthe hosttoothersecondarydisease.
There are three typesof clinical presentationsof Psittacine BeakandFeatherDisease;the
peracute form,the acute form,and the chronic form. The peracute formaffectsveryyoungchicksand is
rapidlyfatal andconsistsof septicemia,enteritis,andpneumonia. The acute formaffectsweanedchicks
from7 weeksto9 months,andisdescribedbya rapid onsetof crop stasis,weakness, diarrhea,
depression,featherdysplasia, regurgitation,anddeathwithin2weeks. The chronicformusuallyoccurs
inbirdspast the age of 8 to 10 monthsthat are infectedwiththe PBFDvirus. Some of the classicsigns
notedare a lackof powderonthe beak,delayedmolt,thickeningof the feathersheath,apteriazones,
featherdystrophy,overgrownbeak,beaknecrosis,nail necrosis,hemorrhagewithinthe feathershaft,
immunosuppression,secondaryinfections,anddeathwithinafew yearsdependingonthe severityof
the clinical signs.
Control of PBFDV is veryimportantandcan be accomplishedbyPCRtestingall birdsinyour
aviaryto ensure there are nocarriers.If any birdsare infecteditsrecommendedtoremove themfrom
the aviary.Priorto introducinganynewbirdstothe aviarytestingshouldbe done onall new birdsto
ensure there notcarriers.Foraddedsafetya quarantine periodof atleasta monthwithanothertest
priorto introductionintothe aviary,shouldbe done toensure anyrecentlyexposedbirdswill notgo
undetected.Forlarge scale aviariesswabsof the facilitiescanbe done toensure novirusisin the
environment.The PBFDvirusishighlyresistanttomanydisinfectantssoanaggressive decontamination
protocol shouldbe followed.