Topic 9: Derzsy's disease Flashcards
Occurrence of Derzsys
WW, frequent disease
virus clarified by Derszy in 1970
Severe (acute) in young animals with a high mortality, depending on yolk immunity
Pathogen : Derzsys
Parvovirinae, Dependoparvovirus
AKA. goose plague, goose viral hepatitis, goose parvoviral enteritis, goose influenza
Dependovirus, requires the cell to be infected with Adeno, herpes or vaccinia “helper” virus to replicate productively
Goose Parvovirus GPV, Muscovy Duck Parvovirus MDPV
Antigenic and genetic differences, but disease presentation is identical
GPV can affect both species
VP2, one serotype
Culture in goose embryos and fibroblast cells
Nuclear inclusion bodies
Epidimeiology of GPV, MDPV
all breeds of domestic geese and muscovy duck affected
strictly age dependant in both species
up to 100% mortality in birds under 7-10d
progressive resistance develops, losses are negligible by 4-5w of age
NO CS in infected adults/ birds over 5w (antigenic response)
Transmission of GPV, MDPV
Horizontal and Vertical (germinative)
Horizontal, massive amounts shed in faeces,rapid direct and indirect spread
Vertical, infected egg, embryo dies or infected offspring hatches and infects other susceptible day old goslings
Vertical is responsible for the most severe form of outbreak
Subclinical infections, latent carriers, spread through infected eggs
recovered animals may be life long shedders
Pathogenesis of GPV, MDPV
PO, SI epithelium, Viremia, LIVER, CARDIAC MUSLCE< bv wall and other organs
CS of GPV , MDPV
age dependant and pathogenicity, can be sub acute, acute or chronic
7-10 day old chickens, can be 100% mortality
incubation period is 1 week, death within 1-2 days
may be anorexia and recumbency
Peak mortality @ end of 2nd week, 50-60%
1-4w old, partially protection, maternal immunity
- anorexia, lethargy, loss of feathers, inappetence, polydipsia, cold / flu like symptoms (swollen eye lids, nasal discharge)
profuse, white coloured dra, fibrinous pseudomembranes on oral cavity and tongue
forced movements, convulsions due to liver damage, hepatic encephalopathy
If acute stage. is survived, 1w old may develop dwarfism, curved legs, shorter beaks
- disturbed feather growth around back and neck
ascites, penguin like posture
no CS in infected adult birds over 5 weeks
PM Lesions in GPV, MDPV
Ascites, rich in fibrin swollen liver, spleen and pancreas Ball shaped heart, tiger stripes Haemoorhage on membranes Hepatitis, pericarditis, perihepatitis
Dx of GPV, MDPV
CS, PM lesions and HP
Virus isolation, inoculated eggs, embryonic cell cultures
IF, EM, VN, HA
PCR
Necropsy
AB detection, IF, VN, up t 1:16,000 is from vx
Tx of GPV, MDPV
no specific tx, ab therapy to prevent 2º infection
Prevention and control of GPV, MDPV
prevention of infection during first week of life
keeping hatching flocks separate
do not use survivors fro breeding
remove all +ve geese from flock
test imported geese
Hatchery hygiene
Vx of breeding geese obligatory in most countries
Attenuated and inactivated, recombinant amiable
1 at 4w of age,
Barbary duck parvovirus antigens, 2x @1 month before laying period
Re Vx layers, before the nd of laying season
Active immunisation with virulent virus, gives yolk immunity
hyper immune serum for passive protection of day old goslings (expensive)