Topic 9: Derzsy's disease

Question 1

Occurrence of Derzsys

Answer 1

WW, frequent disease

virus clarified by Derszy in 1970

Severe (acute) in young animals with a high mortality, depending on yolk immunity

Question 2

Pathogen : Derzsys

Answer 2

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

Question 3

Epidimeiology of GPV, MDPV

Answer 3

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)

Question 4

Transmission of GPV, MDPV

Answer 4

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

Question 5

Pathogenesis of GPV, MDPV

Answer 5

PO, SI epithelium, Viremia, LIVER, CARDIAC MUSLCE< bv wall and other organs

Question 6

CS of GPV , MDPV

Answer 6

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

Question 7

PM Lesions in GPV, MDPV

Answer 7

Ascites, rich in fibrin
swollen liver, spleen and pancreas 
Ball shaped heart, tiger stripes 
Haemoorhage on membranes 
Hepatitis, pericarditis, perihepatitis

Question 8

Dx of GPV, MDPV

Answer 8

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

Question 9

Tx of GPV, MDPV

Answer 9

no specific tx, ab therapy to prevent 2º infection

Question 10

Prevention and control of GPV, MDPV

Answer 10

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)