Newcastle disease & Avian Influenza Flashcards
Newcastle disease general
• Chicken-turkey-pigeon-pheasant»>waterfowl, humans
• velogenic strains
- fatal viraemia in all age
- viscerotrop & neurotrop (pneumotrop)
• mesogenic strains
- In young chicks: viraemia & respiratory disease
-adult: nervous symptoms
=>Layers: hypopigmented eggs
•infection (in flock):
inhalation (aerosol) ;via conjunctiva; per os
•pathogenesis:
Infection>replication at the mucosa>viraemia>viruses reach all organs>(MODS – multiple organ dysfunction syndrome)
Newcastle disease (Avian Pest) • The pathogen
Paramyxoviridae> Paramyxovirinae> Avulavirus genus • Paramyxovirus-1 (APMV-1)= Newcastle disease virus (NDV) • Virulence categories: -Velogenic +++ ICPI>1,5 ->Viscerotropic – VVNDV – GI tract ->Neurotropic – NVNDV - CNS -Mesogenic ++ ICPI 0,5-1,5 -Lentogenic +(/-) ICPI <0,5 -apathogenic
Velogen-viscerotrop form of ND
Lesions: • multiple haemorrhages • intestinal lesions • conjunctivitis • rhinitis • cyanotic appendices on the head • swelling of the tissues around the eyes and neck • brain and spinal cord lesions • (respiratory lesions) •necrotic Peyer's patches
Velogen-neuro(pneumotrop)ic form of ND
Pathology: • conjunctivitis • cyanotic appendices of the head • swelling of the tissues around the eyes and neck • multiple haemorrhages • respiratory lesions • brain and spinal cord lesions • No intestinal lesions are seen!
Mesogenic strains
Were used for vaccine production • Appear at some areas till now • Lesions • In young chickens: • viraemia can occur • and respiratory lesions • In young adults and adults: • nervous signs • In layers: decreased egg production=>Inflammation in the female genital tract
Newcastle disease
•OIE A-list disease
mandatory report
to state vet services
Human aspects: • Humans are also susceptible • In experimental infection • conjunctivitis, eyelid oedema, lacrimation, viraemia, fever, weakness • Exposure of humans to aerosol containing ND strains during the vaccination should be avoided
Avian influenza
• Pathogen
e 8-sRNS • Orthomyxoviridae • Influenzavirus • type A influenza viruses • round or filamentous
• different HA (haemagglutinin)• and NA (neuraminidase) subtypes
• HA subtype (H1-15)
-Viral surface glycoprotein, Binding (syalic acid in the resp. & GI epithelial cells) Fusion with host
• NA subtype (N1-N9)
-Viral enzyme• Cleaves syalic acid groups
• Escape from host cell
• Forms:
- Apatogenic Avian Influenza, AAI
- Low Pathogenic Avian Influenza, LPAI
- Middle Pathogenic Avian Influenza, MPAI
- Highly Pathogenic Avian Influenza, HPAI
Avian influenza
• Pathogen 2
• the influenza viruses are unstable, variable, mutations often occur
• in birds:
-any type of HA-subtypes can be found,• often H5, H7 HA-subtype is identified
• H5N1 (caused pandemic between 2003-2005)
• infection:
-direct contact, saliva
-respiratory discharge, aerogenous
-virus contaminated water/feed, per os
• the virus is spread by wild birds
Variablility of infuenza viruses • 10 000-1 000 000x times higher rate of mutations compared to other organisms • Only 1% is an exact copy (most are faulty) single mutation=> genetic/antigenic drift • 8 part, segmented genome if multiple viruses in one host segments can be resorted => genetic/antigenic shift
Avian influenza- Symptoms
Main feature:
• viraemia
• general febrile status
• haemorrhages:• respiratory• GI• genital•CNS
• rapid death (even 100%)
Pathology:
•petechial jemorrhage under epicardium
•MYOCRADIAL DEGENERATION=> tiger heart
•multifocal necrosis of pancreas parenchyma
• conjunctivitis, lacrimation
• edema of the head; cyanotic wattles
• multiple hemorrhages and necrosis in the skin
• Haemorrhages in GI tract/ haemorrhagic enteritis: proventriculus, intestines, haemorrhagic inflammation of lnn
•acute inflammation in respiratory tract- w/ haemorrhages and discharge
• Hemorrhagic encephalomyelitis (histopathology!)
Duck plague
• Other name:
• duck viral enteritis (DVE)
• eendenpest (NL), peste du canard (F), Entenpest (D)
• Pathogen: Alphaherpesvirinae dsDNA
• Herpesvirus, duck enteritis virus (DEV)
(Marek, Aujeszky)
• Susceptible species: duck, goose, swan,
• spreading:
-the sick & survived birds shed the virus
-lifelong carrier state& shedding
-wild birds transport the virus
• infection:
-direct contact,-fomites, -Live water can also transmit the virus
Duck plague
• Pathogenesis
1 primary replication at the site of entry 2 in the lymph follicles, in the macrophages 3 viraemia 4 virus reaches all the organs=>liver, mucous membranes, immune organs • clinical findings: -lacrimation, heavy breathing, diarrhea -nervous symptoms -drop in egg production -5-100% mortality • Pathology: -multiple hemorrhages -edema in the subcutaneous connective tissue -oesophagus, cloaca and phallus=>acute inflammation, followed by necrotic inflammation - croupous enteritis - hemorrhagic-necrotic inflammation in the lymph follicles •Histopathology: • liver • esophagus, cloaca • necrotic foci • nuclear inclusion bodies
Turkey coronavirus
• Coronaviridae (TuCoV) – enveloped RNS vírus • 1950’s: North-America, now worldwide • digestive and bursal epithelium • virus shedding for weeks in survivors • diarrhea • today: 1-10% (PEMS) • a study in 2007 found 36% of the farms affected
