POULTRY MED L4: Newcastle Disease (NCD/ ND)

Newcastle disease (ND)

It caused several panzootics in poultry in the 1920s, 1960s and 1970s/80s, all originating in the Middle East

Indonesia, and in Newcastle, UK

ND is a serious highly infectious systemic disease of birds first described in 1926/7 in __ and __

Paramyxoviridae

NDV is one of the 21 currently identified strains of avian paramyxovirus belonging to the family ___, which infect birds

Orthoavulavirus

NDV is one of the 21 currently identified strains of avian paramyxovirus belonging to the genus ___, which infect birds

Avian paramyxovirus type 1(APMV-1)

NDV is a variant of ____ which are negative-sense, single-stranded RNA viruses. NDVs have a range of virulence but all are lethal in fully susceptible birds.

Tropism

NDVs have a restricted tropism to avian species, and it is likely that all avian species may act as host to infection, but some may be more important than others. ___ is a virus's biological preference to infect specific cell types, tissues, or host species

Wild waterfowl, Columbiformes

2 natural reservoir hosts of NCD virus

ducks

All species of domestic poultry are susceptible, although ___ appear to be less susceptible to clinical disease but can still shed virus

typhoons

Outbreaks in the Philippines usually rise after ___

infected birds

Main mode of transmission into farmed animals is through the introduction of ___

fomite

The major pathway for spread of Newcastle disease, other than direct movement of infected live birds, is through __ transmission via human activity on contaminated footwear, clothing, vehicles, feed and equipment. Feral birds can spread virus via fomite transmission.

several

The virus can persist in carcasses, feces and the environment for __ weeks, further complicating the risk pathways.

intestinal

The main methods of transfer between infected birds and susceptible birds include short distance droplet spread (aerosol) or via dust (fomites), particularly following respiratory infection. Respiratory and particularly ___ infections can result in contaminated food or water which can lead to very rapid spread within a poultry house

aerosol

Transmission: Respiratory = through __

droppings

Transmission: Intestinal = through __

5–6

The incubation period for natural exposures to NDV varies between 2 and 15 days, averaging around __ days, but may take 3–4 weeks in some circumstances

Aerosol transmission

__ may have a shorter incubation time than an infection started through ingestion of the virus.

pathognomic

The clinical signs/Gross Lesions of ND are not ___

viscerotropic velogenic

high virulence; causing acute lethal infections with haemorrhagic lesions in the intestines

neurotropic velogenic

(high virulence) causing high mortality involving respiratory and neurological clinical signs but without gut lesions

mesogenic

(medium virulence) involving respiratory and neurological signs but with low mortality

Lentogenic

(low virulence) causing mild respiratory infections

asymptomatic enteric

(low virulence) which cause avirulent infections with replication taking place primarily in the gut

high

virulence level of viscerotropic velogenic & neurotropic velogenic

medium

virulence level of mesogenic

low

virulence level of Lentogenic & asymptomatic enteric

host species, age and immunological status

The course of disease is affected not only by the virulence of the strain involved but also by the ___, ___ and ___

velogenic

Infection can be wide ranging with virulent ___ strains being so acute that sudden death may be the first sign of disease

acute

Less __ signs include depression, diarrhea, edema of the head, and neurological signs including torticolis but with very high levels of mortality

may be soft, or birds stop laying altogether

condition of egg shells

Mesogenic strains

produce respiratory signs with neurological sequela and levels of mortality <50%

Low virulence

___ strains produce mild respiratory disease or none at all

co-infection with other pathogens, and poor husbandry

Exacerbating circumstances (making a bad situation worse) including ___ and ___ may cause apparent increases in virulence

velogenic

Infection with ___ strains can result in necrotic lesions with hemorrhages in several organs.

trachea

Respiratory infections can cause inflammation of the ___ sometimes with hemorrhages. The air sacs may also be inflamed and cloudy.

proventriculus

Intestinal infections may be characterized by hemorrhages including in the ___

ruffled

Birds appear depressed and lethargic with ___ feathers

eyelid

Hemorrhage of the lymphoid tissue of the lower ___

ceca and SI

Hemorrhage and necrosis of ___ and ___

True

T or F: It has NO significant public health risk

Mild conjunctivitis

__ may follow contact with infected birds or following exposure to live virus during mass vaccination processes

1. RT-PCR/rRT-PCR

2. Viral Isolation

2 Diagnostic tests for NCD

RT-PCR/ rRT-PCR

diagnostics that are mainly used in farms because they are fast, and may differentiate NCD infection from vaccination

Viral Isolation

diagnostics Used if there are not enough clinical signs present which makes selection of birds for collection of samples difficult (Takes 2-14 days to isolate the virus)

Ulster and VG/GA

Prophylactic vaccination: Inactivated and live NDV vaccines formulated with NDVstrains of low virulence, such as B1, LaSota, and more recently __ and __, are the most commonly administered vaccines

21

Control: Stamping out followed by __ days without poultry before restocking

True

T or F: There are no treatments for NCD and in most instances all infected birds are culled to contain an outbreak

secondary bacterial infections

Treatment for infections with NDV of low virulence consists of addressing ___ with particular attention to Gram‐negative bacteria

respiratory, gastrointestinal, nervous, and reproductive

The disease affects the __, __, __, and __systems and causes up to 100%mortality in nonvaccinated chickens.

Virus isolation

is the gold standard diagnostic test

Culling

___ infected birds is often necessary to contain ND outbreaks in countries normally free of the virulent virus