Occurrence: Worldwide. Very common. Notifiable disease   Species affected: All. One of the most common respiratory diseases of poultry.   Age affected: All.

Causes: Virus- Newcastle disease virus is a single-stranded, non-segmented enveloped RNA virus belonging to the family Paramyxoviridae. There are three pathotypes: lentogenic (mild disease), mesogenic (moderate disease) and velogenic (severe morbidity and mortality). Spread is airborne by inhalation or by ingestion of the virus.

Effects: Incubation period is 2-15 days. Paralysis, incoordination and central nervous signs following the initial respiratory signs are diagnostic of NDV. Watery eyes and a plug in the eye are seen with lentogenic strains. Coughing, gasping and sane mortality are seen with mesogenic strains. Egg production and egg quality are affected. It may [produce torticollis, paralysis and bloody diarrhoea. High morbidity and mortality occur with velogenic pathotype.

This disease was named after a town in England where it was first isolated. All species of bird of all ages are susceptible to this acute to chronic disease. It is one of the most common respiratory diseases of poultry and occurs worldwide. The agent involved in the aetiology of this disease is a single-stranded, nonsegmented, enveloped, RNA virus belonging to paramyoviruses. Three pathotypes or strains exist. The lentogenic cause mild disease, the mesogenic produce moderate disease and the velogenic produce severe morbidity and mortality.

It is airborne and spread by inhalation or ingestion of virus.

Migratory birds may spread the infection from country to country.

VVND is a notifiable disease.

It is a very common viral disease of poultry worldwide. Most poultry are vaccinated several times against this virus.

(The incubation period is 2-15 days).

Watery eyes and a plug in the eye are seen with lentogenic strains.

Coughing, gasping and sane mortality are seen with mesogenic strains.

It affects egg production and quality (brown broiler eggs turn to white eggs). It may produce torticollis, paralysis and bloody diarrhoea. High morbidity and mortality occur with visceral tropic velogenic (VVND). VVND (exotic) rarely occurs in commercial poultry in the United States. The last outbreak of VVND occurred in 1976 in California and resulted in destruction of 20 million birds. However, outbreaks in pet bird populations are more frequent. It is a common problem in many countries such as the Middle East, Africa and the Far East.

Lesions include cloudy air sacs, congestion and oedema of lungs, abdominal yolk, oedema of bronchi and parbronchi, mucous in trachea and nasal turbinates. Internal haemorrhage may be seen inn VVND (lungs, intestines, gizzard, proventriculus and caecal pouches).

The clinical disease (respiratory and central nervous signs) and gross and microscopic lesions in trachea, nasal trubinates and lungs are helpful in the diagnosis.

Paralysis, incoordination, central nervous signs after first respiratory signs, are diagnostic for NDV. It can be complicated by Mycoplasma or E. coli resulting in CRD and severe air sacculitis. Domestic lento or mesogenic NDV cause mild respiratory disease. Isolate and identify virus from trachea of clinically ill birds in cell culture or chicken embryos for definitive diagnosis.

The HI or ELISA test for measuring a rise in antibody titer is helpful.

Vaccinate by coarse spray or eyedrop at one day, or by water or coarse spray at seven days old. In VVND areas, an inactivated vaccine may also be given at 1 and/or 14 days of age.

Revaccination by water or spray is done at 14-21 days.

Breeders or layers can be vaccinated by water or coarse spray at 6-8 week intervals throughout the growing period in areas with high infection pressure.

An inactivated NDV vaccine can be used at around 18 weeks for breeders or layers. Continue live vaccination throughout lay every 6-8 weeks.

In the US the B1 strain is used fo rhte 1st and 2nd vaccination, and lasota or cloned lasota is used thereafter. Outside ht US, Hitchner B1 is less used because it gives only limited protection. Instead, primovaccination is given with cloned lasota.

NDV vaccination is usually combined with infectious bronchitis (IB) vaccine. Outside the US, it is preferred to give IB and ND separate to avoid interference of these vaccines. Only in case of cloned IB vaccine, combinations can be used without loosing effect.

Biosecurity is important to control the disease. Imported birds are subject to import quarantine regulations.

In many countries, a stamping out policy is used for Newcastle disease. Were allowed, emergency vaccination in case of acute outbreaks help to reduce clinical problems.

A broad-spectrum antibiotic can be given to control secondary invaders, especially E. coli from causing CRD.