Newcastle disease (NCD, atypical avian influenza) is a highly contagious, acute to chronic disease of birds.

Worldwide

All birds

Direct transmission via all body fluids (faeces, eye, nose and throat secretions), indirect transmission via the air and objects. The virus can also be transmitted to the chick already in the egg.

4 to 7 days

Cold symptoms, neurological symptoms, diarrhoea. The clinical picture is reminiscent of avian influenza (bird flu)

There is no treatment for Newcastle Disease...

Newcastle Disease is a notifiable animal disease according to the Animal Health Law (AHL). Prophylactic vaccination is permitted in Austria and is also carried out in chickens, turkeys and pigeons (racing and breeding pigeons).

Newcastle disease last occurred in Austria in poultry in 1997, but is observed sporadically in wild pigeons and rarely in dometic pidgeons.

Newcastle disease is a notifiable disease. The occurrence of clinically suspicious symptoms must be reported to the official veterinarian, who takes the samples and sends them for diagnosis. Only highly pathogenic virus types are notified as disease if a velogenic (highly pathogenic) pathotype of the virus strain is detected by sequencing of the viral fusion protein gene or the virus has a pathogenicity index (ICPI) of 0.7 or higher.

After Newcastle disease is detected, all birds in the affected holding are killed in accordance with the Animal Health Law (AHL).

The causative agent of Newcastle disease is the Newcastle disease virus (avian avulavirus 1, APMV-1), a single-stranded RNA virus from the Paramyxoviridae family. NDV is assigned to the genus Avulavirus. A distinction is made between apathogenic, lentogenic (low virulence), mesogenic (low virulence) and velogenic (high virulence) virus types. The symptoms depend on the virulence of the pathogen.

In the bone marrow and muscles of slaughter poultry, the NCD virus remains infectious for 6 months at -20 ⁰C and up to 134 days at 1 ⁰C. In contaminated stables, the virus remains infectious for 25-30 days depending on the ambient temperature. The infectivity of the virus can be preserved for years by drying out.

Transmission can occur via the air, directly or via objects. The spread of the disease is favoured by the high tenacity of the virus and the broad host spectrum. Sources of infection are often clinically inapparent infected, diseased animals or animals in the incubation period.

NDV is excreted in large quantities via faeces, eye, nasal and throat secretions and all other body fluids. Virus excretion begins during the incubation period and, depending on the bird species affected, can last from 1-2 weeks to several months or about 1 year; in vaccinated animals about 2 weeks. The pathogens are spread directly from animal to animal as well as indirectly via all equipment, house dust and air, shoes and vehicles. Transovarial virus transmission plays a major role, whereby infected chicks hatch from NCD virus-contaminated eggs.

Trade in live or slaughtered poultry or their products plays a role in the introduction of the disease into disease-free regions (introduction also via frozen poultry!). Virus transmission is also possible via the feeding of kitchen waste, litter, feed, housing equipment and transport containers. In comparison, the probability of transmission via wild birds is low. With regard to wild birds, waterfowl and wild chickens are a natural reservoir for epidemics.

Newcastle disease is spread worldwide. The disease has become less significant in recent years due to control measures. In July 2018, an outbreak was reported in domestic chickens in Belgium.

Laboratory diagnosis is carried out by pathogen detection from tracheal/oropharyngeal (throat) and cloacal swabs as well as from animal carcasses (CNS, lung, liver, kidney, heart, intestine) using specific molecular biological methods (real-time RT-PCR, fusion RT-PCR and additional pathotyping using Sanger sequencing) as well as by virus cultivation in egg culture and subsequent haemagglutination test (HA) and haemagglutination inhibition test (HAH). The detection of antibodies using ELISA and HAH is possible, but must be evaluated depending on the situation if vaccination is permitted.

All diseases with a differential diagnosis are possible:

• acutely increasing mortality
• respiratory disorders
• disorders of the central nervous system (CNS)
• drop in laying performance
• Reduction in weight gain
• petechial haemorrhages due to seroses

z. e.g. infectious bronchitis, infectious laryngitis, avian influenza, Marek's disease, avian cholera, mycoplasmosis, deficiency symptoms.

At the slightest suspicion, the responsible official veterinarian must send the legally required samples to the National Reference Laboratory.

Sample type for sampling:

Live animals:

• Throat and cloacal swabs (dry, sterile, no bacteriological swab transport medium)
• Serum

Samples from dead animals:

• Organ material especially brain, lung, liver, kidney, heart, intestine
• Sample transport and short-term storage: at +4 °C

Detection methods according to WOAH

Direct pathogen detection:

• Rapid diagnosis: Quantitative APMV-1 real-time RT-PCR and fusion protein RT-PCR

• Pathotyping of the fusion protein by Sanger sequencing determines whether it is a high or low pathogenic virus

• Virus detection via egg culture and haemagglutination: The pathogen is detected by inoculation of organ suspensions from the brain, lungs, liver, kidneys and heart of diseased animals into the allantoic cavity of 9-11 day old chicken embryos

Indirect virus detection (antibody detection):

• Antibodies can be detected in chronic forms of the disease; however, the vaccination status of the animals must be taken into account.
• Haemagglutination inhibition