Newcastle disease is a highly contagious and fatal viral disease that affects domestic poultry and wild birds. It produces gastrointestinal, respiratory, and neurological signs in poultry. The causative agent is avian paramyxovirus type 1, which has varying levels of pathogenicity in chickens. Newcastle disease virus is transmitted through direct contact with infected secretions via the fecal-oral route or inhalation, or indirectly on objects like cages, clothing, and eggshells contaminated with feces housing the virus.

1. NEWCASTLE DISEASE
 Newcastle disease (ND) is a highly
contagious, generalized viral disease
of domestic poultry, cage and aviary
birds, and wild bird
 It is usually seen in domestic
gallinaceous birds (poultry) as a
rapidly fatal, high-mortality condition
characterized by gastrointestinal,
respiratory and/or nervous signs

2.  In other avian species, the disease
produced by virulent ND viruses ranges
clinically from in apparent to a rapidly
fatal condition
 ND viruses have varying capability
(pathogenicity) to produce clinical
disease in domestic chickens, with some
virus strains showing high levels of
pathogenicity while other strains produce
no disease and are classified as
nonpathogenic (avirulent)

3. Etiology
 ND virus is an avian paramyxoviruses
of type 1serotype (APMV-1). Overall,
there
are nine serotypes of APMV (types 1–9)
Occurrences
World wide in distribution

4. Transmission
Direct contact with secretions of infected
birds; principally via ingestion (faecal/oral
route) and inhalation
Fomites: feed, water, implements,
premises, human clothing, boots, sacks,
egg trays/crates, etc.
 Survival of agent is prolonged by
presence of faeces; as in soiled egg shells
 Hatching chicks may be infected through egg
for some NDV strains; transmission of highly
virulent isolates is uncommon