Newcastle disease virus (NDV) - NDV is endemic in many countries of the world. Some European countries have been free of the disease for years. It is a contagious and fatal viral disease affecting most species of birds. Clinical signs are extremely variable depending on the strain of virus, species and age of bird, co current disease, and pre-existing immunity. .
Classification of the causative agent.
Virus family Paramyxoviridae, genus Rubulavirus.
Temperature: Inactivated by 56°C/3 hours, 60°C/30 min.
PH: Inactivated by acid pH.
Chemicals: Ether sensitive.
Disinfectants: Inactivated by formalin and phenol.
Survival: Survives for long periods at ambient temperature, especially in faeces.
.
NDV is spread primarily through direct contact between healthy birds and the bodily discharges of infected birds. The disease is transmitted through infected birds' droppings and secretions from the nose, mouth, and eyes. NDV spreads rapidly among birds kept in confinement, such as commercially raised chickens.
Hosts .
Many species of birds, both domestic and wild .
The mortality and morbidity rates vary among species, and with the strain of virus .
Chickens are the most susceptible poultry, ducks and geese are the least susceptible poultry .
A carrier state may exist in psittacine and some other wild birds .
Transmission.
Direct contact with secretions, especially faeces, from infected birds .
Contaminated feed, water, implements, premises, human clothing, etc. .
Sources of virus.
Respiratory discharges, faeces .
All parts of the carcass .
Virus is shed during the incubation period and for a limited period during convalescence .
Some psittacine birds have been demonstrated to shed ND virus intermittently for over 1 year .
Symptoms.
Coughing, sneezing, rattling in the windpipe - decreased feed consumption - increased water consumption - nervous symptoms and paralysis - heads down or in circles - stopping egg production - many soft shelled eggs - yellowish cloudy air sacs .
