Newcastle Disease is caused by a virus. The first symptoms usually consists of respiratory distress and rasping followed in 1 or 2 days by a paralysis of legs and wings and bad down between legs or straight back over shoulders. A twisting of the neck (stargazing may also be observed.
In adult birds, loss of production along with some respiratory distress and paralysis after 4 to 6 days.
Many species of birds, both domestic and wild
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
Direct contact with secretions, especially faeces, from infected birds
Contaminated feed, water, implements, premises, human clothing, etc.
The mortality and morbidity rates vary among species, and with the strain of virus
Incubation period is 4-6 days
Sources of virus
Respiratory discharge, feces
Virus is shed during the incubation period and for a limited period during convalescence
Some psittacine birds have been demonstrated to shed the virus intermittently for over 1 year
Endemic in many countries. Some European countries have been free of the disease for years
Symptoms / Diagnosis
Respiratory and/or nervous signs:
gasping and coughing
drooping wings, dragging legs, twisting of the head and neck, circling, depression, inappetence, complete paralysis
Partial or complete cessation of egg production
Eggs are misshapen, rough-shelled, thin-shelled and contain watery albumen
Greenish watery diarrhea
Swelling of the tissues around the eyes and in the neck
Morbidity and mortality depend on virulence of the virus strain, degree of vaccinal immunity, environmental conditions, and condition of the flock
PREVENTION AND CONTROL
There is currently no treatment.
Procedures to control the disease:
Strict isolation of outbreaks
Destruction of all infected and exposed birds
Thorough cleaning and disinfection of premises
Proper carcass disposal
Pest control in flocks
Depopulation followed by 21 days before restocking
Avoidance of contact with birds of unknown health status
Control of human traffic.
One age group per farm ('all in-all out') breeding is recommended
Vaccination with live and/or oil emulsion vaccines
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