Exotic Newcastle Disease
Newcastle disease is a highly contagious viral disease that can be fatal to domestic poultry and other bird species. It is reportable in North Dakota.
Transmission: Newcastle disease virus (NDV) strains are endemic in poultry in most of Asia, Africa and some countries of North and South America. Other countries, including the USA and Canada, are free of those strains in poultry and maintain that status through import restrictions and destruction of infected poultry.
Cormorants, pigeons, and imported psittacine (parrot) species are more commonly infected with NDV and have been sources of NDV infections of poultry. NDV strains of low virulence are prevalent in poultry and wild birds, especially waterfowl.
Infected birds can spread the virus through direct contact with healthy birds and through bodily discharges. Young birds are the most susceptible. The disease is spread easily by mechanical means. Virus-bearing material can be picked up on shoes and clothing and carried from an infected flock to a healthy one. The disease is often spread by manure haulers, rendering-truck drivers, feed delivery personnel, poultry buyers, egg service people, and poultry farm owners and employees. The virus can survive for several weeks in a warm and humid environment on birds' feathers, manure, and other materials. It can survive indefinitely in frozen material. The virus is destroyed rapidly by dehydration and by ultraviolet rays in sunlight.
Clinical signs: Newcastle disease symptoms are primarily those of an acute respiratory disease. Respiratory signs can appear in the flock within 2-12 days after aerosol exposure. Typical respiratory signs are gasping, coughing, sneezing and clicking, rattling, or crackling noises. Neurologic signs may accompany but usually follow the respiratory signs and may include tremors, paralyzed wings and legs, twisted necks, circling, clonic spasms, and complete paralysis. Neurologic signs with diarrhea are typical in pigeons, and are frequently seen in cormorants and exotic bird species. Varying degrees of depression and lack of appetite are seen. Egg production may decrease or cease. Eggs may be abnormal in color, shape, or surface and have watery albumen. Mortality varies but can be as high as 100 percent. Well-vaccinated birds may not show any signs of infection except for decreased egg production, but will shed virus in saliva and feces. Poorly vaccinated birds may develop torticollis, ataxia, or body and head tremors 10–14 days after infection and may recover with supportive care.
Diagnosis: NDV can be isolated from oropharyngeal or cloacal swabs or tissues from infected birds.
Prevention: Newcastle disease can only be eradicated by rapidly destroying all infected flocks and imposing strict quarantine and in-depth surveillance programs. Poultry owners should strengthen biosecurity practices to prevent the introduction of the disease to their flocks. The following are tips on proper biosecurity practices:
- Permit only essential workers and vehicles on the premises. Employees must not have contact with backyard flocks.
- Provide clean clothing and disinfection facilities for all visitors and employees.
- Clean and disinfect vehicles entering and leaving the farm.
- Avoid visiting other poultry operations.
- Keep birds confined and separated from free-roaming chickens.
- Protect flocks from wild birds that may try to nest in poultry houses or feed with domesticated birds.
- Control movements associated with the disposal and handlings of bird carcasses, litter, and manure.
- Take diseased birds to a diagnostic laboratory for examination.
- Use disinfectants.
Zoonotic Risk: The disease has not been reported in people who rear poultry or consume poultry products. Contact the North Dakota Health Department for more information on the risk to humans.