Newcastle Disease in Poultry

Overview

Newcastle disease is a contagious and fatal viral disease affecting all species of birds. It is one of the most infectious diseases of poultry in the world. The mortality in unvaccinated birds can reach 100 percent, and birds may die without any clinical signs of disease.

The Newcastle disease is a worldwide problem. It presents primarily as an acute respiratory disease, but depression, nervous manifestations, or diarrhea may be the predominant clinical form. Severity depends on the virulence of the infecting virus and host susceptibility. It is transmissible to humans. Though it can infect humans, most cases are non-symptomatic; rarely it can cause a mild fever and influenza-like symptoms in humans.

This disease is transmitted most often by direct contact with diseased or carrier birds. Infected birds may shed the virus in their feces, contaminating the environment. Transmission can then occur by direct contact with feces and respiratory discharges. Also by contaminated food, water, equipment, and human clothing. Newcastle disease viruses can survive for several weeks in the environment, especially in cool weather.

The disease is very contagious. Virtually all the birds will be infected within two to six days when the virus is introduced into a susceptible flock,. The virus is present in all parts of the carcass of an infected bird.

Clinical Signs of Newcastle Disease in Poultry

The Newcastle disease affects the respiratory, nervous, and digestive systems. The incubation period for the disease ranges from 2 to 15 days. An infected bird may exhibit the following signs:

• Respiratory: sneezing, gasping for air, nasal discharge, coughing

• Digestive: greenish, watery diarrhea

• Nervous: depression, muscular tremors, drooping wings, twisting of head/neck, circling, complete paralysis

• Partial to complete drop in egg production, production of thin-shelled eggs

• Swelling of the tissues around the eyes and in the neck,

• Sudden death

• Increased death loss in a flock.

Causes of Newcastle Disease in Poultry

Newcastle disease is a contagious viral disease of birds and considered one of the most important poultry diseases worldwide. The disease can vary from mild to severe. A highly contagious and severe form of the disease, called Exotic Newcastle disease (END). It is so deadly that many birds die suddenly without showing any signs of disease.

Both domestic and wild birds can be affected by Newcastle disease. Chickens are very susceptible to the disease. Turkeys, ducks, geese, as well as parrots, pigeons and wild cormorants can also get END.

How it Spreads

The Newcastle Disease is spread primarily through direct contact between healthy birds and the bodily discharges of infected birds. High concentrations of the exotic Newcastle virus are in birds’ bodily discharges, including droppings and secretions from eyes, nose and mouth. This means the disease can be 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. Manure haulers, rendering-truck drivers, feed delivery personnel, poultry buyers, egg service people, and poultry farm owners and employees are culpable transmitters

The Newcastle virus can survive for several weeks. It survives in a warm and humid environment on birds’ feathers, manure, and other materials. It can survive indefinitely in frozen material. However, the virus is destroyed rapidly by dehydration and by the ultraviolet rays in sunlight.

Prevention and Control of Newcastle Disease

Any animals showing symptoms of Newcastle disease should be isolated immediately. New birds should also be vaccinated before being introduced to a flock. An inactivated viral vaccine is available, as well as various combination vaccines. Poultry owners should strengthen biosecurity practices to prevent the introduction of the disease to their flocks.

Biosecurity Measures on the Farm

Recommended biosecurity measures include:

• Establishing an “all-in, all-out” flock-management policy;

• Protecting against exposure to wild birds or water or ground contaminated by wild birds;

• Closing bird areas to nonessential personnel or vehicles;

• Providing employees with clean clothing and disinfection facilities and directions for their use;

• Thoroughly cleaning and disinfecting equipment and vehicles (including tires and undercarriage) when entering or leaving the farm;

• Restricting the borrowing or lending of equipment or vehicles;

• Visiting other poultry farms, exhibitions, fairs, and sales or swap meets are also stopped

• Banning bringing birds in slaughter channels back to the farm.