Newcastle Disease: 10 clinical signs you should know

Newcastle disease is a highly contagious and severe disease often found worldwide, affecting birds, including domestic poultry.

Newcastle Disease in Poultry

Newcastle disease, according to research, is caused by virulent strains of avian paramyxovirus.

The disease appears in three forms: lentogenic (mild), mesogenic (moderate), and velogenic (very virulent).

The lentogenic strains are known to be widespread but cause few disease outbreaks.
It usually presents as respiratory disease, but depression, nervous manifestations, or diarrhea may be the predominant clinical form.

In its highly pathogenic form, Newcastle disease is listed in the World Organisation for Animal Health (OIE) Terrestrial Animal Health Code and reported to the OIE (OIE Terrestrial Animal Health Code).

Interestingly, Newcastle disease can present a similar clinical picture as avian influenza, so laboratory testing is crucial to confirm the diagnosis.

Newcastle disease in humans

The disease transmits by direct contact with diseased or carrier birds.
The Infected birds may shed the virus in their feces, contaminating food, water, equipment, and human clothing.
Newcastle disease viruses are known to survive for several weeks in the environment.

The carcass of an infected bird still has the virus present in all parts. When susceptible birds introduce the virus, all the birds will get infected within two to six days.

Newcastle disease

What are symptoms of Newcastle disease?

The clinical signs are widely different and are dependent on factors such as the particular strain of the virus, concurrent infection with other organisms, environmental stress, immune status, the species of infected bird, and the age of the host (young birds are known to be the most susceptible).

However, some virus strains attack the nervous system, others the respiratory or digestive systems.

Notable Clinical signs include:

Respiratory signs 

  • gasping
  • sneezing
  • coughing
  • rales

Nervous signs 

  • spasms
  • paralyzed wings and legs
  •  twisted necks
  • tremors
  • circling
  •  paralysis

Digestive signs

  • diarrhoea
  • a partial or complete drop in egg production¬†

What is the treatment for Newcastle disease?

Live vaccines are very vital for the control and prevention of Newcastle disease. But, when choosing the particular live vaccine strain, the issue is mostly protection versus the reaction from the birds.

Usually, the best protection comes with undesirable post-vaccine reactions, but the vaccines with a reduced post-vaccine response give more limited protection.

On the global level, a country that shows that it is free of Newcastle Disease will have to allow surveillance and strictly follow the OIE Terrestrial Animal Health Code guidelines.

Finally, poultry producers must put into practice
effective biosecurity procedures to prevent the attack of the disease as described in the OIE Terrestrial Animal Health Code.

To control the disease,there must be 

  • strict isolation/quarantine and humane destruction of infected or exposed birds (OIE Terrestrial Animal Health Code)
  • thorough cleaning and disinfection of premises
  • proper carcass disposal (OIE Terrestrial Animal Health Code)
  • depopulation followed by 21 days without poultry before restocking
  • control of access to poultry farms.

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