Newcastle disease (ND) is a dangerous viral infection that affects chickens and other birds worldwide. It can cause severe health issues in poultry, leading to significant losses. In this guide, we’ll break down the information in a way that’s easy to understand, even for young students!

What is Newcastle Disease?

Newcastle disease is caused by the Newcastle disease virus (NDV), which belongs to the Paramyxoviridae family. The virus can infect birds in different forms, ranging from mild to severe illness depending on the virus strain.

“Understanding Newcastle disease is crucial because it helps in protecting poultry from outbreaks that can affect farm economics and food security.”

— Veterinarian, Dr. John Smith

Synonyms of Newcastle Disease

• Avian paramyxovirus infection
• Fowl plague
• Pneumoencephalitis

Etiology

What Causes Newcastle Disease?
It is caused by a virus called the Newcastle disease virus (NDV).

Another Name for the Virus:
The virus is also known as avian paramyxovirus type 1 (APMV-1).

Virus Family:
NDV is part of a group of viruses called Orthoavulavirus, which belongs to the Paramyxoviridae family.

Epidemiology

Global Distribution

Newcastle disease is a persistent problem worldwide, particularly in:

• Asia: Regions with dense poultry populations and inconsistent vaccination programs.
• Africa: Areas with limited access to vaccines and biosecurity measures.
• South America: Farms with high bird density and inadequate disease monitoring.

The frequency of outbreaks depends on several factors:

• Poultry Density: High-density poultry farming increases the risk of rapid virus spread.
• Biosecurity Levels: Farms lacking stringent measures are more vulnerable to outbreaks.
• Vaccination Coverage: Areas with insufficient or irregular vaccination programs face higher risks.
• Virus Virulence: Some strains of the Newcastle disease virus are highly pathogenic and spread more easily.

Even with preventive efforts, outbreaks occur, highlighting the need for continuous vigilance, effective control strategies, and early disease detection.

Geographic Presence

• Newcastle disease has a global presence, affecting poultry in nearly every continent.
• The virus thrives in regions where vaccination programs are inconsistent, and biosecurity protocols are weak.

Host Range

While chickens are the primary victims of Newcastle disease, other birds are also susceptible:

• Domestic Birds:
  • Turkeys
  • Ducks
  • Pigeons
• Wild Birds:
  • Waterfowl
  • Wild pigeons and doves
  • Raptors and other avian species

“Global cooperation is key to controlling Newcastle disease, as it knows no borders.”

— Poultry Researcher, Dr. Sara Lee

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Predisposing Factors

Some factors that make chickens more likely to get Newcastle disease:

• Inadequate Biosecurity: If farms don’t have strong safety measures to keep out germs, the virus can spread easily.
• Co-infections: If chickens are already sick with other diseases, it can make Newcastle disease even worse.
• Stress Factors: Things like overcrowding, not enough good food, and stressful environments make chickens’ immune systems weaker.
• Vaccination Gaps: Chickens are at higher risk if they aren’t vaccinated properly or if there are gaps in their vaccination schedules.

Transmission

How Newcastle disease spreads:

• Direct Contact: The disease spreads when healthy birds come into contact with sick birds.
• Contaminated Materials: Things like equipment, feed, or water that have touched infected birds can spread the virus.
• Body Fluids: The virus is found in the sick birds’ breath, poop, and other body fluids.
• Mechanical Transmission: Farm equipment and human handlers can carry the virus from one place to another.
• Airborne Spread: The virus can also travel through the air, which makes it easier for the disease to spread.

Clinical Signs and Postmortem Lesions

Clinical Signs

The signs vary depending on the virus strain’s virulence:

Velogenic ND (Highly Dangerous Form):

• Breathing Problems: Severe trouble breathing, gasping for air, open-mouth breathing, coughing, and runny nose.
• Nervous System Issues: Shaking, twisted necks, unable to move legs or wings, and poor balance.
• Stomach Problems: Green, watery poop and not wanting to eat.
• Egg Production Issues: Big drop in eggs laid, with thin or no shells.
• General Signs: Many chickens die, they are very tired, and their feathers look messy.

Mesogenic ND (Moderately Dangerous Form):

• Breathing Problems: Mild to moderate coughing and sneezing.
• Nervous System Issues: Light shaking and occasional balance problems.
• Stomach Problems: Sometimes loose, watery poop.
• Egg Production Issues: Some drop in eggs laid, and eggs may look odd.

Lentogenic ND (Mild Form):

• Breathing Problems: Mild signs like sneezing and coughing.
• Nervous System and Stomach Issues: Rarely seen.
• Egg Production Issues: Little to no effect on eggs.

Postmortem Lesions

Velogenic ND Lesions (Severe Form):

• Windpipe (Trachea): Severe bleeding.
• Proventriculus (Part of Stomach): Bleeding where it meets the gizzard.
• Intestines: Sores and dead tissue.
• Lymph Tissues: Bleeding in the cecal tonsils, and the spleen is bigger than normal.
• Brain: Tiny spots of bleeding.
• Air Sacs (Lungs): Thick and covered with yellowish material.

Mesogenic ND Lesions (Moderate Form):

• Windpipe (Trachea): Slight redness or swelling.
• Proventriculus (Part of Stomach): Small spots of bleeding.
• Spleen: A little bit bigger than normal.
• Air Sacs (Lungs): Thickened walls.

Lentogenic ND Lesions (Mild Form):

• Windpipe (Trachea): Little to no signs of damage.
• Digestive Tract: Usually no damage or problems.

Pathogenesis

How the Virus Works (Pathogenesis):

• Entry: The virus gets into the bird’s body.
• Replication: Once inside, it starts to multiply in the cells that line the organs, especially in the lungs and intestines.
• Spread: After making more copies of itself, the virus spreads through the blood to other parts of the bird’s body.

How sick the bird gets depends on two main things:

• Strength of the Virus: Some types of the virus are stronger and can cause more damage.
• Bird’s Immune Response: This is how well the bird’s body can fight off the virus.

Because of these two factors, some birds may get very sick, while others might only have mild problems.

Diagnosis

Newcastle disease (ND) is a highly contagious viral infection affecting domestic poultry and other bird species, caused by the virulent Newcastle disease virus (vNDV). The disease manifests primarily as an acute respiratory condition, but it can also present with depression, neurological signs, or diarrhea, depending on the virus’s virulence and the host’s susceptibility.

Diagnosis of Newcastle Disease:

1. Clinical Signs: While ND can cause respiratory distress, nervous system disorders, and gastrointestinal issues, these symptoms are not unique to the disease. Therefore, clinical observation alone is insufficient for a definitive diagnosis.

2. Laboratory Testing:

   • Virus Isolation: Collecting samples from the oropharynx or cloaca of affected birds allows for virus isolation through inoculation in embryonated chicken eggs. The presence of hemagglutinating activity, which can be inhibited by NDV-specific antiserum, confirms the virus.
   • Real-time Reverse Transcription Polymerase Chain Reaction (RT-PCR): This molecular technique detects NDV RNA directly from clinical samples, distinguishing between virulent and low-virulence strains.
   • Serology: Assessing antibody levels using hemagglutination-inhibition or enzyme-linked immunosorbent assay (ELISA) tests on paired serum samples can indicate NDV infection, especially in unvaccinated birds.

Differential Diagnosis:

Several diseases exhibit clinical signs similar to ND, necessitating careful differentiation:

• Highly Pathogenic Avian Influenza (HPAI): Both ND and HPAI can cause severe respiratory and systemic signs with high mortality rates.

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• Infectious Bronchitis: This disease primarily affects the respiratory tract and can lead to decreased egg production, resembling ND symptoms.

  Merck Veterinary Manual

• Infectious Laryngotracheitis: Characterized by respiratory distress and nasal discharge, it can be confused with ND.

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• Avian Metapneumovirus Infection: Causes respiratory disease in poultry, similar to ND presentations.

  Merck Veterinary Manual

• Fowl Cholera: A bacterial infection leading to septicemia and sudden death, which can mimic the acute form of ND.

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• Mycoplasmosis: Results in chronic respiratory disease, sharing symptoms with ND.

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• Fowl Pox (Diphtheritic Form): Presents with lesions in the oral cavity and respiratory tract, potentially resembling ND lesions.

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Accurate diagnosis of ND requires a combination of clinical assessment and laboratory testing to distinguish it from these other diseases effectively.

For a visual understanding of Newcastle disease, you may find the following video helpful:

Treatment

Caring for Birds with Newcastle Disease (ND):

• No Specific Antiviral Treatment:
  • There isn’t a special medicine to kill the ND virus.
• Supportive Care to Help Birds:
  • Antibiotics:
    • Give antibiotics to stop other germs from making the birds sicker.
  • Nutritional Support:
    • Provide extra vitamins and minerals to help boost the birds’ immune systems.
  • Environmental Management:
    • Keep the living area comfortable to reduce stress on the birds.
    • Make sure they have good air, the right temperature, and clean water.
  • Veterinary guidance: Always consult a vet for professional treatment.

Conclusion

To manage Newcastle Disease in birds, farmers should use three important strategies. First, they need to keep their farms safe by following good practices to stop germs from spreading, which is called biosecurity. Second, they should give vaccines to their birds to protect them from getting sick. Finally, staying informed about the latest news and information on the disease is very important. By doing these three things, farmers can help keep their chickens healthy and avoid losing money because of the disease. ALSO READ

References

• Research Papers: Peer-reviewed studies on ND epidemiology, pathogenesis, and control measures.
• Veterinary Manuals: Updated guidelines on poultry disease management.
• Government and Institutional Reports: Latest data from health organizations on ND outbreaks and control strategies.
• Scientific Journals: Published research articles on vaccine development and disease prevention.

FAQs