What is Newcastle Disease?

Newcastle Disease (ND) is a highly contagious viral infection that affects chickens and other birds. It is caused by the Newcastle disease virus (NDV), a paramyxovirus that spreads rapidly among poultry. This disease poses a serious threat to poultry farming worldwide, leading to significant economic losses due to high mortality rates and decreased egg production.

Causes and Transmission of Newcastle Disease

ND is caused by the Avian Paramyxovirus Type 1 (APMV-1), which primarily spreads through:

• Direct contact with infected birds – Healthy chickens contract the virus from infected birds through bodily secretions such as saliva, feces, and nasal discharge.
• Contaminated feed and water – The virus can survive in feed, water, and litter, making it easy to spread within poultry farms.
• Aerosol transmission – The virus can spread through the air, especially in crowded poultry houses.
• Contaminated equipment and clothing – Farm tools, cages, and even human clothing can carry the virus from one flock to another.

Symptoms of Newcastle Disease in Chickens

ND manifests in three major forms – lentogenic (mild), mesogenic (moderate), and velogenic (severe). The symptoms vary depending on the strain of the virus but commonly include:

Respiratory Symptoms:

• Gasping and coughing
• Sneezing and nasal discharge
• Labored breathing

Nervous System Symptoms:

• Twisting of the neck (torticollis)
• Paralysis of wings and legs
• Loss of balance and tremors

Digestive and Other Symptoms:

• Watery greenish diarrhea
• Swelling of the head and neck
• Drop in egg production
• Soft-shelled or misshapen eggs

In severe cases, mortality can reach 100%, making early detection and control measures critical.

Diagnosis of Newcastle Disease

Early diagnosis is crucial to prevent widespread outbreaks. Veterinary professionals typically use the following methods:

• Clinical observation – Identifying characteristic symptoms in the flock.
• Laboratory tests – Polymerase Chain Reaction (PCR), virus isolation, and serological tests help confirm the presence of NDV.
• Post-mortem examination – Necropsy findings, such as hemorrhages in the intestines and respiratory tract, aid in diagnosis.

Prevention and Control of Newcastle Disease

Newcastle Disease is highly preventable through proper biosecurity measures and vaccination programs.

Biosecurity Measures:

• Isolate new birds for at least two weeks before introducing them to the flock.
• Limit farm visitors and ensure they follow proper hygiene protocols.
• Regularly disinfect poultry houses, equipment, and footwear.
• Prevent contact with wild birds and rodents, as they can be carriers of the virus.
• Dispose of dead birds properly to prevent the spread of infection.

Vaccination Programs:

Vaccination is the most effective method to protect chickens against Newcastle Disease. Common vaccines include:

• Live vaccines (Lentogenic strains such as LaSota and Hitchner B1) – Administered through drinking water, eye drops, or aerosol.
• Inactivated vaccines – Given via injection, providing long-term immunity.

Poultry farmers should follow strict vaccination schedules recommended by veterinary experts to maintain flock immunity.

Treatment of Newcastle Disease

There is no specific treatment for ND. However, supportive care can help infected birds recover and prevent secondary infections:

• Provide electrolytes and vitamins to boost immunity.
• Use antibiotics to control secondary bacterial infections.
• Ensure proper nutrition and hydration to support recovery.

Economic Impact of Newcastle Disease

Newcastle Disease causes severe economic losses in the poultry industry due to:

• High mortality rates – Velogenic strains can wipe out entire flocks.
• Decreased egg production – Affected layers produce fewer and poor-quality eggs.
• Trade restrictions – Outbreaks lead to bans on poultry exports, affecting the global poultry market.

Conclusion

Newcastle Disease remains a significant threat to poultry farming worldwide. Farmers must implement strict biosecurity measures, adhere to vaccination protocols, and practice good farm management to mitigate its impact. Early detection, rapid response, and preventive strategies are essential in controlling ND and ensuring a healthy, productive flock.