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What is Newcastle disease? Newcastle disease is a term that can send shivers down the spine of anyone who keeps chickens. Understanding this disease is crucial for the health and well-being of your flock. This post will tell you what Newcastle disease is, its symptoms, and how to protect your chickens.

Thought to be first discovered in Newcastle-upon-Tyne in Britain, this is how the disease got its name.

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What is Newcastle Disease?

Newcastle disease is a highly contagious viral infection that affects birds, meaning your chickens. The symptoms can range from mild respiratory issues to severe neurological disorders.

The disease can significantly impact egg production and even lead to high mortality rates in severe cases.

A Definition: Virulent –  a pathogen, usually a virus or bacterium, that is highly infectious, aggressive, and likely to cause disease. In a broader sense, “virulent” can also describe anything extremely harmful, hostile, or poisonous.

Understanding the virulence of certain diseases like Newcastle disease is crucial. A virulent disease strain would spread more quickly and severely impact the flock, requiring immediate and aggressive intervention.

There are actually three levels of virulence of Newcastle: mildly virulent (lentogenic), moderately virulent (mesogenic), and highly virulent (velogenic). Most forms of Newcastle disease in the U.S. are mildly virulent.

Newcastle disease affects chickens in several areas. It affects the intestines, the lungs, the reproductive tract, the nervous system, and the brain.

Symptoms to Look Out For

Respiratory distress

The severity of respiratory distress depends on the virulence or aggressiveness of the virus. In highly aggressive Newcastle disease (ND) that affects the nerves and respiratory system, a rapid drop in egg production, gasping and coughing, and partial paralysis can occur.

Moderately severe ND is similar to the velogenic strain except that the number of deaths is fewer.

The mild strain that affects the respiratory system causes mild breathing problems and rare deaths.

At times, the disease affects the intestines and brains of chickens.

Severe ND that affects the respiratory system and the brain causes sudden death, a swollen head, a quick drop in egg laying, and bloody diarrhea. Death, in this case, is up to a hundred percent.

Mild ND that affects the intestines will show no obvious signs, and there will be no death.

Impact on Poultry Health

  • High mortality rates in severe cases
  • Long-term damage to the respiratory system in aggressive cases
  • Mild strains will show up as mild coughing and gasping but will go away on its own. No long-term effects will be apparent.

Causes and Transmission Man with big boots -

The disease primarily spreads from wild birds to domestic chickens through mice’s feet and people’s shoes after they have stepped in infected areas, direct contact with infected birds, or contaminated equipment. It is highly contagious.

The good news in the U.S. is that Newcastle outbreaks are dealt with quickly and completely by eliminating infected flocks once recognized. Vaccination at hatch is easily done by adding the vaccine to drinking water.

Risk Factors

  • Overcrowding – Having many chickens in close proximity is a sure way of making certain that they all get sick. A good analogy for this is when students go back to school after summer break. Yikes, get ready.
  • Poor sanitation – Since Newcastle is transmitted primarily in feces, keeping up with the chores is a good idea.
  • Introduction of new birds without proper quarantine – If you are not absolutely certain that your new chickens are safe, quarantine them for a month.

How do You Quarantine a Chicken?

Quarantining a chicken is done by isolating a new bird or birds in a separate area for a month.

If you are fairly sure that the new birds are going to be safely added to the flock… that is, you are pretty sure the source of your new chicken(s) is disease-free, you can add a couple of sacrificial chickens from your flock to the quarantine to see if they suffer any adverse effects from being near the new arrival.

On top of this, always finish your chores with the quarantined chickens last. Feed them last. Water them last. You don’t want to chance delivering unwanted disease from the quarantine to your flock.

Isolate any quarantine-related cleanup as well until you know it’s safe to co-mingle waste into your compost.

Diagnosis and Testing

Early diagnosis is crucial for effective treatment and containment of the disease. Professional methods for diagnosis include:

  • Virus isolation
  • Hemagglutination tests

Treatment Options

Treatment for Newcastle disease is mainly supportive, as there is no cure for the viral infection. Early vaccination is the best way to prevent the disease.

Medical Treatments

  • Antiviral medications – Vaccines can be found online, or you can ask your vet. or are online sources where you can find the ND vaccine.
  • Supportive care like electrolytes

Prevention is better than cure, especially when it comes to Newcastle disease.


Regular vaccination schedules are necessary to maintain flock safety. Whether in drinking water or drops administered to the eye or nostril, once at hatch and then boosters every three months is the proper schedule to follow.

Biosecurity Measures

  • Regular disinfection of coops – Disinfection kills bacteria, microbes, and other disease-carrying organisms. It is not the same as cleaning.
  • Quarantine new birds

FAQs (Expertise & Trustworthiness)

Is Newcastle Disease Fatal?

It can be, especially in severe cases.

Can Humans Get Infected?

Temporary eye infections and mild flu-like symptoms can occur after handling infected chickens

How to Disinfect the Coop?

Use a government-approved disinfectant and follow the guidelines.


Newcastle disease is a serious concern for any poultry owner. However, with the right knowledge and preventive measures, you can protect your flock effectively.

Author Bio

Hi. I have over 10 years of experience in raising backyard chickens and enjoy educating others in this field. I enjoy reading books on the subject of chickens, from hatch to coop, searching for new ideas, and finding solutions to old problems.


Last Updated

This article was last updated on 10/14/2023.

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Have you had any experience with Newcastle disease? Share your stories or questions in the comments below. For more chicken health tips, check out our related articles on Fowl Pox and Infectious Laryngotracheitis.


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