Dealing with Newcastle disease in commercial chicken coops – prevention, vaccines and economic damage

Dealing with Newcastle disease in commercial poultry – prevention, vaccines and economic damage

Introduction

Newcastle disease is one of the most contagious and significant viral diseases in the global poultry industry. It is a virus from the Paramyxoviridae family (Avian paramyxovirus type 1), which mainly affects the respiratory, digestive and nervous systems of chickens, but also other bird species.

In commercial poultry, a single outbreak can cause enormous economic damage within a few days.

Ways of infection and spread in the poultry house

The virus is excreted through:

   •   Respiratory secretions

   •   Feces

   •   Contaminated eggs

   •  Equipment, clothing and vehicles

In a crowded poultry house, infection is particularly rapid due to:

   •  Shared ventilation system

   •   Worker turnover

   •   Introduction of wild birds or rodents

The virus is relatively resistant to the environment, especially in cold and humid conditions.

Clinical signs in commercial chickens

In fattening chickens

   •   Shortness of breath, coughing and wheezing

   •   A sharp decrease in food consumption

   •   Sudden death

   •   Nervous damage (paralysis, head rotation – “torticollis”)

In laying chickens

   •  A sharp decrease in egg production

   •  Thin/deformed shells

   •   Decrease in egg quality

The severity of the signs depends on the strain of the virus (valent, mesovalent or lentogenic).

Prevention – Biosecurity as a first line of defense

There is no room for error in commercial snail farming. Key principles:

   •Restrict entry of unauthorized persons

   •Rigorous disinfection of equipment and vehicles

   •Work clothes and designated shoes for each coop

   •Preventing the entry of wild birds

   •“All-in All-out”

Weak biosecurity is the main risk factor for an outbreak.

Vaccines – the mainstay of protection

In Israel and around the world, it is customary to combine:

Live attenuated vaccine

   •   Given in eye drops/drink

   •   Produces a rapid local immune response

   •   Requires periodic repetition

Inactivated vaccine

   •   Given by injection

   •   Produces a high and stable level of antibodies

   •   Common in laying and breeding hens

The combination of live and inactivated vaccines provides optimal protection.

Important to remember: Vaccination reduces clinical signs and mortality – but does not always completely prevent infection and spread of the virus.

Dealing with an outbreak

In many countries, a virulent strain of the disease is required to be reported to the authorities.

Typical measures:

   •   Isolation of the coop

   •   Stopping bird movement

   •   Dilution/culling in severe cases

   •   Thorough disinfection

   •   Serological surveillance in adjacent flocks

A single outbreak may result in the closure of an entire farm.

Economic damage to the industry

The economic impact includes:

   •Direct mortality

   •Dramatic decline in egg production

   •Temporary marketing ban

   •Disinfection, vaccination and operating costs

   •Damage to exports (in cases of national outbreaks)

In developing countries, the disease is considered one of the main causes of the collapse of small poultry farms.

Summary

Newcastle disease is not just a veterinary problem – it is a management, economic and health challenge.

The combination of strict biosecurity, a well-organized vaccination program and constant monitoring is the key to maintaining herd stability and profitability.

In a modern and crowded industry like Israel, prevention is always cheaper than dealing with an outbreak.

*It is always advisable to consult a qualified veterinarian.