History Outbreak of Newcastle Disease in Poultry
The first recognized outbreak of Newcastle disease occurred in 1926, in Java, Indonesia, and subsequently in Newcastle upon Tyne, England. However, similar disease outbreaks had been observed in Central Europe even before this date. For instance, Macpherson attributed the death of all chicks in the Western Isles of Scotland in 1896 to Newcastle disease. Nevertheless, the identification of Newcastle disease as a distinct illness with a viral cause was first made in Newcastle upon Tyne.
Although the disease had similar symptoms to Avian Influenza Virus (fowl plague), it was determined that the Newcastle disease virus was distinct from other illnesses. The name “Newcastle disease” was coined by Doyle after the first occurrence in Britain to differentiate it from other diseases. This name is still in use today. The synonym Avian Paramyxovirus type 1 (APMV-1) is also used when referring to Newcastle disease virus (NDV).
The disease quickly spread worldwide and became a major concern for the poultry industry. Newcastle disease remains a significant threat to poultry globally, especially in developing countries.
What is Newcastle Disease? (ND)
Newcastle disease (ND) is a highly contagious disease prevalent worldwide among birds, including domestic poultry. It is spread by the Newcastle disease virus (NDV), which originates from a virulent strain of Avian Paramyxovirus type 1 (APMV-1).
Newcastle disease primarily affects poultry such as chickens and turkeys. It can also infect wild birds and, in rare cases, humans (causing mild eye or flu-like symptoms that usually resolve without treatment).
There are three forms of Newcastle disease: lentogenic (mild), mesogenic (moderate), and velogenic (highly virulent), all of which are known as Newcastle disease. The velogenic form is further classified as viscerotropic and neurotropic.
The disease commonly presents with respiratory symptoms, but depression and diarrhea are also among its clinical signs. Since poultry Newcastle disease (ND) has clinical signs similar to Avian Influenza, laboratory testing is crucial for confirmation.
It should be noted that this disease can be fatal, especially in unvaccinated poultry. It significantly impacts the poultry industry due to its rapid spread and high mortality rate. Outbreaks of ND have caused significant economic losses due to high mortality rates and the need for disease control measures such as culling and quarantine.
Newcastle disease is a notifiable animal disease, meaning that suspected cases must be reported to the relevant authorities. In the event of an outbreak in an area, it must be reported to the regional health organization or the World Organization for Animal Health (WOAH).
Symptoms of Newcastle Disease in Poultry
The symptoms of Newcastle disease in poultry vary depending on several factors, including the strain of the virus, the species and age of the infected bird (young birds are more susceptible), co-infection with other organisms, environmental stress, and the animal’s immunity. In some cases, infection with virulent strains can lead to high flock mortality. Some strains of the virus attack the nervous system, while others target the respiratory or digestive systems.
In general, the symptoms of Newcastle disease in chickens can be categorized as follows:
- Respiratory Symptoms:
- Gasping and Difficulty Breathing: Birds may struggle to breathe and might open their beaks to gasp for air.
- Coughing and Sneezing: Frequent coughing and sneezing are other common respiratory signs.
- Abnormal Breathing Sounds: Rales, rattling, and other abnormal noises are respiratory symptoms.
- Swelling of the Eyes and Surrounding Tissues: The eyes may become swollen and red.
- Discharge from the Nostrils and Eyes: Watery or mucous discharge may appear from the nostrils and eyes. The tissues around the eyes and neck also swell.
- Nervous Symptoms:
- Tremors and Shaking: Body and muscular tremors, especially in the head and neck, are common nervous symptoms.
- Paralysis: Birds may experience partial or complete paralysis of their wings or legs.
- Head and Neck Twisting: Twisting of the head and neck (torticollis), or turning in circles, are other nervous signs.
- Lack of Coordination and Confusion: Birds may lose their balance and appear disoriented.
- Drooping Wings: The wings may hang limp and appear droopy.
Article: Causes of Poultry Paralysis: A Review of Common Paralyses in Chickens with Symptoms and Diagnosis
- Digestive Symptoms:
- Changes in Droppings: Greenish, watery diarrhea is a key sign.
- Reduced Appetite and Weight Loss: Birds may refuse to eat and become emaciated.
- Reduced Egg Production: This can range from a slight decrease to a complete cessation of egg-laying in laying hens. The eggs may also change in color and appearance, with an abnormal surface and watery albumen.
- Depression and Lethargy: Birds infected with Newcastle disease may appear lethargic and depressed, and they might isolate themselves from the rest of the flock.
- Flock Mortality: Sudden death and increased mortality rates in the flock are often the most devastating symptoms. The mortality rate can vary but can reach up to 100%.
Article: Golden Steps for Poultry Gut Health
Main Transmission Routes of Newcastle Disease in Poultry
Newcastle disease is a highly contagious viral disease in poultry that spreads through various channels. Transmission mainly occurs through direct contact with infected birds, their bodily excretions (such as saliva, feces, and respiratory secretions), and through contaminated equipment, water, feed, and even through the air.
The virus can be transferred to healthy flocks via contaminated tools, equipment, water, feed, manure, and even clothing and shoes. Other ways the Newcastle disease virus spreads to a poultry flock include:
- Airborne Transmission: Newcastle disease can be present in airborne particles and dust. It can spread to healthy poultry through the coughs and sneezes of infected ones.
- Wild Birds and Rodents as Carriers: Wild birds and rodents can also be carriers of the Newcastle disease virus. They can transmit the disease to domestic flocks through contact.
- Vehicle-based Transmission: Newcastle disease can be spread via vehicles that have transported infected poultry, contaminated equipment, manure, feed, or water. The virus can survive on the bodies of birds, in manure, and on other materials for several weeks.
- Transmission via Eggs: In some cases, the Newcastle disease virus can be transmitted to chicks through contaminated eggs, especially if the eggs break in the incubator.
- Human-to-Flock Transmission: Humans can act as mechanical vectors of the disease. By moving contaminated tools and equipment or even by coming into contact with infected poultry, they can spread the disease to other locations. Virus-carrying materials can be transferred from a sick poultry or flock to a healthy one via the shoes and clothing of personnel.
Maintaining hygiene, disinfecting equipment and tools, and controlling the movement of people and vehicles are crucial to preventing disease transmission. NDV can also survive in the environment and on various surfaces for a period, especially under suitable conditions like moderate temperatures. Some birds, such as pigeons, can shed the virus for extended periods.
To prevent the transmission of this disease to a breeding flock, following biosecurity and quarantine principles plays a vital role in preventing its spread.
Speed and Severity of Newcastle Disease Virus Transmission
The Newcastle disease virus is present in all parts of an infected bird’s carcass. The onset of the disease is very rapid, with symptoms appearing and spreading quickly throughout the flock within 2 to 12 days. Once the virus enters a susceptible flock, it can infect the entire group within 2 to 6 days. Newcastle disease is a significant illness in poultry because the virus spreads through the flock so quickly. This is especially true in younger, more susceptible chicks and in high-density environments, where the risk of an outbreak is greater.
The severity of Newcastle disease transmission depends on the type of virus and the bird’s health status. With less virulent strains, the disease may present with milder symptoms and have a longer recovery period. On the other hand, severe strains can cause high mortality in a short time. A highly virulent strain of Newcastle disease can cause 100% mortality within 24 to 48 hours.
It’s important to note that the disease’s incubation period (from infection to the onset of symptoms) can vary from 2 to 15 days. The virus can survive in the poultry house environment for some time, leading to re-infection.
Geographic Distribution of Newcastle Disease in Poultry
This disease exists globally, but it is controlled in many countries. It persists only in parts of Africa, Asia, and South America. However, since wild birds can be carriers of the virus, an outbreak of Newcastle disease is possible wherever poultry farming takes place.
However, certain factors generally intensify the risk of a Newcastle disease outbreak in poultry. The factors that can increase the likelihood of contracting the Newcastle disease virus include:
- High-Density Poultry Farming: In these areas, the high concentration of birds in one location increases the probability of virus transmission.
- Poor Hygiene Conditions: Failure to maintain proper hygiene in poultry farms, such as inadequate cleaning and disinfection, can lead to a disease outbreak.
- Inadequate Ventilation: Poor ventilation in poultry houses can cause harmful gas buildup and reduce the birds’ immunity, increasing their susceptibility to the disease.
- Cold Seasons: The likelihood of a disease outbreak is higher during cold seasons due to a decrease in the birds’ immunity and favorable conditions for the virus to thrive.
Diagnosis of Newcastle Disease in Poultry
Diagnosing Newcastle disease in chickens can be done through two main methods: clinical symptom examination and laboratory testing. However, since Newcastle disease shares similar symptoms with avian influenza, laboratory tests are necessary for a definitive diagnosis. The following are the different types of laboratory testing methods:
- In vivo Test: An “in vivo” test refers to experiments conducted on a whole, living organism (human, animal, or plant), as opposed to experiments performed in a laboratory setting (in vitro).
- Molecular PCR Test: PCR, or Polymerase Chain Reaction, is a laboratory technique used to amplify and identify specific DNA segments. This method is especially useful for diagnosing diseases in poultry and other animals. It’s a highly accurate test used to identify the DNA of the Newcastle disease virus in samples taken from a bird.
- HI Test: The HI test, or Hemagglutination Inhibition, is a serological test used to detect specific antibodies in blood serum. This test is performed to identify Newcastle disease antibodies in a bird’s blood.
Virus Isolation: In this method, the virus is isolated from tissue samples (such as the lungs, intestines, and spleen) and cultured to confirm its presence. - Histopathology: In this method, damaged tissues from the bird are examined under a microscope to look for signs of Newcastle disease.
Outbreaks of Newcastle Disease in Humans
The Newcastle disease virus is considered a zoonotic disease, meaning it can be transmitted from animals to humans. However, Newcastle disease in humans is typically mild and localized.
The main symptom of Newcastle disease in humans is conjunctivitis (redness of the eye). It usually occurs in laboratory workers and those who administer vaccinations. It’s worth noting that this eye inflammation and redness typically resolves on its own within 4 to 7 days.
Biosecurity in Poultry Farms to Prevent the Spread of Newcastle Disease
Using personal protective equipment in poultry farm environments helps prevent disease transmission to personnel. Disinfecting before entering any shed, and wearing gloves and appropriate clothing on the farms are measures that can prevent the spread of Newcastle disease to personnel. In general, to prevent the transmission of the disease to both poultry and staff, the following points must be observed:
- Minimize visitors.
- Wash your hands before and after handling chickens.
- Provide disposable boot covers.
- Change clothes when entering and exiting the poultry farm area.
- Clean and disinfect tools.
- Look for signs of disease.
- Report sick birds immediately.
Article: Preparing the Poultry Shed Before Placing Chicks: The Correct Method for Disinfecting the Poultry Shed
Treatment of Newcastle Disease in Poultry
Generally, there is no specific treatment for Newcastle disease. It is a viral disease that must run its course. However, the symptoms in chickens can be alleviated and recovery supported by using vitamins and certain antibiotics.
In the case of a severe outbreak in a flock, under the direction of the country’s health authorities and following the guidelines of the WOAH (World Organisation for Animal Health), the following policies are implemented:
Control or Quarantine during a Newcastle Disease Outbreak:
- Culling of all infected and exposed poultry (WOAH Terrestrial Animal Health Code).
- Thorough cleaning and disinfection of the premises.
- Proper disposal of carcasses (WOAH Terrestrial Animal Health Code).
- Virus control within the flock.
- Depopulation of the poultry house for 21 days before re-stocking.
- Avoiding contact with birds of unknown health status.
- Controlling access to poultry farms.
- Poultry manure is moistened and covered for 5 to 6 days. The resulting heat kills the virus present in the manure.
Traditional Treatment Methods for Newcastle Disease in Poultry
As mentioned in this article and also in the article on avian bronchitis, viral diseases in humans and poultry generally have no specific cure; they must run their course. However, using electrolytes and vitamins in the poultry’s water and food can aid the recovery process. Since chickens have a reduced appetite during the illness, adding carrots, cinnamon, beet molasses, and baking soda can help improve the food’s flavor and encourage the bird to eat more.
If secondary infections occur, using antibiotics under the supervision of a veterinarian is recommended. Keep in mind that all these methods are for when Newcastle disease is mild. If the disease is severe, treatment is very difficult and often impossible.
Additionally, to eliminate contaminated manure and surfaces, disinfectants, fumigation, and direct sunlight can be easily used.
Ultimately, the following measures are very important and effective in preventing a potential Newcastle disease virus infection and controlling Newcastle disease, as well as other illnesses:
- Keep the poultry flock away from rodents.
- Keep chickens away from wild birds and animals.
- Keep food and water containers clean.
- Follow quarantine principles.
- Wash hands after contact with birds.
- Use shoe disinfectants before entering the shed.
Prevention of Newcastle Disease in Poultry and Vaccination
The best and most effective method for preventing Newcastle disease is vaccination. In most countries that produce poultry on a commercial scale, vaccination is mandatory to prevent the disease. For a country to be recognized as Newcastle disease-free, it must follow the WOAH animal health code. Consequently, all poultry producers are obligated to comply with the WOAH animal regulations to prevent disease outbreaks.
The Iranian Veterinary Organization is one of the countries that collaborates with three international bodies: the WHO, OIE, and FAO. For this reason, in Iran, vaccination against Newcastle disease is mandatory for both broilers and laying hens and is even provided free of charge in rural areas.
There are two main types of Newcastle disease vaccines: live attenuated virus and inactivated virus. Depending on the vaccine type, they are administered in four ways: by injection, eye drops, coarse spray over the birds, and orally, which is typically done by adding the vaccine to the chicks’ drinking water.
Article: Reasons for Vaccination Success
Types of Newcastle Disease Vaccines
Non-Pathogenic Live Vaccine, V4HR Strain (Heat-Resistant): Heat-resistant vaccines have a longer shelf life at ambient and farm temperatures compared to regular live vaccines. This vaccine is used via three methods: eye drops, drinking water, and spray.
Live Newcastle Vaccine, Lasota Strain: This vaccine is also administered via three methods: eye drops, drinking water, and spray. You should not use the spray method if your flock is contaminated with Mycoplasma.
Live Newcastle Vaccine, Clone30 Strain: This vaccine contains the attenuated Clone30 strain propagated in Specific Pathogen-Free (SPF) embryonated eggs. It is used via eye drops, drinking water, and spray. Do not use the spray method if the flock is contaminated with Mycoplasma.
Some vaccines are also combined and cover multiple diseases, such as:
Live Newcastle Disease and Infectious Bronchitis Vaccine (Lasota and H120 Strains): This vaccine is administered via eye drops, drinking water, and spray. Do not use the spray method if the flock is contaminated with Mycoplasma.
Live Newcastle Disease and Infectious Bronchitis Vaccine (B1 and H120 Strains): This live vaccine contains the B1 strain of Newcastle disease and the H120 strain of Infectious Bronchitis, cultured in SPF eggs. It is used in one-day-old and young, susceptible chicks. It is available for administration via eye drops, nose drops, drinking water, and spray.
Inactivated Bivalent Newcastle Disease and Avian Influenza Vaccine (H9 Subtype): This is a viscous, milk-colored emulsion. It covers the Newcastle disease virus (Genotype VII) and the H9N2 Avian Influenza virus, which are the most common circulating viruses in Iran.
Inactivated Trivalent Vaccine for Newcastle Disease, Infectious Bronchitis, and Egg Drop Syndrome for Laying Hens (Lasota + M41 + AV127 Strains): This vaccine is suitable for laying hens and is injected intramuscularly or subcutaneously in the neck before they begin laying. It is administered 4 weeks before the start of egg production. Better immunizing effects are achieved if a live Newcastle disease and Infectious Bronchitis vaccine has been used before this product.
A key point to remember is the importance of selecting the appropriate vaccine. Poultry producers should choose a suitable vaccine based on the type of production, the diseases prevalent in the area, and the most common strains in their geographical region. It is best to plan vaccination schedules and vaccine selection under the supervision of experts in this field.
