Newcastle disease; symptom, transmission, prevention and control in poultry

13/10/2022

Newcastle Disease in Chickens - What is it and what are the symptoms?
Newcastle disease is a highly contagious viral infection caused by avian paramyxovirus serotype 1 virus among poultry, wild birds and caged birds. Depending on the strain, Newcastle disease can have a fatality rate of 100% with little to no symptoms.
The viral part of Newcastle disease affects the respiratory system. It presents itself as an acute respiratory illness. It also compromises the digestive system as well as the nervous system.
While there are many strains, they fall into two main types. The milder Australian Strain and also the highly virulent exotic (overseas) strain. The overseas strains are more infectious. They also have a higher mortality rate.
At present thanks to stringent border security measures, the exotic Newcastle disease is not in Australia. However, you should not dismiss the Australian strain. As this is a disease that is difficult to control, causing widespread damage, it is legally required to report any suspicious chicken deaths to your Vet.

20/09/2022

Prevention and Control
In addition to vaccination, described above, the best way to prevent Newcastle disease from affecting your flock is strict biosecurity. These measures include:
Quarantine New Birds
Be sure to quarantine any new members of the flock at least 12 yards away for a minimum of 4 weeks in order to avoid infecting your flock.
Avoid Contact with Other Birds
Ensure that anyone who will come in contact with the flock has not had contact with other birds (including pets) for at least 24 hours. This includes hunting or visiting live bird markets or events where birds are present.
Establish a Perimeter
Adding a perimeter fence can prevent your chickens from coming in contact with other birds. Be sure the fence completely surrounds the flock and that gates are always closed when not in use. Screens should also be used on poultry houses to keep wild birds out.
Properly Clean Tools & Equipment
Be sure to thoroughly clean and disinfect tools and equipment when they’ve been used in other areas of the farm or in the vicinity of other flocks. You may also want to use a set of dedicated tools and equipment for each flock to avoid contamination.
Keep Rodents & Wild Birds Away
Institute a pest control plan to keep rodents and wild birds away from your flock. Both rodents and wild birds can carry disease and infect your birds.
Establish Waste Management Areas
Isolate the disposal of dead birds and manure management functions to a separate area, away from the flock to minimize contamination.
While Newcastle disease is currently controlled in Canada, the United States, and many western European countries, outbreaks can still occur. That’s why it’s so important to take a proactive approach by vaccinating your birds and practicing scrupulous biosecurity. These measures provide the best chance to raise productive and healthy chickens for years to come.

20/09/2022

Vaccines are available for chickens, turkeys, and pigeons and are used to induce an antibody response, so vaccinated bids must be exposed to a larger dose of vNDV to be infected. Unfortunately, ND vaccines do not provide sterile immunity, and in many areas of the world vaccines are used to prevent losses from sickness and death. Live lentogenic vaccines, chiefly B1 and LaSota strains, are widely used and typically administered to poultry by mass application in drinking water or by spray. Mucosal immunity induced in birds vaccinated by live vaccines applied by these routes decreases the amount of vNDV the vaccinated birds will shed if infected with vNDV, compared with the immune response induced by an inactivated vaccine. Mass vaccination methods are less labor intensive but if not applied properly may lead to

20/09/2022

Diagnosis:
NDV can be isolated from oropharyngeal or cloacal swabs or tissues from infected birds by inoculation of the allantoic cavity of 9- to 11-day-old SPF embryonated chicken eggs. Infection is confirmed by recovery of a hemagglutinating virus that is inhibited with NDV antiserum or by detection of NDV RNA by reverse transcriptase PCR. A rise in NDV antibody titer by hemagglutination-inhibition or ELISA of paired serum samples indicates NDV infection. To confirm diagnosis, identification of an isolate such as vNDV is established by the rapidity of killing day-old SPF chicks inoculated by the intracerebral route, the intracerebral pathogenicity index, or by the presence of a specified amino acid motif at the cleavage site of the fusion protein (F) precursor (FO). Reference laboratories use nucleotide sequence analysis to detect genetic differences for comparison of isolates from different outbreaks and to identify the source of those infections. The acute form of ND should be differentiated from other diseases known to cause high mortality, such as highly pathogenic avian influenza

20/09/2022

Signs and symptoms of Newcastle Disease
Respiratory symptoms: coughing and sneezing, rattling breathing. Increased respiration
Diarrhoea, yellowish-green in colour
Nervous characteristics, tremors and even a twisting of the neck
Depression
Few eggs produced
Softshell eggs
Symptoms can intensify rapidly

20/09/2022

Clinical Findings:
Onset is rapid, and signs appear throughout the flock within 2–12 days (average 5) after aerosol exposure. Spread is slower if the fecal-oral route is the primary means of transmission, particularly for caged birds. Young birds are the most susceptible. Observed signs depend on whether the infecting virus has a predilection for respiratory, digestive, or nervous systems. Respiratory signs of gasping, coughing, sneezing, and rales predominate in infections with loNDV. Nervous signs of tremors, paralyzed wings and legs, twisted necks, circling, clonic spasms, and complete paralysis may accompany, but usually follow, the respiratory signs in neurotropic velogenic disease. Nervous signs with diarrhea are typical in pigeons, and nervous signs are frequently seen in cormorants and exotic bird species. Respiratory signs with depression, watery greenish diarrhea, and swelling of the tissues of the head and neck are typical of the most virulent form of the disease, viscerotropic velogenic Newcastle disease, although nervous signs are often seen, especially in vaccinated poultry. Varying degrees of depression and inappetence are seen. Partial or complete cessation of egg production may occur. Eggs may be abnormal in color, shape, or surface and have watery albumen. Mortality is variable but can be as high as 100% with vNDV infections. Well-vaccinated birds may not show any signs of being infected except for a decrease in egg production, but these birds will shed virus in saliva and f***s. Poorly vaccinated birds may develop torticollis, ataxia, or body and head tremors 10–14 days after infection and may recover with supportive care.

20/09/2022

Epidemiology and Transmission:
Virulent NDV strains are endemic in poultry in most of Asia, Africa, and some countries of North and South America. Other countries, including the USA and Canada, are free of those strains in poultry and maintain that status with import restrictions and eradication by destroying infected poultry. Cormorants, pigeons, and imported psittacine species are more commonly infected with vNDV and have also been sources of vNDV infections of poultry. NDV strains of low virulence are prevalent in poultry and wild birds, especially waterfowl. Infection of domestic poultry with loNDV contributes to lower productivity.
Infected birds shed virus in exhaled air, respiratory discharges, and f***s. Virus is shed during incubation, during the clinical stage, and for a varying but limited period during convalescence. Virus may also be present in eggs laid during clinical disease and in all parts of the carcass during acute vNDV infections. Chickens are readily infected by aerosols and by ingesting contaminated water or food. Infected chickens and other domestic and wild birds may be sources of NDV. Movement of infected birds and transfer of virus, especially in infective f***s, by the movement of people and contaminated equipment or litter are the main methods of virus spread between poultry flocks.

20/09/2022

Etiology and Pathogenesis:
NDV, synonymous with avian paramyxovirus serotype 1 (PMV-1), is an RNA virus and the most important of the 11 known PMV serotypes as a pathogen for poultry. The original classification of NDV isolates into one of three virulence groups by chicken embryo and chicken inoculation as virulent (velogenic), moderately virulent (mesogenic), or of low virulence (lentogenic) has been abbreviated for regulatory purposes. Velogens and mesogens are now classified as virulent NDV (vNDV), the cause of Newcastle disease and reportable infection, whereas infections with lentogens, the low virulence NDV (loNDV) widely used as live vaccines, are not reportable. Clinical manifestations vary from high morbidity and mortality to asymptomatic infections. Severity of infection depends on virus virulence and age, immune status, and susceptibility of the host species. Chickens are the most and waterfowl the least susceptible of domestic poultry; however, some differences may be seen if the NDV strain is adapted to a particular species.

20/09/2022

Newcastle disease is an infection of domestic poultry and other bird species with virulent Newcastle disease virus (NDV). It is a worldwide problem that presents primarily as an acute respiratory disease, but depression, nervous manifestations, or diarrhea may be the predominant clinical form. Severity depends on the virulence of the infecting virus and host susceptibility. Occurrence of the disease is reportable and may result in trade restrictions.

23/08/2022

Newcastle Disease Virus
Newcastle disease virus (NDV) is a paramyxovirus that infects large poultry populations and is controlled by mass vaccination using a modified live vaccine.201 Attenuated NDV strains are being investigated as both vaccine delivery vectors and oncolytic agents.227–229 A number of human clinical trials have been conducted safely with the oncolytic viruses.230,231 Initially, NDV vectors were developed as vehicles for the delivery of SIV or HIV Gag. Murine studies demonstrated that intranasal vaccination with these vectors was safe and elicited Gag-specific T cell response.76,217,232 Progress also has been made in the construction of NDV vectors that deliver HIV Env immunogens. Specifically, NDV vectors encoding gp160, gp140 or gp120 have been shown to be immunogenic in small animals vaccinated mucosally or by intramuscular injection.77,233 Notably, vectors encoding gp160 incorporate Env in the virus particle, suggesting that NDV might be a promising platform for Env spike delivery.77 In fact, novel vectors have been developed that direct budding of Gag-Env particles from infected cells.234 Moreover, co-delivery of Env plus Gag has been shown to enhance immunogenicity in murine models

23/08/2022

Vaccination at day of age in the hatchery using a course spray machine. In areas with VVND multiple live and a killed vaccine can be given to broilers. Pullets and often layers are given multiple live and killed NDV vaccines. B1 type B1 strain and Lasota strains are normally used. A recombinant NDV vaccine also is available for hatcheries by in ovo or SQ injection.

23/08/2022

The incubation period is 2-15 days. Watery eyes and a plug in the eye are seen with lentogenic strains. Coughing, gasping and sane mortality are seen with mesogenic strains. It affects egg production and quality (brown broiler eggs turn to white eggs). It may produce torticollis, paralysis and bloody diarrhoea. High morbidity and mortality occur with visceral tropic velogenic (VVND). VVND (exotic) rarely occurs in commercial poultry in the United States. Outbreaks in pet bird populations are more frequent. It is a common problem in many countries such as the Middle East, Africa and the Far East.

23/08/2022

It is airborne and spread by inhalation or ingestion of virus. Free-flying birds maybe infected with lentogenic viruses and can spread them readily. Exotic birds and backyard birds from tropical areas are also commonly infected with velogenic viruses.

23/08/2022

This disease was named after a town in England where it was first seen. All species of birds of all ages are susceptible to this acute to chronic disease. It is one of the most common respiratory diseases of poultry and occurs worldwide. The agent involved in the aetiology of this disease is a single-stranded, nonsegmented, enveloped, RNA virus belonging to paramyoviruses. Three pathotypes or strains exist. The lentogenic cause mild disease, the mesogenic produce moderate disease and the velogenic produce severe morbidity and mortality.

23/08/2022

Special note: VVND is a notifiable disease. It is a very common viral disease of poultry worldwide. Most poultry are vaccinated several times against this virus.

23/08/2022

Newcastle disease (ND)
Occurrence: Worldwide. Very common. Very virulent NDV is a notifiable disease
Species affected: All. One of the most common respiratory diseases of poultry.
Age affected: All.
Causes: Virus- Newcastle disease virus is a single-stranded, non-segmented enveloped RNA virus belonging to the family Paramyxoviridae. There are three pathotypes: lentogenic (mild disease), mesogenic (moderate disease) and velogenic (severe morbidity and mortality). Spread is airborne by inhalation or by ingestion of the virus.
Effects: Incubation period is 2-15 days. Paralysis, incoordination and central nervous signs following the initial respiratory signs are diagnostic of NDV. Watery eyes and a plug in the eye are seen with lentogenic strains. Coughing, gasping and sane mortality are seen with mesogenic strains. Egg production and quality are affected. It may produce torticollis, paralysis and bloody diarrhoea. High morbidity and mortality occur with velogenic pathotype.

26/06/2022

Despite many years of enforcement of international and national trading regulations, the introduction of the biosecurity concept, harmonization, and spreading of laboratory diagnostic and monitoring techniques, implementation of vaccination programs, ND is still listed among the most damaging poultry diseases considering both clinical and economical consequences.
Some regions or countries like Western Europe, the USA, Brazil, etc. have successfully reduced and even phased out the incidence of the disease so that ND is nowadays considered only an epizootic risk. The vaccination programs, if applied, are always of the “light” type. (“low challenge areas”).
On the contrary, many countries from Latin America, Eastern Europe, Africa, the Middle East, and Asia are still cohabiting with the enzootic form of the disease with continuous waves of unavoidable pressure regularly plaguing them. In these countries, vaccination is considered a routine obligation guided by modest ambitions that are simply restricted to ensuring clinical and economical protection in case of challenge (“high challenge areas”).
Wild bird populations of backyard poultry, small-scale farming operations, and traditional live bird markets ensure the spreading of the ND virus and are important factors explaining where the disease comes from and how it circulates throughout the world.
But ND is also seen, even today, in poultry producing operations that are much better organized, following stringent biosecurity rules and often applying an intensive vaccination program. In fact, this has been a frustrating paradox that has really drawn the attention of veterinarians and production managers until the concept of flock monitoring and flock profiling has become popular.
As a consequence, NDV antibody testing conducted on samples taken from broilers at the end of the growing period or during the production phase in layers has revealed the frequent presence of low antibody positive, or even fully antibody-negative flocks in spite of (sometimes) very intensive vaccination programs including one or more inactivated and several live attenuated Newcastle Disease vaccines.
OIE guidelines for surveillance and disease eradication have been used to eliminate ND from many countries.
However, despite being recognized for almost 90 years, ND is caused by one single serotype of paramyxovirus and having commercially available very efficient vaccines, ND still challenges veterinarians and farmers all around the world. In Asia, particularly, this disease is a constant threat to the profitability of the poultry industry and its proper prevention has become a crucial part of the biosecurity program of any farm.
Vaccination is an important part of the prevention program against this disease. However, in ND endemic countries, day-old chicks carry high levels of maternally derived antibodies that interfere with live as well as killed ND vaccines given at the hatchery up to a point where neutralization is complete and prevent any vaccine take. Furthermore, vaccinations conducted in the farms, either to avoid this early interference or to boost previous immunizations, are very often very poorly conducted. Finally, live attenuated vaccines that are the backbone of a broiler ND vaccination program may be responsible for lesions of the upper respiratory tract, post-vaccination, and rolling reactions that slow down the growth, worsen the flock’s uniformity and leave the chickens susceptible to other pathogens.
Within this context, a new generation of vaccines was needed and the vector technology with rHVT-F vaccines, such as Vectormune® ND, overcomes all these aforementioned hurdles.
In fact, a very significant investment was made by Ceva Animal Health to know and understand the potentialities of this new product. Scientific work inside as well as outside the company, in collaboration with independent research centers, was designed, organized, and conducted. The information related to the vaccine-induced immunity as well as tangible protection results far exceeded our expectations.

26/06/2022

The possibility of a true vertical transmission has been debated. A few cases have been reported in the scientific literature as well as convincing field observations. The contamination of newly hatched chicks would occur by surface contaminated eggs, or contaminated f***s through eggshell cracks, or by exposure to a contaminated environment. However, NDV infection is known to be lethal for the embryo.
Consequently, until further clarification, the wisest way is probably to follow the recommendations of the Terrestrial Code of the OIE (article 10.13.8.) stating that poultry hatching eggs should be derived from parent flocks that have been kept in an ND-free country, zone, or compartment for at least 21 days prior to, and at the time of, the collection of the eggs.
As with avian influenza, limited evidence associating natural infection with the transmission in hatching eggs suggests that these recommendations of the OIE are clearly adequate to prevent the international dissemination of NDV.

26/06/2022

Wild bird populations play an important role in a reservoir of NDV as well as pigeons, backyard, and small-scale farming operations that maintain the infection. Besides, the tradition of live bird markets, cockfighting competitions, smuggling of domestic, zoo, or wild birds participate in the spreading of the virus. Even if poorly documented (especially for pigeons) all of these populations are reservoirs of NDV and important factors explaining why NDV is persisting, where it comes from, how it circulates. It also explains why no region, no country, no poultry operation can be considered as no risk.
However, it is undeniable that the major source of virus to healthy flocks is represented by diseased flocks housed in the same farm or in the neighborhood.
NDV is excreted from infected birds into the environment through exhaled air, respiratory discharges, and f***s and can infect susceptible chickens by aerosols or by ingestion of contaminated feed or water. Its resistance in the environment is rather poor and this explains why cleaning and disinfection are so important.

26/06/2022

Newcastle Disease symptoms can be respiratory, nervous, intestinal symptoms for both clinical and subclinical infections.
ND can be classified into five different categories:
■ Viscerotropic velogenic, a highly pathogenic form in which hemorrhagic intestinal lesions are frequently seen.
■ Neurotropic velogenic, a form that presents with high mortality, usually following respiratory and nervous signs.
■ Mesogenic, a form that presents with respiratory signs, occasional nervous signs, but low mortality.
■ Lentogenic or respiratory, a form that presents with a mild or subclinical respiratory infection.
■ Asymptomatic: a form that usually consists of subclinical enteric infection.

26/06/2022

Today the situation is that despite being known for 90 years, ND still poses huge threats to poultry producers, in enzootic areas as well as in regions or countries considered as free. The result is that better solutions are required regarding both implementations of biosecurity procedures and the availability of more efficacious vaccine solutions if the poultry industry wants to have real control of this disease.

26/06/2022

In high challenge countries, when industrial chickens are experiencing an ND outbreak, they would display high mortality (up to 100%), high morbidity, listlessness, dyspnea, diarrhea, sometimes nervous signs (eg, torticollis, ataxia). At necropsy, internal organs are usually heavily hemorrhagic, especially the proventriculus, the cecal tonsils, the duodenum, the trachea, the brain.
In low challenge countries, industrial chickens are often facing the uncontrolled circulation of lentogenic (vaccine) strains, especially in high densely populated poultry areas. As a result, they may show subtle to overt respiratory signs, because of the inflammation of the trachea. It may worsen in case of suboptimal husbandry conditions (too high stocking density, high ammonia level, wet litter, poor ventilation). As a result, ­ flock uniformity will decrease, and secondary opportunistic respiratory infections (eg, E.coli) may arise with the need to apply antibiotic medication. Ultimately, slaughterhouse condemnations may increase due to excessive airsacculitis.

26/06/2022

Since it was first officially reported in 1926, Newcastle disease (ND) has established as a major disease threat for commercial poultry including chickens, turkeys, quails, pheasants, as well as for hobby and zoo birds.
The disease was discovered in Indonesia in 1926, but is named after Newcastle-onTyne, England, where it occurred in 1927. It is also called ranikhet, pseudo-fowl pest, and avian pneumo-encephalitis.
Newcastle disease is caused by a virus belonging to the family of Paramyxoviridae; it is an avian paramyxovirus of serotype 1 (APMV-1). It affects wild birds and domestic poultry and usually presents as a respiratory disease. Depression, nervous manifestations, or diarrhea may also be the predominant clinical symptoms and mortality. It is an officially regulated disease and, in its velogenic form, must be officially reported to the OIE (OIE Terrestrial Animal Health Code). It also has a zoonotic dimension since initial exposure to infectious material can induce transient and benign conjunctivitis in humans in case of close contact.
Newcastle Disease (ND) is a highly contagious disease that varies widely in the type and severity of symptoms. It is one of the main barriers to international trade of poultry and poultry products and the economic impact of this disease is enormous.
ND is a noti­fiable disease to the World Animal Health Organization (OIE), a global risk analysis can be done. It enables to distinguish high challenge (where ND outbreaks are frequent) from low challenge countries.

28/05/2022

27/05/2022

Symptoms of Newcastle in Chickens
Signs and symptoms appear in a period ranging from two to twelve days after the chicken became infected with the virus, and spreads quickly to the rest of the flock.
The most common symptoms are related to the bird’s respiratory system, which can be:
With very harmful paramyxoviruses, the first sign is sudden death.
Other signs like weakness, depression, greenish diarrhea, lying down, swelling of the face and nervous signs will also be observed.
Torticollis (twisting of the neck), leg paralysis, arching of the body
In laying chickens, the laying of soft-shelled or shell-less eggs is an early sign, followed by total halting of egg production.
Moderately harmful paramyxoviruses are responsible for severe respiratory problems. In adult chickens, there is usually obvious decline in egg production for many months. However, the mortality rate is low. The mildly harmful paramyxoviruses may not cause any disease or just a mild respiratory problem like constant gasps and cough.
All these symptoms are very similar to those of Avian Influenza (Bird Flu). However, a laboratory test is required to confirm the disease. Of all the signs of Newcastle disease in chickens, the most recognized is when the chicken places its head between its legs and begins to move in circles.
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13/11/2021

Newcastle disease is an infection of domestic poultry and other bird species with virulent Newcastle disease virus (NDV). It is a worldwide problem that presents primarily as an acute respiratory disease, but depression, nervous manifestations, or diarrhea may be the predominant clinical form.