Newcastle Disease (Avian Paramyxovirus-1)

Newcastle disease is a highly contagious viraldisease that causes respiratory andneurological signs in various avian species. Itmay cause acute death.

Newcastle disease is caused by avian paramyxovirus-1(APMV-1). APMV-1 generally presents in the followingforms based on clinical signs: lentogenic (mild), mesogenic(moderate), and velogenic (severe). Other names forNewcastle disease include: Avian Paramyxovirus-1(APMV-1), exotic Newcastle disease (END), virulentNewcastle disease (VND), pseudo-fowl pest, pseudo-poultryplague, and Ranikhet disease. Newcastle disease is animportant poultry disease because it is endemic in many areasworldwide, including Asia, Africa, and parts of North andSouth America. Chickens are the most susceptible species andcan experience 100% mortality with velogenic strains within24 – 48 hours. Newcastle disease causes a significanteconomic impact, especially in developing countries that relyheavily on backyard chickens for income and as a proteinsource.

Clinical signsObserved signs can vary greatly depending on the APMV-1strain and bird host factors (species, age, immunity, etc.).

Respiratory signs may include:

• nasal/ocular discharge, gasping for air, coughing or rales,sneezing, and conjunctivitis (swelling around the eyes orface)

Neurological signs may include:

• paralyzed wings or legs, torticollis (twisted neck; Figure1), muscle tremors or spasms.

Weakness, oral discharge (Figure 2) greenish colored diarrhea(Figure 3), decreased egg production, and eggs that arethin-shelled, pale, and/or have a watery albumin may beobserved. With velogenic strains, especially in susceptiblechickens, mortality death may be close to 100% in a flock.

Figure 1. Torticollis in a broiler chicken affected with Newcastledisease. Photo credit: Dr. Lorenzoni.

Figure 2. Abundant oral secretion in a bird affected withNewcastle disease. Photo: Dr. R. Gallardo.

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Figure 3. Greenish fecal material from chickens affected withNewcastle disease. Photo credit: Dr. R. Gallardo.

Necropsy findingsGross lesions may vary but may include hemorrhage of themucosa of the proventriculus (Figure 4), ceca, and smallintestine, due to necrosis of the intestinal wall or lymphoidtissue. In the respiratory tract, hemorrhage and markedcongestion may be seen in the trachea (Figure 5). Airsacculitismay also be seen, shown by thickening of the air sacs andmucus (catarrhal) or cheese-like (caseous) build-up, and isoften associated with secondary bacterial infections. Layingbirds may have egg yolk in the abdominal cavity, degenerativeovarian follicles, and/or hemorrhage of the reproductive tract.

Figure 4. Hemorrhagic proventricular papillae in a chickenaffected with Newcastle disease. Photo credit: Dr. R. Gallardo.

Figure 5. Hemorrhagic trachea of a chicken affected withNewcastle disease. Photo credit: Dr. R. Gallardo.

OccurrenceAPMV-1 has been reported in over 240 bird species, andvelogenic APMV-1 is endemic in many developing countries.Chickens are the most susceptible to the velogenic strain andthe most likely to succumb to disease mortality or have severeclinical signs. Turkeys are usually less susceptible, with lowermortality and less severe morbidity in clinical presentation.Other game bird species such as pheasants, partridges, quail,and guinea fowl have variable susceptibility, but severeclinical signs have been reported with exposure to velogenicstrains. Waterfowl species such as ducks and geese aregenerally the least susceptible and may harbor subclinicalinfections. Psittacine bird species, including parrots,cockatiels, budgerigars, and conures can be infected, and therehave been cases in which they have been subclinical carriersof the virus and have introduced it into areas that werepreviously not affected. A variety of exotic zoo birds such asostriches, owls, raptors, and penguins have been affected tovarying degrees as well. Outbreaks in wild double-crestedcormorants and rock pigeons have been reported throughoutthe U.S. and Canada, with limited spillover into domesticpoultry. There have been sporadic Newcastle diseaseintroductions to U.S. domestic poultry, mainly through theintroduction of imported poultry that were infected, as well aswild bird reservoirs.

There have been three extensive U.S. outbreaks of the virulentNewcastle disease, previously known as exotic Newcastledisease (END), based mainly in southern California. The firstoutbreak occurred from 1971 to 1974 and was linked to theimportation of infected psittacine pet birds into the U.S.During the 2002-2003 outbreak, the disease began in illegallyimported backyard gamefowl and spread to commercial egglayer farms. The most recent outbreak lasted two years, May2018 to May 2020, affected backyard gamefowl and spilledinto commercial layer facilities; in this outbreak, the diseasewas called virulent Newcastle disease (VND) because it wasno longer considered exotic to the U.S. Wild bird introductionof the virus can also occur from cormorants, pigeons, doves,

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and migratory waterfowl, which can be subclinical carriers ofthe disease.

People who are exposed to large amounts of virus mayexperience a mild and typically self-limiting conjunctivitis(eye swelling, irritation and redness) and flu-like symptoms offever, headache, and malaise. Laboratory workers, vaccinecrews, and emergency disease poultry responders are most atrisk. Conjunctivitis usually resolves without treatment but canbe shed in ocular discharge for 4 to 7 days. Due to therelatively minor disease manifestation of Newcastle inhumans, it is not a significant zoonotic disease of public healthconcern and is not considered a foodborne transmitted disease.

TransmissionAPMV-1 is acquired through ingestion or inhalation ofmanure or respiratory secretions from infected birds. The viruscan also be transferred via fomite materials such ascontaminated feed, water, shoes, clothing, vehicles, poultrycrates and egg trays, and, especially, moist fecal material.Transmission can also occur through infected eggs to hatchingchicks for some APMV strains. Incubation period is 2-15days, with an average of 2-6 days in chickens exposed tovelogenic strains. Gallinaceous birds typically shed virus for1-2 weeks. However, psittacine species such as parrots,macaws, and parakeets can be prolonged shedders of APMV-1for months to more than a year.

DiagnosisConfirmation of APMV-1 via laboratory diagnosis isimportant because the virus can mimic many other poultrydiseases such as avian influenza. Diagnostic tests may include:

• Real-Time Reverse-Transcriptase Polymerase ChainReaction (qRT-PCR) – detects the presence of viral RNAfrom swab samples from oropharyngeal or cloacal swabsamples

• Virus isolation (VI) – determines if viable virus is presentby incubating embryonated eggs and determines virustype from swab samples

• Serology Blood Tests (i.e. Enzyme LinkedImmunosorbent Assay (ELISA), Agar GelImmunodiffusion (AGID), Hemagglutination Asssay(HA) / Hemagglutination Inhibition Assay (HI)) -identifies antibodies in blood serum; used as a screeningtest

Differential diagnosesAvian influenza, Avian Paramyxovirus, Infectious bronchitis,Infectious laryngotracheitis, Avian chlamydia, Mycoplasma,Avian cholera (pasteurellosis), Infectious coryza, acutepoisoning (i.e. aflatoxin, insecticides, rodenticides), Egg dropsyndrome (EDS 76), Duck plague (duck viral enteritis)

PreventionBiosecurity remains the most important protection strategy.Practices such as avoiding visiting other places with birds andrestricting visitors around your birds are helpful strategies tolimit disease spread. Prior to anyone entering your poultrypremises, it is recommended to have them park in a designatedarea away from your birds, use a properly maintained footbathor wear designated cleaned footwear and/or clothing, anddisinfect hands. Clean and disinfect poultry equipment such ascages, crates, egg flat/racks, waterers, and feeders prior toreuse. APMV-1 is an enveloped RNA virus and is susceptibleto most common disinfectants. The virus is inactivated byheating to 56 °C (133 °F) for 3 hours or 60 °C (140 °F) for 30minutes. Acidic conditions with a pH ≤ 2 also kill the virus.Similar to other viruses, APMV-1 can survive for long periodsin cool conditions and in organic material such as feces.

Know the signs of illness to report quickly to your local stateDepartment of Agriculture for follow-up to prevent futuredisease spread. The velogenic form of Newcastle disease isreportable to the World Organization for Animal Health (OIE),which provides international guidelines for surveillance anderadication. Biosecurity information is also posted on theUSDA and CDFA websites to provide education to poultryand pet bird owners to prevent disease.

Vaccination with live or inactivated lentogenic strains (i.e. B1and/or LaSota) for chickens, turkeys and pigeons are availableby mass application in drinking water or aerosol droplet spray.Individual birds can also receive eye or nose dropletvaccination. Layer and breeder birds are often vaccinated priorto the first lay to pass on maternal antibodies to their chicks.Chicks may also be vaccinated at 1-4 days of age at thehatchery, especially if the parent stock was not vaccinated, orat 2-3 weeks of age once maternal antibodies wane. There isoften a withdrawal period especially for oil-based vaccines forbirds intended for human consumption.

Vaccination with these lentogenic strains provides only alimited protection against more virulent (mesogenic orvelogenic) APMV-1 strains. Vaccinated birds exposed to moreserious strains may still experience a decline in egg productionand neurological signs, with less mortality. Vaccinated poultrycan continue to shed virus in feces and saliva, despitevaccination status, but may experience reduced respiratoryillness and mortality.

References and suggested readingSaif, Y. M. (2003). Diseases of poultry (11th ed.). Ames, IA:Iowa State Press

World Organization for Animal Health (2013). NewcastleDisease – Technical Disease Card. OIE, Paris. RetrievedFebruary 13, 2019

OIE. 2019.

Iowa State University, Center for Food Security & PublicHealth (2016). Newcastle Disease – Technical Factsheet.

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Merck Veterinary Manual (2018). Newcastle Disease inPoultry. Miller, Patti J.

American Association of Avian Pathologists (2000). AvianDisease Manual (Fifth ed.). Newcastle Disease. KennettSquare, PA.

California Department of Food and Agriculture (2019).Virulent Newcastle Disease.

USDA APHIS VS (2018). Virulent Newcastle Disease Virus(vNDV) Case Definition.

Northeast Wildlife Disease Cooperative (2017). NewcastleDisease.

Senne, D.A., King, D.J. & Kapczynski D.R. (2004). Control ofNewcastle Disease by Vaccination. Dev Biol 119: 165-170.

AuthorsGino LorenzoniAssistant Professor, Poultry Science and Avian Healthagl20@psu.edu814-863-7302

Chrislyn Wood Nicholson, DVM MPHPoultry Specialist / Veterinary Medical OfficerUSDA APHIS VSchrislyn.n.wood@usda.gov

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This article, including its text, graphics, and images ("Content"), is foreducational purposes only; it is not intended to be a substitute for veterinarymedical advice, diagnosis, or treatment. Always seek the advice of a licenseddoctor of veterinary medicine or other licensed or certified veterinary medicalprofessional with any questions you may have regarding a veterinary medicalcondition or symptom.

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