Newcastle Disease of Poultry – An Overview

Poultry sector is a sustainable means of livelihood in developing countries like India. Commercially, it has been accepted as a viable enterprise and thus the fastest-growing segment of the agricultural sector. However, the major obstacle for poultry producers comes from infectious diseases. Newcastle Disease (ND) is the most economically important viral disease of poultry worldwide due to the soaring morbidity and mortality associated with it. 

According to the World Bank, ND is ranked as the third most costly poultry disease, after Avian Influenza (AI) and Infectious Bronchitis (IB). At present, a total of 20 Avian paramyxovirus serotypes (APMV-1 to APMV-20) have been identified in different avian species. ND is caused by Avian orthoavulavirus1 (AOAV-1) formerly designated as Avian avulavirus 1 (AAvV-1) or APMV-1 under the genus Orthoavulavirus within subfamily Avulavirinae of the family Paramyxoviridae. NDV strains have been broadly classified into two classes- class I and class II. The class I comprise of a single genotype 1 and are currently divided into 3 sub-genotypes: 1a, 1b and 1c. Class I isolates are of low virulence and have been recovered from both domestic and wild birds. Whereas, the Class II viruses are genetically more diverse and exhibit wider range of virulence, and the complete analyses identified 21 distinct genotypes (I to XXI, excluding genotype XV that contains only recombinant sequences). 

Since, its first report in 1926 on the island of Java, now part of Indonesia and subsequently in 1927 in Newcastle-upon-Tyne in England, ND has caused tremendous economic losses to the poultry industry worldwide. 

In India, ND was first reported by Edwards in 1928 in Ranikhet region and is popularly called as Ranikhet disease owing to its place of emergence. As for time, it had been a century and the history of ND reflects four major well-established panzootics. 

ND virus (NDV) has a wide host range affecting more than 240 species of birds but the disease varies considerably with different species. ND is directly transmitted by either inhalation or ingestion of virus shed in faeces and respiratory secretions of infected or carrier birds. Indirect transmission through transportation of live bird and poultry product, movement of people and equipment, contaminated feed and water, contaminated fomites, vaccines may also occur. Moreover, spillover event from wild avian species into domestic poultry has also been reported. The incubation period for ND ranges from 2 to 15 days with an average of 5-6 days. 

The disease vary from asymptomatic or mild infection to acute lethal infection with 100% mortality. NDV has been categorized into five pathotypes based on the clinical and pathologic manifestations in infected chickens, designated as follows: 

Velogenic: These are highly pathogenic strains causing mortality upto 100%. 

Viscerotropic velogenic: It is the severe form of ND which causes haemorrhagic intestinal lesions and characteristic haemorrhages at the proventriculus-gizzard junction and in the caecal tonsils. It is also called as “Asian” or “exotic” form of ND. 

Neurotropic velogenic: It causes neurological and some respiratory signs with no gastrointestinal involvement. The typical clinical manifestation includes tremors, ataxia, torticollis, and paralysis of wings and legs. Gross pathologic changes are not observed in the central nervous system. 

Mesogenic: It causes mild to moderate respiratory illness and occasional neurologic. Other symptoms include depression, loss of weight and decreased egg production. Mortality is around 10%. 

Lentogenic or respiratory: These strains are usually associated with a mild or sub-clinical respiratory infection and a small drop in egg production. There is absence of recognizable gross lesions and mortality is usually negligible. 

Asymptomatic:  They cause only the replication of the virus in the intestinal tissue of the infected chicken resulting in subclinical enteric infection. 

ND also has a zoonotic dimension since initial exposure to infectious material can induce transitory unilateral conjunctivitis with congestion, lacrimation, pain and swelling of the sub-conjunctival tissues, which is usually self-limiting.  

Diagnosis of ND is done on the basis of clinical and pathologic manifestations but laboratory confirmation must be done. However, ND must be differentiated with highly pathogenic AI, IB, infectious laryngotracheitis (ILT), and diphtheritic form of fowl pox. Enzyme-linked immunosorbent assay (ELISA) and Haemagglutination Inhibition (HI) test are used for assessing antibody titre in birds. Virus isolation is regarded as the gold standard method for the definitive diagnosis of ND. NDV can be isolated in 9-11 days specific pathogen free embryonated chicken eggs or cell cultures. NDV is biologically characterized on the basis of some in vivo pathogenicity assessment tests namely mean death time (MDT), intracerebral pathogenicity index (ICPI) and intravenous pathogenicity index (IVPI). Molecular pathotyping is predominantly based on RT-PCR followed by the analysis of the amino acid composition at the F cleavage site. According to OIE (World Organization for Animal Health), an NDV isolate to qualify as notifiable, it has to be classified as virulent by possessing at least one of the following: poly basic F cleavage site, MDT value of 40-60 hours, and ICPI value of >0.7 or IVPI >0.5. Other diagnostics include quantitative Polymerase Chain Reaction (qPCR), Microarray hybridisation techniques, Loop mediated isothermal amplification (LAMP) test and, Next-generation sequencing (NGS). Phylogenetic methods can be used to analyze nucleotide sequence data and genotype NDV isolates. 

Isolation of NDV in embryonated chicken eggs: candling (A), disinfection (B), piercing with egg driller (C) and inoculation of virus (D) 

The effective prevention and control of ND depend on routine and regular vaccination along with good biosecurity, management practices and surveillance. Most commonly used NDV conventional vaccines includes: live lentogenic vaccines (e.g. Hitchner-B1, LaSota, V4, NDW, I2 and F) and live mesogenic vaccines (e.g. Roakin, Mukteshwar and Komarov). The inactivated ND vaccines are also used. The ND V4-HR and ND I-2 are naturally thermostable avirulent NDV strain used as live thermostable ND vaccine in many countries in Africa and Southeast Asia. Recently, efforts have been directed towards the development of recombinant vaccines against ND using other avian viruses as vectors and antigenically matched (genotype matched) engineered vaccines. Vaccination programs should be tailored according to local conditions, disease prevalence, severity of challenge, and individual preferences, varying from one area to another.  

The vaccination schedules for backyard, broiler and layer poultry are described below: 

References: 

Alders, R.G. and Spradbrow, P.B. (2001). Controlling Newcastle Disease in Village Chickens: a field manual. Canberra, Australian Centre for International Agricultural Research. Monograph. 82: 112 

Alexander, D.J. (2001). Newcastle disease, The Gordon Memorial Lecture. British Poultry Science, 42: 522. 

Dimitrov, K.M.; Ramey, A.M.; Qiu, X.; Bahl, J. and Afonso, C.L. (2016) Temporal, geographic, and host distribution of avian paramyxovirus 1 (Newcastle disease virus). Infection, genetics, and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases, 39: 22–34. https://doi.org/10.1016/j.meegid.2016.01.008 

Dimitrov, K.M.; Claudio, C.A.L.; Albina, A.E.; Berg, J.B.M.; Briand, F.X.; Brown, I.H.; Chyala, K.C.; Diel, D.G.; Durr, P.A.; Ferreira, H.L.; Gil, A.F.P.; Goujgoulova, G.V.; Grund, C.; Hicks, J.T.; Joannis, T.M.; Torchetti, M.K.; Kolosov, S.; Lewis, B.L.N.; Liu, H.; Miller, P.J.; Monne, I.; Muller, C.P.; Munir, M; Reischak, D.; Sabra, M.; Samal, S.K.; de Almeida, R.S.; Shittu, I.; Snoeck, C.J.; Suarez, D.L.; Borm, S.M.; Wang, Z. and Wong, F.Y.K. (2019). Updated unified phylogenetic classification system and revised nomenclature for Newcastle disease virus. Infection, Genetics, and Evolution. 74: 103917, ISSN 1567-1348, https://doi.org/10.1016/j.meegid. 2019.103917. 

Haryanto, A., Wati. V.; Pakpahan, S. and Wijayanti, N.(2016). Molecular Pathotyping of Newcastle Disease Virus from Naturally Infected Chicken by RT-PCR and RFLP methods. Asian Journal of Animal Science. 10: 39-48. 

OIE (2018). Manual of diagnostic tests and vaccines for Terrestrial Animals, World Organization for Animal Health, Paris, Chapter 3.3.14:964 -983. 

Spradbrow, P.B. (1993-94). Newcastle disease in village chickens. Poultry Science Review 5: 57-96. 

Authors
Sangeeta Das¹ and Pankaj Deka² 

¹PhD Scholar, Department of Veterinary Microbiology, LUVAS, Hisar, Haryana
Ph No. +91 9706590513; email: sangitakashyap9864@gmail.com 

²Assistant Professor, Department of Veterinary Microbiology, College of Veterinary Science, AAU, Khanapara; 
Ph No. +91 6900627690; email: drpankajaau@gmail.com