Prevalence of Newcastle Disease Virus in Wild and Migratory Birds in Haryana, India.

Newcastle disease virus (NDV) can infect approximately 250 avian species and causes highly contagious Newcastle disease (ND) in domestic poultry, leading to huge economic losses. There are three different pathotypes of NDV, i.e., lentogenic, mesogenic, and velogenic. Wild resident (wild) and migratory birds are natural reservoirs of NDV and are believed to play a key role in transmitting the virus to domestic poultry. The present study was conducted to determine the prevalence of NDV in wild and migratory birds in the state of Haryana, India, during two migratory seasons (2018-19 and 2019-20). In total 1379 samples (1368 choanal swabs and 11 tissue samples) were collected from live (n = 1368) or dead birds (n = 4) belonging to 53 different avian species. These samples belonged to apparently healthy (n = 1338), sick (n = 30), and dead (n = 4) birds. All samples were tested for NDV by real-time reverse transcription-PCR using M gene specific primers and probe. Of the 1379 samples, 23 samples from wild birds [Columba livia domestica (n = 12, 52.17%), Pavo cristatus (n = 9, 39.13%), and Psittaciformes (n = 2, 8.69%)] were found positive for NDV. Only one of the 23 samples (from P. cristatus) was positive for F gene, indicating it to be a mesogenic/velogenic strain. These results indicate that both lentogenic and velogenic strains of NDV are circulating in wild birds in Haryana and that further studies are needed to characterize NDV strains from wild/migratory birds and domestic poultry to determine the extent of virus transmission among these populations. This study considers the disease transmission risk from domestic pigeons and parrots to commercial poultry and vice versa, and the results emphasize the need for strict biosecurity strategies to protect commercial poultry in the region.

Prevalencia del virus de la enfermedad de Newcastle en aves silvestres y migratorias en Haryana, India. El virus de la enfermedad de Newcastle (NDV) puede infectar aproximadamente a 250 especies de aves y causa la enfermedad de Newcastle (ND) altamente contagiosa en la avicultura comercial, lo que genera enormes pérdidas económicas. Hay tres patotipos diferentes del virus de Newcastle, que incluyen, lentogénico, mesogénico y velogénico. Las aves silvestres residentes (silvestres) y migratorias son reservorios naturales del virus de Newcastle y se cree que desempeñan un papel clave en la transmisión del virus a las aves domésticas comerciales. El presente estudio se realizó para determinar la prevalencia del virus de Newcastle en aves silvestres y migratorias en el estado de Haryana, India, durante dos temporadas migratorias (2018-19 y 2019-20). En total, se recolectaron 1379 muestras (1368 hisopos coanales y 11 muestras de tejido) de aves vivas (n = 1368) o muertas (n = 4) pertenecientes a 53 especies de aves diferentes. Estas muestras pertenecían a aves aparentemente sanas (n = 1338), enfermas (n = 30) y muertas (n = 4). Todas las muestras se analizaron para detectar al virus de Newcastle mediante transcripción reversa y PCR en tiempo real utilizando iniciadores y una sonda específicos del gene M. De las 1379 muestras, 23 muestras de aves silvestres [Columba livia domestica (n = 12, 52.17 %), Pavo cristatus (n = 9, 39.13 %) y Psittaciformes (n = 2, 8.69 %)] resultaron positivas para el virus de Newcastle. Solo una de las 23 muestras (de P. cristatus) fue positiva para el gene F, lo que indica que se trata de una cepa mesogénica/velogénica. Estos resultados indican que tanto las cepas lentogénicas como las velogénicas del virus de Newcastle están circulando en las aves silvestres de Haryana y que se necesitan más estudios para caracterizar las cepas del virus de Newcastle de las aves silvestres/migratorias y de las aves domésticas para determinar el alcance de la transmisión del virus entre estas poblaciones. Este estudio considera el riesgo de transmisión de la enfermedad de las palomasdomésticas y loros a las aves comerciales y viceversa, y los resultados enfatizan la necesidad de estrategias estrictas de bioseguridad para proteger las aves comerciales en la región.

Detection of Newcastle disease virus and assessment of associated relative risk in backyard and commercial poultry in Kerala, India.

BACKGROUND: Newcastle disease (ND) is an economically important viral disease affecting the poultry industry. In Kerala, a state in South India, incidences of ND in commercial and backyard poultry have been reported. But a systematic statewide study on the prevalence of the disease has not been carried out. OBJECTIVES: A cross-sectional survey was performed to detect the presence of Newcastle disease virus (NDV) in suspect cases and among apparently healthy commercial flocks and backyard poultry, in the state and to identify risk factors for NDV infection. METHODS: Real-time reverse transcription-PCR (RT-PCR) was used to detect the M gene of NDV in choanal swabs and tissue samples collected from live and dead birds, respectively and the results were statistically analysed. RESULTS: The predominant clinical signs of the examined birds included mild respiratory signs, huddling together and greenish diarrhoea. Nervous signs in the form of torticollis were noticed in birds in some of the affected flocks. On necropsy, many birds had haemorrhages in the proventriculus and caecal tonsils which were suggestive of ND. Of the 2079 samples tested, 167 (8.0%) were positive for the NDV M-gene by RT-PCR. Among 893 samples collected from diseased flocks, 129 (14.5%), were positive for M gene with pairwise relative risk (RR) of 15.6 as compared to apparently healthy flocks where 6 out of 650 (0.9%) samples were positive. All positive samples were from poultry; none of the ducks, pigeons, turkey and wild birds were positive. Commercial broilers were at higher risk of infection than commercial layers (RR: 4.5) and backyard poultry (RR: 4.9). Similarly, birds reared under intensive housing conditions were at a higher risk of being infected as compared to those reared under semi-intensive (RR: 6.7) or backyard housing (RR: 2.1). Multivariable analysis indicated that significantly higher risk of infection exists during migratory season and during ND outbreaks occurring nearby. Further, lower risk was observed with flock vaccination and backyard or semi-intensive housing when compared to intensive housing. When the M gene positive samples were tested by RT-PCR to determine whether the detected NDV were mesogenic/velogenic, 7 (4.2%) were positive. CONCLUSIONS: In Kerala, NDV is endemic in poultry with birds reared commercially under intensive rearing systems being affected the most. The outcome of this study also provides a link between epidemiologic knowledge and the development of successful disease control measures. Statistical analysis suggests that wild bird migration season and presence of migratory birds influences the prevalence of the virus in the State. Further studies are needed to genotype and sub-genotype the detected viruses and to generate baseline data on the prevalence of NDV strains, design better detection strategies, and determine patterns of NDV transmission across domestic poultry and wild bird populations in Kerala.

Prevalence of Newcastle disease and associated risk factors in domestic chickens in the Indian state of Odisha.

Newcastle disease (ND), caused by Newcastle disease virus (NDV), is a contagious disease that affects a variety of domestic and wild avian species. Though ND is vaccine-preventable, it is a persistent threat to poultry industry across the globe. The disease represents a leading cause of morbidity and mortality in chickens. To better understand the epidemiology of NDV among commercial and backyard chickens of Odisha, where chicken farming is being prioritized to assist with poverty alleviation, a cross-sectional study was conducted in two distinct seasons during 2018. Choanal swabs (n = 1361) from live birds (commercial layers, broilers, and backyard chicken) and tracheal tissues from dead birds (n = 10) were collected and tested by real-time reverse transcription polymerase chain reaction (RT-PCR) for the presence of matrix (M) and fusion (F) genes of NDV. Risk factors at the flock and individual bird levels (health status, ND vaccination status, geographical zone, management system, and housing) were assessed using multivariable logistic regression analyses. Of the 1371 samples tested, 160 were positive for M gene amplification indicating an overall apparent prevalence of 11.7% (95% CI 10.1-13.5%). Circulation of virulent NDV strains was also evident with apparent prevalence of 8.1% (13/160; 95% CI: 4.8-13.4%). In addition, commercial birds had significantly higher odds (75%) of being infected with NDV as compared to backyard poultry (p = 0.01). This study helps fill a knowledge gap in the prevalence and distribution of NDV in apparently healthy birds in eastern India, and provides a framework for future longitudinal research of NDV risk and mitigation in targeted geographies-a step forward for effective control of ND in Odisha.

Prevalence of Newcastle Disease Virus in Commercial and Backyard Poultry in Haryana, India.

Newcastle disease virus (NDV) causes Newcastle disease (ND) in poultry. The ND is a highly contagious disease, which is endemic in several countries despite regular vaccination with live or killed vaccines. Studies on NDV in India are mostly targeted toward its detection and characterization from disease outbreaks. A surveillance study was undertaken to determine NDV prevalence throughout the state of Haryana from March 2018 to March 2020 using a stratified sampling scheme. The state was divided into three different zones and a total of 4,001 choanal swab samples were collected from backyard poultry, commercial broilers, and layers. These samples were tested for the M gene of NDV using real-time RT-PCR. Of the 4,001 samples tested, 392 were positive (9.8% apparent prevalence; 95% CI: 8.9-10.8%) for the M gene. Of these 392 M gene positive samples, 35 (8.9%; 95% CI: 6.4-12.3%) were found to be positive based on F gene real-time RT-PCR. Circulation of NDV in commercial and backyard poultry highlights the importance of surveillance studies even in apparently healthy flocks. The information generated in this study should contribute to better understanding of NDV epidemiology in India and may help formulate appropriate disease control strategies for commercial and backyard birds.

Complete Genome Sequences of Newcastle Disease Virus Isolates from Backyard Chickens in Northern India.

The molecular characterization of three Newcastle disease viruses (NDV) isolated from backyard chickens in the state of Haryana, India, was undertaken. Two genotype II strains and one genotype XIIIc class II isolate with genome sizes of 15,186 and 15,192 nucleotides (nt), respectively, were identified.