Clinico-pathological assessment of virulent Newcastle Disease Virus in ducks / Avaliação clínico-patológica do Vírus da Doença de Newcastle em patos

Abstract Newcastle disease (ND) is an infectious, highly contagious and lethal disease of avian species. It is considered that ducks are natural reservoir or carrier for Newcastle disease virus (NDV) and are resistant against different strains of NDV. Current study was designed to evaluate the pathogenesis of Newcastle disease in domestic ducks through histopathology, immunohistochemistry (IHC) and serum biochemical changes. For this purpose, eighty ducks were reared for 42 days and divided in two groups A and B. Ducks in group A were challenged with (NDV) at rate of 0.1 ml of ELD50 (virus titer 107.32/100µl) on second week of age, whereas Group B was control negative. Splenomegaly, atrophy of thymus and necrotic lesion in kidney were observed on 9th day of post infection. Hepatic degeneration and mononuclear cell infiltration were noticed in proventriculus and intestine in challenged ducks. Viral antigen detected in lungs, intestine, proventriculus and lymphoid organs of infected ducks through IHC. Albumin and total protein values were significantly low in infected groups A as compared to control group B. ALT, AST, and ALP values were significantly high in infected group A. On 5th and 7th day of post infection oropharyngeal swabs were negative for NDV and cloacal swabs were positive for NDV through Reverse transcriptase polymerase chain reaction. It is concluded that ducks are susceptible to NDV and virulent strain of NDV caused disease in ducks.

Resumo A doença de Newcastle (DN) é uma doença infecciosa, altamente contagiosa e letal de espécies aviárias. Considera-se que os patos são reservatórios ou portadores naturais do vírus da doença de Newcastle (VDN) e são resistentes a diferentes cepas de VDN. O presente estudo foi desenvolvido para avaliar a patogênese da DN em patos domésticos por meio de histopatologia, imuno-histoquímica (IHQ) e alterações bioquímicas séricas. Para este propósito, 80 patos foram criados por 42 dias e divididos em dois grupos A e B. Os patos do grupo A foram submetidos ao VDN a uma taxa de 0,1 ml de ELD50 (título viral de 107,32 / 100 µl) na segunda semana de idade, enquanto o Grupo B foi controle negativo. Esplenomegalia, atrofia do timo e lesão necrótica no rim foram observadas no 9º dia pós-infecção. Degeneração hepática e infiltração de células mononucleares foram observadas no proventrículo e intestino em patos infectados. Antígeno viral foi detectado em pulmões, intestino, proventrículo e órgãos linfoides de patos infectados por IHQ. Os valores de albumina e proteína total foram significativamente baixos no grupo A infectado em comparação com o grupo B. Os valores de ALT, AST e ALP foram significativamente altos no grupo A. No 5º e no 7º dia após a infecção, os esfregaços orofaríngeos foram negativos para VDN, enquanto os esfregaços cloacais foram positivos para VDN por meio da reação em cadeia da polimerase via transcriptase reversa. Conclui-se que os patos são suscetíveis ao VDN e à cepa virulenta de VDN que causou doenças em patos.

Understanding the disease and economic impact of avirulent avian paramyxovirus type 1 (APMV-1) infection in Great Britain.

Newcastle disease (ND) is a notifiable disease affecting chickens and other avian species caused by virulent strains of Avian paramyxovirus type 1 (APMV-1). While outbreaks of ND can have devastating consequences, avirulent strains of APMV-1 generally cause subclinical infections or mild disease. However, viruses can cause different levels of disease in different species and virulence can evolve following cross-species transmission events. This report describes the detection of three cases of avirulent APMV-1 infection in Great Britain (GB). Case 1 emerged from the 'testing to exclude' scheme in chickens in Shropshire while cases 2 and 3 were made directly from notifiable avian disease investigations in chicken broilers in Herefordshire and on premises in Wiltshire containing ducks and mixed species, respectively). Class II/genotype I.1.1 APMV-1 from case 1 shared 99.94% identity to the Queensland V4 strain of APMV-1. Class II/genotype II APMV-1 was detected from case 2 while the class II/genotype I.2 virus from case 3 aligned closely with strains isolated from Anseriformes. Exclusion of ND through rapid detection of avirulent APMV-1 is important where clinical signs caused by avirulent or virulent APMV-1s could be ambiguous. Understanding the diversity of APMV-1s circulating in GB is critical to understanding disease threat from these adaptable viruses.

Clinico-pathological assessment of virulent Newcastle Disease Virus in ducks.

Newcastle disease (ND) is an infectious, highly contagious and lethal disease of avian species. It is considered that ducks are natural reservoir or carrier for Newcastle disease virus (NDV) and are resistant against different strains of NDV. Current study was designed to evaluate the pathogenesis of Newcastle disease in domestic ducks through histopathology, immunohistochemistry (IHC) and serum biochemical changes. For this purpose, eighty ducks were reared for 42 days and divided in two groups A and B. Ducks in group A were challenged with (NDV) at rate of 0.1 ml of ELD50 (virus titer 107.32/100µl) on second week of age, whereas Group B was control negative. Splenomegaly, atrophy of thymus and necrotic lesion in kidney were observed on 9th day of post infection. Hepatic degeneration and mononuclear cell infiltration were noticed in proventriculus and intestine in challenged ducks. Viral antigen detected in lungs, intestine, proventriculus and lymphoid organs of infected ducks through IHC. Albumin and total protein values were significantly low in infected groups A as compared to control group B. ALT, AST, and ALP values were significantly high in infected group A. On 5th and 7th day of post infection oropharyngeal swabs were negative for NDV and cloacal swabs were positive for NDV through Reverse transcriptase polymerase chain reaction. It is concluded that ducks are susceptible to NDV and virulent strain of NDV caused disease in ducks.

Assessment of Preparation of Samples Under the Field Conditions and a Portable Real-Time RT-PCR Assay for the Rapid On-Site Detection of Newcastle Disease Virus.

Newcastle disease virus (NDV), also known as virulent forms of avian paramyxovirus serotype 1 (AMPV-1), is the causative agent of Newcastle disease affecting many species of birds and causing heavy losses to the poultry industry worldwide. Early, rapid and sensitive detection of the viruses or the viral nucleic acids is very important for disease diagnosis and control. This study aimed to evaluate sample preparation under field conditions and the application of a real-time RT-PCR method in the portable T-COR4 platform for the rapid, on-site detection of NDV on a farm. In the laboratory setting, the portable real-time RT-PCR assay had a similar performance compared with that obtained with a larger, stationary Rotor Gene real-time thermocycler. In the field conditions, viral nucleic acids were manually extracted just outside of animal units with minimal equipment and real-time RT-PCR detection was performed with the portable thermocycler T-COR4 placed in a nearby room. The portable assay at the farm detected viral RNA in 15 samples and reached an agreement of 83% (39/47) when the same RNA preparations were tested in the Rotor Gene thermocycler under the laboratory setting. The results demonstrated the feasibility of performing field detection but also the need to improve and further simplify sample preparation procedures.

Spatial distribution of free-of-charge pathology submissions to the California Animal Health and Food Safety laboratories during the exotic Newcastle outbreak in 2002-2003.

After the 1971-1973 outbreak of exotic Newcastle disease (END) in California, a free-of-charge diagnostic submission program was created for backyard poultry flocks. This program was implemented to improve disease surveillance in small poultry flocks. The aim of this study was to evaluate the spatial distribution of free-of-charge pathology submissions to the California Animal Health and Food Safety laboratories during the END outbreak in 2002-2003. Cases and controls were selected from within a 100-mile (161-km) radius of each of three laboratories, and their geographic distributions were evaluated. Global clustering of cases was significant around all three laboratories, with mixed results at the local clustering level and the only significant clustering at the focal level around the Davis laboratory with an observed to expected ratio of approximately 5. The area of influence for all three laboratories was about 20 miles (32 km). The significant clustering of cases around the laboratories indicates that more public information about the free-of-charge program could result in coverage of a larger portion of the population; however, the value of the information resulting from increased sampling should be considered relative to the additional cost of obtaining it.