Effect of post-infection vaccination on immune status of Newcastle disease-infected chicken

This study investigated the response of chicks infected with velogenic Newcastle disease virus (NDV) to Newcastle disease vaccine - NDV-I2. A total of 90 day-old cockerel chicks were used for this study. At three weeks of age, the chicks were randomly separated intotwo equal groups of 45 chicks designated A and B. After separation, Group A chicks were vaccinated with NDV-I2 vaccine intraocularly, while Group B chicks were not vaccinated. At six weeks of age, Groups A and B chicks were further randomly separated into sub groups A1, A2, A3 and B1, B2, B3 of 15 chicks each respectively. After separation, chicks in subgroups A2, A3, B2, and B3 were exposed to chicks infected with NDV. Upon manifestation of clinical infections, chicks in subgroups A2 and B2 were revaccinated with NDV-I2 vaccine, while subgroups A3 and B3 were not vaccinated. Percentage morbidity was 42.86, 64.29, 100 and 92.86 % for subgroups A2, A3, B2 and B3 respectively, while percentage mortality was 14.29, 50, 100 and 71.43 % in subgroups A2, A3, B2 and B3 respectively. This study showed that vaccination of previously vaccinated chicks during Newcastle disease outbreak protects the chicks and reduces both morbidity and mortality significantly. Keywords: Cockerels, Newcastle disease, Vaccination, Revaccination, Geometric mean titre, Morbidity, Mortalit

Serum Antibody Levels against Infectious Bursal Disease Virus in Nigerian Village Chickens

The serum antibody levels against infectious bursal disease (IBD) virus in unvaccinated village chickens (n=484) reared in and around Nsukka, Southeast Nigeria were studied using indirect hemagglutination (IHA) test. Result showed a high seroprevalence (88.4%). Therefore, there is need for government involvement in the control of this disease in village chickens through extension services and mass vaccination of poultry population

Newcastle Disease Virus Shedding Among Healthy Commercial Chickens and its Epidemiological Importance

Newcastle disease virus (NDV), shedding among apparently healthy commercial chickens reared intensively in Nsukka and its environs were studied. Samples were collected from birds that were not vaccinated against Newcastle disease (ND), and also from those that were vaccinated but given an interval of 28 days between vaccination and sample collection. Cloacal and tracheal swabs were collected from each bird and a total of 1800 birds were sampled from 72 farms located in the area. The birds in the area were monitored for 15 days post sampling. The samples were examined for NDV by isolation in embryonated chicken eggs through the allantoic cavity route. Result showed an isolation frequency of 3.2% and this could be termed as the prevalence of NDV in clinically healthy chickens in Nsukka area as the birds remained apparently healthy for more than 15 days. We therefore conclude that there is virus shedding among healthy commercial chickens in Nsukka and its environs and this should be considered an important epidemiological factor in the spread of the disease. Healthy carriers can serve as short term reservoirs and transmit the disease to other birds

Lesions of velogenic viscerotropic Newcastle disease virus infection were more severe in broilers than pullets

This study compared the pathologic effects of velogenic Newcastle disease (ND) virus in broilers and pullets using the normal pathogenic dose of the virus following an earlier report that challenge of the two types of chickens with a low dose of the virus caused mortalities in broilers but none in pullets. One hundred and twenty chickens (10 weeks old) were randomly assigned into four groups (n = 30 each): inoculated intramuscularly with velogenic viscerotropic ND virus (vvNDV) pullets – IP, uninfected pullets – UP, infected broilers – IB and uninfected broilers – UB. Anorexia, depression, ruffled feathers, green diarrhoea, tucking of the head under their wings, droopy wings and prostration were observed on days 2 and 3 post inoculation (PI) in groups IP and IB respectively. Mortality in IP and IB was 100%. Weight loss was significant (P < 0.05) by day 4 PI in both IP and IB when compared with their controls. Percentage weight loss in IP and IB were 20.26% and 38.66%, respectively. Proventricular, intestinal and caecal tonsil haemorrhages were significantly (p < 0.05) more severe in group IB than IP. Histopathology showed more severe necrosis and depletion of the lymphocytes in the bursa of Fabricius, thymus and spleen of group IB than IP. The above observations show that the lesions of vvNDV infection may be more severe in IB than IP