Title : Enhancing delivery of thermostable Newcastle disease vaccine and demonstration of vaccine efficacy and antibody responses of chicken in central Ethiopia
Abstract:
Vaccination is the process of administering vaccine to stimulate immune responses against risks of field infection. However, the outbreak and high prevalence of Newcastle disease (ND) results in 90% to 100% mortality of chickens. A prospective vaccination experimental study was carried out in selected areas of Ethiopia to generate immune responses, demonstrate the delivery system and evaluate the efficacy of thermostable I-2strain Newcastle diseases (ND) vaccine against velogenic, mesogenic and lentogenic strains of ND viruses. A total of 180 chickens comprised of Horro (n=60), Koekoek (n=60) and DZ white(n=60) were included and monitored in this field experiment. The level of ND antibody titer in the chickens were profiled using hemagglutination inhibition technique (HI). In this experiment, a total of 91 chicken breeds were given thermostable ND vaccine and its delivery protocols were demonstrated to farmers. Additionally, a total of 120 households were treated for the demonstration of gate step technologies during the study period. The efficacy of oral drinking water application of thermostable ND vaccine was compared with the ocular application of thermostable NDV-I2 vaccine. The present result showed that NDV-I2 vaccine applied by eye-dop or drinking-water protected chickens against field strains. The result also showed that a significant increment in antibody titers was linearly related to vaccination with protective antibody levels (≥1:16) rising from 12.1% pre-vaccination to 65.9% post-vaccination (p < 0.0001). After the first vaccination, 90% and 93% of chicken had antibody titer of ≥ log23 (protective level) in the group vaccinated via drinking water and eye drop respectively and hundred percent (100%) of the vaccinated chicken produced antibody responses for the survival-ship. The HI test revealed that, out of the 91 sera tested, 9 (2.5 %) chickens were negative for NDV antibodies (Abs) and had NDV antibody titer below the minimum protective titer of log23 and 89 chickens (97.5%) were positive for NDV Abs; had NDV antibody titer above log23. This showed that thermostable NDV-I2 vaccine is a suitable vaccine for oral application under Ethiopian conditions. It is therefore recommended that, biosecurity measures, combined vaccines and surveillance techniques be emphasized and ensured, in order to prevent ND infection among flocks and the use of thermostable ND-I2 vaccine could contribute to food security if it could be used by rural poultry farmers.
Key words: Antibody, Chicken, Disease, Test, Vaccine,
