Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 5/2/2015
Publication Date: 1/3/2017
Citation: Bertran, K., Susta, L., Miller, P.J. 2017. Avian influenza virus and Newcastle disease virus. In: Hester, P.Y., editor. Egg Inovations and Strategies for Improvements. Little Rock, AR: Oxford Academic Press. p. 547-559. doi:10.1016/B978-0-12-800879-9.00051-2. Interpretive Summary: Avian influenza viruses (AIVs) and Newcastle disease viruses (NDVs) infect poultry and cause the birds to lay fewer eggs, misshapen eggs, and sometimes even stop egg production all together. Vaccination may help decrease this affect, but every situation is different. The vaccine type, vaccine protocol, immunity level induced, and challenge virus that infect the birds will all pay a role. This chapter describes the clinical disease, gross and microscopic lesion observed in the reproductive tract of non-vaccinated and vaccinated egg laying hens after they are infected with AIV and NDV strains with varying abilities to cause clinical disease. In some instances, even the live vaccine viruses can decrease egg production. While the viruses can be found inside of embryos, the more virulent viruses usually kill the embryos, decreasing the likelihood of birds hatching and spreading the viruses. Cooking non fertile eggs used for human consumption would sufficiently inactivate virus making the eggs safe to eat.
Technical Abstract: Avian influenza virus (AIV) and Newcastle disease virus (NDV) severely impact poultry egg production. Decreased egg yield and hatchability, as well as misshapen eggs, are often observed during infection with AIV and NDV, even with low-virulence strains or in vaccinated flocks. Data suggest that in order to decrease or prevent egg drops upon challenge with either highly pathogenic AIV (HPAI) or virulent NDV (vNDV) serum antibody titers in hens need to be higher than the amount required to simply abate morbidity and mortality. Vertical transmission is also occasionally reported with both viruses. However, the high mortality and drastic drop in egg production caused by HPAI or vNDV, as well as the exceedingly low rate of transmission of less pathogenic strains into eggs, make vertical spread epizootiologically irrelevant. Nonetheless, since both viruses may be found inside of eggs, proper cooking prior to consumption is sufficient to prevent transmission to humans.