Abstract

Numerous microbial agents, encompassing viral, bacterial, and parasitic pathogens, contribute to significant mortality in turkey flocks, adversely affecting the global turkey industry. This review presents a comprehensive overview of these microbial threats, with an updated epidemiological perspective focusing on Egypt, while emphasizing their broader implications for the turkey industry worldwide. Viral pathogens, such as the Newcastle disease virus, avian influenza virus, avian metapneumovirus, and turkey hemorrhagic enteritis virus, are associated with mortality rates reaching up to 100% in both young and adult turkeys. Additionally, turkey coronavirus has been reported to cause mortality rates of up to 50% in turkey poults. Bacterial infections, which may act as primary or secondary pathogens, also contribute to significant mortality in turkeys. Key bacterial agents include Mycoplasma spp., Bordetella avium, Ornithobacterium rhinotracheale, avian pathogenic Escherichia coli (APEC), Pasteurella multocida, and Salmonella spp. Furthermore, parasitic diseases, particularly histomoniasis and coccidiosis, are responsible for elevated mortality rates in turkey flocks.