Absence of Avian Metapneumovirus A and B in Eggs Indicates No Vertical Transmission
Avian metapneumovirus (aMPV) is a major pathogen of poultry worldwide, associated with respiratory disease and significant economic losses in the poultry industry. During 2023 and 2024, subtypes A and B were detected in commercial turkey and chicken flocks across several U.S. states, marking a resurgence and geographic expansion of the virus within the country. This renewed presence raises concerns regarding transmission dynamics, control strategies, and the broader impact on poultry health and production.
A recent study published in Avian Diseases confirmed the widespread detection of aMPV subtypes A and B in U.S. poultry flocks, particularly in turkeys and chickens. The investigations demonstrated that although the virus primarily infects the respiratory tract, there is no evidence of vertical transmission from hens to eggs or embryos. Multiple farms reported clinical respiratory signs and decreased productivity, yet the absence of viral RNA in eggs supports the conclusion that horizontal transmission, via aerosols or mechanical vectors, potentially involving wild birds, remains the principal route of spread. Current evidence indicates that vertical transmission of aMPV subtypes A and B does not play a significant role in the dissemination of the virus within commercial turkey flocks in the United States.
