Morphing Chicken Pathogens Behind House Finch Deaths

Scientific detective work has partially reconstructed how a bacteria causing respiratory illness in domestic poultry jumped to the wild House Finch population and morphed to cause an eye disease, killing at least half the population of that songbird in eastern North America. Wesley Hochachka, assistant director of Bird Population Studies at Cornell’s ornithology lab, talks about the importance of understanding how diseases evolve and jump to new hosts.

Hochachka says: “Even a zombie apocalypse needs a good backstory, because no disease emerges out of thin air. Learning these backstories is important because we expect that the same general process of disease emergence will occur repeatedly.

“One of the major causes of new diseases is when a bacterium or virus switches hosts. For a new disease to emerge this way, the pathogen must physically travel between different host species and likely also mutate genetically so that it can reproduce and spread in the new species.

“All the lineages of bacteria that have successfully spread in House Finches can be traced back to a single progenitor. The descendants from this progenitor traveled from east to west across North Americaand adapted to changing conditions by becoming either more or less virulent.

“These results do more than reveal the origins of the House Finch eye disease – they show that it is often easier than people think for a disease organism to come into contact with one or more potential new hosts, with emergence of new diseases limited by the ability of pathogens to adapt to new hosts.”

NOTE: This research, from a collaboration that includes the Cornell Lab of Ornithology, is published in the Proceedings of the Royal Society B.

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