The bird flu virus that is spreading through American dairy cows can probably be traced back to a single spillover event.
Late last year, scientists believe, the virus jumped from wild birds into cattle in the Texas panhandle.
By this spring, the virus, known as H5N1, had traveled hundreds of miles or more, appearing on farms in Idaho, North Carolina and Michigan.
Instead, it hitched a ride with its hosts, the cows, moving into new states as cattle were transported from the outbreak’s epicenter to farms across the country.
Many facilities focus on just one step in the production process — producing new young, for instance, or fattening adults for slaughter — and then send the animals on.
Locations:
Texas, Idaho , North Carolina, Michigan, United States