In early February, dairy farmers in the Texas Panhandle began to notice sick cattle. The buzz soon reached Darren Turley, executive director of the Texas Association of Dairymen: “They said there is something moving from herd to herd.”
Nearly 60 days passed before veterinarians identified the culprit: a highly pathogenic strain of the bird flu virus, H5N1. Had it been detected sooner, the outbreak might have been swiftly contained. Now it has spread to at least eight other states, and it will be hard to eliminate.
At the moment, the bird flu hasn’t adapted to spread from person to person through the air like the seasonal flu. That’s what it would take to give liftoff to another pandemic. This lucky fact could change, however, as the virus mutates within each cow it infects. Those mutations are random, but more cows provide more chances of stumbling on ones that pose a grave risk to humans.
Why did it take so long to recognize the virus on high-tech farms in the world’s richest country? Because even though H5N1 has circulated for nearly three decades, its arrival in dairy cattle was most unexpected. “People tend to think that an outbreak starts at Monday at 9 a.m. with a sign saying, ‘Outbreak has started,’” said Jeremy Farrar, chief scientist at the World Health Organization. “It’s rarely like that.”