A strain of bird flu that has not been previously found in cows has been detected in U.S. dairy cows, the U.S. Department of Agriculture (USDA) said Wednesday, raising concerns about the continued spread of the virus.
- Since the H5N1 virus spread across the United States last April, it has reduced milk production in dairy cows, killed millions of hens, pushed up egg prices and infected nearly 70 people.
- The USDA said genome sequencing of milk from Nevada found a different strain, called genotype D1.1, the first time it has been found in dairy cows. Previously, all 957 cases of bird flu in dairy cows reported since late March were caused by another strain, genotype B3.13, according to the USDA.
- Reuters reported the discovery of the second strain on Wednesday, before the Agriculture Ministry’s announcement.
- The second strain was the dominant genotype in wild birds this past fall and winter and has also been found in poultry, the USDA said. The discovery of the strain in dairy cows came as part of a program the agency began in December to test milk for avian influenza.
- “We’re seeing that the H5N1 virus itself is smarter than all of us are,” said Beth Thompson, South Dakota’s state veterinarian.
- “It’s adapting itself so it’s not just staying in poultry and wild waterfowl. It’s finding a home in mammals.”
- J.J. Goicoechea, director of the Nevada Department of Agriculture, said wild birds may have introduced the second strain to Nevada cattle. He said ranchers needed to take extra safety measures to protect their livestock.
- “We obviously didn’t do everything we could and everything we should have done, otherwise it wouldn’t have gotten in,” he said.
- The Nevada Department of Agriculture said January 31 that cattle herds in two counties were quarantined due to the discovery of avian influenza.
- Gail Hansen, a veterinarian and public health consultant, said it’s important that the USDA quickly contain the outbreak in Nevada so the strain doesn’t spread to cows elsewhere.
- Last year, avian influenza spread across the United States as infected cattle were shipped from Texas after the virus first jumped from wild birds to cows.
- “We didn’t have it under control before,” Hansen said. “We want to avoid that happening in Nevada.”
- Experts say dairy herds that have been previously infected may be at risk of being infected by the second strain.
- “It looks like we have a new strain of the virus now that may have some ability to evade immunity associated with other strains of the virus and could potentially fuel epidemics among animals and wildlife,” said Gregory Gray, a professor at the University of Texas Medical Branch who studies cattle diseases.
- “It’s shocking.”