It seems that there may have been an overflow of the H5N1 bird flu virus of wild birds in dairy cattle. The Arizona Department of Agriculture announced on Friday that it had found the virus in milk from a herd of cows in Maricopa County, which contains the capital of the state, Phoenix.
This is the first detection of H5N1 in dairy cows in Arizona, making it the 17th state in which affected cows were found. Almost 970 herds have tested positively since the outbreak was first identified at the end of March 2024.
The Arizona detection took place as part of the national milk test strategy of the US Department of Agriculture, which samples bulk milk in search of the presence of H5N1 viruses. Last week USDA and Nevada’s Department of Agriculture announced a detection of H5N1 in Dairy Kudes.
Because it was first discovered that bird flu viruses infected cows and spread under herds, it was thought that all detections were connected – that there had been a single leap of the H5N1 virus in cows, probably in Texas at the end of 2023 or early 2024. That assessment was based on the current analysis of the genetic sequences of the viruses, which belong to a family of H5N1 known as Clade 2.3.4.4b, Genotype B3.13.
But the discovery of the virus in Milk from Nevada Kudes at the beginning of January – results that were only released last week – showed that another version of the virus was responsible for those infections. That virus belonged to the same clade, but was from the D1.1 -Genotype, a version of the virus responsible for a serious infection of a teenager in British Columbia, Canada, in November, and the death of a person who has a backyard Had Flock in Louisiana in January.
The virus isolated from the milk of the herd of Arizona was also a D1.1 virus, but apparently another version of it.
“This detection of Aviaire Influenza is consistent with a D1.1 -genotype and not related to the recent Nevada detection of this virus,” ” Arizona’s statement said. “This D1.1 -Genotype does not wear characteristics that would make it more likely to infect people.”
When the Nevada detection was made public, flu scientists warned that more overflow in cows were probably, considering how common H5N1 is in wild birds throughout the country. But Arizona’s announcement still came as a surprise.
“I definitely thought that more jumps would be found by testing milk. But I have to confess that I didn’t think it would happen so quickly, nor in my own backyard when I looked north, about Maricopa County, to what happens in Nevada! “Michael Worobey, an evolutionary biologist at the University of Arizona, told Stat per text.
Prior to the outbreak in cows, the United States had discovered only one human H5N1 infection, with a person involved in clearing infected poultry in Colorado. That infection took place in 2022.
But in the past year there have been 69 confirmed human cases, and a number more where Staatslaboratories have seen a positive result, but extra tests in the Centers for Disease Control and Prevention cannot confirm the case, often due to low levels of viral material or Demolition of the sample during transport. The majority of these cases have taken place in people with direct contact with dairy cows or poultry clocks, which are also susceptible to contracting the virus by wild birds.