Bird flu has been detected in a dairy cattle herd in Wyoming, the state’s agriculture department said on June 7, making it the 12th confirmed state where the highly pathogenic avian influenza virus has been detected in cows.
Inspectors with the U.S. Department of Agriculture’s (USDA’s) National Veterinary Services Laboratory have confirmed the presence of bird flu in a dairy cattle herd in Wyoming, the Wyoming Livestock Board said in a June 7 statement. The discovery is the first confirmed case of the avian influenza virus in Wyoming.
“The Wyoming Livestock Board encourages all dairy producers to closely monitor their herd and contact their herd veterinarian immediately if their cattle appear symptomatic,” Hallie Hasel, Wyoming state veterinarian, said in a statement.
“The primary concern with this diagnosis is on-dairy production losses, as the disease has been associated with decreased milk production. The risk to cattle is minimal and the risk to human health remains very low.”
Since late March, the highly pathogenic avian influenza virus has been reported in more than 80 dairy herds across the country.
While dairies are required to prevent milk from sickened animals from entering the food chain, the Centers for Disease Control and Prevention (CDC) says that the pasteurization process of heating milk to a high temperature kills active bird flu viruses, making such milk safe for human consumption.
Human Infections
So far three human infections have been reported in the United States (two in Michigan and one in Texas), with all three cases reported among dairy farm workers. The latest case, in Michigan, was the first human case to report more typical symptoms of acute respiratory illness associated with influenza virus infection, including bird flu, according to the Michigan Department of Health and Human Services (MDHHS).In the first human case in Michigan, eye symptoms occurred after a direct splash of infected milk to the eye, while in the second case, respiratory symptoms emerged after direct exposure to an infected cow, per Michigan health officials. Neither infected individual was wearing personal protective equipment (PPE).
“This tells us that direct exposure to infected livestock poses a risk to humans, and that PPE is an important tool in preventing spread among individuals who work on dairy and poultry farms,” Dr. Natasha Bagdasarian, MDHHS chief medical executive, said in a statement. “We have not seen signs of sustained human-to-human transmission, and the current health risk to the general public remains low.”
Scientists are on alert for changes in the virus that could signal that it is adapting to spread more easily among humans. The CDC said in a recent update that the variant of the bird flu virus that sickened herds in Texas—known as clade 2.3.4.4b—was lethal to ferrets in experiments designed to mimic the disease in humans.
Seasonal flu, by contrast, makes ferrets sick but doesn’t kill them, according to the agency, which also found that the virus spread easily among healthy ferrets when placed in contact with infected ones, but was less efficient than other flu strains at spreading by respiratory droplets.
The ferret findings haven’t changed the CDC’s assessment that the risk to humans from the disease is low. So far, there have been no signs of person-to-person transmission.