Dairy cows infected with avian flu in five U.S. states have died or been slaughtered by farmers because they did not recover, state officials and academics told Reuters.
Iowa, which is projected to be the tenth biggest milk-producing state this year, is the first new state to find an infected dairy herd since the U.S. confirmed an outbreak in Colorado on April 26.
A third U.S. dairy worker tested positive for bird flu after exposure to infected cows, and was the first to suffer respiratory problems, U.S. officials said on Thursday.
The bird flu strain that has infected dairy cattle herds in nine U.S. states has been detected in alpacas, says the United States Department of Agriculture (USDA).
Bird flu vaccines for laying hens are effective in practice, the Dutch government said on Tuesday, while confirming plans to vaccinate poultry against the virus.
Feeding raw milk contaminated with bird flu to mice infected them with the virus, adding to evidence that consumption of unpasteurized milk is not safe for humans, according to a study published on Friday in the New England Journal of Medicine.
A Michigan health official on Wednesday said that a dairy worker had contracted bird flu, the second U.S. human case reported since the virus was first confirmed in dairy cattle in late March.
The U.S. Centers for Disease Control on Tuesday advised states to aid in H5N1 bird flu surveillance by increasing testing of influenza A virus samples during the summer to help detect even rare cases of transmission of the virus in humans.
A U.S.-based wastewater detection dashboard has identified high levels of influenza A (a subtype of H5N1 bird flu) in Illinois and Florida—two states that have not yet reported positive cases of the disease in dairy herds.