A new human bird flu case in the U.S. has been found further west than in the past, this time in a dairy worker in Colorado. It’s the fourth human case of highly pathogenic avian influenza that’s been detected related to an outbreak among U.S. dairy cows.
Previous cases were reported in Texas and Michigan, according to the Centers for Disease Control and Prevention, which announced detection of the new case Wednesday. The dairy worker was treated for symptoms and has since recovered from the infection, which occurred in April.
While the strain of avian influenza designated H1N5 has proven deadly for some people worldwide, cases so far related to this outbreak have shown up as pink eye among people who work closely with infected dairy herds.
The Department of Agriculture reported that, as of Wednesday, there were 139 dairy herds that had tested positive for bird flu, located in a total of 12 states: Colorado, Idaho, Iowa, Kansas, Michigan, Minnesota, New Mexico, North Carolina, Ohio, South Dakota, Texas and Wyoming.
Monitoring for spread
“CDC has been watching influenza surveillance systems closely, particularly in affected states, and there has been no sign of unusual influenza activity in people, including in syndromic surveillance,” the public health agency’s notice reported. Risk to humans from the outbreak is considered low, the CDC said.
Among monitoring efforts, the CDC maintains a wastewater map of the country that shows levels of influenza A detection in the past two weeks. That includes bird flu, but doesn’t separate it out from other influenza A strains. Nor does it say whether the virus samples came from animals or humans. “It could come from a human or from an animal like a bird or an animal product, like milk from an infected cow,” according to the explanation of the map.
As NBC reported, “The CDC recommends that anyone in contact with dairy cattle wear protective equipment, including safety glasses, waterproof aprons and boots that can be sanitized.”
USDA, Food and Drug Administration and CDC officials have said that while avian flu remnants were found in milk samples from infected dairy cows, milk that has been pasteurized was tested and proved safe for people to consume. Testing of dairy, beef and poultry products similarly showed they are safe to eat as long as they are handled properly and cooked adequately, as Deseret News previously reported.
Animal infections
While bird flu has been found most often in birds, it has also been found in a variety of animals, from sea lions to bears. It was detected in Idaho alpacas, North American river otters, Virginia possums, a couple of Utah mountain lions and a red fox.
As Deseret News reported, “Avian influenza in the United States has been detected in big cats, mountain lions, bobcats, brown bears, black bears and polar bears, bottlenose dolphins, grey seals, harbor seals, red foxes, coyotes, fishers, American martens, North American river otters, raccoons, skunks, Virginia possums and Abert’s squirrels. There have been outbreaks in cattle and in mink. But most of the wild mammal infections are considered ‘dead end,’ meaning a mammal ate an infected bird, got infected and died without contributing to spread of the virus.”
But there’s no indication that the virus has mutated in ways that facilitate easy spread to or among humans, although health officials are watching closely. To become a pandemic, the CDC said that “sustained person-to-person spread is needed.”