The USDA says nine states have cow herds that are infected with bird flu. Some of those herds are here in Colorado, where the first infection was detected in the northeastern part of the state in April.
Dr. Jason Lombard, a veterinary epidemiologist at Colorado State University, says that number has now grown.
“ There are four infected herds in Colorado that have been detected, 66 in nine states across the United States. We're asking people if you've got clinical signs of disease, which is usually pretty pronounced in terms of decreased feed intake, decreased milk production, cows that don't look very, very happy, they're not doing their normal activities, such as eating, lying down, ruminating. Those are the types of cows that we're looking for that could have this disease.”
Dr. Lombard says the first infected herd was identified earlier this year in Texas.
“And it took them quite a while to figure out what actually was causing the clinical signs in those cows. And interestingly, it was a cat that had died on a farm that was submitted, that was initially tested for high path. avian influenza and was positive because the virus is pretty rough on cats, it does kill a lot of the cats that come in contact with it. And so a deceased cat was submitted to a laboratory and that's how they diagnosed highly pathogenic avian influenza.”
The virus has been detected in milk, so milking parlors are one possible site of transmission. But Dr. Lombard says consuming pasteurized milk is safe.
“FDA has done studies, they came out with results of a study earlier this month where they did find pieces of the virus in milk, but when they inoculated those into eggs, there was no virus grown. So that tells us that the organism was in the milk, the pasteurization essentially inactivated the virus, and now it's unable to grow. So it's inactive, essentially dead virus in the milk. And so there's really no risk to humans consuming that milk is what FDA has said. Now the raw milk is a completely different scenario because that milk is generally not treated. And we don't advise the consumption of raw milk just because there's multiple diseases that people could acquire through the consumption of raw milk.”
The sale of raw milk is prohibited in Colorado except through cowshare programs. The Colorado Department of Agriculture and the USDA has guidance on their websites for dairy farmers to help limit the spread of the virus. But Dr. Lombard says dairy operations are complex and officials are still investigating where exactly transmission of the virus is occurring.
“So we have milk trucks, milk drivers, we have feed, we have a lot of personnel. And it's unknown if one of those is most important or all of those important in movement of this virus. And that's one of the things that we're trying to determine is what are the highest priority risks so that we can give producers good biosecurity practices that they can implement to manage those risks.”
The Center for Disease Control says there are three confirmed cases of humans contracting the virus from cows. All are dairy farm workers, one in Texas and two in Michigan.
Information about the virus in Colorado is available through the Colorado Department of Agriculture at ag DOT colorado DOT gov
