The California Department of Public Health (CDPH) yesterday announced that sampling of retail raw milk for avian flu turned up a positive sample, based on testing at the Santa Clara Public Health Laboratory, with results confirmed the state's food safety lab.
Since H5N1 avian flu was first detected in US dairy cattle earlier this year, health officials have emphasized the risk of drinking raw milk, which can harbor H5N1 and several other pathogens.
Milk from infected cows contains extremely high levels of the H5N1 virus. Pasteurization inactivates the virus, and though H5N1 viral fragments have been found in some retail milk samples, none contained live virus.
Milk produced in Central Valley outbreak region
The CDPH urged consumers to avoid drinking a batch of whole raw milk produced by Raw Farm, LLC, based in Fresno County. The farm is located in California's Central Valley, which has experienced a surge of avian flu outbreaks in dairy cattle—402 since late August.
The California Department of Agriculture has been testing bulk raw milk samples weekly since the virus first began infecting the state's dairy cattle.
Based on the state's request, the company issued a voluntary recall on the affected batch of milk. No related human illnesses have reported, and health officials have urged customers to return any remaining product to the retail point of purchase.
Concerns about human transmission risk
The US Centers for Disease Control and Prevention (CDC) says about 4.4% of US adults consume raw milk at least once a year, and though concerns persist about whether raw milk or products made with raw milk could transmit the avian flu virus to people, the level of risk isn't currently known.
Unpublished mouse studies suggest a risk of infection from oropharyngeal (mid-throat) administration of contaminated milk. Drinking unpasteurized milk contaminated with H5N1 could bind to a limited number of receptors in the upper airways or, if the milk were aspirated, could infect lower-airway receptors that allow better H5N1 binding.
In the United States, though most human H5N1 cases this year have occurred in people exposed to sick dairy cattle or poultry, two have unexplained exposure.
USDA confirms more poultry outbreaks in 5 states
In other developments, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed seven more avian flu outbreaks across five states, including three in hard-hit California.
Two of California's outbreaks occurred at commercial farms, including a layer pullet facility that has nearly 539,000 birds in Merced County and a duck meat farm in Tulare County that has nearly 97,000 birds. The other is a backyard flock in Madera County.
One of the outbreaks struck another commercial turkey farm in Utah's Piute County, affecting 35,500 birds.
Meanwhile, three of the outbreaks involved backyard birds in different states: Arizona's Maricopa County, Idaho's Lemhi County, and Oklahoma's Roger Mills County.
