Perhaps you’ve noticed the egg aisle at the grocery store sometimes being completely empty. At the Safeway in Pollock Pines, signs posted apologize for the inconvenience, blaming an outbreak of avian influenza.
The “Highly Pathogenic Avian Influenza,” or H5N1 virus, has been affecting wild birds across the country since at least 2021. More recently, the virus jumped to chicken and other poultry birds, elephant seals and now dairy cattle. In the most recent outbreak, a single human case has been detected in Texas.
Solano and Yolo counties issued a health advisory last week urging people to avoid raw milk and other dairy products due to recent detections of the H5N1 virus in these products.
Solano County Public Health Officer Dr. Bela Matyas told Insight’s Vicki Gonzalez they released the warning to the public, even though the virus hasn’t been detected in California.
“We don't want to wait for human transmission to occur,” he said. “We don't want to wait for it to already beat the problem. We want to get ahead of it.
Matyas and Dr. Dean Blumberg, chief of pediatric infectious diseases at UC Davis Health, spoke with Gonzalez about the outbreak and what the risks are to the public.
This interview has been edited for length and clarity.
Interview highlights
What exactly is H5N1?
Blumberg: So there's a bunch of different influenza strains. Some of them only infect humans and some of them affect different animal species, and this H5N1 traditionally has infected primarily birds, but it does have some cross-species transmission.
There have been previous outbreaks in cases going back more than two decades. Why is it concerning now?
Blumberg: Now what we're seeing is transmission from birds to dairy, to cattle, and that's different. And then we've had transmission from the cattle to workers who've been working with the cattle herds. That's different.
Is that unusual to you given that you walk in the world of infectious diseases?
Blumberg: When we have transmission between species, sometimes this can occur with very, very close contact. And if there's like one case that's transmitted — remember with Covid we had some transmission to cats and dogs — and one case here or there is not that big of a deal. If it tends to be widespread though, that's new. Then that can be concerning because that can infect many different cattle, that can affect transmissions to other species, including humans, and that can have economic consequences as well.
Are dairy workers more susceptible to getting this virus?
Blumberg: Certainly. There has been a case in a dairy worker, and so that's something that would be sort of a frontline exposure that [we] would be most concerned about. And then the other concern is could it be transmitted by dairy products.
Why are raw dairy products the concern versus pasteurized?
Blumberg: Pasteurization doesn't sterilize dairy products, but it does significantly reduce any chance of infection, by 99.99%. That's pretty darn good. The raw milk, however, does not have that protection, and so that is a risk of transmission. And studies have shown that this virus has been detected in raw milk samples, and so that's why it's of concern that it may be transmitted via that entity.
Both Solano and Yolo counties put out a joint release, a health advisory, warning about consuming raw milk and raw dairy products. Why did you decide to release this advisory now and also jointly with Yolo County?
Matyas: As Dr. Blumberg points out, the recent news of this virus being in cattle, dairy cattle in particular, is what's concerning. Because there has been a lot of evidence to date showing that this virus is in raw milk. Now, can it transmit to a human from the raw milk? We don't really know, but it's concerning that it's present. And clearly pasteurization gets rid of it, so that's why the raw milk in particular is our concern.
Historically, raw milk has been responsible for transmitting to people brucellosis, tuberculosis, E. Coli, Salmonella, there’s even been anecdotes of rabies. So raw milk is a high-risk food product, raw dairy is high risk. And so the reason for the timing is that this particular concern in dairy cattle has been spreading across the country. We haven’t had any defined or definitive identification of cattle here in California so far, but we have seen an increase of influenza A in wastewater in many parts of the Bay Area not accompanied by human cases being reported. And so that implies, at least it infers, that there might very well be a risk in wild animals and in domesticated animals, like cattle.
The pattern of what we're seeing is worrisome. And so we wanted to issue this press release now because we don't want to wait for human transmission to occur. We don't want to wait for it to already be the problem, we want to get ahead of it. And we believe that by warning people against consuming raw milk and raw dairy, they'll be protected from whatever risk may occur.
Are you working with producers of raw milk in both of your counties? Because, at the end of the day, this also impacts their industry as well and their livelihoods.
Matyas: It does, and you know, everything in life is a balance. The California Department of Food and Agriculture oversees that particular ag environment. And so we are working through CDFA as well as with our county ag departments to make our dairy farmers aware of our concerns to try to implement some direct cattle testing so that we can have more direct information.
I definitely am not interested in harming business or the economy. But at the same time, our obligation is to protect human health and in the weighing of this balance, we have to focus more on making sure people have the information to protect themselves.
There has only been a single human case, detected in Texas, but what kind of symptoms should someone watch out for?
Blumberg: The symptoms range from very mild — just like eye irritation, conjunctivitis — to a flu-like illness. So respiratory symptoms cough, sneezing, running nose, fever, muscle aches and fatigue. The scary thing about it is that some cases can be very mild, but historically the mortality rate has been over 50%.
Given that we have a pandemic very near in our hindsight, do you think we're better prepared to handle something, whether it's H5N1 or the next virus that comes our way?
Blumberg: On the one hand we are better prepared. We've had the experience with Covid. I think people do appreciate what public health officers bring to the table and how important public health is to people because of Covid. On the other hand, there have been proposed cuts to public health funding and that's a real concern because going through a boom or bust cycle with funding is really a problem. We really need some consistent funding in that area to make sure that we can respond to these threats.
Correction: A previous version of the story misidentified Solano County Public Health Officer Dr. Bela Matyas. It has been corrected.
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