- A growing bird flu outbreak has many people wondering whether another pandemic is looming.
- Millions of birds in U.S. poultry farms and some cattle herds have been affected, but the overall risk to humans remains low.
- Still, a number of human cases have been documented as a new CDC report indicates the virus may be silently spreading to humans who don’t show any symptoms.
- Recent research shows the bird flu virus may be just a few mutations away from transmitting more readily to humans, which could elevate risk.
If you haven’t yet been sick this winter, you likely know someone who has.
Respiratory virus activity remains elevated nationwide as previously contained diseases like tuberculosis and measles make an unsettling resurgence.
Meanwhile, a growing bird flu outbreak is of increasing concern. A recent Morbidity and Mortality Weekly Report (MMWR) from the Centers for Disease Control and Prevention (CDC) shows three new human cases of the H5N1 bird flu virus.
All three individuals were veterinarians working with multiple animals, including dairy cattle. However, none of them had worked with cattle that had known or suspected bird flu, although one did work with H5N1-positive poultry. None of the human cases exhibited any symptoms, suggesting the virus may be stealthily spreading to humans.
However, the CDC is reiterating that the overall risk to humans remains low.
For context, bird flu has affected more than 160 million birds in 51 states, but only 70 human cases of bird flu have been reported. All but five of these cases were detected following exposure to cattle and poultry. One bird flu-related death has occurred.
Like any respiratory virus, bird flu is constantly mutating. This is evident in the recent rise in the number of domestic cats and other wild animals that have contracted the virus. Compared to humans, the mortality risk for some animals is much higher.
Still, according to recent research, bird flu could be just a few mutations away (or less) from transmitting more readily to (and among) humans.
Earlier this month, the CDC accidentally posted and then deleted data about bird flu transmission between cats and humans. As the U.S. Department of Agriculture scrambles to rehire recently laid-off workers tied to the nation’s bird flu response, many Americans may be left wondering whether another pandemic is on the horizon.
However, unlike the COVID-19 pandemic, the U.S. is far more prepared for a pandemic-level response. A bird flu vaccine for poultry has already received conditional approval.
To learn more about bird flu risk, Healthline spoke with William Schaffner, MD, professor of preventive medicine and infectious diseases in the Department of Health Policy at Vanderbilt University Medical Center in Nashville, to find out just how worried we should be about the virus and what can be done to minimize any risk.
Is bird flu ‘silently spreading’ to humans?
Schaffner: There may well be some silent spread. Public health Investigators spoke with these veterinarians about trying to find any potential contact with an animal known to be infected, but the veterinarians may have had contact with many animals, not all of whom had been tested, so they could have acquired their infection in that fashion.
This doesn’t necessarily imply person-to-person spread but spread from an undefined animal source. I think that is the more likely way these veterinarians became infected, whether it’s a veterinarian or a farm worker contracting the virus from an unknown source. Maybe it’s poultry, maybe it’s livestock or cattle.
Is the risk to humans still low?
Schaffner: Yes, indeed — very, very low. There still is no evidence of easy person-to-person spread. In fact, I don’t think we have any evidence that any of the cases documented in the United States spread their infection to another close contact. So, this virus still has not acquired the genetic capacity to spread readily from person to person.
If it should develop that capacity, we might well be on the threshold of another pandemic. These pandemic influenza viruses in the human population occur every 10 to 20 years, but this has not happened yet with this bird flu virus, which, in its previous forms, has changed over time and has been circulating in the wild bird population and in domestic poultry for about 20 years.
But I’m not diminishing the fact that it has gotten into mammalian species, most prominently dairy cattle, but also mink cats, domestic cats, and even in certain zoos in other mammalian species. So there is concern, clearly.
In the public health and infectious disease community, influenza-like illnesses are being sampled, and molecular fingerprinting of these viruses is being done. It’s like our radar system, picking up the earliest possible indication that this virus may have changed to become more dangerous to the human population.
How likely is human-to-human transmission?
Schaffner: I’m afraid I can’t reassure you a whole lot. There are two ways this bird flu virus could acquire mutations that allow it to be transmitted readily to humans and from humans to humans.
First, these viruses multiply constantly in wild birds, poultry, dairy cattle, and perhaps other mammalian species by millions and trillions of times. So they’re multiplying all the time, and, by chance alone, such a mutation could occur.
This is less likely than the other way these pandemic influenza viruses have transitioned from birds to humans. Some animals can be infected both with the bird flu virus and with the human flu; they’re biologically able to do that. That animal, notoriously, is the pig.
Back in 2009, we had swine flu because that virus came via the pig from birds. An individual pig can become infected with the bird flu virus but also simultaneously infected with a human flu virus. These two viruses multiply in the pig simultaneously. They can trade genes. The bird flu virus could pick up from the human virus the ability to infect humans readily, known as reassortment. In other words, the genes are reassorted and trade genetic elements.
That’s the more common way for these new pandemic viruses to appear on the global scene, and we can’t tell you whether or when this will happen. It can happen next Tuesday. It can happen 10 years from now or not. This bird flu virus hasn’t done that yet, so what we can do is do surveillance. We set up this diagnostic radar system looking at these influenza viruses all over the world constantly, and now we have the scientific capacity to do their molecular fingerprinting so we can look at their genes. We couldn’t do that readily 15 or 10 years ago.
Should we be concerned about backyard birds?
Schaffner: Domestic cats can be infected with bird flu, which causes serious illness. That’s been well established. It was quickly determined that was the case with barnyard cats around dairy cows. They consumed contaminated milk and became ill.
I don’t think we’re seeing cats infected in a backyard bird feeder or bird bath, but could it happen? Yes.
Depending upon your level of concern, I would say to use disposable gloves as you handle your bird feeder and your bird bath. When you come into the house, discard those gloves and wash your hands thoroughly. If you have a household cat and you’re concerned, taking down your bird feeder for the time being is a simple thing you can do.
Can you catch bird flu from your cat?
Schaffner: If your pet cat gets bird flu, it’s pretty unlikely you could catch bird flu from your cat.
But as with any sick animal, I would be careful when handling it, particularly if it has an infectious illness. Listen to your veterinarian and wear gloves while you’re trying to comfort the animal.
When can we expect a bird flu vaccine?
Schaffner: There is already a blueprint or template for making a bird flu vaccine. It was made several years ago, and the United States stockpiled a certain amount of vaccine as a starter in case we had to use it.
Since the virus has changed a little bit over time, we’re now updating that vaccine, and we’ll have at least a starter amount in the national stockpile to be used In high risk populations, should that become necessary.
We’re working on vaccines for both humans and animals. Since bird flu is not an immediate threat to humans, there are no current plans to implement it. Looking ahead, it would probably be targeted first at people who work with poultry and people who work with dairy cows, because they’re likely at the greatest risk. That would be just the start before we roll out a more comprehensive vaccination program,
if we thought a pandemic was starting, as with all influenza vaccines, they do best in preventing serious disease. They cannot prevent every infection. You can’t prevent epidemics or pandemics, but you can minimize their serious impact and reduce hospitalizations and deaths.
As the CDC likes to say about the influenza vaccine, it turns wild into mild, to make the point that it reduces the severity of the illness rather than being able to prevent each and every illness.
Could there be a bird flu pandemic?
Schaffner: We can’t predict the future. We’ve gone 20 years without it, and this bird flu, in its various variants, has been around for 20 years, and it hasn’t happened yet. I will say there will be another influenza pandemic sometime. Will it be bird flu or another? Another bird flu or swine flu? We can’t say. When will it happen? Nobody knows.
You have to be prepared on the public health side, which takes resources. You have to keep your guard up and have a response capacity; sometimes, we lose track of that when we think about infectious diseases, influenza included.
We’ve been concerned about bird flu as a potential problem, but we’re also in the middle of a very large seasonal influenza outbreak, and the acceptance of the seasonal influenza vaccine has been much less than we would like.
My message to the public is, next fall, in preparation for the next flu outbreak, please make a resolution to get vaccinated and bring your entire family along to be vaccinated. That will blunt the impact of the next influenza outbreak because we will have another influenza outbreak next winter. I don’t know whether mild, moderate, or severe, but we’re going to have one.
Takeaway
A growing bird flu outbreak has left many people wondering just how concerned we should be. While millions of birds in U.S. poultry farms and cattle herds in some states have been affected, the overall risk to humans remains low.
Still, the bird flu virus may be just a few mutations away from spreading more easily to (and possibly between) humans, which could elevate risk.
A bird flu vaccine for poultry is already underway, and experts say an updated vaccine for humans will be available should the outbreak ever reach pandemic-level concern.
Bird Flu Spread to Humans May Be a Few Mutations Away, but Overall Risk Is Low
Source: Pinoy Lang Sakalam
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