Dr. Nahid Bhadelia: Avian influenza
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Since first being detected in the U.S. in 2022, H5N1 bird flu has been responsible for ongoing sporadic outbreaks of disease among poultry flocks, dairy cattle, wild birds, and wild mammals, as well as dozens of cases in humans.
On January 13, 2025, SciLine interviewed: Dr. Nahid Bhadelia, an infectious diseases physician, associate professor of medicine, and founding director of the Center on Emerging Infectious Diseases at Boston University. See the footage and transcript from the interview below, or select ‘Contents’ on the left to skip to specific questions.
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Introduction
[0:00:19]
NAHID BHADELIA: My name is Nahid Bhadelia. I’m an infectious diseases physician and associate professor of medicine at Boston University School of Medicine and the founding director of Boston University’s Center on Emerging Infectious Diseases. My focus is clinical care, health systems, preparedness, and infection control related to emerging infectious diseases.
Interview with SciLine
Can you give some background information on highly pathogenic avian influenza (H5N1)?
[0:00:47]
NAHID BHADELIA: Highly pathogenic avian influenza, H5N1, is an influenza virus—a virus that we’ve known about for a few decades. Over the last couple of decades, the World Health Organization has recorded nearly 1000 cases, and about half of those have resulted in deaths globally. However, in the last few years, this virus is changing its behavior. It’s now expanding in more geographic areas. For example, as of 2022 we saw our first case of H5N1 here in the United States, in a human. Additionally, we’re seeing this virus is spreading in many more mammalian species—over 40 mammalian species—and we’re seeing, at least in wildlife, decimation of this virus, with concern that it’s adapting to better infect mammals. As of last spring, this virus has then made a jump from birds into dairy cows, which has led to a scenario where many more humans may now come into contact with dairy farms, cows on dairy farms that are being infected. That has led to a number of what we call sporadic infections, where the infection is transmitted from an animal into human here in the United States. Thankfully, we do not see any evidence of sustained human-to-human transmission currently.
What are some of the important questions scientists are still trying to answer about H5N1?
[0:02:02]
NAHID BHADELIA: One of the major things that scientists are trying to figure out is how this virus is transmitting between animals on farms, between animals in the wilderness. How much transmission is happening between mammals in the wild, which can give us a sign about how the propensity of this virus may be and how close it is to potentially adapting to humans. Another thing that we’re looking at closely, aside from its ability to transmit, is other features of the virus at the genetic level, such as its ability to evade our antiviral medications, such as oseltamivir, which is our first-line treatment. So, keeping an eye on the genetic evolution of the virus is another question that we are following closely.
What is the federal government’s role in monitoring and managing H5N1, and how might the incoming Trump administration change this approach?
[0:02:55]
NAHID BHADELIA: Traditionally, federal agencies, as well as offices such as the Office of Pandemic Preparedness and Response Policy, focus on setting nationwide guidance, investing in large investments, such as novel vaccines, in large programs that may help states implement more local activities. As well as raising the scientific knowledge about the virus through investments in studies at the NIH and other agencies, just the FDA and USDA. The way that the United States public health system is organized is that majority of the local and state implementation is left to state departments, state and local departments of public health, in partnership with CDC, which has to be invited into states. States can then work with local producers as well as populations and communities within their borders to potentially take funds that have been designated for state activities, allocate more funds, as well as actually implement the programs that could have an effect in blocking the transmission of this virus. So, from that perspective, although we do not yet know what the Trump administration’s focus may be on H5N1 in the coming months. We do know that the activities at the state level can continue or be augmented depending on the severity and spread of this virus in the in the coming months.
Should people take any precautions with milk or food, or when interacting with animals?
[0:04:23]
NAHID BHADELIA: The good news is H5N1 is much easier to kill as a virus than most other pathogens out there. Hence, actions such as pasteurization of milk can render this virus inactive even if it was present in the raw milk formation. Hence, if you drink pasteurized milk, you’re completely safe. People who may have access to raw milk should be aware that aside from H5N1—which may or may not cause infection during consumption—there are other bacterial infections, such as Mycobacterium bovis, as well as E. coli and other gastrointestinal bacteria that can affect humans who drink raw milk. Most other raw products, such as eggs or meats, can be rendered safe by cooking them to ensure an internal temperature of 165 Fahrenheit. Cooking most things will kill the virus, making it safe for consumption. I also want to raise some awareness in the fact that since there are so many species in our environment that potentially could be infected with this virus, including wild birds. About 133 million birds in commercial, wild, and backyard flocks have been infected with H5N1 since 2022 here in the United States. Consumers should always also be aware that interacting with wildlife or other animals directly could potentially lead to transmission of a virus if the animal is infected.
Is it safe to feed birds outside?
[0:05:53]
NAHID BHADELIA: I think the safest thing as we try to figure out the spread of this virus is to not have bird feeders in your backyard, particularly if you are in an area of the of the country or state where there is high H5N1 activity. However, if you do end up having bird feeders, or if you do end up having backyard flocks, one of the most important things that you need to do is to be aware of any sick or dead birds that could potentially have been infected with H5N1 and to not handle those dead birds without calling your local health department or your wildlife agency.
How can people know if there are high levels of H5N1 in their area?
[0:06:34]
NAHID BHADELIA: You can find out whether there is high levels of H5N1 animal infections by going to the USDA website or the CDC website, which is tracking wastewater positivity in many parts of the country. CDC is also tracking potential influenza activity, including H5N1 at the human level at states, through their influenza illness network statistics.
What should owners of backyard chickens know about H5N1?
[0:07:07]
NAHID BHADELIA: Owners of backyard flocks should be aware that since this virus is transmitting among many wild birds, there’s a possibility that their flocks may be infected through a transmission between wild birds and domestic birds. Hence, it is critically important that if you notice sick or dead birds, to not handle those animals yourself but to call your local health department or your local wildlife agent agency. Once that animal has been disposed of, it is important that you be aware that infected animals can leave a virus behind in terms of littering and droppings and other potential areas within their environment that may remain contaminated. Hence, it’s important that you handle all contaminated areas with personal protective equipment. There’s great guidance on the CDC website by going to cdc.gov/birdflu/caring.
What can pet owners do to protect their pets from H5N1?
[0:08:09]
NAHID BHADELIA: One of the more troubling trends we’ve noticed, particularly in areas where domestic or peridomestic animals like cats and dogs, particularly cats, when they coexist among domestic animals such as cows, there have been infections in cats that has led to neurological disease and death. A lot of times this has been associated with consumption of raw milk by cats or through contamination of virus in the area. If owners have both domestic animals that are cows or other farm animals, as well as more peridomestic animals or pets such as cats, they should again be make an effort to separate the two, ensuring that there’s no transmission or infection between those animals. And if you see any of those animals being sick, to report that illness again to your local health department or your wildlife agency.
Could H5N1 become the next human pandemic?
[0:09:11]
NAHID BHADELIA: H5N1 could become the next human pandemic. However, when and if it’s certain that it would, it is, that is what is currently not known. Current studies show that there is very low barrier for mutation for this virus to potentially become more adaptable to infect the upper airways in humans, which means the virus would exist a little bit closer to the upper airways, allowing humans to transmit between themselves, which would lead to sustained human-to-human transmission that could lead to a potential outbreak, an epidemic, and potentially a future pandemic. Our hope, though, is that if we limit the spread of this virus among humans—between animals and humans—and then among humans, that it would not get to a point where it potentially becomes the level of pandemic that we saw with COVID-19.
Do you have any advice for reporters covering this topic?
[Posted January 13, 2025 | Download video]
