Safeguarding Against H5N1 Influenza Spillover: Protecting Human, Animal, and Environmental Health

May 10, 2024

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Discover strategies to combat H5N1 influenza spillover in cattle, emphasizing collaborative efforts to ensure the safety of human, animal, and environmental well-being.

Cows and other animals have been found to be infected with H5N1.

(Adobe Stock 10407374 by AF)

In the face of complex health challenges, the One Health approach is an example of collaboration and innovation, intertwining human, animal, and environmental health perspectives. Gregory C. Gray, MD, MPH, a proponent of this approach, illuminated its benefits in the context ofavian flu or H5N1.

Gray is the Robert E. Shope, MD, professor in infectious disease epidemiology in the Departments of Internal Medicine (Infectious Diseases), Microbiology & Immunology, Global Health & Emerging Diseases at the University of Texas Medical Branch in Galveston, Texas.

“Whenever we encounter complex problems that require multiple disciplines, professionals, and institutions, One Health is a great way to go,” Gray told Infection Infection Control Today^® (ICT^®) in an exclusive interview. “Certainly, this H5N1, epizootic in cattle, is a great example; it involves industry, the agricultural industries, people, occupational risk, animals, and the environment. In these sorts of complex problems and settings, while there is evidence by all the media discourse, multiple different players have interests, such as different branches of the government, the agricultural industries, people who care for animals, and people who are trying to understand how viruses move. So, the White House way is a great way to come together and focus on a specific problem. And that's what we're doing to set this one up.”

The emergence of zoonotic diseases like the H5N1 influenza strain underscores the interconnectedness of human, animal, and environmental health. Gray emphasized how such complex problems demand a multidisciplinary approach involving diverse professionals and institutions. In the case of the H5N1 outbreak in cattle, the involvement of industries, agricultural sectors, health care workers, and environmental experts becomes paramount to understanding and addressing the issue's root causes.

The spillover of H5N1 influenza strains from birds to various animal species, including cattle, raises concerns about the potential for further human transmission. “Moving not only to the common targets, domestic poultry and wildlife, particularly avian species, we're seeing some bizarre phenomena concerning these groups of viruses spilling over,” Gray said. “It causes infections and lots of unusual animals, carnivores, large carnivores, small carnivores, sea lions, seals, recently livestock like goats, and then, of course, the cattle.”

Gray highlights the need for rigorous surveillance and expert collaboration to decipher the mechanisms behind such spillover events. Understanding how these viruses spread and evolve is crucial in developing effective strategies to mitigate risks and protect public health.

Gray told ICT what the scientists are asking, “What is going on with these viruses? Are we at risk for even greater morbidity and more species, including humans? Could this virus change in an aggressive way and cause severe illness and death in humans? Yes, absolutely.”

The unique challenges posed by H5N1 influenza in cattle prompt a reevaluation of current surveillance and response mechanisms. Gray stresses the importance of partnerships between professionals studying virus transmission in animals and those concerned with occupational exposure and environmental impact. By pooling expertise and resources, stakeholders can gain valuable insights into disease transmission dynamics and formulate evidence-based interventions.

Central to the Gray’s discussion with ICT is the significance of early detection and response. Gary advocates for educational programs targeting frontline workers, including infection preventionists and epidemiologists, to enhance their awareness and preparedness. Recognizing the signs of animal illness, such as increased morbidity and unusual symptoms, can serve as early warning signals for potential outbreaks.

Then Gray mentioned farm cats. “Some interesting observations are some of the first farm cats, some of the first showing illness, and maybe a sentinel for other farms. If you see your cats dying, [also] watch out for birds. Several bird species have been observed to be sick and die and associated with cattle morbidity; some of those birds have been positive for the virus.”

Unfortunately, a bird hit hard with H5N1 is the bald eagle.

However, investigators are still trying to figure out how H5N1 is transmitted. “We're still trying to put this all together, and it will take some study before we can make informed, data-driven decisions. So right now, people are making suggestions, but those suggestions on what to do about it will likely change as we get better information.”

The classification of influenza strains, such as H5N1, underscores the complexity of virus-host interactions and the potential for cross-species transmission. Gray explained how genetic variations in hemagglutinin and neuraminidase proteins determine a virus's affinity for different host species, highlighting the importance of understanding these molecular mechanisms in disease surveillance and management.

Despite the current challenges posed by H5N1 influenza, Gray remains cautiously optimistic about the ability to respond effectively. While concerns about virus mutation and transmission persist, he emphasizes the importance of proactive surveillance and collaboration in mitigating risks and safeguarding public health. “Colostrum milk is something that our colleagues in the dairy industry and the veterinary industry are wrestling with. How well does pasteurization work, and what techniques are used for different products? How well does it work? We think it works well. But we need to verify that many people are doing that right now with testing.”

But that isn’t all. “What is worth being concerned about is if these viruses change, become more varied, and adapted to humans, causing human-to-human transmission. That's why we need to partner with the industry in a way that protects them. So, they'll be willing to work in partnership. We need to protect their businesses somehow, and we can work together to get our minds around the unusual manifestation of these strains of viruses. Manifesting can move in new ways; why? And how. We've got to rethink things.”

ICT asked Gray to explain the mechanisms of transmission of H5N1. He said they are still trying to figure it out. Gray said,

“We're all scratching our heads here. How did this happen? How is it moving? And how do we stop it? And so, this is an example of something that caught us. Perhaps partly because without routine surveillance for novel respiratory diseases and livestock, I would argue we should now be kind of playing catch up. So, it will involve partnerships with professionals who study virus transmission in animals and professionals who worry about how occupational exposures for animal workers can be affected. And people who are concerned about the environment. does the virus do through direct contact with small particles and aerosols, is it in the water, is it in the feed somehow, through defecation of, for instance, migrating birds and passerine birds? So, there's a lot to learn before we can get out what the primary risk factors are means for this, to move within cattle, and between herds of cattle and then spilling over to other species.”

Gray continues. “One of the things I think that needs to be done is we need to find a way to protect the farms. They're willing to acknowledge when they have an incursion of the virus, which will likely involve some compensation. So, if you have cattle that seem to be infected, you lose milk production, or cattle die and are no longer as useful if the government were to find a way to compensate at least partially those farms. Farms would be more willing, I think, to come forward and say, “Hey, we got a problem. Come, look at us. Help us study our farm. So, we can stop this not only for the future of our farm but for other farms.”

Gray said, “I'm not too worried just now, but I think we need to monitor these viruses to make sure they don't change and become more dangerous to the animals or people.”

Then he said his diet had not changed.

“I'm still eating poultry and beef and enjoying dairy products because I think we have some of the finest agricultural industries in the world. And the people are very good at keeping out dangerous pathogens that many other countries, especially in the developing world, commonly suffer. You may not hear about some of these, but Foot and Mouth Disease, African swine fever, and classic classical swine fever during the forms of viruses; because our professionals are very good, we don't have these problems. Commonly in the United States, we have ways to prevent it. But the migrating birds probably have introduced this in a new way. We're going to have to get some plans to protect the farms, but no need to panic. I wouldn't stop buying milk, beef, or even poultry products right now because we have pretty good systems already controlling some of these things.”

Gray does have one more serious worry—pigs: “I'm more concerned if it gets into pigs because the pigs already have a number of influenza viruses with which they could exchange components of an avian flu virus. And then we might have something worse come out. Has the virus just exchanged genetic components? There's a big concern in the pig industry now to keep these avian viruses that are now being amplified in cattle, and certainly have always been amplified in poultry and live birds, keep them out of the pig barns with pig farms because it will potentially cause a lot more harm to the pigs and humans if it gets in there.”

As the world navigates the evolving landscape of infectious diseases, the One Health approach offers a holistic framework for understanding and addressing complex health challenges, as seen through the H5N1 lens. By integrating human, animal, and environmental health perspectives, the world can enhance resilience and capacity to respond to emerging threats, ensuring a healthier future for all.