New Avian Influenza Strain Sparks Fears of Next Zoonotic Endemic: Scientists Call for Collaborative Response
A highly virulent avian influenza strain has been sweeping across the United States, grabbing headlines as egg prices skyrocket at the beginning of the year, and sparking concerns about a potential new zoonotic pandemic in popular media. A research team from the University of Maryland (UMD) has investigated the emergence and evolution of the lethal H5N1 bird flu strain in North America to understand what sets this outbreak apart from previous ones.
They discovered that the fact that avian flu is killing wild birds and that infections are no longer just seasonal but happen all year round are signs of dangerous changes in the U.S. They came to the conclusion that in order to control the spread of a disease that cuts across authorities and disciplines, there is an urgent need for unprecedented collaboration at a national and regional level. The group predicts that H5N1 will probably become endemic, presenting potential threats to the economy and food security.
The findings were published today, in the journal Conservation Biology.
“We’ve been dealing with low pathogenic avian influenza for decades in the poultry industry, but this is different,” adds co-author Jennifer Mullinax.
Diseases with a low pathogenic potential are less widespread and simpler to control than those with a high potential.
“This high pathogenic virus is wiping out everything in numbers that we’ve never seen before,” Mullinax warns. “This paper illustrates how unprecedented it is, and describes what we think is coming. It’s really a call to arms saying, we can’t afford to address this from our individual silos. Federal agencies, state agencies, the agriculture sector and wildlife management, we are all going to have to deal with this together, because we can’t afford not to.”
The team’s findings are based on an examination of five distinct data sources that include details on the prevalence of highly pathogenic avian influenza in wild birds and poultry, with an emphasis on the USA and Canada and a worldwide database from 2014 through early 2023.
The data reveals the rapid spread of the highly virulent H5N1 bird flu from Eurasia to the U.S., where it was initially recorded in late 2021. By October 2022, the virus had caused 31 known mass mortality events among wild birds, leading to approximately 33,504 detections in the U.S. and Canada. Furthermore, over 58 million domestic poultry in the U.S. and 7 million in Canada were either infected or had to be culled to control the disease’s transmission.
In contrast, a 2015 outbreak of the highly pathogenic H5N8 bird flu in the U.S. necessitated the culling of 50 million poultry birds. However, the virus was successfully eliminated in North America within the same year, primarily due to its limited impact on wild birds, which facilitated easier containment through poultry culling. The H5N1 outbreak, on the other hand, presents new and unprecedented challenges.
“Unlike H5N8, this disease is heavily impacting wild birds,” comments lead author Johanna Harvey. “It’s difficult to estimate how many birds are truly affected across wild populations, but we’re seeing dramatic disease impacts in raptors, sea birds and colonial nesting birds. And we now have the highest amount of poultry loss to avian influenza, so this is a worst-case scenario.”
The information gathered also highlights a transition from a traditionally seasonal illness to one that persists year-round. In the past, avian flu outbreaks, whether the low pathogenic variety endemic to the U.S. or the highly pathogenic H5N8 experienced in 2015, would typically emerge in the autumn months. This pattern allowed farmers to brace for the seasonal outbreaks, take necessary measures such as culling flocks to control the disease’s spread, and allocate almost an entire year to recuperating from losses. However, this novel virus seems to be maintained throughout the entire year, as evidenced by the detection of the illness in wild birds during the summer months and poultry outbreaks arising in both spring and autumn seasons.
While designating a disease as endemic entails a complex procedure, the study’s authors believe that the U.S. is likely to mirror the situation in Europe, where highly pathogenic avian influenza has already been considered an endemic illness rather than one that can be eradicated.
To address this challenge, the researchers advocate for a management strategy rooted in a technique known as Structured Decision-Making. This approach involves assembling key stakeholders with relevant knowledge, experience, or vested interests, differentiating between known and unknown factors, and defining clear objectives and actionable steps with quantifiable outcomes. This method bears a striking resemblance to the way human pandemics are managed.
“Good decision science is what you do when you don’t know what is going to happen next,” adds Mullinax.
“This is a novel virus for North American birds, so no one knows if their immune systems will adapt, or how long that will take, or what that will look like. Where do we direct our funds for maximum benefit? Is it a vaccine? How do we track it in wild birds? Do we test the water or the soil? What are the triggers for different actions, and how do we measure if we’re succeeding? These decisions have to be made on multiple scales.”
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