Michael Coston
Editor, Senior Moderator
Declining Mammalian Spillover Submissions To USDA Over Past 8 Months
#18,991
The USDA maintains a dashboard of Detections of Highly Pathogenic Avian Influenza in Mammals - which is highly dependent upon State Animal Health Officials submitting samples for testing - has recorded 674 confirmed infections in mammalian wildlife (excluding livestock) since early 2022.
As you can see by the map above, some northern and western states have reported literally scores of infected wildlife, while others (particularly in the south and east) have reported few or none.
Admittedly, it may come down to differences in climate and terrain (swamps vs. forests vs. deserts) and the fact that infected wildlife often die in remote places where their carcasses are quickly scavenged by other animals, making them unlikely to be discovered or tested.
But it also possible that some states are more proactive in investigating, and reporting suspected cases, than others.
Curiously, despite increased reports of infected birds in 2025, we've seen a huge drop off in reports of infected wildlife confirmed by the USDA since last spring. This comes after a significant surge in submissions in late 2024 and into early 2025 (see graph below).
The above graph is based on collection dates, not confirmation dates (which may come months later). During the 1st 3 months of 2025, the USDA averaged 43 positive submission per month.
In the 8 months since the, that number has dropped 90%, averaging just 4 per month (note: given delays in testing/reporting those numbers could change). Exactly what accounts for this precipitous plunge isn't clear.
The USDA officially added domestic cats to their list on May 30th, 2024 (they subsequently backfilled a number of previous reports), and - as the following graph illustrates - infected house cats were a big story for the rest of that year and into early 2025.
But once again, we see the same dramatic drop off in positive reports since last spring.
It is possible that these declining numbers truly represent a drop in mammalian spillovers (which would be a positive sign) since we are also seeing a similar trend in infected U.S. livestock and mammalian wildlife reports from around the world.
But they may simply mirror our growing weariness from - or indifference to - the HPAI threat. The public remains largely apathetic (see Two Surveys (UK & U.S.) Illustrating The Public's Lack of Concern Over Avian Flu), and many governments are more than happy to downplay the threat for political or economic reasons.
We continue to see pleas from public health agencies and researchers for better surveillance and reporting (see here, here, here, here, here, and here); yet many countries continue to hold outbreak information close to their vest (see From Here to Impunity)
The problem with all of this is; viruses don't read and are not influenced by sanitized reports. They simply do whatever they can do.
And while ignorance on our part may be bliss, it can also be tragically short-lived.
https://afludiary.blogspot.com/2025/12/declining-mammalian-spillover.html
#18,991
The USDA maintains a dashboard of Detections of Highly Pathogenic Avian Influenza in Mammals - which is highly dependent upon State Animal Health Officials submitting samples for testing - has recorded 674 confirmed infections in mammalian wildlife (excluding livestock) since early 2022.
As you can see by the map above, some northern and western states have reported literally scores of infected wildlife, while others (particularly in the south and east) have reported few or none.
Admittedly, it may come down to differences in climate and terrain (swamps vs. forests vs. deserts) and the fact that infected wildlife often die in remote places where their carcasses are quickly scavenged by other animals, making them unlikely to be discovered or tested.
But it also possible that some states are more proactive in investigating, and reporting suspected cases, than others.
Curiously, despite increased reports of infected birds in 2025, we've seen a huge drop off in reports of infected wildlife confirmed by the USDA since last spring. This comes after a significant surge in submissions in late 2024 and into early 2025 (see graph below).
The above graph is based on collection dates, not confirmation dates (which may come months later). During the 1st 3 months of 2025, the USDA averaged 43 positive submission per month.
In the 8 months since the, that number has dropped 90%, averaging just 4 per month (note: given delays in testing/reporting those numbers could change). Exactly what accounts for this precipitous plunge isn't clear.
The USDA officially added domestic cats to their list on May 30th, 2024 (they subsequently backfilled a number of previous reports), and - as the following graph illustrates - infected house cats were a big story for the rest of that year and into early 2025.
But once again, we see the same dramatic drop off in positive reports since last spring.
It is possible that these declining numbers truly represent a drop in mammalian spillovers (which would be a positive sign) since we are also seeing a similar trend in infected U.S. livestock and mammalian wildlife reports from around the world.
But they may simply mirror our growing weariness from - or indifference to - the HPAI threat. The public remains largely apathetic (see Two Surveys (UK & U.S.) Illustrating The Public's Lack of Concern Over Avian Flu), and many governments are more than happy to downplay the threat for political or economic reasons.
We continue to see pleas from public health agencies and researchers for better surveillance and reporting (see here, here, here, here, here, and here); yet many countries continue to hold outbreak information close to their vest (see From Here to Impunity)
The problem with all of this is; viruses don't read and are not influenced by sanitized reports. They simply do whatever they can do.
And while ignorance on our part may be bliss, it can also be tragically short-lived.
https://afludiary.blogspot.com/2025/12/declining-mammalian-spillover.html