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U.S. Department of Health and Human Services


Influenza is for the birds…and dogs, pigs, horses, and humans

Author: ASPR Critical Infrastructure Protection Team
Published Date: 2/3/2016 3:58:00 PM
Category: Public Health Preparedness;

On the surface, it might seem like we had a really mild flu season.  As 2015 came to a close and most were making plans for the New Year, more than 13,000 people were tested for seasonal influenza A in a single week. Of those, 157 were positive, and one additional novel A infection was confirmed, reflecting an unusually low level of human influenza activity across the nation so far this season.

However, animals haven’t been quite so lucky.  Last year saw a number of influenza A outbreaks in several different species, including horses, dogs, birds and pigs. 

Outbreaks that start in an animal population might not stay there.   One Health, the concept that animal, human and environmental health are connected,  can help us work more effectively with partners across different disciplines, such as doctors, veterinarians, ecologists, and public health experts, to identify and address emerging threats to health that start in animal populations.  

Global ecologic research has confirmed that influenza A viruses are especially likely to make the jump from animal to human hosts.  Influenza A viruses are able to mutate easily causing large-scale or even global outbreaks. They are responsible for all six historical pandemics and the only flu strain with the capability to present such a threat in the future. 

In 2015, we saw three influenza A outbreaks in horses, and a canine influenza A strain was also introduced into the U.S.  Even in the face of all these threats to health, the veterinary community has been able to mitigate many of the potential impacts of these outbreaks.  Quarantine prevented the spread of the equine viruses.  A vaccine has been developed for the newly imported canine influenza, though the dogs have no natural immunity to the virus.  

The outbreak of highly pathogenic avian influenza (HPAI) is a more serious threat.  Avian-origin strains have traditionally been responsible for most prior pandemics and may cause severe disease in humans. The 2015 HPAI epidemic represents the single most devastating outbreak of an animal disease in US history. The first case was reported from a mixed poultry flock in Oregon in December 2014, and eventually identified as H5N8. Another subtype, H5N2, was also later identified from a backyard flock in Kansas in March 2015. The two viruses eventually spread to the Midwest where they decimated commercial chicken and turkey populations, exhibiting a mortality rate between 90-100% and resulting in the loss of approximately 48 million birds. Surveillance has been ongoing in preparation for a possible reintroduction this season, which recently occurred with the report of highly pathogenic H7N8 in a single commercial turkey flock in Indiana Eight other positives have been reported in the area; however, all are low pathogenic.

No human infections of HPAI have been reported as a result of these outbreaks.

Influenza A outbreaks in animals may foreshadow similar outbreaks in humans and available animal health countermeasures could have later implications for people too. As we consider a comprehensive approach to preparedness, remember that the broader One Health approach can help us bring together different kinds of expertise. Knowledge fuels preparedness and helps mitigate the impacts of health emergencies on businesses and, in turn, on our nation’s critical infrastructure.

Interested in learning more?  Contact the Critical Infrastructure Protection staff with your questions at or leave a comment on this blog post.


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