Pig flu in humans more common than we think?

 Prepared for publication on the One Health Initiative website and submitted January 3, 2011 by:


John Friary, MPH, MS

Global Pathogens Laboratory

Emerging Pathogens Institute

Department of Environmental and Global Health

College of Public Health and Health Profession

University of Florida, Gainesville, FL (USA)


Three months ago this website, (, reported that the Centers for Disease Control and Prevention (CDC) had confirmed that four children had been recently infected by a new pig-origin influenza virus that is a hybrid of the 2009 pandemic human virus and a North American pig virus. As of January 3, 2012, the count had risen to 11 children and 1 adult in five states. This virus has been found in US pigs, but not enough testing of pigs has been done to estimate how widespread it is. In addition, only six of these people had any contact with pigs, which means that this virus may be spreading from person to person.


No link has been found between the infected people from different states, and the CDC is concerned that there may be many more infections with these viruses, but they are simply not being identified.


Determining how prevalent these viruses really are in pigs may permit a better understanding of how these viruses spread to people.



     The Centers for Disease Control and Prevention. Update: Influenza Activity – United States, October 2, 2011-Novermber 26, 2011. Morbidity and mortality weekly report. 2011;60(48);1646-1649. Available at:

     The Centers for Disease Control and Prevention. “Have You Heard?”: CDC confirms two human infections with novel influenza viruses. Available at:  (Accessed Dec 22, 2011).