Swine producers certainly remember the moniker placed on the pandemic H1N1 strain of influenza that swept across the world in 2009:  “Swine Flu”.  Even though there was no evidence whatsoever that any of the people initially affected had any contact with pigs, the name stuck.  The reason for this was that genetic analysis of the virus revealed that it contained genetic material of the influenza viruses commonly associated with pigs. 

While this occurrence was unfortunate for swine producers who watched while their animals were unfairly blamed in this pandemic, it served as a reminder of the role that pigs can potentially play in human influenza infections.  Swine have long been considered a potential “mixing vessel” for influenza.  What this means is that pigs are one of the few species that can be infected by influenza viruses from several different species (namely pigs, birds, and people) at the same time.  This presents a condition where genetic material from one virus can combine with that of another virus, resulting in the emergence of a new strain of virus.  These new strains may have different characteristics than the initial viruses.  For instance the newly emerged viruses may be more (or less) virulent, or exhibit differences in their ability to infect animals and people). 

Since 2005, there have been a handful (26 to be exact) of cases documented in which swine-origin influenza viruses have infected people.  All of these people recovered from their illnesses.  Most were children 18 years or younger.  In the great majority of cases, contact with pigs—and not necessarily sick pigs—was implicated in the infection.  A few people were determined to have become infected due to close contact with ill people who had presumably contracted their disease from pigs, but sustained human-to-human transfer of these infections was not observed. 

Worth considering is the fact that, while it’s possible to contract influenza from contact with pigs, that chance pales in comparison to the chance of contracting influenza from one of the estimated 5-20% of the population that gets sick from influenza each year. 

Even though influenza infections between pigs and people are rare, because of the potential role of pigs in transmission, some precautions to limit this spread may be wise to implement. 

Workers who are in close contact with pigs on a daily basis, especially groups of pigs undergoing respiratory signs such as a barking cough, sneezing, sluggishness, and decreased appetite, should take special precautions such as hand washing, wearing gloves, or possibly wearing N95 face masks.  Basic biosecurity measures such as changing boots and coveralls should definitely be employed.

People who feel symptoms of influenza such as fever, chills, headache, and body aches should not enter swine barns, due to the possibility of pigs becoming infected from sick people.  All people who have regular contact with swine should make sure they receive seasonal influenza vaccination every year.