Influenza A viruses occur in many animals, including humans, swine (pigs) and wild birds. The virus in question is akin to previous H3N2 human infections, but also contains a genetic piece of the 2009 H1N1 virus, health officials in Pennsylvania said in a statement.
The first case occurred in Indiana and three more turned up in Pennsylvania. The three patients in Pennsylvania all reported attending the Washington County Fair Aug. 13-20. There appears to be no link between the Indiana and Pennsylvania cases, the health officials said.
Currently, it does not appear the new virus is spreading from person to person but health officials were investigating the cases to learn more about it.
"One patient has recovered and the other two are recovering. Our investigation will continue to focus on the seriousness of the virus," the health officials said.
"Currently, we don't have any evidence to support that this novel influenza A virus will lead to a pandemic, as we haven't yet been able to prove that it is being transmitted from human to human. As with any new influenza A virus, public health officials are working to learn more about the source of this particular strain and to determine how/if it can be spread from person to person."
These Pennsylvania cases were similar to that of seasonal flu, and included fever, lethargy, lack of appetite and coughing. Other influenza symptoms may also include a runny nose, sore throat, eye irritation, nausea, vomiting and diarrhea, and anyone with flu symptoms should seek treatment from a physician, health officials said.
Notable deaths of 2014 [PHOTOS]