The number of swine-flu variant cases in the United States has grown over the last week and includes a rare variant of the H1N1 strain.
The U.S. Centers for Disease Control and Prevention recently reported that are currently 305 H3N2v swine-origin influenza cases in the United States, including nine new cases confirmed over the last week, according to CIDRAP News
In Missouri, a rare case of swine-origin H1N1v carrying the M (matrix) gene from the 2009 H1N1 pandemic virus was recently confirmed. It is only the second time the CDC has reported finding such an isolate. The previous case was found in Wisconsin in 2011.
The CDC's weekly flu update credits increased surveillance for H3N2v for finding the Missouri case. The patient in question became ill after having direct contact with pigs and has since recovered, CIDRAP News
The majority of the 305 H3N2V cases involved people that were exposed to pigs at county and state fairs. They originated across 10 states. Indiana has seen the most cases with 138, while the newest cases were found in Michigan, Minnesota, Ohio and Wisconsin.
The CDC has repeatedly said that there have been few identifiable cases of human-to-human transmission of H3N2v, and no evidence that human-to-human transmission is ongoing.