Ten Confirmed H3N2v Cases at Butler County Fair In Ohio
August 1, 2012
Preliminary laboratory results on ten samples indicate similarities to the influenza virus, (H3N2)v. All individuals in Butler County’s investigation also had direct contact with swine, however the Centers for Disease Control and Prevention (CDC) have not yet confirmed any of the cases.
The above comments from today’s Butler County Health Department press release describe lab confirmation of H3N2v in 10 people associated with the Butler County Fair in Hamilton, Ohio. Positive samples are forwarded to the CDC for sequence confirmation.
All H3N2v human sequences since the outbreak at the West Virginia day care center in Nov/Dec, 2011 have been a novel H3N2v which has an N2 lineage commonly found in H3N2v swine, which is distinct from the first 10 H3N2v cases in 2011 which had an N2 matching swine H1N2.
Prior to the LaPorte outbreak in Indiana, only two swine H3N2 sequences matching recent human cases had been identified (A/swine/North Carolina/A01203272/2012 and A/swine/Indiana/A01203509/2012). Most recent swine isolates (other than the unpublished LaPorte isolates) have matched the constellation seen in the earlier 2011 cases. These matches included four June, 2012 isolates from Ohio.
However, 10 confirmed H3N2v cases from one venue would be a record, and the new novel sub-clade appears to be efficiently transmitting in humans (the West Virginia outbreak included 23 symptomatic contacts and none had a swine exposure) and swine 12/12 swine from the LaPorte fair with H3N2v confirmed, including asymptomatic swine.