Six H3N2v Cases In Queen Anne’s County Maryland
August 17, 2012
The Maryland Department of Health and Mental Hygiene has identified the influenza virus strain influenza A (H3N2v), in six Queen Anne’s County residents (five children and one adult) who had direct contact with pigs. In addition, the Maryland Department of Agriculture identified influenza A with a similar testing pattern in pigs from four Queen Anne’s County farms with which the sick people had contact. The pig testing is preliminary and will be confirmed by additional testing. H3N2v is the same virus strain that has been found recently in a number of other states.
The above comments from a press release by the Maryland DHMH describe six H3N2v cases who had contact with influenza A positive pigs. However, it is unclear if the residents infected the pigs or vice verse. This report follows an earlier report today on 10 H3N2v cases in Huntingdon County in central Pennsylvania, which follows reports of 3 H3N2 cases in West Virginia and 2 cases in Wisconsin, as well as two more cases in Illinois. These are in addition to the explosion of cases in OH, where today’s report increased the number of cases to 79 in 21 counties, and Indiana, where 138 cases have been confirmed in 23 counties.
Although these cases have been linked to swine exposure, most have been mild and testing without swine linkage would have been unlikely. Moreover, all 2012 sequences have matched a novel H3N2v sub-clade, first detected in West Virginia at a day care center with no swine exposure for the index case or 23 cases of ILI in contacts (one of which was tested and was also H3N2v positive).
The widespread detection of large clusters of H3N2v cases signals efficient human to human transmission, CDC qualifiers notwithstanding.