Tests designed to detect a new variant of the swine flu virus in patients may not always be effective, according to the federal Centers for Disease Control.
Researchers at the agency tested seven commercially available Rapid Influenza Detection Tests (RIDT). Four were able to detect the presence of seven variants of the H3N2v virus, all of which have a gene in common with the H1N1 virus. That virus, commonly known as swine flu, was designated a pandemic by the World Health Organization. It caused hundreds of thousands of deaths worldwide in 2009 and 2010.
Of the other three tests the CDC evaluated, one detected five of the seven variants, another detected three of the variants, and a third detected only one. All the variants carry a gene in common with the H1N1 swine flu virus.
The number of H3N2v cases has risen sharply, with 153 incidents reported from July 12 to August 9 of this year. At this point, the virus is confined to animal-to-human transmission, with most of the patients reporting contact with pigs. But the CDC didn’t rule out the possibility of eventual human-to-human transmission.
The CDC said the results indicated the need for careful testing. Doctors who have patients with suspected H3N2 should forward the results of testing to a public-health laboratory.
