Idaho providers requested to “think influenza” this summer

New strains of influenza detected in the U.S. may eventually circulate more widely; therefore, it is important to track the emergence of these strains in the human population. Infections with a relatively new influenza A(H3N2v) variant virus have been reported in the U.S. since 2011, and an increased number were reported from several states last summer. Persons diagnosed with this illness have usually reported exposure to symptomatic or asymptomatic pigs at agricultural fairs. Although instances of limited human-to-human spread have been identified, sustained transmission of H3N2v has not occurred. No infections of this variant strain have been detected in Idaho to date, but the fair season is upon us and it is important for providers to be aware of testing recommendations for persons with influenza-like illness (ILI) who may have had contact with swine.

From July through September 2012, 306 H3N2v infections including 16 hospitalizations and one death were identified in 10 states, including Utah. Since June of this year, 12 infections have already been reported, all in Indiana, most associated with visits to swine exhibits at agricultural fairs. Additional cases are anticipated from other states as the fair season continues into early fall. Symptoms experienced by persons with H3N2v illness in 2012 and 2013 have been similar to seasonal influenza, and have included fever, cough, pharyngitis, myalgia, and headache.

Patients with ILI, with recent exposure to pigs or attendance at an event where pigs were present, should be tested for influenza by the Idaho Bureau of Laboratories (IBL). Commercially available rapid tests may or may not detect H3N2v in respiratory specimens; therefore, a negative rapid test would not exclude infection. Nasopharyngeal swabs or other respiratory samples from such patients, including those initially rapid test negative or positive, can be submitted to IBL for influenza testing. IBL will screen specimens for influenza A and B; influenza A specimens will be evaluated further for subtype. Additional testing can be conducted if novel or unusual subtypes (non-seasonal) are detected. Novel influenza A virus infections, including H3N2v infections, are reportable in Idaho.

To learn more about risk factors for transmission, populations at risk, and medical management of H3N2v infections, visit the CDC website: http://www.cdc.gov/flu/swineflu/h3n2v-cases.htm  or contact South Central District Health Public Health District-Mary Jensen @ 737-5969.

Questions about sample submission?

Contact Lisa Smith at IBL at 208-334-2235 x228

Idaho Bureau of Laboratories, 2220 Old Penitentiary Road, Boise ID 83712