The Centers for Disease Control and Prevention (CDC) issued a health advisory August 3, 2012, due to an increase in H3N2v influenza virus infections seen in several states in recent weeks. These illnesses have been caused by a variant virus known to be circulating among swine since at least 2010. Additional cases are expected, as CDC and affected states further investigate these illnesses. Clinically, these cases are consistent with seasonal flu, with symptoms including fever, cough, pharyngitis, myalgia, and headache. There have been no cases of H3N2v influenza detected in Oregon, either among pigs or humans.
Clinicians treating patients with influenza-like illness ((fever equal to or greater than 100 F) and (cough or sore throat)) and known exposure to swine within 7 days of illness should report these cases to their local health department (pdf). PCR testing can be provided by the state public health laboratory (OSPHL), but must be approved by the local health department. A negative rapid test (RIDT) should not be considered conclusive evidence of lack of influenza infection. See the August 10, 2012 MMWR for information on RIDTs and H3N2v virus.
At this time, Oregon’s flu surveillance activities include 1) reporting of pediatric influenza deaths; 2) hospitalizations in the Portland metro area (Clackamas, Multnomah and Washington Counties); 3) reports from Oregon virology laboratories; and 4) a sentinel provider network of clinicians who report “influenza-like illness” and submit specimens to the Oregon State Public Health Laboratory (OSPHL) for testing. Because OSPHL routinely subtypes influenza strains and forwards any nonsubtypeable ones to CDC, we expect to identify novel strains among any of these cases detected by current surveillance (i.e. reportable deaths, hospitalizations, and outpatient cases seen by sentinel providers). In addition, outbreaks of influenza-like illness are reportable.
Read the CDC health alert (pdf) for H3N2v prevention information, or go to the communicable disease public information page. CDC has posted information on these viruses and human illness, which can be found here: http://www.cdc.gov/flu/swineflu/h3n2v-factsheet.htm. In additon, interim information for clinicians is posted to the CDC website.
Updates on US case counts can be found on the CDC H3N2v information page.