CDC Warns Physicians About New H3N2v Infections, Offers Updated Resources

July 10, 2013 04:21 pm News Staff

The CDC is warning physicians and consumers that the first cases( of influenza A variant (H3N2v) virus infection for 2013 were reported during the week of June 24. According to the agency, the reported cases were associated with exposure to swine at an agricultural fair in Indiana(

Micrograph of influenza A variant (H3N2v)

"Reportedly, pigs at the fair also tested positive for H3N2 infection," the CDC said in a June 28 news update. "This outbreak may foreshadow a number of such outbreaks this summer based on what happened last summer when multi-state outbreaks resulted in 309 reported H3N2v cases, including 16 hospitalizations and one death. Genetic sequencing by the CDC on one of the Indiana samples has confirmed that the H3N2v virus in Indiana is 99 percent similar to the H3N2v viruses detected last summer."

More recently, the CDC issued an advisory via its Health Alert Network( The July 5 communication updates clinicians on H3N2v activity and summarizes the agency's revised H3N2v case definitions and recommendations for H3N2v surveillance for the summer and fall of 2013. It also links physicians to information on 2013 testing recommendations, as well as to guidance for local and state public health officials regarding surveillance for and investigation of human infections with H3N2v.

In 2012, most individuals with H3N2v reported exposure to pigs, particularly at agricultural fairs. Although most illness was mild, serious illness also was observed. None of the recent Indiana cases required hospitalization, and no deaths have been reported.

Symptoms of H3N2v infection generally are consistent with those of seasonal influenza and may include fever, cough, pharyngitis, myalgia and headache. No sustained human-to-human spread of the virus has been detected, although sporadic limited spread of H3N2v has occurred in the past.