The Centers for Disease Control and Prevention (CDC) reported last week the apparent first human case of influenza A (H3N2) variant (H3N2v) virus in Ohio.
The infected patient was hospitalized as a result of H3N2v illness, but has completely recovered. No ongoing human-to-human transmission has been identified and the case reported close contact with swine in the week prior to illness onset.
Public health and agriculture officials are investigating the extent of disease among humans and swine and no increases in influenza-like illness in the community have been reported.
Genetic sequencing of the H3N2v virus conducted at CDC showed that this virus has the nucleoprotein (NP) and the matrix (M) gene from the 2009 H1N1 virus, which is a slightly different combination of internal genes than H3N2v viruses reported in previous years. However, this H3N2v virus has the same genetic composition as influenza viruses previously isolated from swine in the U.S. this summer.
In 2013, the CDC tallied 19 H3N2v from five states, while in 2012, the federal health agency reported 309 cases. The first year the novel influenza virus surfaced was 2011 when 12 people were reportedly infected.
H3N2v is a non-human influenza virus that normally circulates in pigs and that has infected humans. Viruses that normally circulate in pigs are “swine influenza viruses.” When these viruses infect humans, they are termed “variant” viruses.
Symptoms of H3N2v infection in people are similar to those of seasonal flu viruses and can include fever and respiratory symptoms, such as cough and runny nose, and possibly other symptoms, such as body aches, nausea, vomiting, or diarrhea. Infections with influenza viruses (including variant viruses like H3N2v) can sometimes cause severe disease, even in healthy people. This can include complications, such as pneumonia, which may require hospitalization, and sometimes results in death.
People who are at high risk of developing complications if they get influenza include children younger than 5 years of age, people 65 years of age and older, pregnant women, and people with certain long-term health conditions, such as asthma, diabetes, heart disease, weakened immune systems, and neurological or neurodevelopmental conditions. For more infectious disease news and information, visit and “like” the Infectious Disease News Facebook page