Information for Health Professionals on
Influenza A Variant Viruses H3N2v and H1N2v

In 2012, 9 confirmed novel influenza cases were identified in Minnesota. Five cases were identified as swine-origin H3N2 strain (H3N2v), and 4 were identified as swine-origin H1N2 variant (H1N2v). Both strains include the M gene from the influenza A(H1N1)pdm09 virus. Six cases (4 H1N2v, 2 H3N2v) were associated with the Minnesota State Fair and 3 cases were associated with live animal markets. All had direct or indirect contact with swine. In 2013 additional cases have been noted among county fair attendees in the U.S.

Surveillance, Reporting, Specimen Collection and Testing

H3N2v and H1N2v

  • Commercially available rapid influenza diagnostic tests may not detect H3N2v, H1N2v, or H1N1v in respiratory specimens. MDH is very interested in conducting RT-PCR testing for surveillance purposes on outpatients with illness compatible with influenza* who meet any of the following criteria:

    • Recent (7 days or less) direct or in-direct contact with swine
    • Recent attendance at an agricultural fair where swine were present
    • Recent contact with a confirmed case of variant or swine influenza A infection (such as H3N2v, H1N2v, or H1N1v).

*Illness compatible with influenza may present as influenza-like illness (ILI) [fever > 100°F plus cough and sore throat]. Note that influenza may not cause fever in all patients (especially in patients < 5 years of age, > 65 years of age, or patients with suppression of their immune system).

MDH is also conducting enhanced surveillance through established sentinel influenza surveillance sites.

Seasonal Influenza and H7N9

Use of Rapid Influenza Diagnostic Testing

Commercially available rapid influenza diagnostic tests may not detect H3N2v, H1N2v, or H1N1v in respiratory specimens.

Treatment

Clinicians should consider antiviral treatment with oral oseltamivir or inhaled zanamivir in patients with suspected or confirmed variant or swine influenza virus infection. Antiviral treatment is most effective when started as soon as possible after influenza illness onset. Testing at the Minnesota Department of Health may take several days and the decision to treat should be based on clinical judgment.

  • H3N2v Treatment
    CDC information on treatment of H3N2v. Recommendations for treatment of H3N2v and H1N2v are the same. Attention: Non-MDH link

Further information on diagnosis and treatment

Updated Monday, December 30, 2013 at 07:43AM