Information for Health Professionals on
Influenza A Variant Viruses
(H3N2v, H1N2v, H1N1v)
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
- Specimen Collection and Testing for Influenza A Variant Viruses
Criteria and process for specimen collection and testing for Influenza A Variant Viruses
H3N2v, H1N2v, H1N1v
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
- Influenza Information for Health Professionals
- Information For Health Professionals on Novel Influenza A Virus (H7N9)
Use of Rapid Influenza Diagnostic Testing
Commercially available rapid influenza diagnostic tests may not detect H3N2v, H1N2v, or H1N1v in respiratory specimens.
- Evaluation of Rapid Influenza Diagnostic Tests for Influenza A (H3N2)v Virus Infections and Updated Case Count – United States, 2012 (PDF). CDC Morbidity and Mortality Weekly Report 2012. Early Release August 10, 2012. Attention: Non-MDH link
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.
Further information on diagnosis and treatment
- CDC: Information on Influenza A(H3N2)v
Background, case count, protection measures, and other resources.
Attention: Non-MDH links
- More information for health professionals regarding specimen collection, submission, and treatment for influenza.
Influenza Information for Health Professionals | Information For Health Professionals on Novel Influenza A Virus (H7N9)