Pandemic (2009) H1N1 (also known as Novel or Swine-Origin) Influenza A Virus

Mayo Medical Laboratories is committed to offering timely updates and information regarding laboratory testing options for influenza A. During 2009, much attention was given to the newly emergent pandemic (2009) H1N1 Influenza A virus, also known as novel or swine-origin influenza A. This virus arose in Mexico and very quickly spread throughout the world, gaining the highest level of Pandemic status (level 6) by the World Health Organization (WHO).

The year of 2009 was marked by 2 separate off-season peaks of infection caused by the pandemic H1N1 virus. Now in 2010, H1N1 is circulating only at very low levels throughout the United States, and is no longer considered a pandemic threat by the WHO. Based on previous trends, it is expected that H1N1 will continue to circulate along with seasonal influenza A viruses and have a peak prevalence in the winter months.

For detection of both pandemic (2009) H1N1 and seasonal influenza A viruses, clients may order the Mayo Medical Laboratories #88544 Influenza Virus Type A and Type B RNA by Rapid PCR. This is the test of choice for detecting acute illness with any of the influenza viruses. If the result is positive, it indicates that influenza A is present in the sample, but it does not differentiate Pandemic (2009) H1N1 influenza from other seasonal influenza A subtypes.

Alternative Influenza Tests

Although alternative influenza A tests such as culture and serology are available, they are not recommended for primary detection of the pandemic (2009) H1N1 strain. Rapid antigen detection tests may be available to some clients in their own health care settings, but the sensitivity and specificity of these tests are highly variable, and confirmation of negative results using culture or PCR may be recommended.

To learn more about influenza A and the pandemic (2009) H1N1 strain, see:

• CDC H1N1 Web Site.