CDC

  Swine Influenza - 9 May 2009  11:00 AM

A New Virus Emerges

Novel influenza A (H1N1) is a new flu virus of swine origin that was first detected in April, 2009. The virus is infecting people and is spreading from person-to-person, and has sparked a growing outbreak of illness in the United States with an increasing number of cases being reported internationally as well.

CDC anticipates that there will be more cases, more hospitalizations and more deaths associated with this new virus in the coming days and weeks because the population has little to no immunity against it. Novel influenza A (H1N1) activity is now being detected in two of CDC’s routine influenza surveillance systems as reported in the May 8, 2009 FluView. FluView is a weekly report that tracks U.S. influenza activity through multiple systems across five categories.

The May 8 FluView found that the number of people visiting their doctors with influenza-like-illness is higher than expected in the United States for this time of year. Second, laboratory data shows that regular seasonal influenza A (H1N1), (H3N2) and influenza B viruses are still circulating in the United States, but novel influenza A (H1N1) and “unsubtypable”* viruses now account for a significant number of the viruses detected in the United States.

It’s thought that novel influenza A (H1N1) flu spreads in the same way that regular seasonal influenza viruses spread; mainly through the coughs and sneezes of people who are sick with the virus.

CDC continues to take aggressive action to respond to the outbreak. CDC’s response goals are to reduce the spread and severity of illness, and to provide information to help health care providers, public health officials and the public address the challenges posed by this new public health threat.

Increased Testing

CDC has developed a PCR diagnostic test kit to detect this novel H1N1 virus and has now distributed test kits to all states in the U.S. and the District of Columbia and Puerto Rico. The test kits are being shipped internationally as well. This will allow states and other countries to test for this new virus. This increase in testing will likely result in an increase in the number of confirmed cases of illness reported. This, combined with ongoing monitoring through Flu View should provide a fuller picture of the burden of disease in the United States over time.