Influenza Sentinel Surveillance Program

By watching for outbreaks of flu and testing for different strains of flu, public health agencies can help prepare for and control outbreaks, determine appropriate treatments, assess the usefulness of antiviral drugs, and evaluate the effectiveness of vaccines.

Each week, sentinel physicians, university health centers, hospitals/medical centers and public health agencies across the state report "influenza-like illness" (ILI) to the national Centers for Disease Control and Prevention (CDC) and collect samples for virus strain identification. The reports include the total number of patient visits to each ILINet provider for that week and the number of those patients with ILI, broken down into five age groups. For purposes of this surveillance program, ILI is defined as fever of 100 degrees Fahrenheit or higher along with a cough or sore throat.

For the 2009-2010 flu season, 93 health providers in 52 counties throughout the state have been regularly reporting influenza-like illness to CDC. This group of ILINet providers includes a wide variety of physician practice types (pediatrics, family practice and internal medicine) in 32 local health department and local health district offices, 37 private practices, 6 hospitals, and 18 college and university student health centers.

The ILINet program allows for timely identification of circulating influenza virus strains can help detect new strains with pandemic potential. The emergence of 2009 H1N1 was first detected through this system long before illness was widespread in the US, allowing more time for vaccine development and implementation of other pandemic control measures. The samples collected through the ILINet system also help determine whether circulating strains are well matched to the vaccine and whether they are resistant to any of the antiviral drugs.

While ILINet providers are encouraged to report year round, the official start of the 2010-11 influenza season is October 3, 2010.

For North Carolina's flu season reports for 2010-2011 and previous flu seasons, see the N.C. Influenza Update (updated weekly). For comparable national data, see the CDC weekly reports. North Carolina flu and pneumonia mortality data is published in the N.C. Detailed Mortality Statistics annual report (see ICD 10 codes J10-J18) on the State Center for Health Statistics web site.

General information about influenza is available on the N.C. DHHS flu page, flu.nc.gov, and on the CDC’s flu web page.

North Carolina's General Communicable Disease Control Branch and the State Laboratory of Public Health have continuously participated in the U.S. Influenza Sentinel Physicians Surveillance Network since the 2000-2001 flu season.