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Outpatient Influenza-like Illness Surveillance Network (ILINet)

What is an influenza sentinel provider?

The Outpatient Influenza-like Illness Surveillance Network, or ILINet, is a program is conducted by the US Centers for Disease Control and Prevention and state health departments which collects influenza surveillance data from volunteer sentinel healthcare providers. Providers who participate in the ILINet program collect and report information about the level of influenza-like illness (ILI) currently seen in their practice. Data reported by ILINet providers, in combination with other influenza surveillance data, provide a national picture of influenza virus and ILI activity in the U.S. There are more than 2,900 ILINet sentinel providers in all 50 states, Puerto Rico, the District of Columbia, and the U.S. Virgin Islands.

What data do ILINet providers collect? How and to whom are data reported?

ILINet providers tally and report each week the total number of patients seen at their practice for any reason. They also tally and report number of patient visits for influenza-like illness by age group (0-4 years, 5-24 years, 25-49 years, 50-64 years, >65 years). ILINet providers submit their weekly totals to a web site every week. Most providers report that it takes them fewer than 30 minutes a week to compile and report their data.

Influenza-like Illness (ILI) Case Definition

A patient with ILI is defined as having:

  • Fever (≥ 100° F [37.8° C], oral or equivalent)
  • Cough and/or sore throat
  • Without a known cause other than influenza

These data are transmitted once a week via the Internet or fax to a central data repository at CDC. Most providers report that it takes them fewer than 30 minutes a week to compile and report their data.

Who can be an ILINet Provider?

Providers in many types of practices are eligible to become ILINet providers:

  • Emergency Medicine
  • Family Practice
  • Infectious Disease
  • Internal Medicine
  • OB/GYN
  • Pediatrics
  • Student Health
  • Urgent Care 

Practice settings that are not eligible are elementary, middle, or high school health centers, and any type of institutional setting such as nursing homes or prisons.

Why Volunteer?

Influenza viruses are constantly evolving, and cause substantial morbidity and mortality each year. Flu-associated deaths range from 3,000 to a high of about 49,000 annually. ILINet data is critical for tracking influenza activity at the local, state and national level. ILINet providers who also participate in virologic surveillance activities by collecting and submitting nasopharyngeal swabs on selected patients help identify the influenza strains that are currently circulating in their communities. ILINet data, in combination with other influenza surveillance data, is also used to guide prevention and control activities, vaccine development, and patient care guidelines. You can play a role in providing information that is vital to protecting the public's health.