Influenza (Flu) Surveillance

  • Purpose: To understand when and where influenza activity is occurring, to monitor influenza-related illness, outbreaks, hospitalizations, and deaths, and to determine circulating and emerging influenza virus strains.
  • Key Information: Geographic spread and activitiy level of influenza in the state, laborartory test results, and influenza-related hospitalizations and deaths. Influenza-like illness (ILI) is defined as patients with a fever over 100°F with cough and/or sore throat (unless there is a known cause other than the flu).
  • Collection Period: Data is collected and analyzed weekly throughout the flu season from October to May.
  • How data are collected The Department of Health has a number of methods for gathering data. This includes gathering reports on the number of patients with influenza-like illness (ILI) from a sample of sentinel physicians and collecting data from hospitals throughout the state. The services of the State Health Laboratory are used to determine the circulating strains of influenza. Additionally, a staffs of epidemiologists work with CDC guidance to determine flu activity levels. (more)

Rhode Island Numbers

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Influenza Activity Level is Widespread (as of April 12, 2014)

Last updated: April 23, 2014

Activity is categorized as: No Activity, Sporadic, Local, Regional, or Widespread based on evaluation by the State Epidemiologist according to guidelines established by the Centers for Disease Control and Prevention. (more scroll to Category 5)

Physician Office Visits for Influenza-Like Illness

Notes: This data is reported to Centers for Disease Control Prenvention by physicians enrolled as "sentinel providers", a group of community-based practices and university health clinics. There were 20 sentinel provider practices in the 2012-2013 season who report the number and age group of patients with "influenza-like illness" (ILI) - those with a fever over 100°F, a cough and/or sore throat with no other known cause.

Influenza-Like Illness by Age Group

Influenza-Like Illness compared to New England and United States

Strains of Influenza and Positive Laboratory Results

Source: State Health Laboratory influenza results reported to the World Health Organization (WHO) and the National Respiratory and Enteric Virus Surveillance System (NREVSS) through a secure online website. The weeks are based on the Morbidity and Mortality Weekly Report (MMWR) by the Centers for Disease Control Prenvention.