Influenza (Flu) Surveillance Summary
Influenza (Flu) Surveillance in Indiana
State health officials say they will be providing a weekly update on influenza (flu) activity in Indiana each Wednesday, starting September 23, 2009. This update will include general information on flu activity, based on surveillance across the state, but will NOT include flu case counts on either the state or the county level. A summary of influenza surveillance in Indiana will be posted on this site every Wednesday.
The Indiana State Health Department will be monitoring all influenza activity in the state, both seasonal influenza and the 2009 H1N1 influenza A through the use of influenza sentinel surveillance and the Public Health Emergency Syndromic System (PHESS). Through this system, data is collected from hospital emergency departments on a daily basis and analyzed by the State Health Department’s epidemiologists. State health officials will also be tracking hospitalizations from influenza-like illnesses and pneumonia and flu-related deaths and reporting that information on a statewide level.
Indiana has 58 influenza sentinel sites distributed around the state in outpatient settings. When individuals seek medical care for influenza-like illness at the sentinel sites, the practitioner performs a nasal swab and sends it to the state laboratory. The state laboratory tests the swab for influenza A and if it is positive, the laboratory does further testing to determine the subtype of influenza. This allows state health officials to determine what types of influenza viruses are circulating.
During the spring of 2009, as the novel H1N1 influenza was beginning to spread across the United States, Indiana confirmed its first case after a patient was seen with influenza-like illness at a flu sentinel site and had routine testing as part of this surveillance system. Since the pandemic was declared in June 2009, the State Health Department has increased the number of sentinel sites across the state to improve surveillance.
Week 39 (September 27-October 3, 2009) Summary
- Based on data from emergency rooms and flu sentinel sites, there continues to be more influenza-like illness being reported than at this time over the past two years.
- The current percentage (3.8%) of patients who presented at an emergency department with a chief complaint of influenza-like illness is at the same level as the influenza season peak during the 2008-2009 flu season.
- Younger populations (0-25 years of age) continue to have the highest tendency to seek care for influenza-like illness at sentinel provider clinics.
- Universities continue to experience slightly higher levels of influenza-like illness in their population compared to other sentinel sites.
- The number of flu-related hospitalizations significantly increased 12 percent from week 38.
- No influenza-associated deaths were reported to the ISDH during week 39.
- Since September 1, 2009, of the specimens testing positive for influenza, 93 percent were 2009 H1N1 flu. .
