1. Texas ILINet Structure and Operation 2002-2008 86 th Annual Texas Public Health Association Conference April 21-23, 2010 South Padre Island, Texas Gary Heseltine MD MPH Infectious Disease Control Unit Chronic Illnesses Demand Chronic Attention

2. Overview What is ILINet What is the structure of ILINet – Where does the data come from – Who is represented How does ILINet operate – Data handling – Stability of operation Possible Improvements to ILINet

3. Influenza Like Illness (ILI) Net CDC hosted syndromic reporting system – Fever > 100 o F and cough or sore throat Clinicians report weekly – Total number patient visits – Total number of patients diagnosed with ILI Cases divided into 4 age strata Statewide weekly ILI index – Combine data from all clinicians ILI index = total ILI patients/total patient visits

4. Texas ILI Index: What Does It Mean?

5. ILINet Evolution YearReportersILI PatientsTotal VisitsCountiesReport/County 2002131,23779,85291.44 2003448,232184,848311.42 20046918,244517,845332.09 200510124,020696,806422.40 200611139,6071,018,809522.13 200712341,9631,018,790612.02 200812434,3351,041,898582.14 Total 167,6384,558,848

6. Reporters

7. Total Number of Weekly Submissions by Reporter 2002-2008

8. Weighting

9. 8

10. Tuning Surveillance Levels Weight county Weight block Data View county Data View block

11. ILINet Data: Two Issues 1.ILINet data reported to the state does not reflect county populations – Weight county contributions to reflect underlying population proportion – Use sampling index to guide resource allocation and recruiting for ILINet to obtain proportionality 2. Sampling method itself: non-probability – Clinicians (reporters) are volunteers- bias – Convenience sample - bias – Use a probability sample to correct for ILINet sampling bias before submission to the state