1. Enhancing Disease Surveillance with Spatial-temporal Results Patricia Araki, MPH County of Los Angeles – Department of Public Health Acute Communicable Disease Control Program

2. Introduction Basic types of surveillance: –Active –Passive –Enhanced  Syndromic Surveillance Origins of Syndromic Surveillance –9/11 –Primary purpose: identify outbreaks before definitive diagnoses are made

3. Type of surveillance that looks at trends within syndrome categories Daily Emergency Department (ED) admission data from participating hospitals Classify each ED visit by chief complaint into syndrome categories Tally and compare observed to expected values using statistical algorithm What is Syndromic Surveillance and how is it conducted?

4. Mapping and cluster analysis: Data within each syndrome category are analyzed by patient zip code using SaTScan™ –Likelihood ratio is calculated for each point/cluster –Most likely cluster is determined by selecting the maximum likelihood ratio (scan statistic) over all possible clusters –p-value for the most likely cluster is calculated via Monte Carlo hypothesis testing Results may then be visualized by using ESRI ArcGIS or SAS Graph

5. Graphing SaTScan™ Geospatial results Key info about the most likely cluster appears in red text above the map Zip codes in most likely cluster are listed below the map in black text Zip code colored red is the center of the most likely cluster Zip code(s) colored in grey are other zip codes in the most likely cluster

6. Spatial-temporal results Day 1 Day 2 Day 3 Day 4 Day 5 Day 6

7. Example: Potential school Meningitis outbreak On November 14, 2006, ACDC was alerted to a high school student who attended school while symptomatic for meningitis Public health officials offered prophylaxis at the school Two students eventually confirmed positive Data were assessed for both temporal trends and spatial SatScan TM clusters –Neurological syndrome visits –Potential meningitis CCs: “Fever,” “headache,” “meningitis”

8. findings… RA STS PALPITATIONS,BLURRED VISION PTS MOTHER STS MENINGITIS SYMPTOMS FTH STS MENINGITIS BREAK OUT FATHER ST EXP MENINGITIS,H/A NAUSEA FEVER PT STS MENINGITIS BREAK OUT AT CV HIGH RA STS MENINGITIS,ALLERGIC REACTION PT STS RT ARM NUMB,BLURRED VISION VOMITING,HEADACHE,FEVER HEADACHE,VOMITING,FEVER NECK STIFFNESS/BACK PAIN/ R/O MENINGHITIS FEVER SORETHROAT HEADACHE ABNORMAL VAG BLEED FEVER/HEADACHE HEADACHE FEVER R/O MENENGITIS

9. Application of Syndromic Surveillance and SaTScan™ to LA County data sources Emergency department logs NRDM-OTC (medication sales) KP-Nurse Call Coroners Poison Control EMS Fire/dispatch Hepatitis

10. Resources SaTScan™: www.satscan.org Syndromic surveillance: www.syndromic.org