BACKGROUND: Shigellosis is an acute bacterial illness characterized primarily by diarrhea accompanied by fever, nausea, and other gastrointestinal symptoms. Early identification of cases will aid in the prevention of further disease spread. Positive lab reports of Shigella sp.are primarily reportable within one business day in Kentucky via the state’s National Electronic Disease Surveillance System (NEDSS). Local health departments, including Louisville Metro Public Health and Wellness (LMPHW), must interview cases using a standardized questionnaire and enter the results into NEDSS. Two other statewide electronic systems, Business Objects and Outreach, are also used for lab results and data analysis. We evaluated shigellosis reporting in Louisville using the three state-mandated systems to gage the system’s effectiveness and efficiency for surveillance.
METHODS: We used CDC’s 2011 “Updated Guidelines for evaluating Public Health Surveillance Systems” for the evaluation focusing on simplicity (ease of use), data quality (completeness and mismatches), positive predictive value, and timeliness (days from first positive lab results to notifying LMPHW). Mismatches were defined as differences between NEDSS entries and paper investigations. We also assessed the number of relevant fields each system contributes to an outbreak line list, and if such information can be queried electronically or not. Shigellosis cases from January 1st, 2016 to October 31st, 2016 were used in the evaluation and analysis. Final analysis was completed using Microsoft Excel (2010) and SPSS Statistics (version 21).
RESULTS: During the study period, 83 shigellosis cases were reported to LMPHW and entered into NEDSS with 1 duplicate. Completeness and mismatch rates for address information were 100% and 1.2% respectively, 98.8% and 1.2% for gender, 86.8% and 7.2% for phone numbers, and 95.2% and 4.8% for race. Additionally, 74.4% of reports were reported within the required time to LMPHW, and the PPV case definition accuracy was 98.8%. Food handler status was incomplete for 13.3% entries with 13.3% mismatched, and daycare/school status was unmarked for 9.6% entries with 22.9% mismatched.
CONCLUSIONS: Shigellosis follow-up investigations are based on laboratory results and demographic information. The omitted and wrong information generates additional work which delays a public health response. Using three data systems to compile a line list with relevant fields was difficult, requiring manual matching and manual entry which delayed analysis of information in outbreak situations. Therefore, improvements in the electronic surveillance systems will result in better outbreak responses at the local level.