METHODS: Tennessee Department of Health (TDH) SFGR surveillance records were matched to death certificates issued during 1995–2014 with SFGR-related diagnosis codes (International Classification of Disease, Ninth and Tenth Revisions), and to two patient series: patients with SFGR-positive serologic specimens from a reference laboratory during 2010–2011, and tertiary medical center patients with SFGR-positive serology during 2007–2013 identified through laboratory record review. Chart reviews were performed on both groups and patients were classified according to the Council of State and Territorial Epidemiologists’ (CSTE) case definition, which requires meeting both laboratory and clinical criteria.
RESULTS: Of 27 patients identified by death certificate, 8 (30%) were reported to TDH but not correctly identified as deceased. Of 254 SFGR-positive specimens from the reference laboratory, we classified 129 (51%) as confirmed or probable cases following chart review; of which 58 (45%) were correctly classified in TDH records, while 41 (32%) were incorrectly classified as suspect or not a case, and 30 (23%) were missing from TDH records. Of 98 confirmed or probable medical center cases, 33 (34%) were reported to TDH and correctly classified as confirmed or probable, 19 (19%) were incorrectly classified as suspect or not a case, and 46 (47%) were missing from TDH records.
CONCLUSIONS: Cases and fatalities from SFGR are underreported and misclassified. SFGR-attributable deaths are inconsistently documented. The complex case definition requiring clinical information might contribute to the substantial proportion of misclassified cases. Efforts are needed to improve SFGR surveillance.