BACKGROUND: Coccidioidomycosis (Valley Fever), endemic in Southern California, is an infection resulting from the inhalation of airborne spores of Coccidioides immitis or C. posadasii. In California, coccidioidomycosis must be reported to local health departments within seven calendar days. This evaluation assessed attributes of coccidioidomycosis surveillance in San Diego County (SDCo) utilizing Centers of Disease Control and Prevention surveillance evaluation guidelines.
METHODS: Incident reports in the SDCo web-based confidential morbidity registry (WebCMR) and death data in the SDCo vital records database were used to identify coccidioidomycosis cases between 2010 and 2014. Data quality was assessed by examining the completeness of surveillance records data. Cases were reviewed for potential misclassification, accuracy of residency status, and duplicate reports. System timeliness was evaluated by examining the time between the receipt of the case report and case closure. To assess representativeness, the number of coccidioidomycosis cases in WebCMR was examined by type of reporting facility.
RESULTS: A total of 1086 disease incidents were obtained from the WebCMR. Duplicate incidents, and/or misclassification in disease resolution status, residency status or combinations of these factors were identified in 22/1086 (2.1%). Eight incidents were misclassified as SDCo residents, and 14 were duplicates. After review, incidents were classified as follow: 701 (64.5%) confirmed, 12 (1.1%) indeterminate, 128(11.9%) non-residents, 235(21.7%) not cases and 3 (. 28%) suspect cases. The Predictive Value Posistive (PVP) for confirmed cases was 64.5%. Most cases (>90%) had complete demographic information; onset date (26.3%), occupation (34.7%) and race/ethnicity (73.2%) had the lowest completeness percentages. Reporting sources for confirmed cases included diverse hospitals, laboratories, and providers. The median time between the date the case was received compared to the time the case was closed was 26 days for confirmed cases. Lastly, 4/12 (33%) of deaths that met case definition for coccidioidomycosis were not found in WebCMR.
CONCLUSIONS: Stability, acceptably, and flexibility are relative strengths of the coccidioidomycosis surveillance system. Opportunities for improvement were found in data quality, sensitivity, PVP and simplicity. The evaluation identified misclassification issues for coccidioidomycosis, which may impact public health actions for these diseases. Recommended strategies to improve surveillance include utilizing a voluntary case report form to enhance collection of demographic information; establishing a duplicate incident and verification of residency validation process as part of quality assurance; and introducing an electronic notification system from vital records to report coccidioidomycosis deaths to the surveillance system.