Evaluation of the surveillance of hemolytic uremic syndrome in British Columbia: should it remain reportable?

BACKGROUND: Hemolytic Uremic Syndrome (HUS) was made reportable in British Columbia (BC) in 1998 to detect, control and prevent verotoxigenic Escherichia coli (VTEC) cases. Concerns about under-reporting of HUS cases triggered the assessment of the sensitivity and timeliness of the reporting process in order to guide recommendations around reportability of this syndrome in BC.
METHODS: The BC hospitalization database was used to estimate the total number of HUS cases from April 30, 1998 to December 31,2005. HUS and VTEC cases reported in the integrated Public Health Information System (iPHIS), and HUS cases reported by a surveillance form were linked to hospitalized cases. The proportion of HUS cases detected by each of the surveillance processes was assessed. The time interval between onset of diarrhea and reporting of HUS and VTEC cases to the BC Centre for Disease Control was compared.
RESULTS: 57 HUS cases were hospitalized. Sensitivity of reporting through the surveillance form and through iPHIS was 7.0% and 19.3%, respectively. The median time interval between onset of diarrhea and reporting of both HUS and VTEC cases to iPHIS was seven days. The median time interval for reporting HUS cases via the surveillance form was 25 days.
CONCLUSIONS: HUS cases were severely under-reported, the timeliness of reporting of these cases had no advantage when compared to the reporting of VTEC cases, and no public health action aimed at reducing the transmission of VTEC infections resulted from this surveillance system. The reportability of HUS in BC needs to be reconsidered, or its surveillance considerably improved.