Currently submitted to: JMIR Public Health and Surveillance
Date Submitted: Jun 15, 2026
Open Peer Review Period: Jun 17, 2026 - Aug 12, 2026
(currently open for review)
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Exploring SaTScan for the detection of acute hepatitis C outbreaks in California, 2020-2023
ABSTRACT
Background:
Acute hepatitis C virus (aHCV) outbreaks in California are identified by local health jurisdictions through investigation of cases reported by laboratories and healthcare providers to the state’s public health surveillance system. However, acute hepatitis C cases are widely underreported, limiting timely outbreak detection and early intervention. SaTScan has been proposed as a valuable tool to better detect disease clusters that may be missed by traditional surveillance, even when the disease is underreported, but it is not routinely utilized for acute hepatitis C surveillance.
Objective:
To evaluate SaTScan’s ability to identify verified acute hepatitis C outbreaks using public health surveillance data, we conducted a retrospective cluster analysis followed by a prospective point-of-concept (POC) scan to evaluate detection performance.
Methods:
We geocoded acute hepatitis C cases reported to the California Department of Public Health (CDPH) from January 2022 to December 2023. Cases among people experiencing homelessness were included using proxy locations corresponding to their reporting jurisdiction. First, we applied a retrospective space-time permutation scan to determine if any detected significant clusters corresponded to a verified acute hepatitis C outbreak reported in California. We then conducted a prospective POC scan using cases reported between August 2020 and August 2022 to simulate real-time surveillance prior to the detected acute hepatitis C outbreak. We assessed detection performance using recurrence intervals (RI) and positive predictive value (PPV).
Results:
Of the 236 reported acute hepatitis C cases in California from January 2022 to December 2023, 98% (231) were successfully geocoded. The retrospective scan identified one significant cluster that corresponded to a verified outbreak in Los Angeles County. The prospective POC scan detected the same outbreak one day after the second outbreak-related case was reported based on symptom onset. The cluster exceeded the RI threshold (1.7 years), and two of three outbreak-related cases were identified, yielding a PPV of 67%.
Conclusions:
SaTScan successfully identified a verified acute hepatitis C outbreak using both retrospective and prospective space-time permutation scans, demonstrating its potential to enhance real-time surveillance. However, detection performance depends on the timeliness and completeness of case reporting. Future research should explore prospective use of SaTScan with real-time surveillance data to fine-tune signaling thresholds and scan statistic parameters to assess broader applicability for acute hepatitis C outbreak detection. Clinical Trial: None
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