Detecting Nonreportable Disease Trends Using Electronic Health Records: Human Parvovirus B19 in Minnesota, January 2019 Through September 2024

Objectives: In 2024, an increase in human parvovirus B19 (B19) infections among pregnant patients resulting in severe fetal complications highlighted the lack of routine surveillance methods for nonreportable infections. We examined the utility of electronic health record (EHR) data for investigating statewide trends in nonreportable infections, using B19 as a case study. Methods: We used EHR data from 10 health systems aggregated by the Minnesota Electronic Health Record Consortium to analyze statewide B19 trends in Minnesota. We mapped health system data to a common data model using concept identifiers, a standardized medical coding vocabulary. We examined the frequency of B19-associated laboratory testing, diagnoses, and pregnancy complications among Minnesota residents from January 2019 through September 2024, focusing on females of reproductive age (15-44 y) when examining B19-associated pregnancy complications. Results: B19 testing and test positivity increased in 2024 compared with the preceding 60 months. From January 2019 through September 2024, 47 females of reproductive age had B19-associated pregnancy complications within 60 days of a B19 diagnosis or positive laboratory test result. Of these, 19 (40.4%) occurred from January through September 2024 and 28 (59.6%) occurred during the preceding 60 months. Conclusions: These findings support the use of EHR data for disease trend analyses, particularly for rare conditions, care processes, and nonreportable diseases.