Changes in Microbial Foodborne Pathogen Detection in Beijing, China, Before and After the COVID-19 Pandemic: Single-Center Retrospective Study.

Abstract

Background: Foodborne diseases remain a significant global public health concern, imposing substantial health and economic burdens. The COVID-19 pandemic altered health care-seeking behaviors, infection control practices, and infectious disease epidemiology; however, its association with microbial foodborne pathogens remains incompletely characterized.

Objective: This single-center retrospective study aimed to analyze changes in bacterial and viral foodborne pathogen detection using clinical and etiological data from patients at an infectious diarrhea clinic in a tertiary Beijing hospital over 6 years and to inform prevention strategies in the postpandemic era.

Methods: We collected data from patients presenting to the Infectious Diarrhea Clinic of Peking University Third Hospital (a grade A tertiary care center serving the Haidian District and surrounding areas of Beijing) from January 2018 to December 2019 (prepandemic) and from January 2022 to December 2023 (postpandemic). The years 2020 and 2021 were excluded due to major disruptions in clinical services and surveillance during the peak pandemic period. Etiological results were obtained from the Beijing Haidian District Center for Disease Control and Prevention. Diagnostic methods, laboratory protocols, specimen collection procedures, reagent kits, instrumentation, and testing criteria remained consistent throughout the study period. Cases were divided into 2 groups based on time period, and χ2 tests were used for comparisons. The positivity rate was calculated as patients with at least 1 target pathogen detected divided by all patients who provided stool specimens.

Results: In total, 1064 patients were included (561 in group A and 503 in group B). From 2018 to 2019, 155/561 specimens tested positive for foodborne pathogens (27.6%, 95% CI 23.9%-31.3%), including 22 Salmonella, 24 Vibrio parahaemolyticus, 66 diarrheagenic Escherichia coli (DEC), and 43 Norovirus cases. From 2022 to 2023, 82/503 specimens tested positive (16.3%, 95% CI 13.1%-19.5%), including 13 Salmonella, 7 V parahaemolyticus, 45 DEC, and 17 Norovirus cases. The overall positivity rate was significantly lower in the postpandemic period than in the prepandemic period (27.6% vs 16.3%, P<.05). Students and males aged 16-25 years were the most represented demographic groups. DEC remained the predominant pathogen in both periods. The detection rates of V parahaemolyticus, from 24/561 (4.3%) to 7/503 (1.4%) (P=.005), and Norovirus, from 43/561 (7.7%) to 17/503 (3.4%) (P=.002), were significantly lower in the postpandemic period.

Conclusions: Among patients attending a single infectious diarrhea clinic in Beijing, the detection rates of microbial foodborne pathogens were significantly lower in the postpandemic period compared with the prepandemic period. These findings may reflect changes in health care-seeking behavior, infection control practices, food consumption patterns, and/or testing practices during this period; however, this observational study cannot establish causation. Targeted surveillance and health education for students and young adults remain important. These results may not be generalizable to community-level incidence or other settings; further multicenter studies are warranted.