JMIR Publications

ABSTRACT

Background:

Foodborne diseases remain a significant global public health concern, imposing substantial health and economic burdens. The COVID-19 pandemic, which began in 2020, altered healthcare-seeking behaviors, infection control practices, and the epidemiology of various infectious diseases; however, its association with the detection of microbial foodborne pathogens remains incompletely characterized.

Objective:

This single-center retrospective study aimed to analyze changes in the detection patterns of bacterial and viral foodborne pathogens by conducting an in-depth analysis of clinical and etiological data from patients attending an Infectious Diarrhea Clinic at a tertiary hospital in Beijing over a six-year period, and to provide evidence to inform prevention strategies in the post-pandemic 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) between January 2018 and December 2019 (pre-pandemic) and between January 2022 and December 2023 (post-pandemic). The years 2020 and 2021 were excluded due to major disruptions in clinical services and surveillance during the peak pandemic period. Etiological monitoring results were obtained from the Beijing Haidian District Center for Disease Control and Prevention. The diagnostic methods, laboratory protocols, specimen collection procedures, reagent kits, instrumentation, and testing criteria remained consistent throughout the study period. Cases were divided into two groups based on time period, and chi-squared tests were used for comparisons. The positivity rate was calculated using the total number of patients who provided stool specimens and underwent testing as the denominator and the number of patients with at least one target pathogen detected as the numerator.

Results:

A total of 1,064 patients were included (561 in Group A, 503 in Group B). From 2018 to 2019, 155 of 561 specimens tested positive (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 of 503 specimens tested positive (16.3%, 95% CI: 13.1%-19.5%), including 13 Salmonella, 7 Vibrio parahaemolyticus, 45 DEC, and 17 norovirus cases. The overall positivity rate was significantly lower in the post-pandemic period than in the pre-pandemic period (27.6% vs. 16.3%, P<0.05). 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 Vibrio parahaemolyticus (4.3% [24/561] to 1.4% [7/503], P=0.005) and norovirus (7.7% [43/561] to 3.4% [17/503], P=0.002) were significantly lower in the post-pandemic period.

Conclusions:

Among patients attending a single Infectious Diarrhea Clinic in Beijing, the detection rates of microbial foodborne pathogens were significantly lower in the post-pandemic period compared to the pre-pandemic period. These findings may reflect changes in healthcare-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, and further multicenter studies are warranted.