关键词: 食源性寄生虫病, 血清阳性率, 空间自相关分析, 时空扫描, 大理白族自治州

Abstract:

Objective To systematically unravel the spatiotemporal distribution and clustering characteristics of seroprevalence of IgG antibodies against six major foodborne parasites in Dali Bai Autonomous Prefecture, Yunnan Province, based on serological testing data, so as to provide insights into precision diseases prevention and control. Methods Serum samples were collected from individuals admitted from Dali Bai Autonomous Prefecture Institute of Schistosomiasis Control from 2019 to 2023, and serum IgG antibodies against pathogens of six major zoonotic parasitic diseases were detected using enzyme-linked immunosorbent assay (ELISA) or colloidal gold immunochromatography, including taeniasis/cysticercosis, angiostrongyliasis, trichinosis, fascioliasis, echinococcosis, and paragonimiasis. Geographic distribution was visualized using the software ArcMap 10.8, and the overall spatial clustering pattern of IgG antibody seropositivity was identified using Moran’s I index within the study area. High-value (hot spots) and low-value (cold spots) clusters were identified with local statistics within the study area, and spatiotemporal scan analysis was performed with the software SaTScan 10.1 based on the Poisson model to identify spatiotemporal clusters of IgG antibody positivity against parasites. Results A total of 3 131 serum samples were tested from 2019 to 2023, and the overall seroprevalence of IgG antibodies against foodborne parasites was 23.3% (728/3 131) in Dali Prefecture, with seroprevalence of 52.5% (139/265), 50.5% (161/319), 26.7% (211/789), 14.6% (140/961), and 9.7% (77/797) from 2019 to 2023, respectively, appearing a tendency towards decline over years (χ² = 387.55, P < 0.01). Single infections were predominant (18.6%, 583/3 131), followed by dual infections (4.2%, 132/3 131). Counties with the three highest overall seropositivity included Yunlong County (53.2%, 58/109), Nanjian Yi Autonomous County (35.5%, 33/93), and Xiangyun County (32.7%, 33/101). The Moran’s I index was all negative each year from 2019 to 2023, ranging from -0.20 to -0.03, indicating no spatial autocorrelation in the seropositivity across years (all P > 0.05), which was consistent with a random spatial distribution pattern. Hotspot areas exhibited a random spatial distribution, with significant hotspots shifting from western regions (Yunlong County, Yangbi Yi Autonomous County) to central regions (Dali City) and then to eastern areas (Midu County) over time. Spatiotemporal scans identified two statistically significant clusters, including Heqing County (2021 to 2022, RR = 6.47, P < 0.01) and Weishan Yi and Hui Autonomous County (2021 to 2022, RR = 5.30, P < 0.01). Parasite IgG antibody-positive samples were primarily derived from farmers (86.1%, 627/728), males (59.1%, 430/728), and individuals at ages of 40 to 59 years (55.6%, 405/728), and no gender-, age- or occupation-specific seroprevalence was seen (χ² = 1.97, 7.73, 10.64, all P > 0.05). Conclusion The overall risk of foodborne parasitic infections declines in Dali Prefecture; however, the spatial pattern appears a complex landscape that is characterized by global randomness, local clustering, and dynamic shifts of hotspots. Differentiated, precision interventions are needed for long-term high-burden areas, anomalous clusters, and dynamic hotspots, and health education and behavioral interventions are prioritized for high-risk individuals, particularly farmers.

Key words: Foodborne parasitic disease, Seroprevalence, Spatial autocorrelation analysis, Spatiotemporal scan, Dali Bai Autonomous Prefecture