Abstract:

Objective To understand the endemic status of echinococcosis in Dali Bai Autonomous Prefecture, Yunnan Province (hereafter Dali) to provide reference basis for prevention and control of the disease in the province. Methods According to the Technical Scheme for Hydatid Disease Control in Yunnan Province, a retrospective survey was performed on all retraceable echinococcosis cases recorded in Dali Prefecture First people’s Hospital, the First Affiliated Hospital of Dali University, Dali City First People’s Hospital, The first People’s Hospitals and Centers for Disease Control and Prevention of counties Eryuan, Jianchuan, Heqing, Binchuang, Yangbi and Yunlong, as well as in the National Infectious Disease Reporting Information Management System from 2016 to 2022. In addition, sampling survey was conducted in 2016—2022. Using cluster random sampling method, 6 counties (Er Yuan, Jian Chuan, He Qing, Bin Chuan, Yang Bi and Yun Long) were selected, from each of which 3 townships were seleted annually, and then no less than 3 villages were selected from each township. From the selected villages, no less than 500 permanent residents at the age over 3 years were examined by abdominal ultrasonography. Hydatid disease was diagnosed based on ultrasonic imaging combined with epidemiological history and clinical manifestation. Serological tests were performed for those suspected cases. A questionnaire was carried out in enrolled participants with age over 6 year old for the awareness of infection and prevention of hydatid disease. A dog was selected from each household in each village to detect the coproantigen of Echinococccus by ELISA. In each county (city), visceral organs were collected from locally raised sheep, pigs and cattle for examining hydatid cysts by necropsy. All data were statistically analyzed using SPSS 17.0 software. Results A total of 161 cases were found in 12 counties through retrospective investigation. Among them, the number of cases found in hospitals accounted for 50.01% (95/161), and the number of cases found in surveys accounted for (40.99%, 66/161). The confirmed cases accounted for (78.89%, 127/161), the clinical cases accounted for (21.12%, 34/161). The accounted for cystic echinococcosis in males and females were 40.37% (65/161) and 59.63% (96/161), without statistically significant difference between gender (χ² = 3.851，P < 0.05). The accounted for increased with age (χ² = 188.520, P < 0.05), the group of 40-49 years old (22.36%, 36/161) was highest other group, with a statistically significant difference between age groups (χ² = 188.520，P < 0.05). Most echinococcosis cases were found in farmers (87.58%, 141/161) and students (6.83%, 11/161). The ethnic groups with cases are mainly Bai (63.35%, 102/161) and Han (22.36%, 36/161). There are statistically significant differences among professions and ethnic groups (χ² = 286.898, 101.030; both P < 0.05). A total of 543 villages were investigated in 6 counties from 2016 to 2022. A total of 265 983 residents were examined by ultrasound, of whom 66 (24.81/100 000) were detected with hydatid disease, all infected with Echinococcus granulosus. Eryuan County has the highest prevalence rate (39.03/100 000, 23/51 248), and Yunlong County has the lowest prevalence rate (5.23/100 000, 2/38 243). The detection rate of echinococcosis in the population was the highest in 2017 (149.03/100 000), and the lowest in 2021 (11.41/100 000), showing a downward trend since 2017. The overall dog coproantigen positive rate was 1.48% (218/14 766), with the highest positive rate (2.40%, 44/1 837) in Yunlong County, and the lowest positive rate (0.73%, 18/2 470) in Binchuan County. The overall hydatid detection rate in livestock (sheep, cattle and pigs) was 0.09% (16/18 416), and the infection rates of Echinococcus in livestock in Eryuan County and Yangbi County were 0.45% (15/3 349) and 0.03% (1/3 202), respectively. No infected livestock were found in other counties, with 0.06% (3/5 369) in 2017, 0.15% (7/4 771) in 2018 and 0.22% (6/2 769), respectively. The infection rates of cattle and pigs were 0.02% (1/4 715) and 0.13% (15/11 427), respectively, and no infection was found in sheep. The overall awareness rate for echinococcosis among the investigated population was 72.71% (4 494/6 181), The awareness rate of Yunlong County, Yangbi County, Heqing County, Jianchuan County, Eryuan County and Binchuan County was 88.76% (1 137/1 281), 79.31% (594/749), 77.66% (918/1 182), 74.49% (800/1 074), 64.10% (759/1 184) and 40.23% (286/711), respectively (χ² = 109.991, P < 0.05). Conclusion Echinococcosis in Dali showed a moderate prevalence. It is imperative to strengthen health education for key population including women, aged 40-49 group, farmers, and the Bai ethnic group.

Key words: Echinococcosis, Epidemiology analysis, Retrospective analysis, Dali