Abstract:

Objective To identity the dynamic changes of echinococcosis in Sichuan Province, and to provide reference for further prevention and control. Methods According to the National Echinococcosis Disease Surveillance Plan (2020 Edition), surveillance work was conducted in 35 different classified echinococcosis-endemic counties in Sichuan Province. In counties of types Ⅰ and Ⅱ, random cluster sampling method was used to select surveillance villages. Ultrasonographic examination was carried out to screen no less than 1 000 people. In type Ⅲ counties, all outpatients of the ultrasound department in the county-level hospitals were included in the surveillance of echinococcosis. One to five primary schools were randomly selected in each county to conduct student ultrasonographic screening (500 students in counties of types Ⅰ and Ⅱ, 1 500 students in type Ⅲ counties). All fecal samples detected by immunological method, including 10 domestic dog feces of each village in endemic towns and 200 canine feces around settlements or on both sides of rural roads. Each county was required to monitor 50-300 yaks or 100-500 sheep in centralized or scattered slaughterhouses, while the counties endemic with alveolar echinococcosis were required to capture 500 small mammals in mixed endemic counties. And the echinococcosis infections in viscera of intermediate hosts were identified by touching detection or autopsy methods. Questionnaires were used to investigate 300 students’ knowledge and health behavior development regarding to echinococcosis control in each county. Chi-square test was used to compare the rates. Results From 2021 to 2023, a total of 170 881 people were screened in surveillance villages of Sichuan Province, with a total prevalence rate of 0.328% (561/170 881). The prevalence rates from 2021 to 2023 were 0.334% (209/62 639), 0.458% (257/56 103), and 0.182% (95/52 139), respectively, with statistically significant differences (χ² = 62.94, P < 0.01). The detection rates of new patients from 2021 to 2023 were 3.19/100 000, 0, and 1.92/100 000, respectively, with no statistically significant difference (Fisher value = 1.62, P > 0.05). 77 308 primary school students were screened from 2021 to 2023, and no new patients with echinococcosis were found. The prevalence rate of alveolar echinococcosis (0.181%, 310/170 881) was higher than that of cystic echinococcosis (0.132%, 226/170 881) (χ² = 13.19, P < 0.01), and the prevalence rate of female (0.395%, 360/91 102) was higher than that of male (0.252%, 210/79 779) (χ² = 22.66, P < 0.01). There were statistical differences in the prevalence among different age groups and regions (χ² = 77.74, 261.54, P < 0.01). The positive rates of Echinococcus spp. coproantigen in domestic dogs were 0.50% (133/26 450), 0.38% (108/28 264) and 0.24% (72/29 847) from 2021 to 2023, showing a decreasing trend by year (χ² = 26.19, P < 0.01). The positive rate of canine feces in the wild in 2021 (1.60%, 37/2 312) was significantly higher than it in 2022 (0.40%, 11/2 720) and 2023 (0.35%, 10/2 844) (χ² = 33.47, P < 0.01). During 2021 to 2023, the prevalence in livestock were 0.92% (82/8 898), 1.07% (78/7 312) and 1.24% (92/7 416), respectively, with no statistical difference between years (χ² = 3.90, P > 0.05), and the prevalence in small mammals were 3.48% (442/12 684), 2.58% (231/8 955) and 1.39% (129/9 286), with a decreasing trend by year (χ² = 93.20, P < 0.01). The awareness rates of knowledge on echinococcosis prevention among primary school students from 2021 to 2023 were 92.62% (11 114/11 999), 92.17% (10 221/11 089) and 93.32% (10 491/11 242), respectively, with statistical significance (χ² = 11.05, P < 0.05). From 2021 to 2023, the qualified rates of no touching the dog was 75.47% (9 056/11 999), 73.24% (8 122/11 089) and 82.19% (9 240/11 242), respectively, and that of washing hands before meals were 70.72% (8 486/11 999), 75.63% (8 387/11 089) and 80.76% (9 079/11 242), respectively, and that of no feeding dogs with raw livestock viscus were 87.82% (10 537/11 999), 83.25% (9 232/11 089) and 92.47% (10 395/11 242). The difference in health behavior qualification rates of students between different years was statistically significant (χ² = 274.81, 316.96, 444.35; all P < 0.01). Conclusion The detection rate of new echinococcosis patients and the positive rate of animal hosts in Sichuan have decreased steadily or maintained a low level, and the rate of health awareness and behavior among the population is gradually increasing. However, some regions have significant fluctuations, and it is necessary to continuously strengthen comprehensive prevention and control measures to prevent the resurgence of the endemic.

Key words: Echinococcosis, Surveillance, Sichuan Province