Abstract:

Objective To investigate the prevalence of echinococcosis in Changdu City. Methods Administrative villages were selected using stratified cluster sampling method in counties of Jiangda, Gongjue, Leiwuqi, Dingqing, Chaya, Basu, Zuogong, Mangkang, Luolong, Bianba, and Karuo District, covering four types of regions (pastoral area, semi-agricultural and semi-pastoral area, agricultural area, and town). Two hundred residents were selected for B ultrasound examination, and blood samples were collected from those with suspected infection. Specific antibody against Echinococcus in serum was detected by ELISA. Twenty household raising dogs were selected from each village, and Echinococcus antigen in dog feces was detected by ELISA. In each village, 10 sheep/pigs or 5 cattle were selected to examine internal organs including liver and lung. The ages of animals and number of cysts found were recorded. At least 300 adult rodents were caught within 1 km away from the spots of the residents who were detected to have alveolar echinococcosis, and hydatid cysts in liver and lung were examined by autopsy. Twenty villagers were randomly selected in each village, and no less than 50 students were selected from each of grades 4-6 in primary schools(one primary school from each county) for survey on the knowledge of echinococcosis prevention and behaviors by questionnairing. Results Sixty-eight villages were examined in 11 counties/regions of Changdu City, all were found with cases of cystic echinococcosis, and all had cases of alveolar echinococcosis except Mangkang County. The morbidity rate by B ultrasound was 1.44% (206/14 289). The estimated prevalence of hydatid diseases in Changdu City was 1.50%, with an estimated number of cases being 9 842, and they were dominated by cystic echinococcosis (81.07%, 167/206). The prevalence elevated with age, being highest in the population group of ≥ 70 years (4.05%, 9/222); it was significantly different among occupations (χ² = 208.146, P < 0.05), being highest in herdsmen (4.66%, 103/2 208); and it showed a trend of decrease with higher educational level (χ² = 6.831, P < 0.05), being highest in those illiterates (2.00%, 149/7 455). The prevalence of hydatid diseases in pastoral area, semi-agricultural and semi-pastoral area, agricultural area, and town were 1.71% (48/2 800), 1.69% (144/8 506), 0.43%(11/2 578) and 0.74% (3/405), respectively (χ² = 15.726, P < 0.01). The prevalence showed a significant difference among populations with different types of production activities(χ² = 25.335, P < 0.05). The infection rate was 2.17% (2/92) in intermediate host rodents and 12.09% (41/339) in livestock. The antigen positive rate in dog feces was 5.74% (78/1 358). The qualifying rate on the knowledge of echinococcosis control was 17.83% (271/1 520) in residents and 21.82% (340/1 558) in pupils (χ² = 7.714, P < 0.05). Conclusion Echinococcosis is widely prevalent in Changdu City, with a high infection rate and a high risk of infection.

Key words: Echinococcosis, Prevalence, Changdu City