Abstract:

Objective To investigate the prevalence of echinococcosis in Lhasa. Methods A stratified cluster sampling method was used to select 8 counties (Damxung, Lhünzhub, Nyêmo, Maizhokunggar, Dagzê, Qüxü,Doilungdegen and Chengguan) in Lhasa City to investigate the prevalence of echinococcosis, and they were divided into pastoral area, semi-agricultural and semi-pastoral area, agricultural area and towns based on the type of production. Villages for investigation were assigned into the 8 counties with an appropriate proportion. In each village, at least 200 residents were examined by B ultrasound. When there were fewer than 200 people in a village, residents from its neighbor village would be enrolled. 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 and behaviors in relation to echinococcosis prevention by questionnairing. Twenty dog-raising households 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 number of cysts found were recorded. Difference in prevalence among groups was analyzed by χ² test. Results In 2016, the prevalence of echinococcosis in Lhasa was 1.38% (151/10 917), dominated by cystic echinococcosis (82.12%, 124/151). There was no significant difference in prevalence among the counties (χ² = 13.322, P > 0.05) and between males (1.12%, 48/4 267) and females (1.55%, 103/6 650) (χ² = 3.425, P > 0.05). All age groups were found with hydatid disease, with the ≥ 70 years group having the highest prevalence (2.99%, 19/635). The prevalence showed a trend of increase with age (χ² = 39.544, P < 0.01). The prevalence was higher in herdsmen (3.16%, 38/1 263), semi-farmer-and-herdsmen (1.93%, 15/777), and houseworkers (1.59%, 8/504) , with a significant difference among occupations (χ² = 53.199, P < 0.01). There was a significant difference in prevalence among educational levels (χ² = 34.138, P < 0.01), highest in the illiterates (2.08%, 99/4 755) and lowest in those with a high school level or above (0.47%, 3/638). There was also a significant difference in prevalence between the settled-down residents (3.03%, 8/264) and the nomadic population (1.34%, 143/10 653) (χ² = 4.215, P < 0.05). In addition, the prevalence was highest in pastoral area (2.63%, 40/1 995) and lowest in town (0.84%, 21/2 512) (χ² = 11.206, P < 0.05). The qualified rate on knowledge of echinococcosis prevention in selected residents was 40.20% (907/2 256). The positive rate of Echinococcus antigen in dog fecal samples was 6.30% (66/1 047). The prevalence of hydatid infection was 16.36% (29/185) in livestock. Conclusion There is a high prevalence of hydatid disease in Lhasa, especially in pastoral area.

Key words: Echinococcosis, Lhasa City, Prevalence