Abstract: Objective To understand the prevalence and characteristics of human echinococcosis in Lhasa City. Methods Population based screening for echinococcosis was performed in 2017 by abdominal ultrasound scanning using a portable ultrasound scanner. Diagnosis was made according to the Diagnostic Criteria for Echinococcosis (WS 257-2006), combined with epidemiological history and clinical manifestations. Suspected cases further received a serological test with ELISA to detect serum IgG antibody against Echinococcus antigen. Data were analyzed using the SPSS 20.0 statistical software. Results The overall detection rate of human echinococcosis in Lhasa City was 0.24% (935/392 592) in 2017. The detection rate in females (0.28%, 533/193 671) was significantly higher than that in males (0.20%, 402/198 921) (P < 0.05). Echinococcosis was found in all age groups, with the highest prevalence in the group of ≥ 70 years (0.90%, 106/11 769) and the lowest in the group < 10 years (0.09%, 48/54 181). In the age groups of 50-59, 60-69, and ≥ 70 years, the prevalence in females(0.51%, 111/21 812; 0.93%, 92/9 924; 1.06%, 70/6 629, respectively) was significantly higher than those in males (0.35%, 73/20 853; 0.57%, 51/8 988; 0.70%, 36/5 140, respectively) (P < 0.05). Among the groups of different educational levels, the illiteracy and semi-illiteracy group had the highest detection rate of echinococcosis (0.45%, 369/82 206), while the college and higher group had the lowest(0.14%, 26/18 124). In the illiteracy and semi-illiteracy and the primary school group, the detection rates in females (0.54%, 232/43 171; 0.36%, 148/40 655) were both significantly higher than those in males (0.35%, 137/39 035; 0.28%, 118/41 786) (P < 0.05). The occupation distribution of echinococcosis showed that the prevalence was found the highest in the herdsman-farmer group (1.20%, 59/4 923) and the lowest in students (0.12%, 79/64 398). The prevalence in females of herdsman group and the group of other occupations was 0.96% (93/9 675) and 0.26% (201/77 235), respectively, being significantly higher than those in males(0.52%, 53/10 139 and 0.14%, 113/79 483, respectively) (P < 0.05). The lifestyle distribution indicated that the prevalence was the highest in those settled in winter and nomadic in summer(1.70%, 26/1 529), among them the females showed the prevalence (2.65%, 21/792; 0.28%, 431/153 203) significantly higher than those in males(0.68%, 5/737; 0.20%, 309/156 215, respectively)(P < 0.05). Among the groups engaging in different types of production, the prevalence was found the highest in the group of livestock farming (0.57%, 128/22 351), and the lowest in the agriculture group (0.20%, 266/130 298). In all production type groups, except the herding-farming group, higher prevalence was found in females of all other groups including town residents (0.24%, 246/104 250), livestock farming group (0.73%, 82/11 162), and agriculture group (0.24%, 149/62 149) respectively, which were significantly higher than those in males (0.19%, 195/103 092; 0.41%, 46/11 189 and 0.17%, 117/68 149, respectively) (P < 0.05). Furthermore, the prevalence varied in different counties (districts), ranging at 0.18%-0.41%, with the highest in Damshung County(0.41%, 102/24 588) and lowest in Nyemo County (0.18%, 48/26 768). The prevalence was higher in the counties of Lhundup (0.28%, 135/48 848), Damshung (0.41%, 102/24 588) and Medro Gongkar (0.28%, 117/41 689), compared with Chengguan District (urban area of Lhasa) (0.21%, 378/180 594) (P < 0.05). Conclusion The survey indicates that females, people at age ≥ 70, in the occupation of herding-farming, with living style being settled in winter and nomadic in summer, illiterate and semi-illiterate, and engaging in livestock farming are at higher risk of contracting echinococcosis in Lhasa area.

Key words: Echinococcosis, Detection rate, Population