Abstract:

Objective To understand the prevalence of echinococcosis in Nyingchi City in Tibet Autonomous Region. Methods A stratified cluster sampling method was used to select 6 counties among pastoral area, agricultural area, semi-agricultural and semi-pastoral area, and town, from August to October, 2016. In each county, the number of villages for survey was determined by the population size of each county. Two hundred residents were selected, residents aged > 1 year received B-ultrasound examination in combination with epidemiological history, clinical manifestations and imaging features for diagnosis. Those suspected were also subjected to a serological test. In each village, 20 local residents were selected using a random number table method, and in each county, a primary school was selected, from which 50 students of grades 4-6 were selected. Their knowledge on hydatid disease control and their behaviors were surveyed by face-to-face Q & A. In each village, 20 dog-raising households were selected using a random number table method, and in each household fecal samples (1-3 g) were collected from only one dog. Echinococcus antigen was detected by ELISA in dog feces. 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. Prevalence of hydatid disease in cattle and sheep was investigated by biopsy combined with PCR. Statistical analysis was carried out using SPSS 19.0 statistical software. Results A total of 28 villages were investigated in 6 counties, and 5 016 residents received B-ultrasound examination, among whom 47 were detected with hydatid disease, comprising 42 cases of cystic hydatid disease(89.36%, 42/47) distributed in the 6 counties and 5 cases of alveolar hydatid disease(10.64%, 5/47) distributed in 3 counties (Gongbu Jiangda, Chayu, Bomi). The prevalence in males and females was 0.78% (17/2 167) and 1.05 % counties(30/2 849), respectively. From the youngest of 2 years to the oldest of 93 years, each age group was found with hydatid disease, and the prevalence increased with age (χ² = 16.151, P < 0.05). There was no significant difference in the prevalence by education levels (χ² = 3.073, P > 0.05). Of the only two production types in Nyingchi City, the prevalence was higher in semi-agricultural and semi-pastoral area (1.01%, 44/4 376) than in agricultural area (0.47%, 3/640) (χ² = 1.733, P > 0.05). Higher prevalence in semi-agricultural and semi-pastoral area was also found in males (4.02%, 8/199) and females (3.43%, 7/204). The antigen positive rate in dog feces was 3.59% (18/501), 3.21% (11/343) in domestic dogs and 4.43% (7/158) in stray dogs (χ² = 0.467, P > 0.05). The infection rate in rodents in Chayu County was 1.45% (5/345). Only 1 pig was detected. The qualified rate of knowledge on hydatid disease control was 27.40% (385/1 405). Conclusion Cystic hydatid disease is prevalent in all the 6 counties, while alveolar hydatid disease is detected in 3 counties of Nyingchi.

Key words: Echinococcosis, Prevalence, Tibet Autonomous Region, Nyingchi City, Current status