Cystic echinococcosis in semi-nomadic pastoral communities in north-west China

In order to determine the prevalence of human cystic echinococcosis (CE) in semi-nomadic traditional pastoralist groups in north-west China, 2 large c ommunity studies were undertaken in Altai and Tacheng Prefectures in 1990/9 1 and 1995/96, respectively. The Kekergash community (Altai) comprised main ly ethnic Kazakhs, whereas the Narenhebuke community (Tacheng) comprised ma inly Mongolians. Populations were screened for CE by abdominal ultrasound s can (US) and serological tests. The total prevalence of confirmed human CE was higher in Narenhebuke (27%, 49/1844) than in Kekergash (0.9%, 17/1861; P < 0.01). Within each community there was no significant difference of CE prevalence between the Kazakh and Mongolian groups, although Han Chinese ex hibited twice the rate of CE (4.9%) in Narenhebuke compared to the dominant Mongolian population For each community, human CE prevalence increased wit h age and there was a greater risk associated with the practice of home sla ughter of livestock. Dogs were screened for Echinococcus granulosus infecti on and re-infection levels using a highly specific coproantigen test. The p roportion of dogs with positive coproantigen tests was significantly higher in Narenhebuke (36.0%, 50/139) compared to Kekergash (17.8%, 16/90). In Na renhebuke the re-infection levels of dogs, as determined by coproantigen po sitivity, were higher in the winter quarters (49.4%, 39/79) compared to the summer quarters (18.3%, 11/60; P < 0.01). Furthermore, coproantigen re-tes t positivity was 25% at 3 months and 29.2% at 7 months. Highest dog coproan tigen positivity was obtained over the winter period.