Echinococcosis in Tibetan populations, western Sichuan Province, China.

We screened 3,199 people from Shiqu County, Sichuan Province, China, for abdominal echinococcosis (hydatid disease) by portable ultrasound combined with specific serodiagnostic tests. Both cystic echinococcosis (CE) (Echinococcus granulosus infection) and alveolar echinococcosis (AE) (E. multilocularis) were co-endemic in this area at the highest village prevalence values recorded anywhere in the world: 12.9% were infected with one or the other form (6.8% CE and 6.2% AE). Prevalences of both CE and AE were significantly higher in female than male patients and increased with the age of the person screened. Pastoral herdsmen were at highest risk for infection (prevalence 19.0%). Prevalence of CE varied in 5 townships from 0% to 12.1%, whereas AE prevalence ranged from 0% to 14.3%. Risk factors associated with both infections included the number of owned dogs, frequency of contact with dogs, and sources of drinking water.