Abstract: Objective To make an epidemiological investigation on echinococcosis in Darlag County，Guoluo Tibetan Autonomous Prefecture of Qinghai Province. Methods Local participants were screened for echinococcosis using B ultrasound from August to September in 2007. IHA was carried out to detect antibody in human sera. Indirect ELISA using recombinant-AgB and Em18 antigen was conducted to further diagnose the human alveolar echinococcosis （AE）and cystic echinococcosis（CE）. The prevalence of echinococcosis in wild rodents, yaks, sheep and dogs was examined either by dissection or through slaughterhouses. Adult worms and hydatid cysts were detected by PCR-RFLP to discriminate 3 Echinococcus species and genotype of Eg. Dog feces were tested by double antibody sandwich ELISA method to confirm the coproantigen positive rate. Results 1 723 people were examined by ultrasound and 236 were clinically diagnosed as hydatid diseases with an overall morbidity of 13.7%，of which 5.5% were CE and 8.2% were AE. Prevalence in males and females was 11.6% and 15.6% respectively with a statistically significant difference （χ ²=7.0，P＜0.05）. Prevalence in herdsmen and monks/nuns was as high as 23.0% and 13.2%，respectively. Adult worms were found in 5 out of 9 stray dogs by necropsy. 27 of 239 pikas（Ochotona curzoniae）were infected by E. shiquicus （11.3%）. CE prevalence in sheep and yaks was 26.4% and 5/16 respectively. The Eg genotype was G1（sheep strain）. Conclusion Three species of Echinococcus，e.g. E. granulosus，E. multilocularis and E. shiquicus are all prevalent in Darlag County. The prevalence of both AE and CE in human population is high in the area. Domestic dogs are the pri-mary definitive host for both E. granulosus and E. multilocularis.

Key words: Echinococcosis, Epidemiology, Survey, Qinghai