ABSTRACT
The double diffusion test was used for detecting cross serological reactions between hydatid fluid antigens and sera of ruminants infested with different helminth parasites. The whole hydatid fluid antigen showed positive reactions with sera of sheep infested with Cysticercus tenuicollis, sera of cattle infested with Cysticercus bovis, sera of buffalos infested with Fasciola gigantica and Paramphistomum species and sera of cattle harbored Fasciola gigantica and Moniezia species. Sera of cattle infested with Paramphistomum species were negative. No cross reactions were detected when the purified antigen was used against the previously mentioned sera. The sensitivity of double diffusion test for diagnosis of hydatidosis using purified antigen was 96.6%