Echinococcus granulosus: additional studies on selected sera from seronegative patients with hydatidosis.

Human hydatidosis-positive sera, which resulted negative in serological tests but positive on surgery, were examined with I.H.A. and E.L.I.S.A. techniques using a standardized antigen and a new antigen (the 0.8 M antigen) from sheep hydatid fluid. The present study demonstrated that the 0.8 M antigen was the most effective, and that sensitivity of any given antigen depends upon the method adopted.