Flocculation tests in hydatid disease.

A new serological technique of diagnosing human hydatid disease, employing polystyrene latex particles coated with hydatid cyst fluid, and a modified technique using bentonite particles are described. Comparison of the latex test with the complement-fixation test performed on 102 sera has shown a total agreement of 98% and an agreement of 93.1% in the positive specimens. The bentonite test and the complement-fixation test performed on 126 sera have shown a total agreement of 97.6% and an agreement of 90.1% in the positive specimens. Both flocculation tests are simpler to perform than the complement-fixation test. They are specific, and sensitivity closely parallels that of the complement-fixation test, with 6.9% and 6.1% of the positive specimens showing higher sensitivity in the latex and bentonite tests respectively. The bentonite test was less sensitive than the complement-fixation test in one case. None of the latex tests showed less sensitivity. The antibody active in the latex test has been demonstrated in a gamma globulin fraction of the antiserum. Some differences in the behaviour of flocculating and complement-fixing properties of sera are discussed.