Cystic echinococcosis (CE) is a major public health problem with a worldwide distribution in both humans and animals. Diagnosis of this disease by simple and rapid immunoassays is a priority. The objective of the present study was to standardize and evaluate the
latex agglutination test (LAT) as a simple test for the detection of circulating hydatid
antigen in serum. The subjects in this study included 141 patients in the following groups: surgically confirmed CE cases (18), ultrasound-proven cases (26), presumptive CE cases (47), controls with other
parasitic disease (25), and healthy controls (25). A
polystyrene latex (0.81 microm)
suspension was used as a carrier particle for hydatid
antibodies in the test. The
latex particles were sensitized with hyperimmune hydatid antiserum raised in rabbits. The hydatid antibody-sensitized
latex particles were used for the detection of hydatid
antigens in serum. The results of the study showed that the LAT could detect the circulating hydatid
antigen in 13 (72%) of 18 patients with surgically confirmed CE, 17 (65%) of 26 patients with ultrasound-proven CE, and 19 (40%) of 47 presumptive cases of CE. The test detected
antigen in 1 (4%) of 25 controls with other
parasitic disease, and no
antigen was detected in the serum of 25 healthy controls. The LAT showed a sensitivity of 72%, a specificity of 98%, a positive predictive value of 93%, and a negative predictive value of 91%. The present study is the first report of the LAT for the detection of hydatid
antigen in serum in the diagnosis of CE.