Evaluation of three serological tests for the diagnosis of hydatid disease.

A number of techniques is used for the serological diagnosis of hydatid disease; however previous investigations suggest variable degrees or reliability for each test. This study reports an evaluation of the sensitivity and specificity of three commonly used serological tests for hydatid disease; complement fixation (CF), haemagglutination (HA) and the fluorescent antibody (FA) techniques. The results of these serological tests are compared in a series of specimens from 116 hospital patients, 21 of whom were confirmed surgically as having hydatid disease. A similar high degree of sensitivity was found for each of the three serological tests examined. The CF and HA tests gave negative results in two patients with confirmed hydatid disease, and the result of the FA test was negative in only one patient. The HA test was the most specific with no false positive reactions, but only two false positive reactions occurred with the FA test. The CF test was the least specific as the reaction was positive in nine patients without hydatid disease. When the results of both FA and HA tests were considered together, all 21 cases of hydatid disease were detected and false positive reactions occurred in only two patients.