Detection of specific Echinococcus granulosus antigen 5 in liver cyst bioptate from human patients

Eighty one liver cyst fluid samples obtained by fine needle aspiration biopsy (FNAB) in human patients were examined for specific E. granulosus antigen 5 (Ag5). The patients were suspected cases of hepatic cystic echinococcosis (CE) but protoscolices and hooks had not been found in the cyst bioptates. Presence of Ag5 was tested for using enzyme linked immuno-sorbent assay (ELISA) technique with monoclonal antibody against Ag5. Sensitivity of the test was approximately 1 ng of antigen/1 ml of examined fluid. Positive results were obtained in the control group of six patients having protoscolices and/or hooks in biopsy samples from liver cysts. Positive Ag5 results were also obtained in the samples from 89 fertile cysts and 28 sterile cysts originated from 15 naturally infected pigs as an experimental control group. Ag5 was present in nine cases (11.1%) out of 81 liver cyst fluid samples from suspected CE patients. In 25 human patients the sensitivity of the microscopic examination for protoscolices and/or hooks in FNAB material was 64% (16/25). In pig hydatid cysts the sensitivity of the microscopic examination for protoscolices and/or hooks in FNAB material was 86.5% and of the detection of Ag5-100%. In conclusion, examination of hepatic cyst biopsy samples for specific Ag5 resulted in increased detection of liver echinococcosis in human patients.