Relevance of circulating antigen detection to follow-up experimental and human cystic hydatid infections

We analysed specific antibody (Ab) and circulating antigen (CAg) profiles a long experimental mouse infection using as control a group of mice immunize d with intact but dead parasites, Results from this experiment showed an ea rly major CAg peak followed by a larger Ab peak which partially overlaps wi th other minor CAg peaks. These results suggest that CAg may be a marker of early mouse infection. In order to study the relevance of these findings i n humans we similarly analysed by ELISA 148 sera provided by retrospective post-surgical follow-tip of 19 patients. Available records showed that 14 p atients developed new cysts one to ten years after surgery while no new dis ease was observed in the other-five. Some of the former patients showed CAg as early as two months after surgery while no CAg was observed in the othe r five patients at any time. In addition, a collection of 38 sera obtained before surgery were similarly tested and five of them showed only CAg, whil e 18 showed only Ab and 12 sera showed Ab&CAg. These results in humans are consistent with the findings in the mouse experimental model and suggest th at CAg may be an early marker of hydatid infection, thus being relevant for post-surgical follow-up.