A preliminary study of clinical staging in clonorchiasis.

Antibody responses to infection with metacercaria of Clonorchis sinensis were studied in triplet cats. Elevated IgM antibody first appeared seven days after infection, followed by elevation of IgA and IgG. The peak titers of IgM and IgA antibodies were found at 3 weeks and 11 weeks, respectively. IgG antibody was elevated at 3 weeks and reached a peak, then a plateau at 13 weeks. Duration of antibody detection after infection was 1 week to 5 weeks for IgM, and 2 weeks to 28 weeks for IgA. IgM and IgA antibody titers decreased to normal level spontaneously without significant effect by the treatment. Using the animal model, the three clinical stages were classified according to the antibody patterns: i.e. acute stage, IgM(+) IgA(+) IgG(+); subacute stage, IgM(-) IgA(+) IgG(+); Chronic stage, IgM(-) IgA(-) IgG(+). Of 77 human patients with clonorchiasis, there were 3 (3.9%) patients who had subacute infection and 74 (96.1%) patients were in chronic stage.