Persistence of IgG, IgM, and IgE antibodies in human trichinosis.

An enzyme-linked immunosorbent assay (ELISA) was used to detect serum IgG, IgM, and IgE antibodies against Trichinella spirals s. str. following an outbreak of human trichinosis in 1989 in Chiang Rai Province, Thailand, for two years and seven months in order to observe diagnostic sensitivity of ELISA as well as the persistence of antibodies. It was found that the sensitivity of IgG-ELISA, as determined from biopsy-positive cases, reached 100% on the 50th day of infection. For IgM-ELISA, peak sensitivity was 93.33% at the 57th and IgE-ELISA 100% at the 85th day of infection. Two years and seven months after infection, the diagnostic sensitivity of IgG-ELISA was 88.24%, and that of IgE-ELISA was 47.06%, while the sensitivity of IgM-ELISA was only 11.76%. It was suggested from the data that IgM-ELISA is a helpful indicator of infection within three years. Other two groups of trichinosis cases, i.e., high-titer and seroconversion cases, were also studied. Antibody response curves were constructed from mean ELISA values from each group. It was revealed that all curves were similar in shape, independent of the group studied. The only exception was IgG-antibody response in the high-titer group, which showed the highest antibody level at the first collection of blood samples, i.e., 23 days after infection.