Parasite-specific antibody response in Trichinella sp. 3 human infection: a one year follow-up.

Sera from patients with confirmed or suspected trichinellosis were examined for 1 year to detect the presence of parasite-specific antibodies (IgG, IgM, and IgE) using the enzyme-linked immunosorbent assay (ELISA). The indirect ELISA was used to detect specific IgG (ELISA-IgG) and specific IgM (ELISA-IgM); an amplified technique proved the most reliable for detection of specific IgE (a-ELISA-IgE). The immunofluorescence (IF) test was used to detect specific IgG (IF-IgG). The patients were from an outbreak of trichinellosis in Salsomaggiore (northern Italy) in 1986. The parasite was isolated and isoenzymatically typed as Trichinella sp. 3. The specificity of our tests was greater than 95%. During the 1st period of infection, all tests used gave practically the same positivity rate (78.2-86.9%). One year after infection, ELISA-IgG gave the highest positivity rate (55%). With the other tests, the positivity rate was 20-38.5%. At the 2nd month of infection, the IF-IgG test was the most discriminating in patients with confirmed and suspected trichinellosis, but ELISA-IgG proved the most reliable test for detecting specific immunoglobulins in late human trichinellosis infection.