Antigen host response differences between the animal-type strain and human-clinical Pythium insidiosum isolates used for serological diagnosis in Thailand.

The detection of Pythium insidiosum-specific-immunoglobulin-G antibody (Pi-Ab) with enzyme-linked immunosorbent assay (ELISA) test depends on the source of antigen. In this study, the Pi-Ab levels in 140 serum samples from patients with pythiosis were evaluated by ELISA using antigens from 10 P. insidiosum clinical isolates in comparison with antigen from the equine-standard-type strain. The ELISA values (EVs), calculated from antibody levels from serum of patients with pythiosis or other infections versus healthy controls, were significantly higher in the test with clinical-isolates antigen than the standard-equine-type strain (6.0 ± 2.6 vs 4.0 ± 1.7, respectively; P < .0001). ELISA with antigen from human source might be more proper diagnosis test.