The estimation of different ELISA procedures for serodiagnosis of human trichinellosis

The most important confirmative diagnostic test for trichinellosis is the presence of the muscle larvae in a tissue biopsy but this direct method has a low sensitivity of light and moderate infections. The aim of presented study was to compare the usefulness of the results obtained by three ELISA procedures for Trichinella spp. diagnosis in human outbreaks.

All sera (cases and controls) were tested for anti-Trichinella antibodies (immunoglobulin G) using commercially available Novatec KIT and two other ELISA procedures based on excretory-secretory (ES) antigens on Trichinella spiralis muscle larvae. The main differences in ELISA procedures were: the protein concentration in antigen, dilution of human serum samples, conjugate and the time of conjugate incubation. Additional differences were noticed in ES antigen preparation procedures as well as in T. spiralis isolates used in these procedures. Serum samples were obtained from 22 symptomatical patients from Poznafi region (West Poland), geographic area where human outbreak had occurred. Control serum samples were obtained from 20 patients from an open population from a non endemic trichinellosis area.

The results were analyzed in terms of both: statistical and epidemiological point of view. Linear regression analysis and correlations coefficient r between OD values of total 22 patients obtained in three ELISA procedures were positive and high statistically significant. Three ELISA procedures revealed different cut-off values and positivity rates for outbreak. However, the majority of positive samples were found as positive in three procedures, but some of them were positive in two or one procedure only. These individual variability in sera reactivity observed in three ELISA procedures could be very important from epidemiological point of view.