Standardization and evaluation of an enzyme immunoassay for diagnosis and seroepidemiology of human trichinosis

Abstract

An enzyme immunoassay (EIA) in solid phase'in which a whole soluble Trichinella spiralis antigen and a single serum dilution were used was standardized and its capacity for detecting total anti-trichinella antibodies for diagnostic and seroepidemiological purpose was evaluated. Dose response curves showed that a working dilution of 1:100 permitted an adequate differentiation between trichinosis patients with low circulating antibodies concentration and non infected individuals; the response was linear between OD values of 0.15 and 0.64. A group of 720 sera from trichinosis free general population showed an arithmetic mean of OD values of 0.07 and a standard deviation of 0.03. OD values were < (X) + 3S in 98,1% of those sera; between > X k+ 3S and < X k + 4S in 1,25% and between > X k + 4S and < X k + 5S in the remaining 0.14%. An OD value = X k + 5S was used as a diagnostic criterion to study sera from four human trichinosis outbreaks; 80 sera from trichinosis patients with different immunofluorescence assay (IFA) titers, and 20 sera from hydatid patients. The proposed EIA differentiates sera from infected and non infected populations both efficiently and reliably. It also showed a good correlation with the IFA results. All sera from hydatid patients showed OD values < X k + 4S.