Estandarización de ELISA IgM e IgA para el inmunodiagnóstico de la triquinosis humana / Standarization of ELISA IgM and IgA for inmunodiagnosis of human trichinosis

RESUMO

An ELISA test for trichinosis using as antigen a larvae soluble fraction from trichinella spiralis was carried out for the detection of IgM and IgA specific antibodies in 45 serum samples from patients confirmed or suspected to have trichinosis by strong clinical and epidemiological evidences. All the patients had positive serology detected by precipitin test, bentonite floculation test, indirect hemagglutination tes and ELISA IgG test. The cut off value was determined using two criteria. Criterion A was determined in each plate, using three positive controls and two negative ones; the average of the negative controls and the weakest positive control, muliplied by a 1,2 factor was, considered the cut off value. Criterion B was determinated using the average plus three standard deviations from 64 apparently halthy persons serum samples. In both cases, three serum dilutions (110, 1100 and 1500) were used. The sensitivity of ELISA IgM was 100,0, 93,3 and 82,2 percent using serum dilution of 110, 1100 and 1500 respectively (criterion A) and 100,0, 97,8 and 95,6 percent for the same dilutions (criterion B), whereas the values for ELISA IgA were 100,0 91,1 and 86,7 percent (criterion A) and 100,0 100,0 and 91,1 percent (criterion B). In order to find out the specificity of ELISA IgM and ELISA IgA, additional 118 serum samples from individuals with other parasitoses, such as cysticercoss (18) hydatidosis (39), fascioliasis (12), toxocariasis (30), Chagaïs disease (12) and individuals with non specif eosinophilia (7), were also tested. ELISA IgM presentes a specificity of 92,3, 93,4 and 97,3 percent (criterion A) and 96,2, 97,8 and 97,8 percent (criterion B) whereas the results for ELISA IgA were 97,8, 98,9 and 99,4 percent (criterion A) and 98,4 percent for the 110 and 1100 dilutions and 100,0 percent for the 1500 dilution (criterion B). The positive predictive values of ELISA IgM were 76,3, 77,8 and 88,1 percent (criterion A) and 86,5, 91,7 and 91,5 percent (criterion B) whereas the negative ones were 100,0, 98,3 and 95,7 percent (criterion A) and 100,0, 99,4 and 98,9 percent (criterion B). The positive predictive values of ELISA IgA were 91,8, 95,3 and 97,5 percent (criterion A) and 93,8, 93,8 and 100,0 percent (criterion B) whereas the negatives ones were 100,0, 97,9 and 96,8 percent (criterion A) and 100,0, 100,0 and 97,8 percent (criterion B). The use of ELISA IgM and ELISA IgA in the inmunodiagnosis of trichinosis is discussed