A slide micro-immunoenzymatic assay (micro-SIA) to detect
antibodies to non-particulate Toxoplasma gondii antigens is
described. This assay allows the diagnosis of toxoplasmosis
infection in about 1 hr. Twenty-four determinations can be
performed per slide. Five hundred ng of antigen and 5 or 10 ul
drop of each reactive are necessary per well. The clear
contrast of colours obtained for negative and positive sera
after the test is finished, allows direct discrimination of
the results. However, it is possible to quantify the results
of the reaction using a minireader. Sera dilution cutoff
value, determined as the most frequent titre for the general
population, is 1:100. The toxoplasma micro-SIA correlates well
with indirect immunofluorescence (IIF), its sensitivity is at
least three times as much as IIF. The test has an intra and
inter assay variation coefficient of 5.46% and of 6.24%
respectively. Sera obtained at random from argentinian people
were analyzed and a 56% of infection was found. The main
features of the Toxoplasma micro-SIA are its simplicity,
sensitivity, reproducibility, and the virtual absence of
background making it very suitable for screening tests.