Evaluation of a Latex Agglutination Test for Toxoplasmosis

Abstract

Four hundred ninety-seven human sera were examined for anti-toxoplasma antibody by latex agglutination (LA) and hemagglutination (HA). Sera from patients with heterophile titers were also tested by LA. Most discrepancies between HA and LA occurred with sera that had LA titers of 1:8 and 1:16. Heterophile antibodies may be involved in some of these. Antibodies were not detected by LA in 214 of 254 sera (84.3%) which also were negative in the HA test. LA titers (1:8 or greater) were obtained in 224 of 243 sera (92.2%) which were positive in the HA test. The storage of sensitized latex at refrigerator temperatures did not adversely affect its reactivity. Agglutination of latex particles has been used for serological diagnosis of a variety of diseases (Singer and Plotz, 1956; Carlisle and Saslaw, 1958; Christian et al., 1958; Muraschi, 1958; Fischman, 1960; Fleck and Evenchik, 1962; and Muraschi et al., 1962). Siim and Lind (1960) demonstrated antibodies to toxoplasma with acrylic particles 0.5 ,u in diameter sensitized with an extract of toxoplasma and obtained promising results, but mentioned that further studies were needed to confirm their results. Later Bozdech and Jira (1961) reported a latex agglutination (LA) test for toxoplasmosis done in test tubes and involving centrifugation before reading. Their test, evaluated with the complement-fixation (C-F) test, did not appear sensitive enough. They reported that 157 out of 575 (27.3%) sera which were positive in the CF test were negative in the latex agglutination test. Roussel (1964) studied the use of bentonite and kaolin particles for the serodiagnosis of toxoplasmosis and reported that sensitized kaolin particles used in an agglutination test for toxoplasmosis were specific and reproducible. In view of the results of Roussel and also Siim and Lind it seemed feasible to explore the possibility of using latex and adapting the procedure of Bozdech and Jira to a modified slide agglutination test such as described by Szyfres and Kagan (1963) which would eliminate the use of tubes and large volumes of reaction