Diagnostic value of tests for Toxoplasma gondii-specific antibodies in patients undergoing bone marrow transplantation.

The value of Toxoplasma gondii-specific antibodies for the diagnosis of reactivated toxoplasmosis in immunocompromised patients is controversely discussed. The present study was performed to investigate the value of testing for antibodies against Toxoplasma gondii in patients undergoing bone marrow transplantation (BMT). Of 75 patients enrolled in the study, 53 (70.7%) were seropositive before BMT. Of these, 7 (13.2%) developed parasitemia after BMT as detected by polymerase chain reaction (PCR); three of these developed clinical symptoms compatible with reactivated toxoplasmosis that resulted in fatal toxoplasmosis in two cases. We did not detect specific antibody patterns or changes in specific antibody titers that could have predicted the development of parasitemia. Notably, 18 (81.8%) of 22 patients without specific IgG before BMT showed anti-T. gondii IgG after BMT, but none of them developed parasitemia. The results of the present study indicate that blood from both the donor and the recipient should be tested before BMT. Seronegative patients should be tested regularly after BMT to detect primary infections. Routine serological monitoring of patients seropositive before BMT does not contribute to the diagnosis of reactivated disease following BMT. In contrast, blood of seropositive patients should be screened by polymerase chain reaction (PCR) for Toxoplasma-specific DNA for the diagnosis of reactivation of infection with T. gondii.