The use of donor and recipient screening for Toxoplasma in the era of universal trimethoprim sulfamethoxazole prophylaxis

Background. Toxoplasmosis is a serious complication of solid organ transplantation. The highest risk of infection and disease occurs in heart recipients with primary infection transmitted by a seropositive donor to a seronegative recipient (donor-recipient mismatch). Toxoplasmosis has been reported to occur in noncardiac transplant recipients; however, no large studies examining the frequency of such events or the need for serologic screening exist. Methods. A retrospective cohort study of 1,006 solid organ transplant recipients transplanted in our center between 1984 and 1997 was performed to examine the incidence of Toxoplasma seroconversion, reactivation, and clinical toxoplasmosis and to evaluate the impact of trimethoprim sulfamethoxazole (TMP/SMX) prophylaxis on these outcomes. Results. Pretransplant Toxoplasma seroprevalence was 13.4% in donors and 17.8% in recipients. The incidence of Toxoplasma donor-recipient mismatch was 9.5% during the 14-year study period, and only 39.1% of mismatched recipients received TMP/SMX prophylaxis. Only four patients seroconverted, of whom two had received prophylaxis. There were no cases of clinical disease; either primary or reactivation. Conclusions. We therefore conclude that in transplant centers with low Toxoplasma seroprevalence, routine screening for Toxoplasma in solid organ donors and recipients is not necessary, particularly in the era of routine TMP/SMX prophylaxis.