In light of the recent OPTN policy requirement to test all deceased donors for Toxoplasma gondii (Policy 2.9, available here), some clinicians have asked for additional information to help them decide whether to accept organ offers from donors with a positive or pending Toxo screening result. Some have also asked how best to treat Toxo-negative recipients of organs from Toxo-positive donors.
While individual transplant programs must always apply their best medical judgment in considering organ offers, the OPTN/UNOS Disease Transmission Advisory Committee (DTAC) offers the following information to help clinicians assess the relative risk between a positive or pending test result and implications for the care of a potential recipient.
- Heart transplant recipients are at highest risk for donor transmission, as the organism has a propensity to live in muscle (including cardiac muscle). The organism may still be transmitted in transplants of other organ types, but at a much lower rate.
- The highest risk for donor-transmitted toxoplasmosis is in a mismatched situation; Toxo-negative recipients who receive the organ from a positive donor (Donor IgG +/ Recipient IgG-).
- Toxoplasma IgG is the only test required by OPTN policy. Toxoplasma IgM is difficult to interpret due to high false positive rate, and its use is discouraged. Since latent asymptomatic infection persists for life, the only way to determine if donors are infected is to test them for antibodies to Toxoplasma gondii.
- The risk of transmitting Toxoplasma can be greatly reduced by giving the recipient prophylactic antibiotics. This is strongly recommended in mismatched heart transplant recipients and should be considered for other organs.
- The best prophylactic antibiotic is Trimethoprim/sulfamethoxazole (TMP/SMX). For patients who cannot tolerate TMP/SMX, the optimal agents for prophylaxis are uncertain, but alternatives are available, including atovaquone and pyramethamine.
- While Toxo-negative recipients should be informed if there is a risk of donor-derived Toxoplasma, it is important to emphasize to them that taking prophylaxis can significantly reduce their risk of acquiring the disease.
For additional information, visit the “Toxoplasma Screening and Reporting of Test Results” course available on the Patient Safety section of UNOS Connect. Related information is also available in the articles cited below.
Wolfe C, Wilk A, Tlusty S, Sifri C, Morris M, Mehta A, Kaul D. Donor-Derived Toxoplasmosis in Solid Organ Transplant 2008 – 2015: Opportunities for Improvement. [abstract]. Am J Transplant. 2016; 16 (suppl 3).
Schwartz BS, Mawhorterb SD and the AST Infectious Diseases Community of Practice. Parasitic infections in solid organ transplantation. Amer J Transpl 2013; 13: 280–303
Fernandez-Sabe N, Cervera C, Farinas MC, et al. Risk factors, clinical features, and outcomes of toxoplasmosis in solid-organ transplant recipients: A matched case-control study. Clin Infect Dis 2012; 54: 355–361.
Campbell AL, Goldberg CL, Magid MS, Gondolesi G, Rumbo C, Herold BC. First case of toxoplasmosis following small bowel transplantation and systematic review of tissue-invasive toxoplasmosis following noncardiac solid organ transplantation. Transplantation
2006; 81: 408–417.
Israelski DM, Chmiel JS, Poggensee L, Phair JP, Remington JS. Prevalence of Toxoplasma infection in a cohort of homosexual men at risk of AIDS and toxoplasmic encephalitis. J Acquir Immune Defic Syndr 1993; 6: 414–418.
Martina MN, Cervera C, Esforzado N, et al. Toxoplasma gondii primary infection in renal transplant recipients. Two case reports and literature review. Transpl Int 2011; 24: e6–12.
Montoya JG. Laboratory diagnosis of Toxoplasma gondii infection and toxoplasmosis. J Infect Dis 2002; 185(Suppl 1): S73–82.