Toxoplasmosis in Transplant Recipients

Europe, 2010-2014

Florence Robert-Gangneux; Valeria Meroni; Damien Dupont; Françoise Botterel; José M. Aguado Garcia; Marie-Pierre Brenier-Pinchart; Isabelle Accoceberry; Hamdi Akan; Isabella Abbate; Katia Boggian; Fabrizio Bruschi; Jordi Carratalà; Miruna David; Lubos Drgona; Olgica Djurković-Djaković; Maria Carmen Farinas; Francesca Genco; Effrossyni Gkrania-Klotsas; Andreas H. Groll; Edward Guy; Cédric Hirzel; Nina Khanna; Özgür Kurt; Lia Monica Junie; Tiziana Lazzarotto; Oscar Len; Nicolas J. Mueller; Patricia Munoz; Zoi Dorothea Pana; Emmanuel Roilides; Tijana Stajner; Christian van Delden; Isabelle Villena; Hervé Pelloux; Oriol Manuel


Emerging Infectious Diseases. 2018;24(8):1497-1504. 

In This Article

Abstract and Introduction


Transplantation activity is increasing, leading to a growing number of patients at risk for toxoplasmosis. We reviewed toxoplasmosis prevention practices, prevalence, and outcomes for hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT; heart, kidney, or liver) patients in Europe. We collected electronic data on the transplant population and prevention guidelines/regulations and clinical data on toxoplasmosis cases diagnosed during 2010–2014. Serologic pretransplant screening of allo-hematopoietic stem cell donors was performed in 80% of countries, screening of organ donors in 100%. SOT recipients were systematically screened in 6 countries. Targeted anti-Toxoplasma chemoprophylaxis was heterogeneous. A total of 87 toxoplasmosis cases were recorded (58 allo-HSCTs, 29 SOTs). The 6-month survival rate was lower among Toxoplasma-seropositive recipients and among allo-hematopoietic stem cell and liver recipients. Chemoprophylaxis improved outcomes for SOT recipients. Toxoplasmosis remains associated with high mortality rates among transplant recipients. Guidelines are urgently needed to standardize prophylactic regimens and optimize patient management.


Toxoplasmosis is a zoonosis that infects humans and other warm-blooded animals worldwide; prevalence and clinical severity vary by geographic area.[1] After primary infection, the parasite persists lifelong within dormant tissue cysts. Transmission to humans mainly occurs by ingestion of food or water contaminated with oocysts from feces of infected felids or undercooked meat containing cysts.[2] Although largely asymptomatic in adults, toxoplasmosis is a life-threatening opportunistic infection in immunocompromised patients of all ages. Similar to Pneumocystis pneumonia, toxoplasmosis has become more frequently diagnosed for patients receiving immunosuppressive therapy than for patients with HIV infection.[3,4] The growing number of grafts makes transplant patients a population at increasing risk. In transplant recipients (solid organ transplant [SOT] or hematopoietic stem cell transplant [HSCT]), disease can result from reactivation of past latent infection or from primary infection acquired through contaminated food or through a transplanted organ containing latent cysts.[5] In contrast to incidence among HIV-infected patients, the incidence of toxoplasmosis among transplant recipients is poorly documented; published studies reporting patient series are scarce,[6–8] and the literature consists mostly of case reports.[2,9–12]

The risk for reactivation of chronic infection varies according to the immunosuppressive protocol and therefore according to the type of graft;[13] risk is highest for seropositive allo-HSCT recipients receiving a seronegative graft. Among SOT recipients, the risk of a seronegative recipient (R–) acquiring infection from a seropositive donor (D+) organ (D+/R–) depends on the organ type; risk is highest for heart transplant recipients. Prevention measures rely on pretransplant serologic screening of donor, recipient, or both and on chemoprophylaxis; however, guidelines and regulations differ largely among countries. Regarding chemoprophylaxis, a multicenter study in France revealed variable practices in terms of regimen and duration of treatment.[4] Some experts have proposed a tight clinical and molecular follow-up protocol for HSCT patients, aiming at early diagnosis of Toxoplasma reactivation to improve survival rates,[14–16] but the cost:benefit ratio of this strategy is still under debate. We reviewed prevention practices implemented in European countries and evaluated the burden of toxoplasmosis among HSCT and SOT recipients.