Toxoplasma prophylaxis in haematopoietic cell transplant recipients: a review of the literature and recommendations

Guidelines for the management of Toxoplasma gondii infection and disease in patients with haematological malignancies and after haematopoietic stem-cell transplantation: guidelines from the 9th European Conference on Infections in Leukaemia, 2022

Patients with haematological malignancies might develop life-threatening toxoplasmosis, especially after allogeneic haematopoietic stem-cell transplantation (HSCT). Reactivation of latent cysts is the primary mechanism of toxoplasmosis following HSCT; hence, patients at high risk are those who were seropositive before transplantation. The lack of trimethoprim-sulfamethoxazole prophylaxis and various immune status parameters of the patient are other associated risk factors. The mortality of toxoplasma disease-eg, with organ involvement-can be particularly high in this setting. We have developed guidelines for managing toxoplasmosis in haematology patients, through a literature review and consultation with experts. In allogeneic HSCT recipients seropositive for Toxoplasma gondii before transplant, because T gondii infection mostly precedes toxoplasma disease, we propose weekly blood screening by use of quantitative PCR (qPCR) to identify infection early as a pre-emptive strategy. As trimethoprim-sulfamethoxazole prophylaxis might fail, prophylaxis and qPCR screening should be combined. However, PCR in blood can be negative even in toxoplasma disease. The duration of prophylaxis should be a least 6 months and extended during treatment-induced immunosuppression or severe CD4 lymphopenia. If a positive qPCR test occurs, treatment with trimethoprim-sulfamethoxazole, pyrimethamine-sulfadiazine, or pyrimethamine-clindamycin should be started, and a new sample taken. If the second qPCR test is negative, clinical judgement is recommended to either continue or stop therapy and restart prophylaxis. Therapy must be continued until a minimum of two negative PCRs for infection, or for at least 6 weeks for disease. The pre-emptive approach is not indicated in seronegative HSCT recipients, after autologous transplantation, or in non-transplant haematology patients, but PCR should be performed with a high level of clinical suspicion.

Omega-3 and omega-6 polyunsaturated fatty acids and their potential therapeutic role in protozoan infections

Protozoa exert a serious global threat of growing concern to human, and animal, and there is a need for the advancement of novel therapeutic strategies to effectively treat or mitigate the impact of associated diseases. Omega polyunsaturated fatty acids (ω-PUFAs), including Omega-3 (ω-3) and omega-6 (ω-6), are constituents derived from various natural sources, have gained significant attention for their therapeutic role in parasitic infections and a variety of essential structural and regulatory functions in animals and humans. Both ω-3 and ω-6 decrease the growth and survival rate of parasites through metabolized anti-inflammatory mediators, such as lipoxins, resolvins, and protectins, and have both in vivo and in vitro protective effects against various protozoan infections. The ω-PUFAs have been shown to modulate the host immune response by a commonly known mechanism such as (inhibition of arachidonic acid (AA) metabolic process, production of anti-inflammatory mediators, modification of intracellular lipids, and activation of the nuclear receptor), and promotion of a shift towards a more effective immune defense against parasitic invaders by regulation the inflammation like prostaglandins, leukotrienes, thromboxane, are involved in controlling the inflammatory reaction. The immune modulation may involve reducing inflammation, enhancing phagocytosis, and suppressing parasitic virulence factors. The unique properties of ω-PUFAs could prevent protozoan infections, representing an important area of study. This review explores the clinical impact of ω-PUFAs against some protozoan infections, elucidating possible mechanisms of action and supportive therapy for preventing various parasitic infections in humans and animals, such as toxoplasmosis, malaria, coccidiosis, and chagas disease. ω-PUFAs show promise as a therapeutic approach for parasitic infections due to their direct anti-parasitic effects and their ability to modulate the host immune response. Additionally, we discuss current treatment options and suggest perspectives for future studies. This could potentially provide an alternative or supplementary treatment option for these complex global health problems.

Pre-Transplantation Strategies for Infectious Disease Mitigation and Prevention

Pediatric Infectious Disease (ID) clinicians play a critical role in helping prevent and mitigate infectious risks in children peri- and post-transplantation. Prevention starts during the pre-transplant evaluation and persists throughout the solid organ transplant and hematopoietic cell transplant continuum. The pre-transplant evaluation is an opportunity to screen for latent infections, plan preventative strategies, optimize immunizations, and discuss risk mitigation practices. An ideal pre-transplant evaluation establishes a relationship with the family that further promotes post-transplant infectious risk reduction. This manuscript builds on shared pediatric ID prevention strategies, introduces updated ID testing recommendations for transplant donors/candidates, highlights emerging data, and identifies ongoing knowledge gaps that are potential areas of research.

Parasitic infections in hematopoietic stem cell transplant recipients

INTRODUCTION

Hematopoietic stem cell transplantation (HSCT) is a vital treatment for various hematological disorders. However, HSCT recipients face increased risks of infectious complications due to immunosuppression. Parasitic infections are a significant concern in this vulnerable population and can lead to substantial morbidity and mortality. This review examines parasitic infections in HSCT recipients, focusing on major infections affecting different organ systems, including intestinal parasites (Giardia spp., Entamoeba histolytica, and Cryptosporidium spp.), hematologic parasites (Plasmodium spp. and Babesia spp.), and tissue/visceral parasites (Toxoplasma gondii, Leishmania spp., and Trypanosoma cruzi).

METHODS

A systematic search of relevant literature was conducted and included studies up to August 2023. Databases included PubMed, Google Scholar, were queried using specific keywords related to parasitic infections in HSCT patients. The epidemiology, risk factors, clinical presentation, diagnostic methods, and treatment approaches for each infection were evaluated.

RESULTS AND CONCLUSION

Knowing the epidemiology, risk factors, and clinical presentations are crucial for timely intervention and successful management. By emphasizing early detection, effective therapies, and the unique challenges posed by each of these infections, this review highlights the importance of tailored strategies for HSCT recipients. Future research can further refine management protocols to enhance care and outcomes for these patients.

Hassan A, Mohamed K, Alfaifi MS, Elshazly H, Alamri ZZ, Wakid MH, Gattan HS, Altwaim SA, Al-Megrin WAI, Younis S. Zinc oxide nanoparticles produced by Zingiber officinale ameliorates acute toxoplasmosis-induced pathological and biochemical alterations and reduced parasite burden in mice model

BACKGROUND

Although, approximately 30% of the world's population is estimated to be infected with Toxoplasma gondii (T. gondii) with serious manifestations in immunocompromised patients and pregnant females, the available treatment options for toxoplasmosis are limited with serious side effects. Therefore, it is of great importance to identify novel potent, well tolerated candidates for treatment of toxoplasmosis. The present study aimed to evaluate the effect of Zinc oxide nanoparticles (ZnO NPs) synthesized using Zingiber officinale against acute toxoplasmosis in experimentally infected mice.

METHODS

The ethanolic extract of ginger was used to prepare ZnO NPs. The produced ZnO NPs were characterized in terms of structure and morphology using Fourier Transformed Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), UV- spectroscopy and scanning electron microscopy (SEM). The prepared formula was used in treatment of T. gondii RH virulent strain. Forty animals were divided into four groups, with ten mice per group. The first group was the uninfected, control group. The second group was infected but untreated. The third and the fourth groups received ZnO NPs and Spiramycin orally in a dose of 10 mg/kg and 200 mg/kg/day respectively. The effect of the used formulas on the animals survival rate, parasite burden, liver enzymes -including Alanine transaminase (ALT) and aspartate transaminase (AST)-, nitric oxide (NO) and Catalase antioxidant enzyme (CAT) activity was measured. Moreover, the effect of treatment on histopathological alterations associated with toxoplasmosis was examined.

RESULTS

Mice treated with ZnO NPs showed the longest survival time with significant reduction in the parasite load in the livers and peritoneal fluids of the same group. Moreover, ZnO NPs treatment was associated with a significant reduction in the level of liver enzymes (ALT, AST) and NO and a significant increase in the antioxidant activity of CAT enzyme. SEM examination of tachyzoites from the peritoneal fluid showed marked distortion of T. gondii tachyzoites isolated from mice treated with ZnO NPs in comparison to untreated group. T. gondii induced histopathological alterations in the liver and brain were reversed by ZnO NPs treatment with restoration of normal tissue morphology.

CONCLUSION

The produced formula showed a good therapeutic potential in treatment of murine toxoplasmosis as demonstrated by prolonged survival rate, reduced parasite burden, improved T. gondii associated liver injury and histopathological alterations. Thus, we assume that the protective effect observed in the current research is attributed to the antioxidant capability of NPs. Based on the results obtained from the current work, we suggest greenly produced ZnO NPs as a chemotherapeutic agent with good therapeutic potential and high levels of safety in the treatment of toxoplasmosis.

The role of Curcuma longa essential oil in controlling acute toxoplasmosis by improving the immune system and reducing inflammation and oxidative stress

Background

Chemotherapy with synthetic drugs is the principal approach for toxoplasmosis treatment; however, recent studies reported the limitations and adverse side effects of these chemical drugs.

Objective

This study aimed to examine the in vitro and in vivo effects of Curcuma longa essential oil (CLE) against the Toxoplasma gondii RH strain.

Methods

The in vitro effect of different concentrations of CLE on T. gondii tachyzoites was assessed by cell viability assay. Flow cytometry and apoptosis analysis were performed, and nitric oxide production by CLE was also evaluated in tachyzoites. BALB/c mice were orally treated with various doses (1.25, 2.5, and 5 mg·kg^-1·day^-1) of CLE for 2 weeks. After the induction of acute toxoplasmosis in the mice, their survival rate and the mean number of peritoneal parasites were checked. The hepatic level of antioxidant enzymes and oxidative stress markers was evaluated by commercial kits. The mRNA expression level of proinflammatory cytokines such as interleukin 1-beta (IL-1β) and interferon-gamma (IFN-γ) was evaluated by quantitative real-time PCR.

Results

CLE, especially at 50 µg/ml, showed potent inhibitory effects on T. gondii tachyzoites. It increased the survival rate (ninth day) and reduced the mean number of peritoneal tachyzoites in the infected mice. CLE dependently increased (p < 0.01) the number of necrotic and apoptotic cells as well as NO production. CLE significantly (p < 0.05) reduced the hepatic level of oxidative stress markers but increased (p < 0.001) the antioxidant enzymes and proinflammatory cytokines in the infected mice, with no important toxicity for vital organs.

Conclusion

The findings of this survey revealed the significant in vitro inhibitory effects of CLE on T. gondii tachyzoites. The results also exhibited promising in vivo effects of CLE. CLE improved the survival rate of infected mice and reduced the parasite number in them. Although the mechanisms of action of CLE are not clear, our study demonstrated its beneficial effects on acute toxoplasmosis by strengthening the immune system and reducing inflammation and oxidative stress. Still, more studies are required to confirm these results.

Incidence of Pneumocystis pneumonia in Immunocompromised Patients without Human Immunodeficiency Virus with Intravenous Pentamidine Prophylaxis: A Systematic Review and Meta-Analysis

Background: Trimethoprim-sulfamethoxazole (TMP-SMX) is a first-line Pneumocystis pneumonia pneumonia) (PCP) prophylaxis agent, but monthly intravenous pentamidine (IVP) is used in human immunodeficiency virus (HIV)-uninfected immunocompromised hosts because IVP is not associated with cytopenia and delayed engraftment. Method: We performed a systematic review and meta-analysis to estimate breakthrough PCP incidence and adverse reactions in HIV-uninfected immunocompromised patients receiving IVP. MEDLINE, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov were searched from their inception until 15 December 2022. Results: The pooled incidence of breakthrough PCP with IVP was 0.7% (95% CI, 0.3–1.4%, 16 studies, 3025 patients) and was similar when used as first-line prophylaxis (0.5%; 95% CI, 0.2–1.4%, 7 studies, 752 patients). The pooled incidence of adverse reactions was 11.3% (95% CI, 6.7–18.6%, 14 studies, 2068 patients). The pooled adverse event-related discontinuation was 3.7% (95% CI, 1.8–7.3%, 11 studies, 1802 patients), but was lower in patients receiving IVP monthly (2.0%; 95% CI 0.7–5.7%, 7 studies, 1182 patients). Conclusion: Monthly IVP is an appropriate second-line agent for PCP prophylaxis in certain non-HIV immunocompromised hosts, especially in patients with hematologic malignancies and hematopoietic stem cell transplant recipients. Using IVP for PCP prophylaxis as an alternative to oral TMP-SMX while patients are unable to tolerate enteral medication administration is feasible.

A 10-year retrospective analysis of Toxoplasma gondii qPCR screening in allogeneic hematopoietic stem cell transplantation recipients

Weekly blood Toxoplasma gondii DNA screening using real-time quantitative polymerase chain reaction (qPCR) has been implemented in all allogeneic hematopoietic stem cell transplantation (alloHSCT) recipients at our hospital. We retrospectively analyzed the consequences of a positive blood qPCR in the management of Toxoplasma infection (TI) and disease (TD).From 2011 to 2020, 52 (4.13%) of 1 257 alloHSCT recipients had at least one positive qPCR, 45 (3.5%) with TI and seven (0.56%) with TD (central nervous system involvement). Forty-four patients were qPCR-positive before day 100, 30 without and 14 with anti-Toxoplasma prophylaxis. Twenty-five of them (56.8%) started or continued prophylactic dosage treatment: all became qPCR-negative, including 20 (80%) receiving only prophylactic dosage treatment. Twenty-four of them (54.5%) received non-prophylactic dosage treatment: qPCR became negative in 22/24 (91.7%), while TI contributed to death in two cases. Six of the eight patients diagnosed after D100 had breakthrough TI or TD. No death was attributable to TI or TD. qPCR kinetics available for 24 patients increased until anti-Toxoplasma treatment began, then decreased with all treatment regimens.Clinical follow-up and qPCR monitoring with quantification of the parasitic load appears a reasonable strategy to avoid TD and to use minimal effective dosage of anti-Toxoplasma treatments.

Cerebral Toxoplasmosis As the Initial Presentation of HIV: A Case Series

The HIV epidemic afflicts millions across the globe, and Sub-Saharan countries bear a disproportionately high burden. Cerebral toxoplasmosis is commonly seen as the disease progresses but is rarely ever reported as the initial manifestation of HIV. The clinical presentation, co-existing risk factors, and outcomes remain underreported. The objective of this article is to report cerebral toxoplasmosis as the initial manifestation of HIV. This is a consecutive series of three patients that presented to a community hospital in Pennsylvania, United States, with a variety of neuropsychiatric symptoms and were found to have cerebral toxoplasmosis. The findings are compared with existing literature on cerebral toxoplasmosis as the initial manifestation of HIV. Cerebral toxoplasmosis as the initial manifestation of HIV is a rarely reported phenomenon. Hyponatremia may be linked with this disease-complex, although further studies are warranted to establish a causal relationship. Co-infection with hepatitis viruses is also a common finding in these patients.

Acute exacerbation of pulmonary toxoplasmosis during corticosteroid therapy for immune thrombocytopenia: A case report and literature review

RATIONALE

Pulmonary toxoplasmosis (PT) is an infectious disease that can be fatal if reactivation occurs in the recipients of hematopoietic stem cell transplantation (HSCT) who were previously infected with Toxoplasma gondii. However, whether the toxoplasmosis reactivation is an actual risk factor for patients receiving immunosuppressive therapies without HSCT remains unclear. Therefore, reactivated PT is not typically considered as a differential diagnosis for pneumonia other than in patients with HSCT or human immunodeficiency virus (HIV).

PATIENT CONCERNS

A 77-year-old man presented with fever and nonproductive cough for several days. He was hospitalized due to atypical pneumonia that worsened immediately despite antibiotic therapy. Before 4 months, he was diagnosed with immune thrombocytopenia (ITP) and received corticosteroid therapy. Trimethoprim-sulfamethoxazole (ST) was administered to prevent pneumocystis pneumonia resulting from corticosteroid therapy.

DIAGNOSIS

The serological and culture test results were negative for all pathogens except T. gondii immunoglobulin G antibody. Polymerase chain reaction, which can detect T. gondii from frozen bronchoalveolar lavage fluid, showed positive results. Therefore, he was diagnosed with PT.

INTERVENTION

ST, clindamycin, and azithromycin were administered. Pyrimethamine and sulfadiazine could not be administered because his general condition significantly worsened at the time of polymerase chain reaction (PCR) examination.

OUTCOMES

The patient died of acute respiratory distress syndrome despite anti-T. gondii treatment. An autopsy revealed a severe organizing pneumonia and a small area of bronchopneumonia.

LESSONS

PT should be considered as a differential diagnosis in patients with pneumonia, particularly in seropositive patients who receive immunosuppressive therapies even for other than HSCT or HIV.

Toxoplasmosis after allogeneic haematopoietic cell transplantation: experience using a PCR-guided pre-emptive approach

OBJECTIVES

Prophylaxis with trimethoprim-sulphamethoxazole (TMP-SMZ) is recommended in Toxoplasma-seropositive allogeneic haematopoietic cell transplant (HCT) recipients to prevent reactivation, but it is associated with numerous side effects. We report our experience of a pre-emptive approach guided by a polymerase chain reaction (PCR) in patients not receiving prophylaxis.

METHODS

In this retrospective, single-centre experience, seropositive recipients and seronegative recipients receiving a graft from a seropositive donor were screened by PCR for the presence of Toxoplasma gondii DNA in peripheral blood until at least 6 months after transplantation. Confirmed PCR positivity triggered a pre-emptive anti-Toxoplasma therapy. Cases of Toxoplasma reactivation (using the European Society for Blood and Marrow Transplantation definitions) were compared with four controls (without reactivation), matched in time and recipient serostatus, to identify risk factors for reactivation by multivariate analysis.

RESULTS

From November 2001 to August 2020, 1455 consecutive adult patients (59 cases and 1396 controls) were screened. The overall 1-year cumulative incidence of toxoplasmosis was 4.1% and the 1-year cumulative incidence in the seropositive recipients was 8.5%. Reactivation was associated with second transplant (OR 2.51, 95%CI 1.28-4.94, p 0.011), myeloablative conditioning (OR 2.24, 95%CI 1.17-4.41, p 0.011), total body irradiation (OR 2.29, 95%CI 1.17-4.44, p 0.010), acute graft-versus-host disease (GvHD) (OR 2.27, 95%CI 1.26-4.08, p 0.008) and use of high-dose corticosteroids (OR 2.08, 95%CI 1.14-3.78, p 0.018). In multivariate analysis only acute GvHD remained significant (adjusted OR 2.54, 95%CI 1.16-5.71, p 0.021).

CONCLUSIONS

A PCR-based pre-emptive approach might serve as an acceptable alternative for patients unable to start with or to continue TMP-SMZ prophylaxis. Acute GvHD was identified as the single independent predictor for reactivation.

Clinical characteristics and incidence of toxoplasmosis after autologous hematopoietic stem cell transplantation: A retrospective study and literature review

BACKGROUND

Toxoplasmosis is a rare but life-threatening infection occurring in immunocompromised hosts, including allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. However, thus far, the clinical features and incidence of toxoplasmosis in autologous HSCT (auto-HSCT) recipients remain unknown. This retrospective survey aimed to analyze 152 patients who received auto-HSCT between 1998 and 2017.

METHODS

Serological tests for Toxoplasma gondii-specific IgG were performed on 109 (71.7%) recipients, and 12 pre-HSCT recipients (11%) were Toxoplasma seropositive. Among the 12 recipients, three who did not receive trimethoprim-sulfamethoxazole (TMP/SMX) prophylaxis developed cerebral, pulmonary or disseminated toxoplasmosis due to reactivation after auto-HSCT and died despite treatment.

RESULTS

The incidences of toxoplasmosis were 2% and 25% among 152 auto-HSCT recipients (five recipients received auto-HSCT two times) and 12 pre-HSCT Toxoplasma seropositive recipients, respectively. Further, we conducted a literature review and identified 21 cases of toxoplasmosis following auto-HSCT. In these previous cases, the mortality rate was high, especially for pulmonary and disseminated toxoplasmosis. Our findings suggest that, similar to toxoplasmosis after allo-HSCT, toxoplasmosis after auto-HSCT is a fatal complication.

CONCLUSIONS

Serial screening of T. gondii-specific IgG before HSCT could contribute to the detection of Toxoplasma reactivation and allow for prompt diagnosis and treatment. The present study is the first to reveal the incidence of toxoplasmosis after auto-HSCT among seropositive patients in Japan.

Risk of reactivated toxoplasmosis in haematopoietic stem cell transplant recipients: a prospective cohort study in a setting withholding prophylaxis

OBJECTIVES

Reactivation of latent toxoplasmosis may be life-threatening in haematopoietic stem cell transplant (HSCT) recipients. We conducted an 8-year-long prospective study on the diagnosis and monitoring of reactivated toxoplasmosis in paediatric HSCT recipients. The primary objective was to determine the incidence of reactivated toxoplasmosis in a setting that withholds prophylaxis until engraftment. The second objective was to identify the subgroups of HSCT recipients particularly prone to reactivation who may benefit the most from regular PCR follow-up.

METHODS

Serological and qPCR screening targeting the Toxoplasma 529 bp gene was performed before HSCT, and continued by weekly monitoring after HSCT for a median time of 104 days.

RESULTS

Reactivated toxoplasmosis was diagnosed in 21/104 (20.2%), predominantly in allo- (19/75) and rarely in auto-HSCT (2/29) recipients. Over 50% (14/21) of cases were diagnosed during the first month after HSCT, while awaiting engraftment without prophylaxis. Toxoplasma disease evolved in only three (14.3%, 3/21) patients, all treated by allo-HSCT. Reactivation was more frequent in patients treated for acute lymphoblastic leukaemia (3/27, p 0.03) and especially, in recipients of haploidentical stem cells (10/20, p 0.005). Seronegative status of the donor (where was known) contributed to 75% (12/16) cases of reactivated toxoplasmosis after allo-HSCT.

DISCUSSION

The presented results show that peripheral blood-based qPCR, both before and after HSCT, is a valuable asset for the diagnosis of reactivated toxoplasmosis, whereas the results of serology in recipients should be interpreted with caution. Weekly qPCR monitoring, at least until successful engraftment and administration of prophylaxis, allows for prompt introduction of specific treatment.

Detection and treatment of cerebral toxoplasmosis in an aplastic pediatric post-allogeneic hematopoietic cell transplant patient: a case report

BACKGROUND

Cerebral toxoplasmosis infection presents with non-specific neurologic symptoms in immunocompromised patients. With lack of measurable adaptive immune responses and reluctance to sample affected brain tissue, expedient diagnosis to guide directed treatment is often delayed.

CASE PRESENTATION

We describe the use of cerebrospinal fluid polymerase chain reaction and plasma cell-free DNA technologies to supplement neuroimaging in the diagnosis of cerebral toxoplasmosis in an immunocompromised pediatric patient following allogeneic hematopoietic cell transplantation for idiopathic severe aplastic anemia. Successful cerebral toxoplasmosis treatment included antibiotic therapy for 1 year following restoration of cellular immunity with an allogeneic stem cell boost.

CONCLUSIONS

Plasma cell-free DNA technology provides a non-invasive method of rapid diagnosis, improving the likelihood of survival from often lethal opportunistic infection in a high risk, immunocompromised patient population.

Toxoplasma gondii infection in children after allogeneic hematopoietic stem cell transplantation: A case report and literature review

INTRODUCTION

Toxoplasmosis is a life-threatening complication after hematopoietic stem cell transplantation (HSCT). However, for several reasons, clinicians know little about Toxoplasma infection.

CASE PRESENTATION

We report a case of toxoplasmosis that was diagnosed by bone marrow smear and metagenomic next-generation sequencing (mNGS) after HSCT in a boy. Additionally, we summarize the characteristics of toxoplasmosis after pediatric HSCT reported in the literature published in PubMed.

CONCLUSION

Clinicians should increase their awareness of toxoplasmosis in children after HSCT and implement pre-transplant screening and post-transplant monitoring and prevention in future according to the national conditions of our country.

Molecular diagnosis of toxoplasmosis: recent advances and a look to the future

INTRODUCTION

Toxoplasmosis is a globally distributed parasitic infection that can be particularly severe when opportunistic or congenital. Its diagnosis requires accurate and rapid techniques that rely mainly on serology and molecular methods.

AREAS COVERED

The aim of this review was to discuss the positioning of the molecular diagnosis of toxoplasmosis according to the different clinical situations possibly resulting from infection with T. gondii, and to detail recent developments in this technique. The English and French literature were searched with the following keywords: 'Toxoplasmosis', "Molecular diagnosis" and 'PCR'.

EXPERT OPINION

Molecular techniques have revolutionized the diagnosis of toxoplasmosis, and practices have considerably evolved over the past decades. However, there is still a high degree of inter-laboratory heterogeneity which impairs comparisons between results and studies. Efforts to standardize practices are underway.

Response to Trimethoprim-Sulfamethoxazole in a Pediatric Hematopoietic Stem Cell Transplant Recipient With Disseminated Toxoplasmosis: A Case Report

We describe the presentation and treatment of a patient who developed ongoing fever and diagnosed with disseminated toxoplasmosis post-hematopoietic stem cell transplantation. He was initially treated with trimethoprim-sulfamethoxazole (TMP-SMX) and there was dramatic improvement in his fever curve. He successfully completed a modified course of therapy.

Stage-Specific Oligonucleotide Primers for the Diagnosis of Toxoplasmosis Among Iranian Pediatric Heart Transplant Recipients; Evaluation of Cotrimoxazole as a Preventive Therapy

Background: Toxoplasmosis is an opportunistic infection that affects solid organ transplant (SOT) recipients. The parasite transmission may be occurred from a Toxoplasma-seropositive donor to a Toxoplasma-seronegative recipient by organ transplantation. Objectives: In this study, a nested PCR was carried out using different primers targeting the B1, SAG4, and MAG1 genes to assess Toxoplasma infection in pediatric heart transplantation at Shahid Rajaei Heart Center in Tehran. Methods: Blood samples were collected from 46 pediatric heart transplant patients aged 1 - 17 years referring to Rajaei Cardiovascular and Medical Research Center from 2018 - 2019. All patients were on oral administration of Trimethoprim-sulfamethoxazole (cotrimoxazole). Blood samples were collected, and peripheral blood mononuclear cell (PBMC) isolation using the Ficoll gradient method was performed. DNA was extracted from PBMC, and nested PCR was carried out. Serologic tests were performed using ELISA to determine IgG and IgM anti - Toxoplasma gondii antibodies. Results: The results of serologic tests showed that all 46 patients had negative anti-T. gondii IgM antibody. Furthermore, 6 (13.05%) and 3 (6.5 %) out of the 46 patients were positive for IgG T. gondii antibody before and after transplantation, respectively. All 46 patients were evaluated using PCR using B1, MAG-1, and SAG-4 genes, and PCR results were negative. Conclusions: In general, due to the negative results of Toxoplasma with PCR using B1 and bradyzoite-specific genes (SAG-4 and MAG-1), it is possible that the results obtained in this study are because of prophylaxis with cotrimoxazole.

Disseminated Toxoplasmosis in a Child Following Allogeneic Hematopoietic Cell Transplantation

A 23-month old female with hypoplastic myelodysplastic syndrome underwent allogenic hematopoietic cell transplantation (HCT), complicated by development of acute exotropia. Bilateral chorioretinal scars and a ring enhancing brain lesion were identified in further workup. Disseminated toxoplasmosis post-allogeneic HCT was subsequently confirmed by serologic and polymerase chain reaction testing results.

Clinical characteristics and outcomes of toxoplasmosis among transplant recipients at two US academic medical centers

Toxoplasma gondii can cause severe opportunistic infection in immunocompromised individuals, but diagnosis is often delayed. We conducted a retrospective review of solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients with toxoplasmosis between 2002 and 2018 at two large US academic transplant centers. Patients were identified by ICD-9 or ICD-10 toxoplasmosis codes, positive Toxoplasma polymerase chain reaction test result, or pathologic diagnosis. Data were collected regarding transplant type, time from transplant to toxoplasmosis diagnosis, clinical and radiographic features, and mortality at 30 and 90 days. Twenty patients were identified: 10 HSCT recipients (80% allogeneic HSCT) and 10 SOT recipients (60% deceased donor renal transplants). Rejection among SOT recipients (70%) and graft-versus-host disease (GVHD) prophylaxis among HSCT recipients (50%) were frequent. Median time from transplant to toxoplasmosis diagnosis was longer for SOT than HSCT (1385 vs. 5 days, P-value .002). Clinical manifestations most commonly were encephalitis (65%), respiratory failure (40%), renal failure (40%), and distributive shock (40%). Cohort 30-day mortality was 45%, and 90-day mortality was 55%. Diagnosis was postmortem in 25% of the cohort. Further evaluation of toxoplasmosis screening is needed for noncardiac SOT recipients, HSCT recipients with GVHD, and periods of increased net immunosuppression.

Anti-Toxoplasma IgG assays: What performances for what purpose? A systematic review

Chronic infection with Toxoplasma gondii is attested by the detection of specific anti-Toxoplasma IgG. A wide panel of serologic methods is currently marketed, and the most suitable method should be chosen according to the laboratory resources and the screened population. This systematic review of evaluation studies aimed at establishing an overview of the performances, i.e. sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of marketed anti-Toxoplasma IgG assays, and discussing their technical characteristics to guide further choice for routine diagnostic use. According to PRISMA guidelines, the search performed in PubMed and Web of Science databases recovered 826 studies, of which 17 were ultimately included. Twenty commercial anti-Toxoplasma IgG assays were evaluated, in comparison with an accepted reference method. Most of them were enzyme-immunoassays (EIAs, n = 12), followed by agglutination tests (n = 4), immunochromatographic tests (n = 3), and a Western-Blot assay (WB, n = 1). The mean sensitivity of IgG assays ranged from 89.7% to 100% for standard titers and from 13.4% to 99.2% for low IgG titers. A few studies pointed out the ability of some methods, especially WB to detect IgG early after primary infection. The specificity of IgG assays was generally high, ranging from 91.3% to 100%; and higher than 99% for most EIA assays. The PPV was not a discriminant indicator among methods, whereas significant disparities (87.5%-100%) were reported among NPVs, a key-parameter assessing the ability to definitively rule out a Toxoplasma infection in patients at-risk for opportunistic infections.

Hemophagocytic lymphohistiocytosis induced by Toxoplasma gondii infection diagnosed by a bone marrow biopsy and DNA next-generation sequencing in an allogeneic hematopoietic stem cell transplant recipient

In the United States, toxoplasmosis following allogeneic hematopoietic stem transplant (allo-HCT) is very rare with a rate only between 0.5% and 2%. The reported rates of hemophagocytic lymphohistiocytosis (HLH) following allo-HCT range between 0.3% and 17%. Secondary HLH due to toxoplasmosis infection is extremely rare. Herein, we report a case of secondary HLH due to toxoplasmosis following allo-HCT. The diagnosis was reached by a bone marrow biopsy and confirmed by DNA next generation sequencing and immunohistochemical (IHC) staining. The IHC staining included CD1a, a stain previously known to react with cells infected by Leishmania, here we show CD1a staining of macrophages infected with Toxoplasma gondii. Our report highlights the utility of bone marrow biopsy in diagnosing parasitic infection underlying HLH in post-transplant settings. The pre-transplant evaluation of patients from low endemic countries, is a great opportunity to obtain a travel history to determine the risks and the preventative measures against opportunistic infections including toxoplasmosis.

Epidemiology, Pathophysiology, Diagnosis, and Management of Cerebral Toxoplasmosis

Toxoplasma gondii is known to infect a considerable number of mammalian and avian species and a substantial proportion of the world's human population. The parasite has an impressive ability to disseminate within the host's body and employs various tactics to overcome the highly regulatory blood-brain barrier and reside in the brain. In healthy individuals, T. gondii infection is largely tolerated without any obvious ill effects. However, primary infection in immunosuppressed patients can result in acute cerebral or systemic disease, and reactivation of latent tissue cysts can lead to a deadly outcome. It is imperative that treatment of life-threatening toxoplasmic encephalitis is timely and effective. Several therapeutic and prophylactic regimens have been used in clinical practice. Current approaches can control infection caused by the invasive and highly proliferative tachyzoites but cannot eliminate the dormant tissue cysts. Adverse events and other limitations are associated with the standard pyrimethamine-based therapy, and effective vaccines are unavailable. In this review, the epidemiology, economic impact, pathophysiology, diagnosis, and management of cerebral toxoplasmosis are discussed, and critical areas for future research are highlighted.

Toxoplasmosis Among 38,751 Hematopoietic Stem Cell Transplant Recipients: A Systematic Review of Disease Prevalence and a Compilation of Imaging and Autopsy Findings

BACKGROUND

Toxoplasmosis in hematopoietic stem cell transplant-recipients (HSCT) can be life threatening if not promptly diagnosed and treated.

METHODS

We performed a systematic review (PubMed last search 03/29/2020) of toxoplasmosis among HSCT-recipients and calculated the toxoplasmosis prevalence across studies. We also created a compilation list of brain imaging, chest imaging and autopsy findings of toxoplasmosis among HSCT-recipients.

RESULTS

We identified 46 eligible studies (47 datasets) with 399 toxoplasmosis cases among 38751 HSCT-recipients. There was large heterogeneity in the reported toxoplasmosis prevalence across studies, thus formal meta-analysis was not attempted. The median toxoplasmosis prevalence among 38751 HSCT-recipients was 2.14% (range 0-66.67%). Data on toxoplasmosis among at-risk R+HSCT-recipients were more limited (25 studies; 2404 R+HSCT-recipients [6.2% of all HSCT-recipients]) although the median number of R+HSCT-recipients was 56.79% across all HSCT-recipients. Median toxoplasmosis prevalence across studies among 2404 R+HSCT was 7.51% (range 0-80%) vs 0% (range 0-1.23%) among 7438 R-HSCT. There were limited data to allow meaningful analyses of toxoplasmosis prevalence according to prophylaxis-status of R+HSCT-recipients.

CONCLUSION

Toxoplasmosis prevalence among HSCT-recipients is underestimated. The majority of studies report toxoplasmosis prevalence among all HSCT-recipients rather than only among the at-risk R+HSCT-recipients. In fact, the median toxoplasmosis prevalence among all R+/R- HSCT-recipients is 3.5-fold lower compared to the prevalence among only the at-risk R+HSCT-recipients and the median prevalence among R+HSCT-recipients is 7.51-fold higher than among R-HSCT-recipients. The imaging findings of toxoplasmosis among HSCT-recipients can be atypical. High-index of suspicion is needed in R+HSCT-recipients with fever, pneumonia or encephalitis.

Supportive Care During Pediatric Hematopoietic Stem Cell Transplantation: Prevention of Infections. A Report From Workshops on Supportive Care of the Paediatric Diseases Working Party (PDWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Specific protocols define eligibility, conditioning, donor selection, graft composition and prophylaxis of graft vs. host disease for children and young adults undergoing hematopoietic stem cell transplant (HSCT). However, international protocols rarely, if ever, detail supportive care, including pharmaceutical infection prophylaxis, physical protection with face masks and cohort isolation or food restrictions. Supportive care suffers from a lack of scientific evidence and implementation of practices in the transplant centers brings extensive restrictions to the child's and family's daily life after HSCT. Therefore, the Board of the Pediatric Diseases Working Party (PDWP) of the European Society for Blood and Marrow Transplantation (EBMT) held a series of dedicated workshops since 2017 with the aim of initiating the production of a set of minimal recommendations. The present paper describes the consensus reached within the field of infection prophylaxis.

Case Report: Immune Dysregulation Due to Toxoplasma gondii Reactivation After Allogeneic Hematopoietic Cell Transplant

Disseminated toxoplasmosis is an uncommon but highly lethal cause of hyperferritinemic sepsis after hematopoietic cell transplantation (HCT). We report two cases of disseminated toxoplasmosis from two centers in critically ill adolescents after HCT: a 19-year-old who developed fever and altered mental status on day +19 after HCT and a 20-year-old who developed fever and diarrhea on day +52 after HCT. Both patients developed hyperferritinemia with multiple organ dysfunction syndrome and profound immune dysregulation, which progressed to death despite maximal medical therapies. Because disseminated toxoplasmosis is both treatable and challenging to diagnose, it is imperative that intensivists maintain a high index of suspicion for Toxoplasma gondii infection when managing immunocompromised children, particularly in those with known positive T. gondii serologies.

Case Report: Severe ARDS in a Pediatric Hematopoietic Stem-Cell Transplantation Recipient Caused by Disseminated Toxoplasmosis

Toxoplasma gondii infection is a severe complication of hematopoietic stem-cell transplantation (HSCT) recipients that can remain unnoticed without a high clinical suspicion. We present the case of a 6-year-old patient with acute lymphoblastic leukemia and HSCT recipient who was admitted to the Pediatric Intensive Care Unit (PICU) on post-transplantation day +39 with fever, hypotension, severe respiratory distress and appearance of a lumbar subcutaneous node. She developed severe Acute Respiratory Distress Syndrome (ARDS) and underwent endotracheal intubation and early mechanical ventilation. Subsequently, she required prone ventilation, inhaled nitric oxide therapy and high-frequency oscillatory ventilation (HFOV). An etiologic study was performed, being blood, urine, bronchoalveolar lavage and biopsy of the subcutaneous node positive for Toxoplasma gondii by Polymerase Chain Reaction (PCR). Diagnosis of disseminated toxoplasmosis was established and treatment with pyrimethamine, sulfadiazine and folinic acid started. The patient showed clinical improvement, allowing weaning of mechanical ventilation and transfer to the hospitalization ward after 40 days in the PICU. It is important to consider toxoplasmosis infection in immunocompromised patients with sepsis and, in cases of severe respiratory distress, early mechanical ventilation should be started using the open lung approach. In Toxoplasma IgG positive patients, close monitoring and appropriate anti-infectious prophylaxis is needed after HSCT.

Toxoplasmosis in Pediatric Hematopoietic Stem Cell Transplantation Patients

Infection due to the protozoa Toxoplasma gondii can be life-threatening in hematopoietic stem cell transplantation (HSCT) recipients. Most cases of toxoplasmosis in HSCT recipients result from reactivation of latent infection in individuals who were Toxoplasma-seropositive before transplantation and did not receive appropriate prophylaxis. Pretransplantation screening with Toxoplasma IgG and IgM antibodies is suggested for all allogeneic HSCT recipients and their donors and all autologous HSCT recipients. Prevention of toxoplasmosis in T. gondii-seropositive HSCT recipients requires primary prophylaxis, preemptive screening, or both. Trimethoprim-sulfamethoxazole (TMP-SMX) is the preferred agent for Toxoplasma prophylaxis and should be continued for 6 months or until the patient is no longer receiving immunosuppression, whichever is longer, assuming that immune reconstitution has occurred. Preemptive weekly screening with whole blood Toxoplasma PCR should be considered for seropositive HSCT recipients if prophylaxis cannot be given or if prophylaxis other than TMP-SMX is used. The signs, symptoms, and radiographic findings of toxoplasmosis in HSCT recipients can be nonspecific, and the diagnosis requires a high degree of suspicion. Common presentations include fever, encephalopathy with mental status changes or seizures, and pneumonia. A Toxoplasma PCR analysis from whole blood (and other body fluids/tissues according to clinical symptoms) should be obtained in patients in whom there is a concern for toxoplasmosis. Treatment with oral pyrimethamine, sulfadiazine, and leucovorin for at least 6 weeks is the first-line therapy and should be followed by secondary prophylaxis. In this article, we review the published literature regarding the epidemiology, clinical presentation, treatment, and prevention of toxoplasmosis in HSCT recipients.

Toxoplasmosis after allogeneic hematopoietic stem cell transplantation: Impact of serostatus-based management

Toxoplasmosis caused by Toxoplasma gondii (T. gondii) is a serious infectious complication after allogeneic hematopoietic stem cell transplantation (HSCT). The incidence of toxoplasmosis varies widely because of the variabilities of seroprevalence among patient populations. The incidence and the optimal management of toxoplasmosis after allogeneic HSCT in a patient population with a low seroprevalence have not been fully evaluated. We conducted a single-center retrospective study evaluating toxoplasmosis in Japanese patients who underwent allogeneic HSCT. Of the 728 evaluable patients, only 5 developed toxoplasmosis with a median onset of day 60 post-transplant (range, day 55-393). The cumulative incidence was 0.7% (95% CI: 0.3%-1.5%) at day 500 post-transplant. Four of the five patients succumbed due to toxoplasmosis. The more recently treated 220 patients (not the earlier 508 patients) were screened for the T. gondii serostatus, and prophylactic treatment with trimethoprim/sulfamethoxazole was applied. All five patients with toxoplasmosis were in the unscreened group, and there was no case of toxoplasmosis after the introduction of the screening and prophylactic treatment. Our results suggest that toxoplasmosis after allogeneic HST is rare but can develop as a life-threatening complication even in the populations with low seroprevalence, and that prophylactic treatment for seropositive patients could effectively prevent toxoplasmosis.

Toxoplasmosis after allogeneic haematopoietic cell transplantation-disease burden and approaches to diagnosis, prevention and management in adults and children

BACKGROUND

Toxoplasmosis is a rare but highly lethal opportunistic infection after allogeneic haematopoietic cell transplantation (HCT). Successful management depends on screening, early recognition and effective treatment.

OBJECTIVES

To review the current epidemiology and approaches to diagnosis, prevention and treatment of toxoplasmosis in adult and paediatric allogeneic HCT recipients.

SOURCE

Search of the English literature published in MEDLINE up to 30 June 2020 using combinations of broad search terms including toxoplasmosis, transplantation, diagnosis, epidemiology, prevention and treatment. Selection of articles for review and synthesis on the basis of perceived quality and relevance of content.

CONTENT

Toxoplasmosis continues to be a major challenge in the management of allogeneic HCT recipients. Here we provide a summary of published case series of toxoplasmosis in adult and paediatric patients post allogeneic HCT. We review and discuss the pathogenesis, epidemiology, clinical presentation, diagnosis and current recommendations for prevention and treatment. We also discuss impacts of toxoplasmosis in this setting and factors affecting outcome, emphasizing attention to neurological, neuropsychological and neurocognitive late effects in survivors.

IMPLICATIONS

Apart from careful adherence to established strategies of disease prevention through avoidance of primary infection, identification of seropositive patients and implementation of molecular monitoring, future perspectives to improve the control of toxoplasmosis in allogeneic HCT recipients may include the systematic investigation of pre-emptive treatment, development of immunomodulatory approaches, antimicrobial agents with activity against the cyst form and vaccines to prevent chronic infection.

Serology for Toxoplasma in Immunocompromised Patients: Still Useful?

Toxoplasmosis represents one of the most common comorbidity factors in solid organ or hematopoietic stem cell transplant recipients as well as in other immunocompromised patients. In the past decades, availability and performance of molecular tools for the diagnosis or the exclusion of toxoplasmosis in these patients have greatly improved. However, if accurately used, serology remains a complementary and essential diagnostic tool for physicians and medical parasitologists for the prevention and management of toxoplasmosis in immunocompromised patients as well. It is required for determination of the immunological status of patients against Toxoplasma. It also helps diagnose and monitor complex cases of opportunistic Toxoplasma infection in immunocompromised patients. New perspectives are available to further enhance their yield and ease of use.

Missed diagnosis and misdiagnosis of infectious diseases in hematopoietic cell transplant recipients: an autopsy study

Hematopoietic cell transplantation (HCT) is potentially curative for patients with hematologic disorders, but carries significant risks of infection-related morbidity and mortality. Infectious diseases are the second most common cause of death in HCT recipients, surpassed only by progression of underlying disease. Many infectious diseases are difficult to diagnose and treat, and may only be first identified by autopsy. However, autopsy rates are decreasing despite their value. The clinical and autopsy records of adult HCT recipients at our center who underwent autopsy between 1 January 2000 and 31 December 2017 were reviewed. Discrepancies between premortem clinical diagnoses and postmortem autopsy diagnoses were evaluated. Of 185 patients who underwent autopsy, 35 patients (18.8%) had a total of 41 missed infections. Five patients (2.7%) had >1 missed infection. Of the 41 missed infections, 18 (43.9%) were viral, 16 (39.0%) were fungal, 5 (12.2%) were bacterial, and 2 (4.9%) were parasitic. According to the Goldman criteria, 31 discrepancies (75.6%) were class I, 5 (12.2%) were class II, 1 (2.4%) was class III, and 4 (9.8%) were class IV. Autopsies of HCT recipients frequently identify clinically significant infectious diseases that were not suspected premortem. Had these infections been suspected, a change in management might have improved patient survival in many of these cases. Autopsy is underutilized and should be performed regularly to help improve infection-related morbidity and mortality. Illustrative cases are presented and the lessons learned from them are also discussed.

Parasitic Infections of the Stem Cell Transplant Recipient and the Hematologic Malignancy Patient, Including Toxoplasmosis and Strongyloidiasis

Hematopoietic stem cell transplantation (HSCT) recipients may infrequently develop parasitic infections at the time of the procedure via contamination from allograft tissue or blood products, and in the post-transplantation period through the traditional route of infection or as a reactivation caused by immunosuppression related to the transplant. To reduce risk, efforts should be directed at performing a comprehensive history, maintaining a high index of suspicion, and adhering to preventive measures. Additional strategies for the prevention, screening and careful follow-up, identification, and pre-emptive treatment of parasitic infections are required to reduce morbidity and mortality in HSCT patients.

Toxoplasma gondii-induced brachial plexus neuropathy after allogeneic hematopoietic stem cell transplantation

Brachial plexus neuropathy is a rare, but underdiagnosed condition, characterized by intense analgesic-resistant shoulder pain, followed by brachial plexus paresis and sensory symptoms. We present a case of brachial plexus neuropathy, induced by Toxoplasma gondii (T. gondii) 17 days after allogeneic hematopoietic stem cell transplantation (alloHSCT) in a patient with acute myeloid leukemia. The diagnosis was made based on the clinical presentation, magnetic resonance imaging (MRI) of the brachial plexus, and positive T. gondii polymerase chain reaction (PCR) in cerebrospinal fluid. The patient was treated with pyrimethamine, sulfadiazine, and levofolinic acid during 6 weeks, with a positive outcome.

Treatment of toxoplasmosis: Current options and future perspectives

Toxoplasmosis is a worldwide parasitic disease infecting about one third of humans, with possible severe outcomes in neonates and immunocompromised patients. Despite continuous and successful efforts to improve diagnosis, therapeutic schemes have barely evolved since many years. This article aims at reviewing the main clinical trials and current treatment practices, and at addressing future perspectives in the light of ongoing researches.

Toxoplasmosis in the non-orthotopic heart transplant recipient population, how common is it? Any indication for prophylaxis?

PURPOSE OF REVIEW

Unlike in orthotopic heart transplant (OHT) setting where toxoplasma prophylaxis is a standard practice in pretransplant toxoplasma seronegative recipients who have received donor hearts from seropositive donors (D+/R-), there is no consensus regarding prophylaxis in non-OHT recipients.

RECENT FINDINGS

The incidence of toxoplasma disease in non-OHT recipients is less than 1% but its true burden is underestimated. Among 31 cases of toxoplasma disease reported from 2004 through 2017, renal and liver transplant recipients comprised of 90% of cases. A total of 94% of 18 recipients with known pretransplant serology were seronegative recipients (mostly D+/R-). Out of 16 recipients with adequate information, 10 (63%) and five (31%) were deemed to be donor derived and nondonor-derived primary toxoplasmosis respectively. Tissue invasive reactivation was uncommon. Almost all cases were described in patients not on prophylaxis at the time of presentation. Universal screening of donor/recipient toxoplasma serology for risk stratification is beneficial as illustrated by reports of fatal cases of toxoplasmosis due to unavailability of positive donor serology results.

SUMMARY

Toxoplasma disease in non-OHT predominantly occurs in pretransplant seronegative recipients- mostly in D+/R- group and is rare in seropositive recipients. Posttransplant prophylaxis should be targeted against the high-risk D+/R- group and should be considered in seropositive recipients in whom unusually high immunosuppression is implemented. Toxoplasma serologies and PCR should be used in combination for the diagnosis of toxoplasmosis in non-OHT patients.

Toxoplasmosis as a cause of life-threatening respiratory distress in a dog receiving immunosuppressive therapy

Disseminated toxoplasmosis is a potentially fatal complication in dogs receiving immunosuppressive therapy, particularly if multiple immunosuppressive drugs are used. Toxoplasmosis should be considered if signs of acute respiratory or hepatic disease develop, and diagnosis would rely on demonstration of organisms via cytology or PCR rather than a single time-point serological assay.

Tissue and blood protozoa including toxoplasmosis, Chagas disease, leishmaniasis, Babesia, Acanthamoeba, Balamuthia, and Naegleria in solid organ transplant recipients- Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of tissue and blood protozoal infections in the pre- and post-transplant period. Significant new developments in the field have made it necessary to divide the previous single guideline published in 2013 into two sections, with the intestinal parasites separated from this guideline devoted to tissue and blood protozoa. The current update reflects the increased focus on donor screening and risk-based recipient monitoring for parasitic infections. Increased donor testing has led to new recommendations for recipient management of Toxoplasma gondii and Trypanosoma cruzi. Molecular diagnostics have impacted the field, with access to rapid diagnostic testing for malaria and polymerase chain reaction testing for Leishmania. Changes in Babesia treatment regimens in the immunocompromised host are outlined. The risk of donor transmission of free-living amebae infection is reviewed. Changing immigration patterns and the expansion of transplant medicine in developing countries has contributed to the recognition of parasitic infections as an important threat to transplant outcomes. Medications such as benznidazole and miltefosine are now available to US prescribers as access to treatment of tissue and blood protozoa is increasingly prioritized.

Toxoplasmosis in Transplant Recipients, Europe, 2010-2014

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.

[Prophylaxis of infections post-allogeneic transplantation: Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

Allogeneic hematopoietic stem cell transplantation is a curative treatment for many hematological diseases. However, this procedure causes the patient to be susceptible to infection. Prophylactic treatments are administered in clinical practice even thought the level of evidence of their effectiveness is not always high. In addition, changes in the transplantation procedures - use of reduced intensity conditioning, development of alternative graft sources - must lead to a rethinking of attitudes towards prophylaxis. Our working group based its recommendations on a review of referential articles and publications on the subject found in the literature. These recommendations concern the prophylaxis of infections caused by HSV1, HSV2, varicella zoster, and hepatitis B, as well as anti-bacterial and digestive decontamination prophylaxis, prevention of pneumocystis, toxoplasmosis, tuberculosis, as well as prophylaxis of fungal infections. Other infectious agents usually involved in infections post-allotransplant have been the subject of another set of recommendations from the French Society of Bone Marrow Transplantation and Cellular Therapy.

Treatment of Toxoplasmosis: Historical Perspective, Animal Models, and Current Clinical Practice

Primary Toxoplasma gondii infection is usually subclinical, but cervical lymphadenopathy or ocular disease can be present in some patients. Active infection is characterized by tachyzoites, while tissue cysts characterize latent disease. Infection in the fetus and in immunocompromised patients can cause devastating disease. The combination of pyrimethamine and sulfadiazine (pyr-sulf), targeting the active stage of the infection, is the current gold standard for treating toxoplasmosis, but failure rates remain significant. Although other regimens are available, including pyrimethamine in combination with clindamycin, atovaquone, clarithromycin, or azithromycin or monotherapy with trimethoprim-sulfamethoxazole (TMP-SMX) or atovaquone, none have been found to be superior to pyr-sulf, and no regimen is active against the latent stage of the infection. Furthermore, the efficacy of these regimens against ocular disease remains uncertain. In multiple studies, systematic screening for Toxoplasma infection during gestation, followed by treatment with spiramycin for acute maternal infections and with pyr-sulf for those with established fetal infection, has been shown to be effective at preventing vertical transmission and minimizing the severity of congenital toxoplasmosis (CT). Despite significant progress in treating human disease, there is a strong impetus to develop novel therapeutics for both the acute and latent forms of the infection. Here we present an overview of toxoplasmosis treatment in humans and in animal models. Additional research is needed to identify novel drugs by use of innovative high-throughput screening technologies and to improve experimental models to reflect human disease. Such advances will pave the way for lead candidates to be tested in thoroughly designed clinical trials in defined patient populations.