Parasitic infections in solid organ transplant recipients

Effective factors in the pathogenesis of Toxoplasmagondii

Toxoplasma gondii (T. gondii) is a cosmopolitan protozoan parasite in humans and animals. It infects about 30 % of the human population worldwide and causes potentially fatal diseases in immunocompromised hosts and neonates. For this study, five English-language databases (ScienceDirect, ProQuest, Web of Science, PubMed, and Scopus) and the internet search engine Google Scholar were searched. This review was accomplished to draw a global perspective of what is known about the pathogenesis of T. gondii and various factors affecting it. Virulence and immune responses can influence the mechanisms of parasite pathogenesis and these factors are in turn influenced by other factors. In addition to the host's genetic background, the type of Toxoplasma strain, the routes of transmission of infection, the number of passages, and different phases of parasite life affect virulence. The identification of virulence factors of the parasite could provide promising insights into the pathogenesis of this parasite. The results of this study can be an incentive to conduct more intensive research to design and develop new anti-Toxoplasma agents (drugs and vaccines) to treat or prevent this infection. In addition, further studies are needed to better understand the key agents in the pathogenesis of T. gondii.

Barriers toward xenotransplantation in Arab World

Organ transplant is a crucial therapeutic strategy offering a life-saving and transformative medical intervention. It provides an opportunity to improve their quality of life and increase their lifespan. The shortage of organs remains a critical global challenge, leading to a prolonged waiting times for organ receivers, which contributes to an increase in morbidity and mortality rates. Hence, xenotransplantation offered a promising solution to the global shortage of organs through the use of animal organs, leading to an increase in donor availability, reducing waiting times, minimizing organ trafficking, improving genetic engineering advancements, and driving scientific innovation. Even though xenotransplantation has many benefits in the clinical setting, it has many barriers that are hindering its achievements and constraining its occurrence. Some barriers to xenotransplant are general, such as the immunological barrier, while others are specific to certain regions due to local causes. The Arab region exhibits disparities in clinical settings compared to the global context, marked by the huge economic crisis and a shortage of trained healthcare professionals. Considering the huge resources and advancements needed in the field of xenotransplantation, this review aims to explore the specific barriers toward xenotransplantation in the Arab countries, highlighting the challenges to overcome these barriers.

Massive Airway Bleeding Caused by Pulmonary Strongyloidiasis in a Patient with a Transplanted Kidney

Introduction

We report a fatal case of massive airway bleeding caused by pulmonary strongyloidiasis in a patient with a transplanted kidney.

Case Presentation

A 47-year-old male, regularly taking immunosuppressants post-kidney transplant, visited our hospital with symptoms of abdominal bloating, nausea, and emesis persisting for three days. After hospitalization, he developed a cough, hemoptysis, and respiratory failure. Sputum analysis confirmed an infestation with Strongyloides stercoralis. Despite receiving albendazole therapy and bronchoscopic management for bronchial hemorrhage, the patient ultimately died due to acute respiratory and circulatory collapse triggered by severe airway bleeding.

Conclusion

Patients undergoing immunosuppressive therapy following kidney transplantation are at increased risk for disseminated strongyloidiasis. Consequently, infectious disease screening prior to transplantation, along with essential preventive pharmacotherapy, is of paramount importance.

Pre-Transplant Seroprevalence, Associated Factors, and Post-Transplant Incidence of Toxoplasma gondii Infection Among Heart Transplant Recipients in Japan

BACKGROUND

Among solid organ transplant (SOT) recipients, heart transplant (HT) recipients are at a higher risk of Toxoplasma gondii infection. As Toxoplasma seroprevalence varies by geographic location, updated local epidemiology is essential to guide preventive and therapeutic strategies. However, the Toxoplasma seroprevalence and incidence of post-transplant toxoplasmosis among SOT recipients in Japan are unknown.

METHODS

We performed a single-center retrospective observational study at an HT center in Tokyo, Japan. All HT recipients aged ≥18 years between 2006 and April 2019 were included. We reviewed patient charts and conducted a questionnaire survey to investigate the risk factors for infection.

RESULTS

Among 105 recipients included in the study, 11 (10.5%) were seropositive before transplant. Ninety-five recipients (90.5%), including all pre-transplant seropositive recipients, answered the questionnaire. The recipients who had lived in Okinawa (odds ratio [OR] 7.5 [95% CI 1.42-39.61]; P = .032) and who reported raw-meat eating habits (OR 4.64 [95% CI 1.04-23.3]; P = .021) were more likely to be seropositive. None of the patients developed symptoms of toxoplasmosis. The post-transplant incidence of other major adverse outcomes was not significantly different according to the pre-transplant serostatus.

CONCLUSIONS

About 10% of HT recipients at an HT center in Tokyo were seropositive for Toxoplasma pre-transplant, and none developed symptomatic toxoplasmosis post-transplant on trimethoprim-sulfamethoxazole. The history of raw meat consumption was associated with seropositivity; therefore, avoiding it might be recommended for HT recipient candidates.

South Asian Transplant Infectious Disease Guidelines for Solid Organ Transplant Candidates, Recipients, and Donors

These guidelines discuss the epidemiology, screening, diagnosis, posttransplant prophylaxis, monitoring, and management of endemic infections in solid organ transplant (SOT) candidates, recipients, and donors in South Asia. The guidelines also provide recommendations for SOT recipients traveling to this region. These guidelines are based on literature review and expert opinion by transplant physicians, surgeons, and infectious diseases specialists, mostly from South Asian countries (India, Pakistan, Bangladesh, Nepal, and Sri Lanka) as well as transplant experts from other countries. These guidelines cover relevant endemic bacterial infections (tuberculosis, leptospirosis, melioidosis, typhoid, scrub typhus), viral infections (hepatitis A, B, C, D, and E; rabies; and the arboviruses including dengue, chikungunya, Zika, Japanese encephalitis), endemic fungal infections (mucormycosis, histoplasmosis, talaromycosis, sporotrichosis), and endemic parasitic infections (malaria, leishmaniasis, toxoplasmosis, cryptosporidiosis, strongyloidiasis, and filariasis) as well as travelers' diarrhea and vaccination for SOT candidates and recipients including travelers visiting this region. These guidelines are intended to be an overview of each topic; more detailed reviews are being published as a special supplement in the Indian Journal of Transplantation .

Describing universal Strongyloides serologic screening among pediatric intestinal and liver transplant recipients

BACKGROUND

Strongyloides spp hyperinfections are a worldwide phenomenon that proves fatal for solid organ transplant recipients. Screening protocols to guide prophylaxis management vary institution to institution from universal to epidemiology driven. Our institution initiated a universal screening protocol regardless of travel history and exposure to ensure no cases were missed.

METHODS

In this study, we describe the outcomes of three Strongyloides sero-positive children whom underwent intestinal or liver transplantation and the experience of universal screening at a tertiary care county hospital in South Florida.

RESULTS

Among the 66 intestine and liver pediatric transplant recipients who were screened for Strongyloides antibodies, only three were identified to be sero-positive via the screening mechanism. Two of three had significant epidemiology risk factors. None of the patients reviewed were found to have developed hyperinfection. However, reflecting on the experience represented by our series of pediatric patients, the risk of any complication related to Strongyloides status appears low. Even among this South Florida population whom come from or travel to endemic regions are in contact with sero-positive individuals, very few illustrate sero-positivity.

CONCLUSION

While institutions continue to analyze the cost-benefit of universal testing vs. universal prophylaxis vs. targeted screening, the decision must encompass the patient population, rolling cumulative incidence, and morbidity and mortality related to this disease.

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.

Reactivation of latent infections in solid organ transplant recipients from sub-Saharan Africa: What should be remembered?

International migration from Sub-Saharan African countries to the European Union and the United States has significantly increased over the past decades. Although the vast majority of these immigrants are young and healthy people, a minority can be affected by chronic conditions eventually leading to solid organ transplantation (SOT). Importantly, these candidates can bear geographically restricted fungal and parasitic latent infections that can reactivate after the procedure. An appropriate evaluation before transplantation followed by treatment, whenever necessary, is essential to minimize such risk, as covered in the present review. In short, infection due to helminths (Schistosoma spp. and Strongyloides stercoralis) and intestinal protozoa (Entamoeba histolytica, Giardia lamblia or Cyclospora cayetanensis) can be diagnosed by multiple direct stool examination, serological assays and stool antigen testing. Leishmaniasis can be assessed by means of serology, followed by nucleic acid amplification testing (NAAT) if the former test is positive. Submicroscopic malaria should be ruled out by NAAT. Screening for Histoplasma spp. or Cryptococcus spp. is not routinely indicated. Consultation with an Infectious Diseases specialist is recommended in order to adjust preemptive treatment among Sub-Saharan African SOT candidates and recipients.

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.

Malaria and encephalopathy in a heart transplant recipient: A case report in the context of multiorgan donation

INTRODUCTION

Malaria is an endemic infection in tropical circles. It can be transmitted from mosquitoes bite, but exceptional cases have been attributed to multiorgan transplantation.

CASE REPORT

This is a 34-year-old woman who received a heart transplant for final-stage dilated cardiomyopathy. Over the hospitalization, she developed fever, cephalalgia, and tonic-clonic seizures with MRI findings compatible with posterior reversible encephalopathy. A thick blood smear revealed hemoparasitic forms of Plasmodium vivax. Afterward, malaria was also diagnosed in recipients of one kidney and liver of the same organ donor. First-line treatment with artesunate was prescribed for 3 days and chloroquine with primaquine thereafter for 14 days. The patient was discharged and returned to the emergency department 5 days later, complaining of gastrointestinal symptoms and developed multiorgan failure that led to death.

CONCLUSION

We report a case of malaria transmission through heart transplantation. Despite adequate and supervised treatment, it can be related to a fatal outcome. Malaria screening in organ donors should be considered in regions where endemicity can lead to rare cases of transmission by transplantation.

Parasite burden and red blood cell exchange transfusion for babesiosis

BACKGROUND

The association between parasite burden and end-organ dysfunction in subjects with Babesia microti infection has not been extensively studied, nor has the optimal role of red blood cell exchange (RCE) transfusion in babesiosis treatment. This retrospective chart review evaluates the associations between parasitemia, end-organ dysfunction, and outcomes in babesiosis patients treated with antimicrobial agents and RCE compared to those treated with antimicrobial agents alone.

MATERIALS AND METHODS

We evaluated adults (≥18 years of age) with laboratory-confirmed babesiosis who were admitted between 2011 and 2017 to Yale New Haven Hospital, located in a Babesia-endemic region of the Northeastern United States. Patient demographics, parasitemia levels, clinical and laboratory indicators of end-organ dysfunction, and outcomes were examined.

RESULTS

Ninety-one subjects (mean age 65.1 years, 69.2% male) were studied. Subjects were stratified according to peak parasitemia: <1% (n = 34), 1-5% (n = 24), 5-10% (n = 15), and >10% (n = 18). Laboratory measures indicating degrees of hemolysis, coagulopathy, and pulmonary, renal and hepatic dysfunction differed significantly across peak parasitemia levels. Median length of hospital stay increased with each successive peak parasitemia level (P < .001). These results indicate a strong association between peak parasitemia level and disease severity. Nineteen subjects underwent RCE, all with peak parasitemia ≥9% and some degree of end-organ dysfunction.

CONCLUSIONS

Babesia microti parasitemia is closely associated with disease severity, though not all subjects with end-organ dysfunction had high-grade parasitemia. Our data suggest that the use of parasitemia >10%, coupled with clinical status, is a reasonable indicator for RCE in babesiosis patients.

Comparison of serologic status of Toxoplasma gondii infection in pre- and post-heart transplantation in a pediatric population: A preliminary study

BACKGROUND

Toxoplasmosis is an important opportunistic infection in immunocompromised children, especially in heart transplant recipients. This study aimed to investigate pre- and post-transplant serology for toxoplasmosis along with post-transplant PCR in pediatric heart transplant patients.

METHODS

This cross-sectional study was performed on 38 heart transplant recipients aged 1-17 years, by the end of 2018. Pre- and post-transplant IgM and IgG titrations were measured using ELISA method. Nested PCR of B1 gene was performed to identify Toxoplasma gondii (T gondii) infection after transplant.

RESULTS

Totally, 11.4% of patients had positive IgG and 91.4% had negative IgM for toxoplasmosis before heart transplantation. The mean of pre-transplant IgG titration for seropositive and seronegative patients was 22.32 ± 15.30 IU/mL and 1.49 ± 1.15 IU/mL, respectively (P < .001). All cases were on chemoprophylaxis with trimethoprim-sulfamethoxazole (TMP/SMX). The mean of post-transplant IgG titration was 1.62 ± 1.87 IU/mL, which was negative for all cases. Investigating pre-transplant, IgM titration, 5.7% were positive, 91.4% were negative, and 2.9% were borderline. All cases were post-transplant IgM negative. The mean of post-transplant IgG titrations was significantly higher in the first 6 months (3.26 ± 2.68 IU/mL) compared to 6-12 (1.30 ± 1.34 IU/mL; P = .039) and > 12 months (1.07 ± 1.27 IU/mL; P = .004) time periods. The result of PCR for B1 gene in all cases was negative.

CONCLUSIONS

Chemoprophylaxis with TMP/SMX seems to be effective in prevention of T gondii infection or reactivation among pediatric heart transplantation population. Anti-T. gondii-IgG level alone may not be sensitive enough for evaluation of the infection at least after 6 months post-transplantation.

Toxoplasma gondii Monitoring in Liver Transplantation Patients: A Single Center Cross-Sectional Study in an Italian Hospital

Toxoplasma gondii (TG) is one of the most widespread intracellular parasites in the world, despite the slight declining trend in industrialized countries. Whilst the infection is often asymptomatic in immunocompetent hosts, in immunocompromised patients such as organ transplant recipients it can have important clinical sequels with even fatal consequences. We retrospectively reviewed 568 primary liver transplants (LT) from deceased donors from 2012 to 2017. Data were analyzed adjusting for year, gender, and age. The study objective was to assess the incidence of post-transplant TG infection and adherence to international guidelines for primary chemoprophylaxis. Prior to transplantation, 42.4% of recipients tested seronegative and 56.5% seropositive, while 36.6% of donors were seropositive and 40.4% showed undetermined serology. Anti-TG antibody titer was higher in patients born abroad (71.4%) versus Italy (54.8%). Among recipients at high risk of post-transplant TG infection, 82.7% of them received chemoprophylaxis, while in 17.3% of cases no prophylaxis was administered. At a mean (SD) follow-up of 21.2 (12.4) months no case of TG infection has been observed. Despite the low rate of adherence to recommendations, prophylaxis of high-risk LT recipients provides control of post-transplant TG infection risk. Review of current guidelines is warranted for low-risk populations.

Transmission of Toxoplasma gondii Infection Due to Bone Marrow Transplantation: Validation by an Experimental Model

Toxoplasmosis is an opportunistic infectious disease and may present a fatal outcome for human bone marrow transplant (BMT) recipients, due to the rapid disease course in immunosuppressed individuals. Several reports about occurrence of toxoplasmosis after BMT have been published in the literature, but this disease has been associated mainly due to reactivation of latent infection rather than primary infection. Even though there are reports of acute toxoplasmosis in recipients who were seronegative for T. gondii, suggesting transmission of infection after BMT, the source of infection in those cases has not been clearly demonstrated, whether it is due to the transplantation procedure by itself or from environmental source. Thus, the present study aimed to observe if it could be possible to demonstrate the parasite‘s ability to infect bone marrow (BM) cells and cause toxoplasmosis, when using an experimental model. Our results showed that 11% of hematopoietic and 7.1% of nonhematopoietic lineages may become infected when using in vitro experiments. Also, in vivo experiments demonstrated that, when C57BL/6 mice were infected with RH-RFP or ME-49-GFP T. gondii strains, the BM cells may be infected at different time points of infection. The parasites were detected by both fluorescent microscopy and qPCR. Also, when those BM samples were collected and used for BMT, the transplanted animals presented high rates of mortality and 87.5% of them became seropositive for T. gondii. Taken together, our results clearly demonstrated that it is possible to acquire primary T. gondii infection from the donor cells after BMT. Therefore, we are emphasizing that, before transplantation, serological screening for T. gondii infection from both donors and recipients, in addition to DNA search for this parasite from donor bone marrow cells, are necessary procedures to avoid the risk of T. gondii infection for immunocompromised patients.

Vaccinations in kidney transplant recipients: Clearing the muddy waters

Vaccine preventable diseases account for a significant proportion of morbidity and mortality in transplant recipients and cause adverse outcomes to the patient and allograft. Patients should be screened for vaccination history at the time of pre-transplant evaluation and vaccinated at least four weeks prior to transplantation. For non-immune patients, dead-vaccines can be administered starting at six months post-transplant. Live attenuated vaccines are contraindicated after transplant due to concern for infectious complications from the vaccine and every effort should be made to vaccinate prior to transplant. Since transplant recipients are on life-long immunosuppression, these patients may have lower rates of serological conversion, lower mean antibody titers and waning of protective immunity over shorter period as compared to general population. Recommendations regarding booster dose in kidney transplant recipients with sub-optimal serological response are lacking. Travel plans should be part of routine post-transplant assessment and pre-travel vaccines and counseling should be provided. More studies are needed on vaccination schedules, serological response, need for booster doses and safety of live attenuated vaccines in this special population.

Infectious Disease Transmission in Solid Organ Transplantation: Donor Evaluation, Recipient Risk, and Outcomes of Transmission

In 2016, the Transplantation Society of Australia and New Zealand, with the support of the Australian Government Organ and Tissue authority, commissioned a literature review on the topic of infectious disease transmission from deceased donors to recipients of solid organ transplants. The purpose of this review was to synthesize evidence on transmission risks, diagnostic test characteristics, and recipient management to inform best-practice clinical guidelines. The final review, presented as a special supplement in Transplantation Direct, collates case reports of transmission events and other peer-reviewed literature, and summarizes current (as of June 2017) international guidelines on donor screening and recipient management. Of particular interest at the time of writing was how to maximize utilization of donors at increased risk for transmission of human immunodeficiency virus, hepatitis C virus, and hepatitis B virus, given the recent developments, including the availability of direct-acting antivirals for hepatitis C virus and improvements in donor screening technologies. The review also covers emerging risks associated with recent epidemics (eg, Zika virus) and the risk of transmission of nonendemic pathogens related to donor travel history or country of origin. Lastly, the implications for recipient consent of expanded utilization of donors at increased risk of blood-borne viral disease transmission are considered.

Infections in Heart, Lung, and Heart-Lung Transplantation

Half a century has passed since the first orthotopic heart transplant took place. Surgical innovations allowed for heart, lung, and heart-lung transplantation to save lives of patients with incurable chronic cardiopulmonary conditions. The complexity of the surgical interventions, chronic host health conditions, and antirejection immunosuppressive medications makes infectious complications common. Infections have remained one of the main barriers for successful transplantation and a source of significant morbidity and mortality. Recognition of infections and its management in this setting require outstanding clinical skills since transplant recipients may not exhibit classic signs or symptoms of disease, and laboratory work has some pitfalls. The prevention, identification, and management of infectious diseases complications in this population are a priority to undertake to improve the medical outcomes of transplantation. Herein, we reviewed the historical aspects, epidemiology, and prophylaxis of infections in heart, lung, and heart-lung transplantation. We also discuss the most prevalent organisms affecting the host and the organ systems involved.

Approach to Transplant Infectious Diseases in the Emergency Department

The emergency department (ED) is an increasingly important site of care for patients who have undergone solid organ transplantation or hematopoietic cell transplantation. It is paramount for emergency physicians to recognize infections early on, obtain appropriate diagnostic testing, initiate empirical antimicrobial therapy, and consider specialty consultation and inpatient admission when caring for these patients. This review provides emergency physicians with an approach to the assessment of transplant patients' underlying risk for infection, formulation of a broad differential diagnosis, and initial management of transplant infectious disease emergencies in the ED.

Strongyloidiasis Current Status with Emphasis in Diagnosis and Drug Research

Strongyloidiasis is a parasitic neglected disease caused by the nematode Strongyloides stercoralis affecting 30 to 100 million people worldwide. Complications, strongly associated with alcoholism, organ transplants, and HTLV-1 virus, often arise due to late diagnosis, frequently leading to patient death. Lack of preemptive diagnosis is not the only difficulty when dealing with this parasite, since there are no gold standard diagnostic techniques, and the ones used have problems associated with sensitivity, resulting in false negatives. Treatment is also an issue as ivermectin and benzimidazoles administration leads to inconsistent cure rates and several side effects. Researching new anti-Strongyloides drugs is a difficult task since S. stercoralis does not develop until the adult stages in Mus musculus (with the exception of SCID mice), the main experimental host model. Fortunately, alternative parasite models can be used, namely, Strongyloides ratti and S. venezuelensis. However, even with these models, there are other complications in finding new drugs, which are associated with specific in vitro assay protocol steps, such as larvae decontamination. In this review, we highlight the challenges associated with new drug search, the compounds tested, and a list of published in vitro assay methodologies. We also point out advances being made in strongyloidiasis diagnosis so far.

Diagnosis and Treatment of Leishmaniasis: Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA) and the American Society of Tropical Medicine and Hygiene (ASTMH)

It is important to realize that leishmaniasis guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. The IDSA and ASTMH consider adherence to these guidelines to be voluntary, with the ultimate determinations regarding their application to be made by the physician in the light of each patient's individual circumstances.

Screening of living organ donors for endemic infections: Understanding the challenges and benefits of enhanced screening

Living organ donor candidates are screened for medical and psychosocial contraindications to donation. One important goal of this process is to prevent donor-derived infectious diseases transmissions. These transmissions are exceptionally rare, but have the potential to cause significant morbidity and mortality. The Organ Procurement and Transplantation Network now requires each recovery hospital to develop a protocol for evaluating living donors for tuberculosis and other geographically-defined endemic pathogens, including Trypanosoma cruzi (the causative pathogen of Chagas' disease), Strongyloides stercoralis, and West Nile Virus (WNV), in addition to universal screening for blood-borne pathogens. Enhanced screening requirements were developed in response to the changing epidemiology and endemicity of these diseases, as well as recent case reports of donor-derived disease transmission. Living organ donor disease screening presents a number of unique challenges to clinicians and policy-makers, including deciding which donors to test, which testing modality to use, when to test, and appropriate interpretation of results. This review will analyze the epidemiology of T. cruzi, S. stercoralis, and WNV, the assays available for screening for these diseases, and the subsequent impact on the living organ donor process . This article is protected by copyright. All rights reserved.

Parasites

Parasites are an important cause of human disease worldwide. The clinical severity and outcome of parasitic disease is often dependent on the immune status of the host. Specific parasitic diseases discussed in this chapter are amebiasis, giardiasis, cryptosporidiosis, cyclosporiasis, cystoisosporiasis, microsporidosis, granulomatous amebic encephalitis, toxoplasmosis, leishmaniasis, Chagas disease, malaria, babesiosis, strongyloidiasis, and scabies.

The neurology of solid organ transplantation

Transplantation is the rescue treatment for end-stage organ failure with more than 110,000 solid organs transplantations performed worldwide annually. Recent advances in transplantation procedures and posttransplantation management have improved long-term survival and quality of life of transplant recipients, shifting the focus from acute perioperative critical care needs toward long-term chronic medical problems. Neurologic complications affect up to 30-60 % of solid organ transplant recipients. Common etiologies include opportunistic infections and toxicities of antirejection medications, and wide spectrum of toxic and metabolic disturbances. Most complications are common to all allograft types, but some are relatively specific for individual allograft types (e.g., central pontine myelinolysis in liver transplant recipients). Close collaboration between neurologists and other transplant team members is essential for effective management. Early recognition of complications and accurate diagnosis leading to timely treatment is essential to reduce the morbidity and improve the overall transplant outcome.

Toxoplasmosis in organ transplant recipients: Evaluation, implication, and prevention

Toxoplasmosis in organ transplant patients can be a result of donor-transmitted infection, or reactivation of latent infection, or de novo infection. Solid organ transplants including heart, liver, kidney, pancreas and small bowel, and hematogenous stem cell transplants have been implicated in the risk of acquiring infection. In contrast to a benign course in immunocompetent individuals, the spectrum of illness is severe in transplant recipients. Clinical manifestations usually occur within the first 3 months of transplant and may present as encephalitis, pneumonitis, chorioretinitis, meningitis, and disseminated toxoplasmosis with multi-organ involvement. The diagnosis of toxoplasmosis in organ transplant patients is often difficult and is an integration of clinical, radiological, and microbiological workup. Preventive measures include pretransplant evaluation and chemoprophylaxis in view of rapidly progressing and fatal outcome of toxoplasmosis in immunocompromised individuals.

Transplantation in the tropics: lessons on prevention and management of tropical infectious diseases

Tropical infectious diseases (IDs) remain a rare complication in transplant recipients even in tropical settings, but this topic has become increasingly important during the last decade due to multiple factors. Interestingly, non-tropical countries report most of the experiences with tropical diseases. The reported experience from non-endemic regions, however, does not always reflect the experience of endemic areas. Most of the guidelines and recommendations in the literature may not be applicable in tropical settings due to logistical difficulties, cost, and lack of proven benefit. In addition, certain post-transplant prevention measures, as prophylaxis and reducing exposure risk, are not feasible. Nonetheless, risk assessment and post-transplant management of tropical IDs in tropical areas should not be neglected, and clinicians need to have a higher clinical awareness for tropical ID occurring in this population. Herein, we review the more significant tropical ID in transplant patients, focusing on relevant experience reported by tropical settings.

Strongyloidiasis with emphasis on human infections and its different clinical forms

Strongyloidiasis (caused by Strongyloides stercoralis, and to a lesser extent by Strongyloides fuelleborni) is one of the most neglected tropical diseases with endemic areas and affecting more than 100 million people worldwide. Chronic infections in endemic areas can be maintained for decades through the autoinfective cycle with the L3 filariform larvae. In these endemic areas, misdiagnosis, inadequate treatment and the facilitation of the hyperinfection syndrome by immunosuppression are frequent and contribute to a high mortality rate. Despite the serious health impact of strongyloidiasis, it is a neglected disease and very little is known about this parasite and the disease when compared to other helminth infections. Control of the disease is difficult because of the many gaps in our knowledge of strongyloidiasis. We examine the recent literature on different aspects of strongyloidiasis with emphasis in those aspects that need further research.

Travel risk assessment, advice and vaccinations in immunocompromised travellers (HIV, solid organ transplant and haematopoeitic stem cell transplant recipients): A review

International travellers with immunocompromising conditions such as human immunodeficiency virus (HIV) infection, solid organ transplantation (SOT) and haematopoietic stem cell transplantation (HSCT) are at a significant risk of travel-related illnesses from both communicable and non-communicable diseases, depending on the intensity of underlying immune dysfunction, travel destinations and activities. In addition, the choice of travel vaccinations, timing and protective antibody responses are also highly dependent on the underlying conditions and thus pose significant challenges to the health-care providers who are involved in pre-travel risk assessment. This review article provides a framework of understanding and approach to aforementioned groups of immunocompromised travellers regarding pre-travel risk assessment and management; in particular travel vaccinations, infectious and non-infectious disease risks and provision of condition-specific advice; to reduce travel-related mortality and morbidity.