The monitoring of hematopoietic stem cell transplant donors and recipients from endemic areas for malaria

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.

Endemic or regionally limited parasitic and fungal infections in haematopoietic stem-cell transplantation recipients: a Worldwide Network for Blood and Marrow Transplantation (WBMT) Review

There is a scarcity of data on endemic and regionally limited fungal and parasitic infections in recipients of haematopoietic stem-cell transplantation (HSCT) outside western Europe and North America. This Worldwide Network for Blood and Marrow Transplantation (WBMT) Review is one of two papers aiming to provide guidance to transplantation centres worldwide regarding prevention, diagnosis, and treatment based on the currently available evidence and expert opinion. These recommendations were created and reviewed by physicians with expertise in HSCT or infectious disease, representing several infectious disease and HSCT groups and societies. In this paper, we review the literature on several endemic and regionally limited parasitic and fungal infections, some of which are listed as neglected tropical diseases by WHO, including visceral leishmaniasis, Chagas disease, strongyloidiasis, malaria, schistosomiasis, histoplasmosis, blastomycosis, and coccidioidomycosis.

Transmission of malaria from donors to solid organ transplant recipients: A case report and literature review

Malaria is a febrile and potentially fatal infection. It is typically transmitted to humans through the bite of Anopheles mosquitoes and less frequently can be contracted through blood transfusions, sharing contaminated needles and syringes, mother-to-child transmission, or after solid organ transplantation. Posttransplant malaria has rarely been reported in the literature, even in endemic areas. We report the cases of three solid organ recipients in which Plasmodium vivax infection was documented during postsurgical evaluation 30 days after transplant surgery. The diagnosis of donor-derived malaria was confirmed in all patients by demonstrating Plasmodium in a peripheral blood smear and by polymerase chain reaction (PCR). All recipients had symptoms. The liver transplant recipient had myalgia, arthralgia, and thrombocytopenia; the kidney transplant recipient developed acute renal failure; and the heart transplant recipient had fever, cephalalgia, and tonic-clonic seizures. Pre-transplant screening of donors and recipients from endemic regions may not be sufficient to safely rule out persistent malaria. In Colombia, according to legislation, no mandatory testing is required for the diagnosis of malaria in organ donors in nonendemic areas. Therefore, donor screening by questionnaire is the only tool for preventing transplant-borne malaria. The migratory trend from Venezuela to Colombia has increased the number of imported cases of malaria, and the infection may be present in endemic and nonendemic regions. Although donor evaluation is not standardized in current guidelines, we suggest that donors be tested for malaria with a peripheral blood smear, detection of specific IgG antibodies against Plasmodium, and techniques such as PCR, if possible.

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.

Still Searching for a Suitable Molecular Test to Detect Hidden Plasmodium Infection: A Proposal for Blood Donor Screening in Brazil

Background

Efforts have been made to establish sensitive diagnostic tools for malaria screening in blood banks in order to detect malaria asymptomatic carriers. Microscopy, the malaria reference test in Brazil, is time consuming and its sensitivity depends on microscopist experience. Although molecular tools are available, some aspects need to be considered for large-scale screening: accuracy and robustness for detecting low parasitemia, affordability for application to large number of samples and flexibility to perform on individual or pooled samples.

Methodology

In this retrospective study, we evaluated four molecular assays for detection of malaria parasites in a set of 56 samples previously evaluated by expert microscopy. In addition, we evaluated the effect of pooling samples on the sensitivity and specificity of the molecular assays. A well-characterized cultured sample with 1 parasite/μL was included in all the tests evaluated. DNA was extracted with QIAamp DNA Blood Mini Kit and eluted in 50 μL to concentrate the DNA. Pools were assembled with 10 samples each. Molecular protocols targeting 18S rRNA, included one qPCR genus specific (Lima-genus), one duplex qPCR genus/Pf (PET-genus, PET-Pf) and one duplex qPCR specie-specific (Rougemont: Roug-Pf/Pv and Roug-Pm/Po). Additionally a nested PCR protocol specie-specific was used (Snou-Pf, Snou-Pv, Snou-Pm and Snou-Po).

Results

The limit of detection was 3.5 p/μL and 0.35p/μl for the PET-genus and Lima-genus assays, respectively. Considering the positive (n = 13) and negative (n = 39) unpooled individual samples according to microscopy, the sensitivity of the two genus qPCR assays was 76.9% (Lima-genus) and 72.7% (PET-genus). The Lima-genus and PET-genus showed both sensitivity of 86.7% in the pooled samples. The genus protocols yielded similar results (Kappa value of 1.000) in both individual and pooled samples.

Conclusions

Efforts should be made to improve performance of molecular tests to enable the detection of low-density parasitemia if these tests are to be utilized for blood transfusion screening.

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.

Molecular diagnosis in clinical parasitology: When and why?

Microscopic detection and morphological identification of parasites from clinical specimens are the gold standards for the laboratory diagnosis of parasitic infections. The limitations of such diagnostic assays include insufficient sensitivity and operator dependence. Immunoassays for parasitic antigens are not available for most parasitic infections and have not significantly improved the sensitivity of laboratory detection. Advances in molecular detection by nucleic acid amplification may improve the detection in asymptomatic infections with low parasitic burden. Rapidly accumulating genomic data on parasites allow the design of polymerase chain reaction (PCR) primers directed towards multi-copy gene targets, such as the ribosomal and mitochondrial genes, which further improve the sensitivity. Parasitic cell or its free circulating parasitic DNA can be shed from parasites into blood and excreta which may allow its detection without the whole parasite being present within the portion of clinical sample used for DNA extraction. Multiplex nucleic acid amplification technology allows the simultaneous detection of many parasitic species within a single clinical specimen. In addition to improved sensitivity, nucleic acid amplification with sequencing can help to differentiate different parasitic species at different stages with similar morphology, detect and speciate parasites from fixed histopathological sections and identify anti-parasitic drug resistance. The use of consensus primer and PCR sequencing may even help to identify novel parasitic species. The key limitation of molecular detection is the technological expertise and expense which are usually lacking in the field setting at highly endemic areas. However, such tests can be useful for screening important parasitic infections in asymptomatic patients, donors or recipients coming from endemic areas in the settings of transfusion service or tertiary institutions with transplantation service. Such tests can also be used for monitoring these recipients or highly immunosuppressed patients, so that early preemptive treatment can be given for reactivated parasitic infections while the parasitic burden is still low.