High prevalence of asymptomatic Leishmania spp. infection among liver transplant recipients and donors from an endemic area of Brazil

Immune response to viscerotropic Leishmania: a comprehensive review

L. donovani and L. infantum infections are associated with a broad clinical spectrum, ranging from asymptomatic cases to visceral leishmaniasis (VL) with high mortality rates. Clinical manifestations such as post-kala-azar dermal leishmaniasis (PKDL) and visceral leishmaniasis-associated hemophagocytic lymphohistiocytosis-mimic (VL-associated HLH-mimic) further contribute to the diversity of clinical manifestations. These clinical variations are intricately influenced by the complex interplay between the host's immune response and the parasite's escape mechanisms. This narrative review aims to elucidate the underlying immunological mechanisms associated with each clinical manifestation, drawing from published literature within the last 5 years. Specific attention is directed toward viscerotropic Leishmania sinfection in patients with inborn errors of immunity and acquired immunodeficiencies. In VL, parasites exploit various immune evasion mechanisms, including immune checkpoints, leading to a predominantly anti-inflammatory environment that favors parasite survival. Conversely, nearly 70% of individuals are capable of mounting an effective pro-inflammatory immune response, forming granulomas that contain the parasites. Despite this, some patients may experience reactivation of the disease upon immunosuppression, challenging current understandings of parasite eradication. Individuals living with HIV and those with inborn errors of immunity present a more severe course of infection, often with higher relapse rates. Therefore, it is crucial to exclude both primary and acquired immune deficiencies in patients presenting disease relapse and VL-associated HLH-mimic. The distinction between VL and HLH can be challenging due to clinical similarities, suggesting that the nosological entity known as VL-associated HLH may represent a severe presentation of symptomatic VL and it should be considered more accurate referring to this condition as VL-associated HLH-mimic. Consequently, excluding VL in patients presenting with HLH is essential, as appropriate antimicrobial therapy can reverse immune dysregulation. A comprehensive understanding of the immune-host interaction underlying Leishmania infection is crucial for formulating effective treatment and preventive strategies to mitigate the disease burden.

Epidemiology and Management of Infections in Liver Transplant Recipients

Background: Improvements in liver transplant (LT) outcomes are attributed to advances in surgical techniques, use of potent immunosuppressants, and rigorous pre-LT testing. Despite these improvements, post-LT infections remain the most common complication in this population. Bacteria constitute the most common infectious agents, while fungal and viral infections are also frequently encountered. Multi-drug-resistant bacterial infections develop because of polymicrobial overuse and prolonged hospital stays. Immediate post-LT infections are commonly caused by viruses. Conclusions: Appropriate vaccination, screening of both donor and recipients before LT and antiviral prophylaxis in high-risk individuals are recommended. Antimicrobial drug resistance is common in high-risk LT and associated with poor outcomes; epidemiology and management of these cases is discussed. Additionally, we also discuss the effect of coronavirus disease 2019 (COVID-19) infection and monkeypox in the LT population.

Asymptomatic Leishmania infection in humans: A systematic review

BACKGROUND

Leishmaniasis is a highly prevalent neglected tropical disease. It mainly presents as two forms: cutaneous and visceral leishmaniasis, the latter being the most severe form. However, asymptomatic cases of Leishmania infection result in an increase in the underreporting and transmission of the protozoan OBJECTIVES: In this study, articles on the incidence of asymptomatic Leishmania infection were systematically reviewed.

METHODS

The publications identified in the Medline/PubMed and Science Direct databases included 4568 articles. Inclusion, exclusion, and eligibility criterion analysis resulted in 83 articles being retained. These studies were mostly performed in Brazil (n = 26) and India (n = 15).

RESULTS

Several detection techniques have been used for diagnosis. Among the species found were L. infantum and L. donovani, which result in visceral leishmaniasis, and L. amazonensis, L. braziliensis, and L. panamensis. The incidence rates varied between the analyzed locations, largely due to sampling and the presence or absence of endemism in the regions. The largest populations analyzed were in two studies performed in India and Nepal. One of these studies evaluated 32,529 people and the incidence rate was 8.3% (n = 2702), while the other study evaluated 21,267 people and the incidence rate was 1.76% (n = 375). Only 14.28% of the studies investigated leishmaniasis in blood donors. Preexisting diseases have also been reported.

CONCLUSION

The findings of this systematic review present the incidence of cases of asymptomatic Leishmania infection worldwide, in addition to detailing the studies and offering information for researchers and health authorities to seek alternatives to reduce the number of leishmaniasis cases.

Leishmania infantum Infection of Primary Human Myeloid Cells

Circulating phagocytic cells often serve as cellular targets for a large number of pathogens such as Leishmania parasites. Studying primary human cells in an infectious context requires lengthy procedures for cell isolation that may affect the analysis performed. Using whole blood and a no-lyse and no-wash flow cytometric assay (NoNo assay), we monitored the Leishmania infantum infection of primary human cells. We demonstrated, using fluorescent parasites, that among monocyte cell populations, L. infantum preferentially infects classical (CD14⁺CD16⁻) and intermediate (CD14⁺CD16⁺) primary human monocytes in whole blood. Because classical monocytes are the preponderant population, they represent the larger L. infantum reservoir. Moreover, we also found that, concomitantly to monocyte infection, a subset of PMNs is infected early in whole blood. Of interest, in whole blood, PMNs are less infected compared to classical monocytes. Overall, by using this NoNo assay, we provided a novel avenue in our understanding of host–leishmania interactions.

Identification of asymptomatic Leishmania infections: a scoping review

BACKGROUND

Asymptomatic Leishmania infection may play an important role in the transmission of the parasite in endemic areas. At present there is no consensus on the definition of asymptomatic Leishmania infection, nor is there a safe and accessible gold standard test for its identification.

METHODS

This paper presents a scoping review to summarize definitions of asymptomatic Leishmania infection found in the literature, as well as to detail the approach (molecular, serological, cellular, and/or parasitological tests) used by researchers to identify this asymptomatic population. A scoping review of published and gray literature related to asymptomatic Leishmania infection was conducted; retrieved citations were screened based on predefined eligibility criteria, and relevant data items were extracted from eligible articles. The analysis is descriptive and is presented using tables, figures, and thematic narrative synthesis.

RESULTS

We conducted a screening of 3008 articles, of which 175 were selected for the full review. Of these articles, we selected 106 that met the inclusion criteria. These articles were published between 1991 and 2021, and in the last 5 years, up to 38 articles were reported. Most of the studies were conducted in Brazil (26%), Spain (14%), India (12%), Bangladesh (10%), and Ethiopia (7%). Of the studies, 84.9% were conducted in the immunocompetent population, while 15.1% were conducted in the immunosuppressed population (HIV, immunosuppressive drugs, and organ transplantation population). We report 14 different techniques and 10 strategies employed by researchers to define asymptomatic Leishmania infection in an endemic area.

CONCLUSIONS

The definition of asymptomatic Leishmania infection is not unified across the literature, but often includes the following criteria: residence (or extended stay) in a Leishmania-endemic area, no reported signs/symptoms compatible with leishmaniasis, and positive on a combination of serological, molecular, cellular, and/or parasitological tests. Caution is recommended when comparing results of different studies on the subject of asymptomatic infections, as the reported prevalence cannot be confidently compared between areas due to the wide variety of tests employed by research groups. More research on the importance of asymptomatic immunosuppressed and immunocompetent Leishmania-positive populations in leishmaniasis epidemiology is required.

Concomitant BK virus infection and visceral Leishmaniasis in a pediatric liver transplant recipient

BACKGROUND

Solid organ transplant recipients are vulnerable to various unusual infections. Visceral Leishmaniasis (VL) is a protozoal opportunistic infection, which may affect the immune-suppressed hosts and solid organ transplant recipients. The BK virus infection is an evolving challenge in kidney transplant recipients. However, there are very few reports of BK virus (BKV) nephropathy involving the native kidney in liver transplant recipients. To the best of our knowledge, this is the first report of the simultaneous occurrence of these rare infections in a liver transplant recipient.

CASE REPORT

The patient was a 9-year-old girl, a case of liver transplantation who presented with the incidental finding of proteinuria, azotemia, and cytopenia. Investigations revealed that she had concomitant BKV nephropathy and visceral leishmaniasis. Both infections were successfully treated.

CONCLUSION

BK virus should be considered as a cause of nephropathy in liver transplant recipients. The presenting features of fever, cytopenia, and splenomegaly in a post-transplant patient should remind of unusual infections such as VL other than the common post-transplant conditions.

Donor acquired visceral leishmaniasis following liver transplantation

Patients who undergo solid organ transplantation are at risk of opportunistic infection associated with immunosuppression. We report a case of confirmed donor derived visceral leishmaniasis (VL), in a patient following liver transplantation causing fever and pancytopenia. The diagnosis was confirmed by bone marrow biopsy, with confirmed positive donor serology, with no other route of transmission. To our knowledge, this is the first case report in the United Kingdom and Europe, of confirmed organ donor transmission of VL. This case report highlights an important consideration of donor derived infections, in the context of solid organ transplantation.

Asymptomatic Leishmania infection in blood donors from a major blood bank in Northeastern Brazil: a cross-sectional study

This study has estimated the risk of Leishmania transmission via blood transfusion in one of the largest blood banks in Northeastern Brazil, where visceral leishmaniasis is endemic. Five hundred blood samples from donors were tested for circulating Leishmania spp. DNA by real-time PCR. Positive samples were tested by a species-specific conventional PCR targeting Leishmania infantum . Overall, 6.2% (95% CI: 4.1–8.3%) of the samples carried Leishmania DNA and in one sample the species was confirmed as L. infantum . No statistically significant differences were found in relation to gender, sex, education level, incomeas well as the place of residence between positive and negative blood donors. Our results confirm the presence of asymptomatic Leishmania carriers among blood donors in a large blood bank in Northeastern Brazil. Considering the studied population, we estimate that for every 1,000 blood donors screened, 41 to 83 will be positive for Leishmania DNA. This finding reinforces the urgent need for elaborating specific Blood bank guidelines to allow the early detection of asymptomatic Leishmania carriers among blood donors before their blood products are transfused to uninfected individuals.

Presence of anti-Leishmania antibodies in candidates for kidney transplantation

OBJECTIVES

Visceral leishmaniasis (VL) is a progressive disease that, left untreated, is typically fatal. The purpose of this investigation was to detect Leishmania sp. infection in hemodialysis patients who had received multiple blood transfusions at a private clinic in Campo Grande, Mato Grosso do Sul state, Midwest Brazil.

METHODS

Fifty randomly selected volunteers were interviewed for collection of demographic, socioeconomic, and epidemiological data. Indirect immunofluorescence (titers positive when ≥1:40) and rK39 immunochromatographic tests were employed for serological investigation.

RESULTS

Males predominated (60%). Age ranged from 20 to 77 years. Most subjects reported being on hemodialysis for at least one year (94%) and 84% were candidates for kidney transplantation, 67% of whom were on the waiting list. Leishmania sp. infection was detected in 32%. Contact with infected dogs was the only variable associated with infection.

CONCLUSIONS

Under immunocompromised conditions, VL is opportunistic and potentially fatal. Despite existing risks, screening for VL is not performed in asymptomatic donors and recipients. The detection of anti-Leishmania antibodies in these patients reinforces the need for infection screening before immunosuppressive treatment is initiated to reduce not only the risks of VL development and severity, but also mortality rates in cases of reactivation of latent infection.

Visceral Leishmaniasis in a Liver Transplant Patient: A Case Report

Leishmaniasis is an infection caused by protozoa of the genus Leishmania, transmitted by sandflies and endemic to more than 88 countries. Visceral leishmaniasis in immunosuppressed patients is a growing concern. We report the case of a 61-year-old male patient with a previous history of alcoholic cirrhosis and portal vein thrombosis who underwent liver transplantation for the treatment of hepatocellular carcinoma. Thirty-six days after the procedure, the patient showed an increase in liver enzymes and was diagnosed with moderate acute rejection of the graft. He was treated with high-dose intravenous corticosteroids, and while showing improvement in biochemical markers, he became febrile 12 days after corticosteroid treatment. He presented daily episodes of fever, even after the use of several antimicrobial, antiviral, and antifungal agents, and a number of negative cultures from different sites were obtained. A bone marrow biopsy was then performed, showing a large number of amastigote forms of Leishmania spp. Treatment with liposomal amphotericin B was initiated; however, the patient progressed to refractory septic shock and death. This case highlights several aspects of visceral leishmaniasis in liver transplant recipients, such as the association of malnutrition to Leishmania infection and the challenges of diagnosing leishmaniasis in cirrhotic patients in which splenomegaly and pancytopenia, the hallmarks of leishmaniasis, may also be attributed to portal hypertension and end-stage liver disease. A high index of suspicion is necessary for the correct diagnosis and treatment of leishmaniasis in this group of patients. This study is compliant with the Helsinki Congress and the Istanbul Declaration.

Leishmania infection in blood donors: A new challenge in leishmaniasis transmission?

Transfusion-transmitted leishmaniasis has been a concern in regions endemic for the disease. Whether immediate or delayed, the risks posed by this mode of transmission call for careful assessment. The purpose of this study was to detect Leishmania infection in blood donors living in an endemic area and to investigate progression to the disease in these individuals. Immunofluorescent antibody test, enzyme-linked immunosorbent assay, leishmaniasis rapid test, and the polymerase chain reaction were applied to 430 donors in an initial evaluation. Of those donors with at least one positive test, 50 were reevaluated four years later by the same methods, as were 25 controls who had been negative on the same tests. In the first evaluation, Leishmania infection was detected in 41.4% (95% CI: 36.7–46.1) of donors (n = 430). None of the 75 reevaluated individuals had developed the disease, but retesting revealed positivity in at least one test in 36.0% (95% CI: 25.1–46.9) of donors. Of the 50 initially testing positive, 50% remained so on retesting. Of the 25 initially negative controls, two tested positive in the subsequent evaluation. The severity of the parasitosis and the risk of transfusion transmission warrant investigation of the potential inclusion of methods for Leishmania detection into blood banks for effective screening of infected donors.

New insights into leishmaniasis in the immunosuppressed

Immunosuppression contributes significantly to the caseload of visceral leishmaniasis (VL). HIV coinfection, solid organ transplantation, malnutrition, and helminth infections are the most important immunosuppression-related factors. This review briefly describes the challenges of these associations. East Africa and the Indian subcontinent are the places where HIV imposes the highest burden in VL. In the highlands of Northern Ethiopia, migrant rural workers are at a greater risk of coinfection and malnutrition, while in India, HIV reduces the sustainability of a successful elimination programme. As shown from a longitudinal cohort in Madrid, VL is an additional threat to solid organ transplantation. The association with malnutrition is more complex since it can be both a cause and a consequence of VL. Different regimes for therapy and secondary prevention are discussed as well as the role of nutrients on the prophylaxis of VL in poverty-stricken endemic areas.

Current approaches to visceral leishmaniasis treatment in solid organ transplant recipients

INTRODUCTION

The increasing number of transplants performed worldwide and the growing global mobility with migration and travel to and from developing countries and tropical areas are bringing new challenges for the management of transplant infectious diseases, previously less commonly seen, such as Leishmaniasis. However, in this scenario there is a lack of information and the current knowledge is based on a few studies. The selection of the most appropriate treatment depends on various factors, such as patient profile, Leishmania species, disease extent, drug availability, concomitant infections and previous treatments. Therapeutic options may include different formulations of amphotericin B, pentavalent antimonials, miltefosine and paromomycin, among others. These drugs can be used alone or in combination. Areas covered: This review is a practical guide for Visceral Leishmaniasis (VL) specific treatment in solid organ transplant recipients (SOT), including therapeutic options and assessment of therapy response. Expert commentary: The main challenges for treatment of leishmaniasis in SOT recipients are related to the duration of therapy, curative criteria and secondary prophylaxis. Immunosuppression dose reduction is often recommended, but such decisions must be made on an individual basis. At present, Liposomal Amphotericin B is the best choice for treatment and prophylaxis.

Leishmaniasis in solid organ and hematopoietic stem cell transplant recipients

Leishmaniasis occurs in <1% of solid organ and hematopoietic stem cell transplant recipients in endemic countries in which transplants are performed. Visceral leishmaniasis (VL) makes up the bulk of reported cases. The onset generally occurs months after transplantation and the mode of acquisition is often impossible to determine, but de novo vector-borne infection and reactivation of inapparent infection are thought to be the principal means. The potential role of clinically inapparent donor infection is uncertain and screening is not currently recommended, nor is it recommended for recipients from endemic areas, some of whom may have detectable circulating protozoan nucleic acid. While transplant recipients with VL often present with the non-specific findings of fever and cytopenia, the additional presence of hepatosplenomegaly in patients from endemic areas should lead to a directed diagnostic evaluation with bone marrow examination and PCR testing of marrow and peripheral blood having a high yield. Management may often be complicated by the presence of concomitant infections. A lipid formulation of amphotericin B is the preferred treatment, especially for VL, but the relapse rate in transplant recipients is approximately 25%. PCR monitoring of blood for either secondary prophylaxis or preemptive therapy requires further study.

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.

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.

Cytokine Release Assays as Tests for Exposure to Leishmania, and for Confirming Cure from Leishmaniasis, in Solid Organ Transplant Recipients

Spain has one of the world’s largest pools of organ donors and is a global leader in terms of the number of transplants it performs. The current outbreak of leishmaniasis in Fuenlabrada (in the southwest of the region of Madrid, Spain) has involved 600 clinical cases since late 2009 (prevalence 0.2%). It may therefore be wise to monitor the town’s transplanted population for Leishmania infantum; its members are immunosuppressed and at greater risk of infection and relapse following treatment. The present work examines the use of cytokine release assays to determine the prevalence of Leishmania infection in this population, and to confirm recovery following treatment for visceral leishmaniasis (VL). The humoral and cellular immune responses to L. infantum were characterized in 63 solid organ transplant (SOT) recipients from Fuenlabrada, 57 of whom reported no previous episode of VL (NVL subjects), and six of whom had been cured of VL (CVL subjects). Seventeen subjects (12 NVL and 5 CVL) showed a patent lymphoproliferative response to soluble Leishmania antigen (SLA). Stimulation of peripheral blood mononuclear cell cultures and of whole blood with SLA led to the production of different combinations of cytokines that might serve to confirm Leishmania infection or recovery from VL and help prevent cured patients from relapsing into this serious condition.

We have used cytokine release assays to determine the prevalence of Leishmania infantum infection in solid organ transplant (SOT) recipients living in an area where the organism is endemic following an outbreak. Some 21.05% of SOT recipients with no previous history of leishmaniasis had been in contact with the parasite; the risk of these individuals becoming infected by Leishmania is high, a consequence of their need to be maintained in an immunosuppressed state. The results indicate the usefulness of whole blood stimulation assays, and of IFN-γ/TNF-α analysis, for determining exposure to Leishmania and confirming cure from visceral leishmaniasis in SOT recipients.

A Novel Molecular Test to Diagnose Canine Visceral Leishmaniasis at the Point of Care

Dogs are the principal reservoir hosts of zoonotic visceral leishmaniasis (VL) but current serological methods are not sensitive enough to detect all subclinically infected animals, which is crucial to VL control programs. Polymerase chain reaction (PCR) methods have greater sensitivity but require expensive equipment and trained personnel, impairing its implementation in endemic areas. We developed a diagnostic test that uses isothermal recombinase polymerase amplification (RPA) to detect Leishmania infantum. This method was coupled with lateral flow (LF) reading with the naked eye to be adapted as a point-of-care test. The L. infantum RPA-LF had an analytical sensitivity similar to real time-PCR, detecting DNA of 0.1 parasites spiked in dog blood, which was equivalent to 40 parasites/mL. There was no cross amplification with dog or human DNA or with Leishmania braziliensis, Leishmania amazonensis, or Trypanosoma cruzi. The test also amplified Leishmania donovani strains (N = 7). In a group of clinically normal dogs (N = 30), RPA-LF detected more subclinical infections than rK39 strip test, a standard serological method (50% versus 13.3% positivity, respectively; P = 0.005). Also, RPA-LF detected L. infantum in noninvasive mucosal samples of dogs with a sensitivity comparable to blood samples. This novel molecular test may have a positive impact in leishmaniasis control programs.

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.

Risk factors, clinical features and outcomes of visceral leishmaniasis in solid-organ transplant recipients: a retrospective multicenter case-control study

Visceral leishmaniasis (VL) is a rare disease in solid-organ transplant (SOT) recipients. Therefore, little is known about the risk factors and disease behavior in the transplant setting. This multicenter, matched case-control study (1:2 ratio) was designed to determine the risk factors, clinical features and outcomes of VL among this population. Control and case subjects were matched by center, transplant type and timing. Thirty-six VL cases were identified among 25 139 SOT recipients (0.1%). VL occurred 5.7-fold more frequently in Brazil than in Spain, presenting a median time of 11 months after transplantation. High-dose prednisone in the preceding 6 months was associated with VL. Patients were diagnosed over 1 month after symptom onset in 25% of cases. Thirty-one patients (86%) were febrile upon diagnosis, 81% exhibited visceromegaly and 47% showed pancytopenia. Concomitant infection was common. Parasites were identified in 89% of patients; the remaining patients were diagnosed by serology. The majority of the patients received amphotericin B. Relapses occurred in 25.7% of cases, and the crude mortality rate was 2.8%. VL after SOT is related to the VL prevalence in the general population. Delayed diagnosis frequently occurs. Liposomal amphotericin is the most commonly used therapy; mortality is low, although relapses are common.

Serological survey of Leishmania infection in blood donors in Salvador, Northeastern Brazil

BACKGROUND

Visceral Leishmaniasis is endemic to Brazil, where it is caused by Leishmania infantum (syn. Leishmania chagasi). Following parasite inoculation, individuals may experience asymptomatic infection, raising the possibility of parasite transmission through the transfusion of contaminated blood products. In the present work, we evaluated the prevalence of asymptomatic Leishmania infection among blood donors in Salvador, northeastern Brazil.

METHODS

Peripheral blood was collected from 700 blood donors attending the Blood Bank of Bahia (HEMOBA/SESAB), from January to September 2010. We evaluated anti-Leishmania serology by ELISA, employing Soluble Leishmania Antigen (sensitivity 90% and specificity 95%). The presence of parasite DNA was determined by qPCR, targeting a single copy gene (G6PD), and by end-point PCR, targeting multiple targets, namely a segment located in the Leishmania rRNA locus (ITS) and the conserved region of kinetoplastid DNA (kDNA) minicircles.

RESULTS

The blood-donor population was comprised of 74.5% of males with a mean age of 34 years. Anti-Leishmania serology by ELISA was positive in 5.4% (38/700) individuals. One individual was also positive for Chagas' disease and another tested positive for Syphilis. Employing qPCR, parasite DNA was not found in any of 38 seropositive samples. However, by ITS PCR, 8/38 (21%) samples were positive and this positivity increased to 26/38 (68%) when we targeted kDNA amplification. Agreement between both techniques (ITS and kDNA PCR) was fair (kappa = 0.219).

CONCLUSIONS

These results indicate that asymptomatic infection is present among the blood donor population of Salvador, a finding that warrants a broader discussion regarding the need to implement specific screening strategies.