Disseminated microsporidiosis in a renal transplant recipient

Microsporidia, a Highly Adaptive Organism and Its Host Expansion to Humans

Emerging infectious disease has become the center of attention since the outbreak of COVID-19. For the coronavirus, bats are suspected to be the origin of the pandemic. Consequently, the spotlight has fallen on zoonotic diseases, and the focus now expands to organisms other than viruses. Microsporidia is a single-cell organism that can infect a wide range of hosts such as insects, mammals, and humans. Its pathogenicity differs among species, and host immunological status plays an important role in infectivity and disease severity. Disseminated disease from microsporidiosis can be fatal, especially among patients with a defective immune system. Recently, there were two Trachipleistophora hominis, a microsporidia species which can survive in insects, case reports in Thailand, one patient had disseminated microsporidiosis. This review gathered data of disseminated microsporidiosis and T. hominis infections in humans covering the biological and clinical aspects. There was a total of 22 cases of disseminated microsporidiosis reports worldwide. Ten microsporidia species were identified. Maximum likelihood tree results showed some possible correlations with zoonotic transmissions. For T. hominis, there are currently eight case reports in humans, seven of which had Human Immunodeficiency Virus (HIV) infection. It is observed that risks are higher for the immunocompromised to acquire such infections, however, future studies should look into the entire life cycle, to identify the route of transmission and establish preventive measures, especially among the high-risk groups.

Encephalitozoon spp. as a potential human pathogen

Encephalitzoon spp. are microsporidia, and intracellular opportunistic pathogens. The hosts of these pathogens include vertebrates, invertebrates, and certain protozoa. In people microsporidia may be opportunistic pathogens for immunocompromised patients (with AIDS or after organ transplantation). Infection with these microorganisms was also described in persons with diarrhea and corneal diseases.

The species causing rare infections in humans, Encephalitozooncuniculi, had previously been described from animal hosts. However, several new microsporidial species, including E. intestinalis and E. hellem, have been discovered in humans, raising the question of their natural origin. Vertebrate animals are now identified as hosts for all three microsporidial species infecting humans, implying a zoonotic nature of these microorganisms. Molecular studies have identified phenotypic and/or genetic variability within these species, indicating that they are not uniform, and have allowed the question of their zoonotic potential to be addressed. The focus of this review is to present the zoonotic potential of E. intestinalis, E. cuniculi, and E. hellem.

Seroprevalence of Encephalitozoon cuniculi and Toxoplasma gondii antibodies and risk-factor assessment for Encephalitozoon cuniculi seroprevalence in Finnish pet rabbits (Oryctolagus cuniculus)

Background

Neurological signs, such as head tilt, torticollis, paralysis, and seizures, are common in rabbits. Differential diagnoses include two zoonotic infections caused by the microsporidial fungi Encephalitozoon cuniculi and the apicomplexan protozoa Toxoplasma gondii. Both infections are mainly latent in rabbits but may cause severe or even fatal disease. Although several international studies have reported the seroprevalence of these pathogens in different commercial rabbit populations, similar prevalence studies and risk-factor analyses among family-owned pet rabbits are uncommon and lacking in Scandinavia. We sought to estimate the seroprevalence and possible risk factors for E. cuniculi and T. gondii among Finnish pet rabbits. We used ELISA to measure E. cuniculi IgG seroprevalence of 247 rabbits and modified direct agglutination test for T. gondii seroprevalence of 270 rabbits. Samples were collected as part of the Finnish Pet Rabbit Health Research project. Internet-based questionnaires (n = 231) completed by the rabbit owners were used for risk-factor analysis.

Results

The apparent seroprevalence of E. cuniculi was 29.2% and true seroprevalence of T. gondii 3.9%. Risk factors were analysed only for E. cuniculi due to the low T. gondii seroprevalence. The final multivariable logistic regression model revealed that rabbits spending the whole summer outdoors had a higher risk of being E. cuniculi seropositive than rabbits with limited outdoor access. Additionally, rabbits living in households with only one or two rabbits had higher risk of being E. cuniculi seropositive than those in multi-rabbit households.

Conclusions

Nearly one third of Finnish pet rabbits participating in this study had E. cuniculi IgG antibodies, indicating previous exposure to this pathogen. The prevalence is similar to that reported previously in clinically healthy rabbit populations in UK and Korea. While the seroprevalence of T. gondii was low (3.9%), antibodies were detected. Therefore, these zoonotic parasitic infections should be considered as differential diagnoses when treating rabbits.

Chronic Infections in Mammals Due to Microsporidia

Microsporidia are pathogenic organism related to fungi. They cause infections in a wide variety of mammals as well as in avian, amphibian, and reptilian hosts. Many microsporidia species play an important role in the development of serious diseases that have significant implications in human and veterinary medicine. While microsporidia were originally considered to be opportunistic pathogens in humans, it is now understood that infections also occur in immune competent humans. Encephalitozoon cuniculi, Encephalitozoon intestinalis, and Enterocytozoon bieneusi are primarily mammalian pathogens. However, many other species of microsporidia that have some other primary host that is not a mammal have been reported to cause sporadic mammalian infections. Experimental models and observations in natural infections have demonstrated that microsporidia can cause a latent infection in mammalian hosts. This chapter reviews the published studies on mammalian microsporidiosis and the data on chronic infections due to these enigmatic pathogens.

Epidemiological and clinical study of microsporidiosis in French kidney transplant recipients from 2005 to 2019: TRANS-SPORE registry

INTRODUCTION

Microsporidiosis is an emerging opportunistic infection in renal transplantation (RT) recipients. We aimed to describe its clinical presentation and treatment.

MATERIALS AND METHODS

We collected microsporidiosis cases identified in RT recipients between 2005 and 2019 in six French centers from the Crystal, Divat and Astre prospective databases.

RESULTS

We report 68 RT recipients with intestinal microsporidiosis; the patients were predominantly male (61.8%), with a median age of 58 (46-69) years. Infection occurred at a median time of 3 (0.8-6.8) years posttransplant. Only Enterocytozoon bieneusi was found. Microsporidiosis manifested as diarrhea (98.5% of patients) with weight loss (72.1%) and acute renal injury (57.4%) without inflammatory biological parameters. The therapeutic approaches were no treatment (N = 9), reduction of the immunosuppressive regimen (∆IS) (N = 22), fumagillin alone (N = 9), fumagillin and ∆IS (N = 19), and albendazole or nitazoxanide and ∆IS (N = 9). Overall clinical remission was observed in 60 patients (88.2%). We observed no acute kidney rejection, renal transplant failure, or death within 6 months after microsporidiosis.

CONCLUSION

E. bieneusi is an underestimated opportunistic pathogen in RT recipients, and infection with E. bieneusi leads to diarrhea with important dehydration and acute renal injury. The treatment is based on the reduction of the immunosuppressive regimen and the administration of fumagillin if available.

Microsporidiosis in Humans

Microsporidia are obligate intracellular pathogens identified ∼150 years ago as the cause of pébrine, an economically important infection in silkworms. There are about 220 genera and 1,700 species of microsporidia, which are classified based on their ultrastructural features, developmental cycle, host-parasite relationship, and molecular analysis. Phylogenetic analysis suggests that microsporidia are related to the fungi, being grouped with the Cryptomycota as a basal branch or sister group to the fungi. Microsporidia can be transmitted by food and water and are likely zoonotic, as they parasitize a wide range of invertebrate and vertebrate hosts. Infection in humans occurs in both immunocompetent and immunodeficient hosts, e.g., in patients with organ transplantation, patients with advanced human immunodeficiency virus (HIV) infection, and patients receiving immune modulatory therapy such as anti-tumor necrosis factor alpha antibody. Clusters of infections due to latent infection in transplanted organs have also been demonstrated. Gastrointestinal infection is the most common manifestation; however, microsporidia can infect virtually any organ system, and infection has resulted in keratitis, myositis, cholecystitis, sinusitis, and encephalitis. Both albendazole and fumagillin have efficacy for the treatment of various species of microsporidia; however, albendazole has limited efficacy for the treatment of Enterocytozoon bieneusi. In addition, immune restoration can lead to resolution of infection. While the prevalence rate of microsporidiosis in patients with AIDS has fallen in the United States, due to the widespread use of combination antiretroviral therapy (cART), infection continues to occur throughout the world and is still seen in the United States in the setting of cART if a low CD4 count persists.

Advancement in our understanding of immune response against Encephalitozoon infection

Microsporidia are a group of obligate, intracellular, spore-forming eukaryotic pathogens, which predominantly infects immunocompromised individuals worldwide. Encephalitozoon spp. is one of the most prevalent microsporidia known to infect humans. Host immune system plays a major role in combating pathogens including Encephalitozoon spp. infecting humans. Both innate and adaptive arms of host immune system work together in combating Encephalitozoon infection. Researchers are conducting studies to elucidate the role of both arms of immune system against Encephalitozoon infection. In addition to cell-mediated adaptive immunity, role of innate immunity is also being highlighted in clearance of Encephalitozoon spp. from host body. Therefore, the current review will give a clear and consolidated update on the role of innate as well as adaptive immunity in protection against Encephalitozoon spp.

Prevalence of Intestinal Parasitic Infection in Cancer, Organ Transplant and Primary Immunodeficiency Patients in Tehran, Iran

Background:

Intestinal parasitic infection in immunodeficient patients especially those with impaired cellular immunity, like neoplasia, renal or heart transplant needs careful consideration. The objective of this study is to evaluate the prevalence of intestinal parasites in different group of patients including cancer patients; organ transplants recipients, and primary immunodeficiency patients.

Methods:

Stool samples from 190 patients including 80 patients with Primary Immunodeficiency, 85 cancer patients and 25 organ transplant recipients were collected; a direct examination with Phosphate buffered saline (PBS) and formalin ether concentration was performed. The DNA was extracted from parasitologically confirmed patients and nested PCR and sequencing was performed and new obtained sequences of Cryptosporidium parvum and Enterocytozoon bieneusi were compared with deposited ones.

Results:

In general, the prevalence of parasites was 26/80 (32.5%) in primary immunodeficiency, 22/85(25.9%) in cancer group, and 7/25 (28%) in organ transplant. The prevalence of intestinal parasitic infections in primary immunodeficiency patients were Blastocystis hominis 13 (16.2%), Giardia lamblia 10 (12.5%), Cryptosporidium 1(1.2%), Chilomastix mesnilii 1 (1.2%), Dientamoeba fragilis 1(1.2%). Of 25 organ transplants, 6 (24%) Cryptosporidium sp were found, all of which were confirmed as Cryptosporidium parvum and one case of Microspora in a heart transplant recipient was confirmed as Enterocytozoon bieneusi by PCR sequencing. The predominant intestinal parasitic infection in cancer patients was 19 (22.3%) Blastocystis hominis followed by two (2.3%) Giardia lamblia and one Dientamoeba fragilis 1 (1.1%).

Conclusion:

The high rate of infection with Blastocystis hominis was found in cancer patients especially colorectal cancer patients, so careful consideration should be given by physicians. Cryptosporidium sp was found to be the major cause of parasitic intestinal infection in patients with organ transplant compared to primary immunodeficiency patients; so transplant recipients undergoing immunosuppressive therapy should be considered as a risk group for acquiring microsporidiosis and Cryptosporidium infection.

Symptomatic respiratory Encephalitozoon cuniculi infection in renal transplant recipients

OBJECTIVES

Encephalitozoon spp. and Enterocytozoon bieneusi are intracellular parasitic fungi from the phylum Microsporidia, which initially localize to the intestine. As opportunistic pathogens, Encephalitozoon spp. in particular can disseminate to the respiratory tract, among other locations. Patients on life-long immunosuppression are at higher risk of such infections, mostly symptomatic.

METHODS

Sputum samples and bronchial washings from 72 renal transplant recipients and 105 patients with various respiratory diseases were screened for Encephalitozoon spp. and E. bieneusi by microscopic examination and genus-specific nested PCR followed by genotyping.

RESULTS

A total of 8.3% (6/72) of immunosuppressed renal transplant recipients and 1.9% (2/105) of patients with various respiratory diseases, both immunocompetent and immunosuppressed, were positive for respiratory microsporidial infection. All six transplant recipients were Encephalitozoon cuniculi-positive by PCR/sequencing and five of them suffered from respiratory symptoms. The presence of microsporidial spores was also confirmed microscopically in three of the transplant recipients. Of the two immunocompetent patients with various respiratory diseases, one had an E. cuniculi infection, while the second had an E. bieneusi infection.

CONCLUSIONS

Life-long immunosuppression in renal transplant recipients increases the risk of respiratory infection by E. cuniculi. Microsporidia should be screened in respiratory samples of these patients, particularly when they have respiratory symptoms.

Solid Organ Transplant and Parasitic Diseases: A Review of the Clinical Cases in the Last Two Decades

The aim of this study was to evaluate the occurrence of parasitic infections in solid organ transplant (SOT) recipients. We conducted a systematic review of literature records on post-transplant parasitic infections, published from 1996 to 2016 and available on PubMed database, focusing only on parasitic infections acquired after SOT. The methods and findings of the present review have been presented based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist. From data published in the literature, the real burden of parasitic infections among SOT recipients cannot really be estimated. Nevertheless, publications on the matter are on the increase, probably due to more than one reason: (i) the increasing number of patients transplanted and then treated with immunosuppressive agents; (ii) the “population shift” resulting from immigration and travels to endemic areas, and (iii) the increased attention directed to diagnosis/notification/publication of cases. Considering parasitic infections as emerging and potentially serious in their evolution, additional strategies for the prevention, careful screening and follow-up, with a high level of awareness, identification, and pre-emptive therapy are needed in transplant recipients.

Confirmed microsporidial graft infection in a HIV-negative renal transplant recipient: A case report and review of the literature

Microsporidia are intracellular organisms most commonly known to cause opportunistic infection in patients with human immunodeficiency virus (HIV). There have been several case reports of infection in solid organ and bone marrow transplant recipients. Here, we report a case of a non-HIV-infected renal transplant patient with microsporidiosis of the renal tract associated with acute graft dysfunction. We also review the literature of 12 previously reported cases of microsporidiosis in patients with renal transplants who had described graft involvement. We review the pattern of illness as well as the common renal biopsy features when microsporidial infection is associated with renal graft infection.

Three Cases of Neurologic Syndrome Caused by Donor-Derived Microsporidiosis

Encephalitozoon cuniculi was transmitted from an infected donor to 3 solid organ recipients, 1 of whom died.

In April 2014, a kidney transplant recipient in the United States experienced headache, diplopia, and confusion, followed by neurologic decline and death. An investigation to evaluate the possibility of donor-derived infection determined that 3 patients had received 4 organs (kidney, liver, heart/kidney) from the same donor. The liver recipient experienced tremor and gait instability; the heart/kidney and contralateral kidney recipients were hospitalized with encephalitis. None experienced gastrointestinal symptoms. Encephalitozoon cuniculi was detected by tissue PCR in the central nervous system of the deceased kidney recipient and in renal allograft tissue from both kidney recipients. Urine PCR was positive for E. cuniculi in the 2 surviving recipients. Donor serum was positive for E. cuniculi antibodies. E. cuniculi was transmitted to 3 recipients from 1 donor. This rare presentation of disseminated disease resulted in diagnostic delays. Clinicians should consider donor-derived microsporidial infection in organ recipients with unexplained encephalitis, even when gastrointestinal manifestations are absent.

Production and characterization of monoclonal antibodies against Encephalitozoon intestinalis and Encephalitozoon sp. spores and their developmental stages

Background

Microsporidia are intracellular obligate parasites traditionally associated with immunosuppressed patients; their detection in immunocompetent patients has increased, highlighting their possible importance as emerging pathogens. Detection of spores in stools, urine, body fluids and tissues is difficult and immunological techniques such as immunofluorescence have proved to be a useful and reliable tool in the diagnosis of human microsporidiosis. For this reason, we have produced and characterized monoclonal antibodies (MAbs) specific for Encephalitozoon intestinalis (the second most frequent microsporidian infecting humans), and other Encephalitozoon species, that can be used in different diagnostic techniques.

Results

Seven MAbs were selected in accordance with their optical density (OD). Four (4C4, 2C2, 2E5 and 2H2) were isotype IgG2a; two (3A5 and 3C9) isotype IgG3, and one Mab, 1D7, IgM isotype. The selected monoclonal antibody-secreting hybridomas were characterized by indirect immunofluorescence antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA), Western blot, immunoelectron microscopy (Immunogold) and in vitro cultures. The study by IFAT showed different behavior depending on the MAbs studied. The MAbs 4C4, 2C2, 2E5 and 2H2 showed reactivity against epitopes in the wall of the spore (exospore and endospore) epitopes located in Encephalitozoon sp. spores, whereas the MAbs 3A5, 1D7 and 3C9 showed reactivity against internal epitopes (cytoplasmic contents or sporoplasm) of E. intestinalis spores. All MAbs recognized the developing parasites in the in vitro cultures of E. intestinalis. Additionally, 59 formalin-fixed stool samples that had been previously analyzed were screened, with 26 (44%) presenting microsporidian spores (18 samples with E. intestinalis and 8 samples with Enterocytozoon bieneusi). Detection of microsporidian spores by microscopy was performed using Calcofluor stain, Modified Trichrome, Quick-Hot Gram Chromotrope, as well as IFAT using MAbs 4C4, 2C2, 2E5 and 2H2. The 4 MAbs tested clearly recognized the larger spores corresponding to E. intestinalis, but showed no reactivity with Enterocytozoon bieneusi spores. The mass spectrometry and proteomic study revealed that the Mabs 4C4, 2C2, 2E5 and 2H2 recognized the Spore Wall Protein 1 (SWP1) as the antigenic target.

Conclusions

The IFAT-positive MAbs exhibited excellent reactivity against spores and developmental stages, permitting their use in human and animal diagnosis. The epitopes recognized (exospore, endospore and cytoplasmic contents) by the different MAbs developed need further study, and may reveal potential targets for vaccine development, immunotherapy and chemotherapy.

Microsporidiosis in pediatric renal transplant patients in Cape Town, South Africa: two case reports

Microsporidia are an emerging group of pathogens associated with life-threatening opportunistic infections in immunocompromised hosts, particularly human immunodeficiency virus (HIV)-infected individuals. There have, however, been recent reports of infection in adult solid organ transplant recipients. We report two cases in children, to our knowledge the first in the paediatric literature. Two 13-yr-old, HIV-seronegative females received deceased donor renal transplants from the same donor. Both patients suffered acute cell-mediated rejection and CMV infection reactivation, managed with intensified immunosuppression and ganciclovir. Pyrexia of unknown origin and intermittent diarrhea in both prompted extensive investigations. In both patients, numerous spores of a microsporidial species were demonstrated in renal tissue on biopsy and in the urine, using modified trichrome and quick-hot Gram-chromotrope staining. Electron microscopy and PCR confirmed Encephalitozoon cuniculi infections. Both patients were successfully treated with 400 mg twice daily of albendazole, with sustained clinical improvement. We recommend that microsporidiosis be considered in the differential diagnosis of pyrexia of unknown origin in severely immunocompromised pediatric solid organ transplant recipients, particularly when associated with diarrhea.

Disseminated microsporidiosis in a renal transplant recipient: case report and review of the literature

Microsporidia are opportunistic pathogens that usually cause a limited disease in the gastrointestinal tract. Occasionally, they can cause disseminated disease. In solid organ transplant recipients, disseminated disease has been reported only rarely. We describe a 68-year-old woman who presented with fever, cough, and acute kidney injury 6 months after kidney transplantation. Dissemination was confirmed by identification of microsporidial spores in urine and bronchoalveolar lavage fluid. Polymerase chain reaction analysis identified the species as Encephalitozoon cuniculi.

Parasitic infections in solid organ transplant recipients

Parasitic diseases are rare infections after a solid organ transplant (SOT). Toxoplasmosis, Trypanosoma cruzi, and visceral leishmanias are the 3 main opportunistic protozoal infections that have the potential to be lethal if not diagnosed early and treated appropriately after SOT. Strongyloides stercoralis is the one helminthic disease that is life-threatening after transplant. This review addresses modes of transmission, methods of diagnosis, and treatment of the most serious parasitic infections in SOT. The role of targeted pretransplant screening of the donor and recipient for parasitic diseases is also discussed.

Identification and characterization of microsporidia from fecal samples of HIV-positive patients from Lagos, Nigeria

Background

Microsporidia are obligate intracellular parasites that infect a broad range of vertebrates and invertebrates. They have been increasingly recognized as human pathogens in AIDS patients, mainly associated with a life-threatening chronic diarrhea and systemic disease. However, to date the global epidemiology of human microsporidiosis is poorly understood, and recent data suggest that the incidence of these pathogens is much higher than previously reported and may represent a neglected etiological agent of more common diseases indeed in immunocompetent individuals. To contribute to the knowledge of microsporidia molecular epidemiology in HIV-positive patients in Nigeria, the authors tested stool samples proceeding from patients with and without diarrhea.

Methodology/Principal Findings

Stool samples from 193 HIV-positive patients with and without diarrhea (67 and 126 respectively) from Lagos (Nigeria) were investigated for the presence of microsporidia and Cryptosporidium using Weber’s Chromotrope-based stain, Kinyoun stain, IFAT and PCR. The Weber stain showed 45 fecal samples (23.3%) with characteristic microsporidia spores, and a significant association of microsporidia with diarrhea was observed (O.R.  = 18.2; CI: 95%). A similar result was obtained using Kinyoun stain, showing 44 (31,8%) positive samples with structures morphologically compatible with Cryptosporidium sp, 14 (31.8%) of them with infection mixed with microsporidia. The characterization of microsporidia species by IFAT and PCR allowed identification of Enterocytozoon bieneusi, Encephalitozoon intestinalis and E. cuniculi in 5, 2 and 1 samples respectively. The partial sequencing of the ITS region of the rRNA genes showed that the three isolates of E.bieneusi studied are included in Group I, one of which bears the genotype B.

Conclusions/Significance

To our knowledge, this is the first report of microsporidia characterization in fecal samples from HIV-positive patients from Lagos, Nigeria. These results focus attention on the need to include microsporidial diagnosis in the management of HIV/AIDS infection in Nigeria, at the very least when other more common pathogens have not been detected.

Parasitic infections in solid-organ transplant recipients

PURPOSE OF REVIEW

To provide an updated perspective of the most common parasitic infections occurring in solid-organ transplant (SOT) recipients.

RECENT FINDINGS

Parasitic infections are an emerging problem in SOT programs and represent a diagnostic and therapeutic challenge. Transplantation in endemic areas - including medical tourism, international travel and migration - justify the necessity of considering parasitic infections in the differential diagnosis of posttransplant complications. Molecular techniques, such as PCR, may improve the diagnostic accuracy and help during the follow-up.

SUMMARY

Parasitic infections are an uncommon but potentially severe complication in SOT recipients. An increase of donors emigrated from tropical areas and more posttransplant patients traveling to endemic areas have led to a rise in parasitic infections reported among SOT recipients. Transplant physicians should get familiar with parasitic infections and promote adherence to preventive measures in SOT recipients.

Tubulinosema sp. microsporidian myositis in immunosuppressed patient

The Phylum Microsporidia comprises >1,200 species, only 15 of which are known to infect humans, including the genera Trachipleistophora, Pleistophora, and Brachiola. We report an infection by Tubulinosema sp. in an immunosuppressed patient.

Microsporidia as emerging pathogens and the implication for public health: a 10-year study on HIV-positive and -negative patients

Despite recent advances in the understanding and diagnosis of emerging microsporidian pathogens, more research is necessary to elucidate their complex epidemiology. In fact, studies that reflect true human-infecting microsporidian prevalence are still inadequate. The present 10-year study was undertaken to examine the occurrence of Microsporidia in 1989 stools, 69 urine and 200 pulmonary specimens from HIV-positive and HIV-negative patients using PCR and DNA sequencing. In stools, 12.0% were Microsporidia-positive. Prevalences of 13.9% and 8.5% were observed for HIV+ and HIV- samples, respectively. The percentage of children that were Microsporidia-positive (18.8%) was significantly higher than that of adults (10.2%). In stools, Enterocytozoon bieneusi (6.3%) and Vittaforma-like parasites (6.8%) were identified. Based on the internal transcribed spacer (ITS) region of E. bieneusi, Type IV (37.5%), Peru 6 (29.2%), D (12.5%), A (8.3%), C (6.3%) and PtEb II (6.3%) genotypes were identified. Microsporidia were detected in 1.5% and 1.0% of urine and pulmonary specimens, respectively. Encephalitozoonintestinalis was detected in urine. In pulmonary specimens, Encephalitozoon cuniculi and Vittaforma-like parasites were identified. An immunosuppressive condition and youth (children) appear to be risk factors for microsporidian infection. Microsporidia seems to have an important impact on public health in Portugal, highlighting the need to implement routine diagnosis.

Microsporidia infection in a mexican kidney transplant recipient

Microorganisms of the microsporidia group are obligated intracellular protozoa that belong to the phylum Microspora; currently they are considered to be related or belong to the fungi reign. It is considered an opportunistic infection in humans, and 14 species belonging to 8 different genera have been described. Immunocompromized patients such as those infected with human immunodeficiency virus (HIV), also HIV serum-negative asymptomatic patients, with poor hygienic conditions, and recipients of bone marrow or solid organ transplantation are susceptible to develop deinfection. Sixty transplanted patients with renal microsporidia infection have been reported worldwide. The aim of this paper is to inform about the 2nd case of kidney transplant and microsporidia infection documented in Mexico.

Latent microsporidial infection in immunocompetent individuals - a longitudinal study

BACKGROUND

Microsporidia (Fungi) have been repeatedly identified as the cause of opportunistic infections predominantly in immunodeficient individuals such as AIDS patients. However, the global epidemiology of human microsporidiosis is poorly understood and the ability of microsporidia to survive and multiply in immunocompetent hosts remains unsolved.

AIMS

To determine the presence of latent microsporidia infections in apparently healthy humans in the Czech Republic, the authors tested sera, urine and stool originating from fifteen persons within a three month period examined on a weekly basis.

METHODS

Sera, stool and urine samples originating from fifteen HIV-negative people at risk with occupational exposure to animals, aged 22-56 years, living in the Czech Republic were tested by indirect immunofluorescence assay (IFA) for the presence of specific anti-microsporidial antibodies, standard Calcofluor M2R staining for the detection of microsporidian spores in all urine sediments and stool smears and molecular methods for the microsporidial species determination.

RESULTS

Specific anti-microsporidial antibodies were detected in fourteen individuals, asymptomatic Encephalitozoon spp. infection was found in thirteen and E. bieneusi infection was detected in seven of those examined. While E. hellem 1A and E. cuniculi II were the major causative agents identified, seven different genotypes of E. bieneusi were recorded.

CONCLUSIONS

These findings clearly show that exposure to microsporidia is common and chronic microsporidiosis is not linked to any clinical manifestation in healthy population. Moreover, our results indicate much higher incidence of microsporidial infections among an apparently healthy population than previously reported. These results open the question about the potential risk of reactivation of latent microsporidiosis in cases of immunosupression causing life-threatening disease.

First cases of microsporidiosis in transplant recipients in Spain and review of the literature

Microsporidia are currently considered emerging pathogens responsible for life-threatening infections in organ transplant recipients. Here, we describe the first cases of intestinal microsporidiosis by Enterocytozoon bieneusi genotype D in two non-HIV-infected renal transplant recipients from Spain. Previously reported cases of microsporidiosis in organ transplant recipients have also been reviewed, highlighting the necessity of considering organ transplant recipients a risk group for microsporidiosis. A systematic search for these parasites is recommended in cases of persistent diarrhea and in the differential diagnosis of other syndromes, such as chronic fever of unknown etiology.

Parasitic infections in solid organ transplant recipients

Parasitic infections are an uncommon but potentially severe complication in solid organ transplant (SOT) recipients. An increase in donors who have emigrated from tropical areas and more transplant recipients traveling to endemic areas have led to a rise in parasitic infections reported among SOT recipients. Clinicians should include these infections in their differential diagnosis and promote adherence to preventive measures in SOT recipients.

Disseminated infection with a new genovar of Encephalitozoon cuniculi in a renal transplant recipient

Disseminated microsporidiosis is a life-threatening opportunistic infection. Here, we report about a previously undescribed genovar of Encephalitozoon cuniculi causing disseminated infection in a non-HIV-infected renal transplant recipient. Disseminated microsporidiosis must be considered in the differential diagnosis of chronic fever in renal allograft recipients, even those without urinary symptoms.

Microsporidiosis in solid organ transplant recipients: two Enterocytozoon bieneusi cases and review

Microsporidiosis first came to prominence as an opportunistic infection in patients with acquired immunodeficiency syndrome. Microsporidia are now emerging pathogens responsible for severe diarrhea during solid organ transplantation. Two main clinical entities can be identified: infection by Enterocytozoon bieneusi, causing diarrhea with limited treatment options; and infection by Encephalitozoon intestinalis, which may disseminate and usually responds to albendazole treatment. We describe here 2 cases of microsporidiosis caused by E. bieneusi in a renal and a liver transplant recipient, respectively, in whom complete clinical efficacy of a short course of fumagillin therapy was obtained. Long-term microbiological eradication was assessed using classical methods and monitored using a real-time quantitative polymerase chain reaction-based method. Both patients experienced drug-induced thrombocytopenia, which resolved after withdrawal of the treatment. We also review the 18 other previously reported cases of microsporidiosis in transplant recipients. In case of persistent diarrhea in solid organ transplant patients, microsporidiosis should be considered. Based on the present experience, treating E. bieneusi infection with 7 days of fumagillin therapy is adequate to eradicate E. bieneusi in this context.

Recognition profiles of microsporidian Encephalitozoon cuniculi polar tube protein 1 with human immunoglobulin M antibodies

Microsporidian Encephalitozoon cuniculi has a unique organelle called a polar tube (PT), the extrusion of which is absolutely required to invade a host cell. We recently detected anti-E. cuniculi PT immunoglobulin (Ig) M antibodies in sera from many healthy individuals. The present one-dimensional (1-D) immunoblot analysis predominantly detected a band at 52 kDa in all of the examined human sera with anti-PT IgM. The use of mouse monoclonal antibody confirmed that the 52-kDa band detected in 1-D immunoblots was an antigen derived from the PT, which represents a glycoprotein nature. In addition, from changes in the immunoreactivity of the 52-kDa band before and after treatment with NaOH, we determined that the 24 human serum samples with anti-PT IgM activities could be roughly grouped into three types: (i) sera containing antibodies against only a saccharic determinant (n=3); (ii) sera containing antibodies against only a proteinic determinant (n=11); and (iii) sera showing dual recognition of saccharic and proteinic determinants (n=10). Further two-dimensional (2-D) immunoblot analysis followed by proteomic analysis confirmed that human sera with anti-PT IgM reacted with E. cuniculi polar tube protein 1 (PTP1). Such circulating IgM antibodies may be important in the first line of defence against E. cuniculi infection.

Fumagillin: an anti-infective as a parent molecule for novel angiogenesis inhibitors

Fumagillin is an active amebicide and anti-infective isolated from the fungus Aspergillus fumigatus. Since its characterization in 1951, fumagillin has been studied extensively for its anti-infective properties. Although fumagillin is not approved for systemic use in the USA, this compound has one of the highest efficacies for the treatment of microsporidial infections in HIV-positive patients. Fumagillin does exhibit some side effects that have deterred its acceptance as a viable treatment, but the current body of research on the synthesis of novel analogs of this molecule shows an exciting and promising revival of this drug as both an anti-infective and antiangiogenic agent.

Parasitic infections in transplant recipients

Parasitic infections are important complications of organ transplantation that are often overlooked in the differential diagnosis of post-transplantation pyrexial illness. Although their frequency is unknown, they seem to be much less prevalent than bacterial and viral infections. Only 5% of human pathogenic parasites have been reported to cause significant illness in transplant recipients. Infection can occur via transmission with the graft or blood transfusion, or be acquired de novo from the environment. Recrudescence of dormant infection can lead to active disease. Post-transplantation parasitic disorders tend to cluster into two clinical profiles. First, an acute systemic illness with anemia, constitutional manifestations and variable stigmata of organ involvement; acute graft dysfunction can lead to confusion and acute rejection. Protozoa including malarial Plasmodium, Leishmania, Trypanosoma and Toxoplasma are associated with this profile. The second typical manifestation encompasses a few localized syndromes, usually associated with the lower gastrointestinal tract, caused by either protozoa (Cryptosporidium and microsporidia) or nematodes (Strongyloides and Ascaris). Dissemination of localized infections can lead to life-threatening systemic manifestations. A high index of suspicion is essential, as diagnosis requires special sampling techniques and laboratory procedures. Definitive diagnosis is usually achieved by detecting the parasite in the patient's tissues or body fluids by histological examination or culture, or by polymerase chain reaction amplification of the parasite-specific antigen sequence. Antibody detection using serological techniques is also possible in a few parasitic infections. Certain lesions have characteristic radiological appearances, hence the value of imaging, particularly in the cerebral syndromes. Treatment is usually straightforward (broad spectrum or specific drugs), yet some species are drug resistant.

Detecting immunoglobulin M antibodies against microsporidian Encephalitozoon cuniculi polar tubes in sera from healthy and human immunodeficiency virus-infected persons in Japan

Encephalitozoon cuniculi, a spore-forming obligate intracellular parasitic pathogen belonging to the phylum Microsporidia, has a unique and highly specialized organelle called the polar tube. Using an enzyme immunostaining assay in which germinated E. cuniculi spores were coated onto plastic surfaces, we tested healthy and human immunodeficiency virus (HIV)-infected individuals in Japan for anti-polar tube antibodies of each immunoglobulin (Ig) class. Anti-polar tube IgG was detected in just 4 of 380 healthy individuals; no anti-polar tube IgA was detected in any individuals; however, unexpectedly, anti-polar tube IgM antibodies were detected in 138 individuals (36%). When the healthy individuals were grouped by age, the highest rate of positivity to anti-polar tube IgM antibodies was seen in individuals aged 20 years old or younger. Fifty-nine percent (24/41) of the individuals aged 20 years or younger were anti-polar tube IgM antibody positive. This rate tended to decrease among individuals in older age groups. However, no anti-polar tube IgM antibodies were detected in 21 HIV-infected persons who were younger than 30 years of age and who had CD4 cell levels below 250/mul. These seroepidemiological results clearly indicate that circulating anti-polar tube IgM antibodies that are capable of strongly reacting with filaments extruded from geminated spores exist and suggest that such antibodies may play a part in protective immunity.

Parasitic central nervous system infections in immunocompromised hosts: malaria, microsporidiosis, leishmaniasis, and African trypanosomiasis

Immunosuppression associated with HIV infection or following transplantation increases susceptibility to central nervous system (CNS) infections. Because of increasing international travel, parasites that were previously limited to tropical regions pose an increasing infectious threat to populations at risk for acquiring opportunistic infection, especially people with HIV infection or individuals who have received a solid organ or bone marrow transplant. Although long-term immunosuppression caused by medications such as prednisone likely also increases the risk for acquiring infection and for developing CNS manifestations, little published information is available to support this hypothesis. In an earlier article published in Clinical Infectious Diseases, we described the neurologic manifestations of some of the more common parasitic CNS infections. This review will discuss the presentation, diagnosis, and treatment of the following additional parasitic CNS infections: malaria, microsporidiosis, leishmaniasis, and African trypanosomiasis.

Zoonotic potential of the microsporidia

Microsporidia are long-known parasitic organisms of almost every animal group, including invertebrates and vertebrates. Microsporidia emerged as important opportunistic pathogens in humans when AIDS became pandemic and, more recently, have also increasingly been detected in otherwise immunocompromised patients, including organ transplant recipients, and in immunocompetent persons with corneal infection or diarrhea. Two species causing rare infections in humans, Encephalitozoon cuniculi and Brachiola vesicularum, had previously been described from animal hosts (vertebrates and insects, respectively). However, several new microsporidial species, including Enterocytozoon bieneusi, the most prevalent human microsporidian causing human immunodeficiency virus-associated diarrhea, have been discovered in humans, raising the question of their natural origin. Vertebrate hosts are now identified for all four major microsporidial species infecting humans (E. bieneusi and the three Encephalitozoon spp.), implying a zoonotic nature of these parasites. Molecular studies have identified phenotypic and/or genetic variability within these species, indicating that they are not uniform, and have allowed the question of their zoonotic potential to be addressed. The focus of this review is the zoonotic potential of the various microsporidia and a brief update on other microsporidia which have no known host or an invertebrate host and which cause rare infections in humans.

Detection and identification of Enterocytozoon bieneusi and Encephalitozoon species in stool and urine specimens by PCR and differential hybridization

Several species of microsporidia can cause disease in humans in both immunocompromised and immunocompetent individuals. Enterocytozoon bieneusi and Encephalitozoon intestinalis are most commonly associated with chronic diarrhea. All Encephalitozoon species, including E. intestinalis, E. hellem, and E. cuniculi, also cause disseminated infections. As distinctive treatment options are available for the different genera, identification is clinically important. We evaluated a PCR with primers directed to a conserved region of the small subunit rRNA gene of microsporidia. Hybridization with a generic microsporidium probe and specific probes for each of the four different species was used for identification. Probes were labeled with ruthenium and detected by electrochemiluminescence. The sensitivity of the assay was tested with plasmids containing the region of interest from each of the four different species and Vittaforma corneae as a control. In addition, the assay was tested with feces spiked with cultured spores from each of the three Encephalitozoon species and V. corneae. An analytical sensitivity of 3.5 x 10(2) to 3.5 x 10(3) spores per g of feces, corresponding to 17 to 170 gene copies per PCR, was found, which is several orders of magnitude more sensitive than microscopy after Uvitex 2B fluorescent staining. Stool samples from 22 microscopically diagnosed patients and from 61 uninfected controls were evaluated, showing a sensitivity of at least 95% and a specificity of 100% compared to microscopy. The method was further tested by spiking urine samples with spores of the different Encephalitozoon species.

Monoclonal antibodies for specific detection of Encephalitozoon cuniculi

Seven species-specific monoclonal antibodies (MAbs) were produced against Encephalitozoon cuniculi and characterized. The MAbs were immunoglobulin G, and when used for indirect microimmunofluorescence microscopy and Western immunoblot assays, they detected E. cuniculi originating from clinical samples. They did not cross-react with other Encephalitozoon species (E. intestinalis and E. hellem) or with a collection of gram-negative bacteria, yeast, and other parasites. The MAbs reacted primarily with 121-, 56-, 45-, 43-, and 41-kDa protein epitopes of E. cuniculi. These epitopes were demonstrated to be E. cuniculi species specific by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We developed MAbs to strains of E. cuniculi that can be used successfully to distinguish E. cuniculi from other microsporidial species in cultures established from clinical specimens. These MAbs may provide a specific, simple, rapid, and low-cost tool for the identification and diagnosis of infections due to microsporidia.

Epidemiology of microsporidiosis: sources and modes of transmission

Microsporidia are single-celled, obligate intracellular parasites that were recently reclassified from protozoa to fungi. Microsporidia are considered a cause of emerging and opportunistic infections in humans, and species infecting humans also infect a wide range of animals, raising the concern for zoonotic transmission. Persistent or self-limiting diarrhea are the most common symptoms associated with microsporidiosis in immune-deficient or immune-competent individuals, respectively. Microsporidian spores appear to be relatively resistant under environmental conditions, and species of microsporidia infecting humans and animals have been identified in water sources, raising concern about water-borne transmission. Sensitive and specific immunomagnetic bead separation and PCR-based methods are being developed and applied for detecting microsporidia in infected hosts and water sources for generating more reliable prevalence data. The most effective drugs for treating microsporidiosis in humans currently include albendazole, which is effective against the Encephalitozoon species but not against Enterocytozoon bieneusi, and fumagillin, which has broader anti-microsporidia activity but is toxic in mammals, suggesting a need to identify better drugs. Strategies to capture and disinfect microsporidia in water are being developed and include filtration, coagulation, chlorination, gamma-irradiation, and ozonation.

Induction of a rapid and strong antigen-specific intraepithelial lymphocyte response during oral Encephalitozoon cuniculi infection

Encephalitozoon cuniculi continues to pose a problem for immunocompromised patients. Previous studies from our laboratory have elucidated the importance of the CD8(+) T cell subset in the protection against systemic parasite infection. There have been no studies related to the mucosal immunity induced against this orally acquired pathogen. In the present study, the immune response generated in the gut after oral E. cuniculi infection was evaluated. An early and rapid increase of the intraepithelial lymphocyte (IEL) population of orally infected animals was observed. This increase in the IEL population started as early as day 3 and peaked at day 7 postinfection with persistent elevation thereafter. At day 7 postinfection, IELs expressed strong cytokine messages (IFN-gamma and IL-10) and were highly cytotoxic for parasite-infected syngeneic macrophages. At an E:T ratio of 80:1, these cells were able to cause >60% Ag-specific target cell lysis. A significant increase in the CD8alphaalpha subset of IEL in response to an oral E. cuniculi infection was observed. To the best of our knowledge, such an early expansion of an IEL population exhibiting strong ex vivo cytotoxicity has not been reported with infectious models. These data suggest that IELs act as important barriers for multiplication of this organism leading to the successful resolution of infection. The protective role of IELs may be due both to their inflammatory (IFN-gamma production and cytotoxic response) as well as immunoregulatory (IL-10 production) properties.

Disseminated microsporidiosis in a pancreas/kidney transplant recipient

Human microsporidiosis has been described most commonly in patients with acquired immunodeficiency syndrome and only rarely in those with other forms of immunosuppression. Only 11 cases of microsporidiosis have been reported previously in solid transplant recipients. To our knowledge, this is the first report to describe a case of microsporidiosis in a pancreas/kidney transplant recipient in whom multi-organ system dissemination was observed. This infection was not detected until postmortem examination of stained tissue sections revealed microsporidian spores that were identified as Encephalitozoon species by transmission electron microscopy. It is suspected that leakage from the duodenal anastomosis to the bladder may have contributed to the dissemination of this infection.