Disseminated microsporidiosis in a pancreas/kidney transplant recipient

Prevalence of Encephalitozoon cuniculi Infection in Guinea Pigs (Cavia porcellus) in Poland with Different Clinical Disorders-A Pilot Study

Encephalitozoonosis is a disease caused by E. cuniculi. It is diagnosed primarily in rabbits but is less frequently so in other animal species. E. cuniculi is classified among Microsporidia-fungi frequently found in the environment, that are resistant to numerous external factors. Apart from rabbits, rodents form the next group of animals most exposed to infection with these pathogens. The objective of the study was to analyze the prevalence of E. cuniculi infection in guinea pigs with different clinical disorders. The study included 67 animals with E. cuniculi infection confirmed via real-time PCR. The infected animals most frequently exhibited nervous and urinary system symptoms, as well as issues with vision organs, while several animals were also recorded as having problems with the respiratory system and thyroid gland dysfunction. The study shows that encephalitozoonosis constitutes a significant problem in rodents kept as domestic animals, which in turn may be a source of infection for humans.

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.

A Case of Intestinal Microsporidiosis in a Renal Transplant Recipient

Post-renal transplant diarrhea is a common clinical presentation. An extensive list of potential etiology adds to the diagnostic dilemma. In cases of prolonged or intractable diarrhea, invasive tests are often performed. Intestinal microsporidia can be diagnosed with simple non-invasive stool polymerase chain reaction (PCR). Based on this case, we propose an easy to follow flow chart and present a literature review on post-renal transplant diarrhea. Further multicenter validation testing is required for the proposed flow chart.

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.

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.

Parasitic Infections Associated with Unfavourable Outcomes in Transplant Recipients

Introduction. The immunosuppression used after transplantation (Tx) is associated with an increased risk of opportunistic infections. In Europe, parasitic infections after Tx are much less common than viral, bacterial and fungal ones. However, diseases caused by parasites are very common in tropical countries. In the last years the number of travellers with immunosuppression visiting tropical countries has increased. Methods. We performed a literature review to evaluate a risk of parasitic infections after Tx in Europe. Results. There is a real risk of parasitic infection in patients after Tx travelling to tropical countries. Malaria, leishmaniasis, strongyloidiasis and schistosomiasis are the most dangerous and relatively common. Although the incidence of these tropical infections after Tx has not increased, the course of disease could be fatal. There are also some cosmopolitan parasitic infections dangerous for patients after Tx. The greatest threat in Europe is toxoplasmosis, especially in heart and bone marrow recipients. The most severe manifestations of toxoplasmosis are myocarditis, encephalitis and disseminated disease. Diarrhoea is one of the most common symptoms of parasitic infection. In Europe the most prevalent pathogens causing diarrhoea are Giardia duodenalis and Cryptosporidium. Conclusions. Solid organ and bone marrow transplantations, blood transfusions and immunosuppressive treatment are associated with a small but real risk of parasitic infections in European citizens. In patients with severe parasitic infection, i.e., those with lung or brain involvement or a disseminated disease, the progression is very rapid and the prognosis is bad. Establishing a diagnosis before the patient's death is challenging.

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.

Microsporidia - Emergent Pathogens in the Global Food Chain

Intensification of food production has the potential to drive increased disease prevalence in food plants and animals. Microsporidia are diversely distributed, opportunistic, and density-dependent parasites infecting hosts from almost all known animal taxa. They are frequent in highly managed aquatic and terrestrial hosts, many of which are vulnerable to epizootics, and all of which are crucial for the stability of the animal-human food chain. Mass rearing and changes in global climate may exacerbate disease and more efficient transmission of parasites in stressed or immune-deficient hosts. Further, human microsporidiosis appears to be adventitious and primarily associated with an increasing community of immune-deficient individuals. Taken together, strong evidence exists for an increasing prevalence of microsporidiosis in animals and humans, and for sharing of pathogens across hosts and biomes.

Microsporidiosis acquired through solid organ transplantation: a public health investigation

BACKGROUND

Encephalitozoon cuniculi, a microsporidial species most commonly recognized as a cause of renal, respiratory, and central nervous system infections in immunosuppressed patients, was identified as the cause of a temporally associated cluster of febrile illness among 3 solid organ transplant recipients from a common donor.

OBJECTIVE

To confirm the source of the illness, assess donor and recipient risk factors, and provide therapy recommendations for ill recipients.

DESIGN

Public health investigation.

SETTING

Two transplant hospitals and community interview with the deceased donor's family.

PATIENTS

Three transplant recipients and the organ donor.

MEASUREMENTS

Specimens were tested for microsporidia by using culture, immunofluorescent antibody, polymerase chain reaction,immunohistochemistry, and electron microscopy. Donor medical records were reviewed and a questionnaire was developed to assess for microsporidial infection.

RESULTS

Kidneys and lungs were procured from the deceased donor and transplanted to 3 recipients who became ill with fever 7 to 10 weeks after the transplant. Results of urine culture, serologic,and polymerase chain reaction testing were positive for E. cuniculi of genotype III in each recipient; the organism was also identified in biopsy or autopsy specimens in all recipients. The donor had positive serologic test results for E. cuniculi. Surviving recipients received albendazole. Donor assessment did not identify factors for suspected E. cuniculi infection.

LIMITATION

Inability to detect organism by culture or polymerase chain reaction in donor due to lack of autopsy specimens.

CONCLUSION

Microsporidiosis is now recognized as an emerging transplant-associated disease and should be considered in febrile transplant recipients when tests for routinely encountered agents are unrevealing. Donor-derived disease is critical to assess when multiple recipients from a common donor are ill.

Prevalence and diversity of Encephalitozoon spp. and Enterocytozoon bieneusi in wild boars (Sus scrofa) in Central Europe

From 2011 to 2012, the occurrence of Enterocytozoon bieneusi and Encephalitozoon spp. was surveyed at 29 randomly selected localities (both forest areas and enclosures) across four Central European countries: Austria, the Czech Republic, Poland, and the Slovak Republic. Isolates were genotyped by PCR amplification and characterization of the internal transcribed spacer (ITS) region using Enterocytozoon and Encephalitozoon-specific protocols. PCR revealed 16 mono-infections of Encephalitozoon cuniculi, 33 mono-infections of Enterocytozoon bieneusi and 5 concurrent infections of both Encephalitozoon cuniculi and Enterocytozoon bieneusi out of 460 faecal samples. Two genotypes (I and II) were revealed by sequence analysis of the ITS region of Encephalitozoon cuniculi. Eleven genotypes, five previously found in other hosts including domestic pigs (D, EbpA, EbpC, G and Henan-I) and six novel (WildBoar1-6), were identified in Enterocytozoon bieneusi. No other microsporidia infection was found in the examined faecal samples. Prevalence of microsporidia at the locality level ranged from 0 to 58.8 %; the prevalence was less than 25 % at more than 86 % of localities. Enterocytozoon bieneusi was detected as a predominant species infecting Eurasian wild boars (Sus scrofa). The present report is the most comprehensive survey of microsporidia infections in wild boars within the Czech Republic and selected Central European countries.

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.

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.

Molecular identification and genotyping of Microsporidia in selected hosts

The work is described by microscopic analysis, the serological analysis (IFAT) and the molecular analysis of isolates from clinical samples (blood, faeces and urine) from ten domestic rabbits (Oryctolagus cuniculus), breed Maličký, four New Zealand domestic rabbits, 11 sows of breed Slo0076akian Improved White and 15 clinically healthy laboratory BALB/c mice. The aim of the study was to validate the suitability of species-unspecific primer pairs 530F and 580R for genotype determination of the Microsporidia strain and species-specific primer pairs ECUNF and ECUNR, SINTF and SINTR and EBIER1 and EBIEF1 for the determination of E ncephalitozoon cuniculi, Encephalitozoon intestinalis and Enterocytozoon bieneusi species for diagnostic purposes. Sequences of animals were compared with those from the GenBank database. In rabbits, two murine genotypes II and four canine genotypes III were identified. Genotype II was identified in mice. The Encephalitozoon intestinalis identified in the sample from swine showed no genetic heterogeneity.

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.

Transplantation and tropical infectious diseases

The number of transplant recipients with tropical infectious diseases is growing due to increasing international travel and the rising number of transplants taking place in the tropics and subtropics. With increases in population migration, the prevalence of individuals infected with geographically restricted organisms also rises. There are three potential categories of tropical infections in transplant patients: (1) donor-related infections transmitted by the graft or through transfusion of blood products; (2) reactivation or recrudescence of latent infections in the donor recipient; and (3) de novo acquisition of infection in the post-transplant period through the traditional route of infection. We present an overall discussion of the association of parasitic (protozoa and helminths) and non-parasitic (viral, bacterial, and fungal) tropical infectious diseases and solid-organ and hematopoietic transplantation. We also suggest potential screening guidelines for some of these tropical infections.

Innate immune responses to Encephalitozoon species infections

Microsporidia are obligate intracellular, eukaryotic fungi, which have gained recognition as opportunistic parasites in immunocompromised patients. Resistance to lethal microsporidia infections requires a Th1 immune response; how this protection is initiated against Encephalitozoon species is the focus of this review article.

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.

Toll-like receptor 2 recognition of the microsporidia Encephalitozoon spp. induces nuclear translocation of NF-kappaB and subsequent inflammatory responses

Microsporidia are obligate intracellular parasites that are ubiquitous in nature and have been recognized as causing an important emerging disease among immunocompromised individuals. Limited knowledge exists about the immune response against these organisms, and virtually nothing is known about the receptors involved in host recognition. Toll-like receptors (TLR) are pattern recognition receptors that bind to specific molecules found on pathogens and signal a variety of inflammatory responses. In this study, we show that both Encephalitozoon cuniculi and Encephalitozoon intestinalis are preferentially recognized by TLR2 and not by TLR4 in primary human macrophages. This is the first demonstration of host receptor recognition of any microsporidian species. TLR2 ligation is known to activate NF-kappaB, resulting in inflammatory cytokines, such as tumor necrosis factor alpha (TNF-alpha) and interleukin-8 (IL-8). We found that the infection of primary human macrophages leads to the nuclear translocation of NF-kappaB in as early as 1 h and the subsequent production of TNF-alpha and IL-8. To verify the direct role of TLR2 parasite recognition in the production of these cytokines, the receptor was knocked down in primary human macrophages using small interfering RNA. This knockdown resulted in decreases in both the nuclear translocation of NF-kappaB and the levels of TNF-alpha and IL-8 after challenge with spores. Taken together, these experiments directly link the initial inflammatory response induced by Encephalitozoon spp. to TLR2 stimulation in human macrophages.

Effect of four antimicrobials against an Encephalitozoon sp. (Microsporidia) in a grasshopper host

Encephalitozoon spp. are the primary microsporidial pathogens of humans and domesticated animals. In this experiment, we test the efficacy of 4 commercial antimicrobials against an Encephalitozoon sp. infecting a grasshopper (Romalea microptera) host. Oral treatment with fumagillin or thiabendazole significantly reduced pathogen spore counts (93% and 88% respectively), whereas spore counts of grasshoppers fed quinine produced a non-significant 53% reduction in spores, and those fed streptomycin a non-significant 29% increase in spores, compared to the control. We observed a moderate dose-response effect for thiabendazole, whereby spore count decreased as drug consumption increased. No thiabendazole-treated animals died, whereas 27% of streptomycin-treated animals died, suggesting that thiabendazole was not toxic at the doses administered. The deaths among streptomycin-treated animals may have been caused by drug toxicity, parasite burden, or both. Although fumagillin and thiabendazole significantly reduced spore counts, in no individual was the pathogen totally eliminated. Our data confirm that microsporidia are difficult to control and that fumagillin and thiabendazole are partially effective antimicrobials against this group. Our study suggests that quinine and related alkaloids should be further examined for antimicrosporidial activity, and streptomycin should be examined as a possible enhancer of microsporidiosis.

Zoonoses in Solid-Organ and Hematopoietic Stem Cell Transplant Recipients

Numerous reports exist of the transmission of zoonoses to humans during and after solid-organ and hematopoietic stem cell transplantation. Donor-derived infections of numerous etiologies, including West Nile virus infection, Chagas disease, toxoplasmosis, rabies, lymphocytic choriomeningitis virus infection, and infection due to Brucella species have been reported. Most zoonoses occur as a primary infection after transplantation, and immunocompromised patients are more likely to experience significant morbidity and mortality from these infections. Risks of zoonotic infection in the posttransplantation period could be reduced by patient education. Increased recognition of the risks of zoonoses, as well as the advent of molecular biology-based testing, will potentially augment diagnostic aptitude. Documented zoonotic infection as it affects transplantation will be the primary focus of this review.

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.

Induction of host chemotactic response by Encephalitozoon spp

Microsporidians are a group of emerging pathogens typically associated with chronic diarrhea in immunocompromised individuals. The number of reports of infections with these organisms and the disseminated pathology is growing as diagnostic tools become more readily available. However, little is known about the innate immune response induced by and generated against these parasites. Using a coculture chemotaxis system, primary human macrophages were infected with Encephalitozoon cuniculi or Encephalitozoon intestinalis, and the recruitment of naïve monocytes was monitored. Encephalitozoon spp. induced an average threefold increase in migration of naïve cells 48 h postinfection, which corresponded to optimal infection of monocyte-derived-macrophages. A limited microarray analysis of infected macrophages revealed several chemokines involved in the inflammatory responses whose expression was upregulated, including CCL1, CCL2, CCL3, CCL4, CCL7, CCL15, CCL20, CXCL1, CXCL2, CXCL3, CXCL5, and CXCL8. The levels of 6 of 11 chemokines also present in the microarray were confirmed to be elevated by protein profiling. Kinetic studies confirmed that secreted CCL2, CCL3, and CCL4 were expressed as early as 6 h postinfection, with peak expression at 12 to 24 h and expression remaining until 48 h postinfection. Neutralization of these chemokines, specifically CCL4, significantly reduced the number of migrating cells in vitro, indicating their role in the induction of monocyte migration. This mechanism of recruitment not only supports the evidence that in vivo cellular infiltration occurs but also provides new hosts for the parasites, which escape macrophages by rupturing the host cell. To our knowledge, this is the first documentation that chemokine production is induced by microsporidian infections in human macrophages.

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.