Emerging microsporidian infections in Russian HIV-infected patients

Global prevalence and risk factors of Enterocytozoon bieneusi infection in humans: a systematic review and meta-analysis

Enterocytozoon bieneusi is one of the most important zoonotic pathogens. In this study, we present a systematic review and meta-analysis of the prevalence of human E. bieneusi infection in endemic regions and analyze the various potential risk factors. A total of 75 studies were included. Among 31,644 individuals tested, 2,291 (6.59%) were E. bieneusi-positive. The highest prevalence of E. bieneusi in the male population was 5.50%. The prevalence of E. bieneusi in different age groups was varied, with 10.97% in teenagers. The prevalence of E. bieneusi in asymptomatic patients (6.49%) is significantly lower than that in HIV-infected patients (11.49%), and in patients with diarrheal symptoms (16.45%). Rural areas had a higher rate (7.58%) than urban ones. The prevalence of E. bieneusi in humans was the highest (6.42%) at altitudes <10 m. Moreover, the temperate zone marine climate (13.55%) had the highest prevalence. A total of 69 genotypes of E. bieneusi have been found in humans. This is the first global study regarding E. bieneusi prevalence in humans. Not only people with low immunity (such as the elderly, children, people with HIV, etc.), but also people in Europe in temperate marine climates should exercise caution to prevent infection with E. bieneusi during contact process with animals.

Case series of intestinal microsporidiosis in non-HIV patients caused by Encephalitozoon hellem

Intestinal microsporidiosis is most often caused by Enterocytozoon bieneusi, and to a lesser extent by species of the genus Encephalitozoon. Until now, Encephalitozoon hellem was not clearly known to induce disease restricted to the intestine, or rarely in HIV subjects or in tropical countries. We report here 11 cases of delineated intestinal microsporidioses due to E. hellem diagnosed in France in non-HIV patients. Briefly, all patients were immunocompromised. They all suffered from diarrhoea, associated in nearly 50% of cases with weight loss. Concerning treatment, 5/11 patients had a discontinuation or a decrease of their immunosuppressive therapy, and 4/11 received albendazole. All patients recovered. Five different genotypes were identified based on the rRNA ITS sequence.

Molecular Detection of Microsporidia in Rabbits (Oryctolagus cuniculus) in Tenerife, Canary Islands, Spain

Enterocytozoon bieneusi and Encephalitozoon spp. are microsporidia with zoonotic potential that have been identified in humans, as well as in a large group of wild and domestic animals. Several wildlife species have been studied as reservoirs of zoonotic microsporidia in mainland Spain, including the European rabbit (Oryctolagus cuniculus). Due to a lack of data on microsporidia infection in wildlife on the Canary Islands, the aim of this work was to analyze the prevalence and identify the species of microsporidia in rabbits in Tenerife. Between 2015 and 2017, a total of 50 fecal samples were collected from rabbits in eight municipalities of Tenerife, Canary Islands, Spain. Seven of the fifty samples (14%) were amplified using nested polymerase chain reaction (PCR) targeting the partial sequence of the 16S rRNA gene, the internal transcribed spacer (ITS) region, and the partial sequence of the 5.8S rRNA gene. Sanger sequencing reveals the presence of Encephalitozoon cuniculi genotype I in two samples (4%), and undescribed microsporidia species in five samples (10%). This study constitutes the first molecular detection and genotyping of E. cuniculi in rabbits in Spain.

Evaluation of the Bio-Evolution Microsporidia generic and typing real-time PCR assays for the diagnosis of intestinal microsporidiosis

Cases of intestinal microsporidiosis infection are underestimated and affect both immunocompromized and immunocompetent patients. Real-time PCR is superseding microscopic examination for its diagnosis in medical analysis laboratories. However, few manufacturers include microsporidia in their PCR panel for the diagnosis of infectious gastroenteritis. Here, we evaluated the performances of the real-time PCR assays microsporidia generic and microsporidia typing (Bio-Evolution, France) on the Rotor-Gene Q real-time PCR cycler (Qiagen, France). We included 45 negative and 44 positive stool samples for Enterocytozoon bieneusi (n = 34, with various genotypes), Encephalitozoon intestinalis (n = 4), Encephalitozoon hellem (n = 4), and Encephalitozoon cuniculi (n = 2). We also studied a four-year survey of an inter-laboratory quality control program including 9 centers that used this commercial assay. Sensitivity and specificity of the microsporidia generic assay were 86.4% and 93.3%, respectively. Encephalitozoon hellem and Encephalitozoon cuniculi were detected by the microsporidia generic PCR assay but not by the microsporidia typing PCR assay. These results were consistent with the results of the inter-laboratory quality control program. In conclusion, Bio-Evolution Real-time PCR assays are useful tools for intestinal microsporidiosis, but negative results for microsporidia typing assays require supplementary analyses to confirm E. hellem or E. cuniculi infections.

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.

Immune Response to Microsporidia

Microsporidia are a group of pathogens, which can pose severe risks to the immunocompromised population, such as HIV-infected individuals or organ transplant recipients. Adaptive immunity has been reported to be critical for protection, and mice depleted of T cells are unable to control these infections. In a mouse model of infection, CD8 T cells have been found to be the primary effector cells and are responsible for protecting the infected host. Also, as infection is acquired via a peroral route, CD8 T cells in the gut compartment act as a first line of defense against these pathogens. Thus, generation of a robust CD8 T-cell response exhibiting polyfunctional ability is critical for host survival. In this chapter, we describe the effector CD8 T cells generated during microsporidia infection and the factors that may be essential for generating protective immunity against these understudied but significant pathogens. Overall, this chapter will highlight the necessity for a better understanding of the development of CD8 T-cell responses in gut-associated lymphoid tissue (GALT) and provide some insights into therapies that may be used to restore defective CD8 T-cell functionality in an immunocompromised situation.

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.

Molecular Identification of Encephalitozoon hellem from Companion Birds Kept in Pet Shops, Japan

To evaluate the role of companion birds as a reservoir of Encephalitozoon hellem infection in humans, the present study determined the prevalence and genotypes of E. hellem from 269 birds in 4 pet shops using polymerase chain reaction (PCR) assay. E. hellem was identified in 4.8% (13/269) of the birds and was detected in all pet shops. Every positive sample corresponded to zoonotic genotype 1A. Considering the low prevalence of E. hellem infection, it is likely that the risk of zoonotic transmission from companion birds kept in pet shops to humans is low in Japan.

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.

DEVELOPMENT OF MICROSPORIDIOLOGY IN RUSSIA

The study of microsporidia and microsporidioses of wild animals in Russia has been initiated in the 60-s of the past century. In the European part of country, microsporidia, infecting agricultural insect pests (All-Russian Institute of Plant Protection), freshwater arthropods and fishes (State Research Institute of Lake and River Fisheries) and the blood-sucking insects such as horseflies (Biology Institute, Karelian Scientific Center) were studied. In the Western Siberia, microsporidia of blood-sucking mosquitoes were studied (Tomsk University). As a result, by 2000, as many as 118 species and 47 genera of microsporidia were found, including 20 taxa new to science, from 100 animal species. Currently, descriptions of new taxa and taxonomic revision of the previously described taxa are performed using the molecular phylogenetic analysis. The novel data on speciation of microsporidia have been obtained, and the coevolution of parasites and their host insects have been confirmed for microsporidia of blood-sucking mosquitoes. During the study of the structure and physiology of microsporidia, it has been demonstrated, that the secretory proteins of microsporidia migrate into the nucleus of the host cell; the factors of parasites suppressing host cell apoptosis and the presence of specific organelles related to the energy metabolism have been revealed; the mitosomes have been found in the spores and not the prespore stages of microsporidia. The role of the Golgi complex in the formation of the extrusion apparatus, as well as the absence of the vesicular secretory transport in microsporidia, has been shown for the first time. For the first time in Russia, cases of microsporidia infection in HIV-infected patients have been identified. Currently, attention is paid to the development of a new universal taxonomic system of microsporidia combining molecular characteristics with a description of the structural and developmental features of each taxon of the parasites. Microsporidia possess many remarkable structural and functional differences from any other organisms thus substantiating an independent field of biological research: “microsporidiology”.

Prevalence and Genetic Characterization of Cryptosporidium, Giardia and Enterocytozoon in Chickens From Ezhou, Hubei, China

Cryptosporidium spp., Giardia spp. and microsporidia are important intestinal protozoa responsible for diarrhea in humans and other mammals. China is a major chicken-raising country, and studies on these protozoa in chickens have important public health significance. Here, we investigated the prevalence and genetic characterization of these parasites in chickens from Ezhou City, Hubei Province, China. In total, 206 stool specimens were collected from chickens in four villages of Ezhou between July 2014 and February 2015. Genomic DNA of each specimen was tested by nested PCR based on the Cryptosporidium small subunit rRNA gene, the Giardia intestinalis triose phosphate isomerase gene, and the internal transcribed spacer of the Enterocytozoon bieneusi rRNA gene, respectively. The public health significance of G. intestinalis and E. bieneusi identified in our study was evaluated via phylogenetic analysis. The infection rates were determined to be 2.43% (5/206), 8.25% (17/206), and 1.94% (4/206) for Cryptosporidium, G. intestinalis, and E. bieneusi, respectively. One sample showed coinfection with G. intestinalis and E. bieneusi. Meanwhile, sequence analysis of the PCR-positive samples showed that the Cryptosporidium was C. baileyi, G. intestinalis was assemblage C, and E. bieneusi was genotype D and novel genotype EZ0008. This is the first report of zoonotic G. intestinalis assemblage C in chickens in the world, and the first report of zoonotic E. bieneusi genotype D in chickens in China. These findings indicate new transmission dynamics and molecular epizootiology.

Multimethodological Approach to Gastrointestinal Microsporidiosis in HIV-Infected Patients

PURPOSE

Microsporidiosis is an opportunistic infection that produces chronic diarrhoea and cholangiopathy in patients with AIDS, mainly caused by two species of microsporidia, Enterocytozoon bieneusi and Encephalitozon intestinalis. The aim of this work was to develop an integral system for the diagnosis of microsporidiosis of the intestine and biliary tract in HIV-infected patients, comprising microscopic and molecular techniques.

METHODS

The study population comprised 143 adult patients of both sexes with diagnosis of HIV infection, with chronic diarrhoea, and with or without HIV-associated cholangiopathy. Stool studies for microsporidia identification of spores were performed on each patient. A video esofagogastroduodenoscopy with biopsy collection was also carried out for routine histology and semi-thin sections stained with Azure II. Species identification was carried out by transmission electron microscopy and/or polymerase chain reaction for the species E. bieneusi and E. intestinalis.

RESULTS

Out of the 143 patients a total of 12.6% (n = 18) were infected with microsporidia. Microsporidia species identified in most cases was E. bieneusi (16/18 cases), followed by E. intestinalis (4/18), all of these last ones in coinfection with E. bieneusi.

CONCLUSIONS

Clinical, imaging, microscopic and molecular analyses, when applied in a systematic and integrated approach, allow diagnosis and identification of microsporidia at species level in AIDS patients with chronic diarrhoea, and with or without HIV-associated cholangiopathy.

Enteric Opportunistic Infection and the Impact of Antiretroviral Therapy among HIV/AIDS Patients from Tehran, Iran

BACKGROUND

Opportunistic parasites have been identified as human pathogens, especially in immunodeficient patients. Microsporidian and coccidian infections cause chronic diarrhea as common clinical manifestation in HIV positive patients. In this study, the frequency of opportunistic infections, including microsporidian and coccidian infections, was evaluated in HIV/AIDS patients from Tehran and phylogenic analysis was performed for E. bieneusi isolates from these patients.

METHODS

One hundred and two stool samples were collected from confirmed HIV/AIDS patients, referred to Consult Center of Behavior Diseases, West Health Center, Iran University of Medical Sciences in Tehran, Iran. The samples were transferred to Research Center of Pediatric Infectious Diseases, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences from Jan 2016 to Dec 2016. After conventional formalin-ether concentration, aniline blue staining method and acid-fast staining technique were used for detection of microsporidian spores and Cyclospora oocysts. DNA was extracted and nested PCR was performed.

RESULTS

Two (1.96%) cases were found to be positive for intestinal microsporidia infection using aniline blue staining method and were confirmed as E. bieneusi by nested PCR. One patient was found with Cyclospora cayetanensis infection by acid-fast staining method and PCR. Giardia lamblia and Blastocystis hominis were detected as non-opportunistic parasites in 1/102 (0.98%) and 2/102 (1.96%) of the HIV positive patients, respectively.

CONCLUSION

With respect to the use of antiretroviral therapy (ART) in HIV positive patients, we found a low frequency of infection.

Molecular Phylodiagnosis of Enterocytozoon bieneusi and Encephalitozoon intestinalis in Children with Cancer: Microsporidia in Malignancies as an Emerging Opportunistic Infection

BACKGROUND : Microsporidia may cause infection in both immunocompromised and immunocompetent populations. The best strategy to control microsporidiosis is obtaining thorough knowledge of its outbreak and pathogenicity. PURPOSE : Because of the lack of precise estimation of microsporidia prevalence among Iranian children with cancer, the current study aimed at evaluating the rate of intestinal microsporidia in children undergoing chemotherapy.

METHODS

 Patients with cancer undergoing chemotherapy in a children's hospital in Northwestern Iran were studied; 132 stool samples were collected and stained by the Weber and Ryan-blue modified trichrome staining techniques. The extracted DNA samples were evaluated by the nested polymerase chain reaction (PCR) method. All positive isolates were sequenced for genotyping and phylogenetic analysis.

RESULTS

A total of 17 (12.8%) samples were microscopically positive for microsporidia infection, whereas only 14 (10.6%) cases were positive based on nested PCR results. In the positive samples detected with nested PCR, the frequency of Enterocytozoon bieneusi and Encephalitozoon intestinalis infections was 71.4% (n = 10) and 28.6% (n = 4), respectively. After sequencing and phylogenetic analysis, the genotype of E. bieneusi was type D and the sequences of the isolated species were similar to those of the registered ones.

CONCLUSION

E. bieneusi is a major contributor to microsporidiosis in young immunocompromised patients in Iran. Microsporidia species are well-detected when confirmatory techniques such as molecular methods are in agreement with staining. So, to ensure this, a suggestion has been made to introduce a certain diagnostic test for microsporidiosis.

Occurrence of zoonotic Enterocytozoon bieneusi in cats in Brazil

Enterocytozoon bieneusi is an opportunistic intestinal pathogen that infects humans and a wide variety of animals worldwide. Our aim in this study was to investigate the occurrence of E. bieneusi in a domestic cat population in Campo Grande, Mato Grosso do Sul, Brazil. Sixty fecal samples from diarrheic cats were subjected to polymerase chain reaction (PCR) and the amplicons were sequenced for identification. E. bieneusi was detected in two samples (3.3%), both identified as genotype D. This genotype has already been reported in animals and humans and is considered a zoonotic genotype. Our findings represent the first report of E. bieneusi in domestic cats in Brazil, reinforcing the importance of identifying this agent as a source of infection in animals and humans.

The opportunistic pathogen Encephalitozoon cuniculi in wild living Murinae and Arvicolinae in Central Europe

Encephalitozoon spp. is an obligate intracellular microsporidian parasite that infects a wide range of mammalian hosts, including humans. This study was conducted to determine the prevalence of Encephalitozoon spp. in wild living rodents from Poland, the Czech Republic and Slovakia. Faecal and spleen samples were collected from individuals of Apodemus agrarius, Apodemus flavicollis, Apodemus sylvaticus, and Myodes glareolus (n = 465) and used for DNA extraction. PCR, targeting the ITS region of the rRNA gene was performed. The overall prevalence of microsporidia was 15.1%. The occurrence of Encephalitozoon cuniculi in the abovementioned host species of rodents has been presented for the first time, with the highest infection rate recorded for A. flavicollis. Sequence analysis showed that the most frequent species was E. cuniculi genotype II (92.5%). E. cuniculi genotypes I (1.5%) and III (6.0%) were also identified.

Socio-Behavioral Risk Factors Associated with Cryptosporidiosis in HIV/AIDS Patients Visiting the HIV Referral Clinic at Cape Coast Teaching Hospital, Ghana

Objective:

To identify the socio-behavioral risk factors associated with cryptosporidiosis among HIV/AIDS patients with chronic diarrhea symptoms visiting the HIV referral clinic at Cape Coast Teaching Hospital, Ghana.

Methods:

A cross-sectional study was conducted among 50 HIV/AIDS patients with recurrent diarrhea. Questionnaires were administered to collect social and behavioral risk factors associated with Cryptosporidium and other opportunistic protozoan parasitic infections in HIV patients. Stool samples were collected for the diagnosis of enteric protozoan pathogens using modified Ziehl-Neelsen and acid-fast staining methods. CD4⁺ cells counts of study subjects were obtained from patients clinical records. The data obtained were analyzed using Pearson chi-square and multivariate-adjusted statistics tool on SPSS 16 for Windows.

Results:

Twenty-seven (54%) of the subjects were infected with enteric protozoan pathogens. The prevalences of Cryptosporidium, Cyclospora and Microsporidium infections were 46%, 32% and 16%, respectively. Cryptosporidium infection was significantly associated with drinking water (ײ=13.528, p<0.001), Cyclospora was associated with the type of drinking water (ײ=14.931, p<0.001) and toilet facilities used by the study subjects (ײ=12.463, p<0.01), whiles Microsporidium infection was associated with hand washing behavior (ײ=12.463, p<0.01). Enteric protozoans were frequently encountered among subjects with CD4+ T-cell count <200 cells/mm³. However, coinfection of Cyclospora spp & Cryptosporidium spp was not observed in CD4⁺ cell count <200 and >500 cells/mm^3. Multivariate analysis showed that the risk factor for Cryptosporidium infection among HIV/AIDS patients was the source of drinking water (pipe borne water 76.2% prevalence: sachet water 25%; OR=0.10, 95%CI: 0.03-0.39, p<0.001).

Conclusion:

We report the risk factor for exposure of Cryptosporidium infection among HIV/AIDS patients for the first time in Ghana. The contamination of drinking water by protozoan parasites should be a public health concern. These results provide the stepping block to understand the transmission dynamics of Cryptosporidium and other opportunistic pathogens in HIV/AIDS infected patients in Ghana.

Molecular diagnosis of microsporidia strains in slaughtered cows of southwest of Iran

Microsporidia is often considered as an opportunistic infection in patients with impaired immune systems such as patients with acquired immune deficiency syndrome, transplant recipients, children and old people. Due to the ability of the parasite to transmit from animals to human as well as the increasing prevalence of parasitic infections and immune deficiency diseases; therefore, the aim of this study was to evaluate molecular diagnosis of microsporidia strains in slaughtered cows of southwest of Iran. Initially, 256 stool samples of cows were collected from 5 regions of Khuzestan province, southwest of Iran and stained by modified trichrome (weber). Then, the parasite spores were examined by optical microscope. Total DNA was extracted from samples using DNA extraction kit for stool (Bioneer) and evaluated by multiplex/nested PCR method. The products of nested-PCR were explored by RFLP method using restriction enzyme MnlI. For genotyping, positive samples of RFLP were sequenced. Of 256, 21 and 48 samples were found positive by the staining and nested PCR tests, respectively. Of 48, 36 samples were Enterocytozoon bieneusi with genotype frequency D (22), J (9) and M (5). Also 9 were detected as Encephalitozoon species among which 2 were E. cuniculi, 6 were E. intestinalis and 1 was E. hellem Eventually, 3 samples were found positive for both Enterocytozoon and Encephalitozoon. The results showed that cows can be a source of microsporidia infections. Due to the zoonotic importance of this parasite and its ability to transmit from animals to humans; the detection and species determination of the parasite seems essential. The highest risk of infection is for individuals with impaired immune systems.

Genotyping of Enterocytozoon bieneusi and Subtyping of Blastocystis in Cancer Patients: Relationship to Diarrhea and Assessment of Zoonotic Transmission

Enterocytozoon bieneusi (E. bieneusi) and Blastocystis are common pathogens responsible for diarrhea in humans, especially in immunocompromised individuals. The number of cancer patients has been increasing and diarrhea is a common clinical symptom in the treatment of cancers. To understand the prevalences and genotypes/subtypes of E. bieneusi and Blastocystis in cancer patients in China, to track the infection sources, and to explore the relationships between E. bieneusi and Blastocystis infections and diarrhea, 381 fecal specimens were collected from cancer patients. Each of them was analyzed for the presence of E. bieneusi and Blastocystis by PCR amplifying and sequencing the ITS region of the rRNA gene and the barcode region of the SSU rRNA gene, respectively. 1.3 and 7.1% of cancer patients were positive for E. bieneusi and Blastocystis, respectively. No statistical differences were observed in the infection rates between the groups by age, gender, and residence. E. bieneusi and Blastocystis were both significantly more common in cancer patients with diarrhea, and significant relationship of Blastocystis to diarrhea was found in chemotherapy group. Two E. bieneusi genotypes (D and a novel one named as HLJ-CP1) and two Blastocystis subtypes (ST1 and ST3) were identified with three novel ST1 sequences. This is the first report of occurrence and molecular characterizations of E. bieneusi and Blastocystis in cancer patients in China. E. bieneusi genotype D and Blastocystis ST1 and ST3 have been identified in humans and animals while one novel E. bieneusi genotype falling into zoonotic group 1, implying a potential of zoonotic transmission.

Zoonotic potential of Enterocytozoon genotypes in humans and pigs in Thailand

Enterocytozoon bieneusi is an opportunistic intestinal pathogen infecting humans and a variety of animals. Its mode of transmission and zoonotic potential are not completely understood. E. bieneusi has been frequently identified in pigs. The objective of our study was to investigate E. bieneusi in pigs and humans in Western and Central Thailand to determine its presence, genetic diversity, and zoonotic potential. A total of 277 human and 210 pig faecal samples were collected and analysed. E. bieneusi was found in 5.4% and 28.1% of human and pig samples, respectively, by nested PCR. Genotyping based on the internal transcribed spacer regions of the small subunit ribosomal RNA demonstrated three known genotypes (D, H, PigEb10) and eight novel genotypes (TMH1-8) in humans, and five known genotypes (D, EbpA, EbpC, H, O) and 11 novel genotypes (TMP1-11) in pigs. All known genotypes identified in humans and pigs had zoonotic potential. Further studies are needed to evaluate zoonotic risk of novel genotypes, as pigs may play an important role in the transmission of E. bieneusi.

First Report of the Human-Pathogenic Enterocytozoon bieneusi from Red-Bellied Tree Squirrels (Callosciurus erythraeus) in Sichuan, China

Enterocytozoon bieneusi is a common opportunistic pathogen causing diarrhea and enteric disease in a variety of animal hosts. Although it has been reported in many animals, there is no published information available on the occurrence of E. bieneusi in red-bellied tree squirrels. To understand the occurrence, genetic diversity, and zoonotic potential of E. bieneusi in red-bellied tree squirrels, 144 fecal specimens from Sichuan province, China, were examined by PCR amplification and sequencing of the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene of E. bieneusi. The overall infection rate of E. bieneusi 16.7% (24/144) was observed in red-bellied tree squirrels. Altogether five genotypes of E. bieneusi were identified: three known genotypes D (n = 18), EbpC (n = 3), SC02 (n = 1) and two novel genotypes CE01, CE02 (one each). Multilocus sequence typing (MLST) analysis employing three microsatellite (MS1, MS3, MS7) and one minisatellite (MS4) revealed 16, 14, 7 and 14 positive specimens were successfully sequenced, and identified eight, three, three and two genotypes at four loci, respectively. In phylogenetic analysis, the three known genotypes D, EbpC, and SC02 were clustered into group 1 with zoonotic potential, and the two novel genotypes CE01 and CE02 were clustered into group 6. The present study firstly reported the occurrence of E. bieneusi in red-bellied tree squirrels in China, and the E. bieneusi genotypes D and EbpC were found in humans previously. These results indicate that red-bellied tree squirrels may play a potential role in the transmission of E. bieneusi to humans.

Repertory of eukaryotes (eukaryome) in the human gastrointestinal tract: taxonomy and detection methods

Eukaryotes are an important component of the human gut, and their relationship with the human host varies from parasitic to commensal. Understanding the diversity of human intestinal eukaryotes has important significance for human health. In the past few decades, most of the multitudes of techniques that are involved in the diagnosis of the eukaryotic population in the human intestinal tract were confined to pathological and parasitological aspects that mainly rely on traditionally based methods. However, development of culture-independent molecular techniques comprised of direct DNA extraction from faeces followed by sequencing, offer new opportunities to estimate the occurrence of eukaryotes in the human gut by providing data on the entire eukaryotic community, particularly not-yet-cultured or fastidious organisms. Further broad surveys of the eukaryotic communities in the gut based on high throughput tools such as next generation sequencing might lead to uncovering the real diversity of these ubiquitous organisms in the human intestinal tract and discovering the unrecognized roles of these eukaryotes in modulating the host immune system and inducing changes in host gut physiology and ecosystem.

Zoonotic Enterocytozoon bieneusi genotypes found in brazilian sheep

The presence of Enterocytozoon bieneusi in sheep has been reported in only three countries worldwide. The present study has found E. bieneusi in Brazilian sheep for the first time; in 24/125 (19.2%) fecal samples by PCR and on 8/10 (80%) farms from three diverse locations. A significantly greater number of lambs (34.1%) were found infected than older sheep (11.1%) (P=0.0036); most of the lambs were less than 6months of age. Farms with an intensive production system had a lower infection rate (10.5%) of infection than semi-intensive farms (23%), but this difference was not statistically significant. Sequencing analysis of the internal transcribed spacer (ITS) region of the rRNA gene revealed four known E. bieneusi genotypes (BEB6, BEB7, I, and LW1) and two novel genotypes (BEB18 and BEB19). Genotypes LW1 and BEB19 clustered within designated zoonotic Group 1 while genotypes BEB6, BEB7, I, and BEB18, and clustered within Group 2. BEB6 was the most prevalent (45.8%), followed by BEB7 (33.3%). Genotypes BEB6, I, and LW1 are zoonotic and can pose a risk to human health for immunocompromised individuals.

Molecular testing for clinical diagnosis and epidemiological investigations of intestinal parasitic infections

Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.

More than a rabbit's tale - Encephalitozoon spp. in wild mammals and birds

Within the microsporidian genus Encephalitozoon, three species, Encephalitozoon cuniculi, Encephalitozoon hellem and Encephalitozoon intestinalis have been described. Several orders of the Class Aves (Passeriformes, Psittaciformes, Apodiformes, Ciconiiformis, Gruiformes, Columbiformes, Suliformes, Podicipediformes, Anseriformes, Struthioniformes, Falconiformes) and of the Class Mammalia (Rodentia, Lagomorpha, Primates, Artyodactyla, Soricomorpha, Chiroptera, Carnivora) can become infected. Especially E. cuniculi has a very broad host range while E. hellem is mainly distributed amongst birds. E. intestinalis has so far been detected only sporadically in wild animals. Although genotyping allows the identification of strains with a certain host preference, recent studies have demonstrated that they have no strict host specificity. Accordingly, humans can become infected with any of the four strains of E. cuniculi as well as with E. hellem or E. intestinalis, the latter being the most common. Especially, but not exclusively, immunocompromised people are at risk. Environmental contamination with as well as direct transmission of Encephalitozoon is therefore highly relevant for public health. Moreover, endangered species might be threatened by the spread of pathogens into their habitats. In captivity, clinically overt and often fatal disease seems to occur frequently. In conclusion, Encephalitozoon appears to be common in wild warm-blooded animals and these hosts may present important reservoirs for environmental contamination and maintenance of the pathogens. Similar to domestic animals, asymptomatic infections seem to occur frequently but in captive wild animals severe disease has also been reported. Detailed investigations into the epidemiology and clinical relevance of these microsporidia will permit a full appraisal of their role as pathogens.

Establishing a New Species Encephalitozoon pogonae for the Microsporidian Parasite of Inland Bearded Dragon Pogona vitticeps Ahl 1927 (Reptilia, Squamata, Agamidae)

The microsporidium parasitizing Inland Bearded Dragons Pogona vitticeps, and developing primarily in macrophages within foci of granulomatous inflammation of different organs, is described as a new species Encephalitozoon pogonae. Establishing the new species was based on sequencing the ITS-SSUrDNA region of the ribosomal gene and consequent SSUrDNA-inferred phylogenetic analyses, as well as on comparison of pathogenesis, host specificity, and ultrastructure among Encephalitozoon species and isolates. The new species is closely related to E. lacertae and E. cuniculi. Analysis of the literature suggests that this microsporidium has been reported previously as an unidentified microsporidian species or isolate of E. cuniculi and may represent a common infection in bearded dragons. All stages of E. pogonae develop in parasitophorous vacuoles. Uninucleate spores on methanol-fixed smears measured 2.1 × 1.1 μm, range 1.7-2.6 × 0.9-1.7 μm; on ultrathin sections spores measured 0.8-1.1 × 1.8-2.2 μm. Ultrastructural study revealed 3-6 polar filament coils, a mushroom-shaped polar disk, and a polar sac embracing half of the volume occupied by the lamellar polaroplast. In activated spores, polar filament everted eccentrically. The overall morphology and intracellular development of E. pogonae were similar to other Encepahalitozoon spp. We also review the existing data on microsporidia infecting reptiles.

Microsporidiosis in Vertebrate Companion Exotic Animals

Veterinarians caring for companion animals may encounter microsporidia in various host species, and diagnosis and treatment of these fungal organisms can be particularly challenging. Fourteen microsporidial species have been reported to infect humans and some of them are zoonotic; however, to date, direct zoonotic transmission is difficult to document versus transit through the digestive tract. In this context, summarizing information available about microsporidiosis of companion exotic animals is relevant due to the proximity of these animals to their owners. Diagnostic modalities and therapeutic challenges are reviewed by taxa. Further studies are needed to better assess risks associated with animal microsporidia for immunosuppressed owners and to improve detection and treatment of infected companion animals.

Interleukin-12-producing CD103+ CD11b- CD8+ dendritic cells are responsible for eliciting gut intraepithelial lymphocyte response against Encephalitozoon cuniculi

Microsporidia, which belong to the kingdom Fungi, are important opportunistic pathogens in HIV-infected populations and organ transplant recipients that are often associated with a broad range of symptoms, such as diarrhea, nephritis, and encephalitis. Natural infection occurs via the oral route, and as a consequence, gut immunity plays an important role in restricting the dissemination of these pathogens. Studies from our laboratory have reported that the pathogens induce a rapid intraepithelial lymphocyte (IEL) response important for host protection. Although mucosal dendritic cells (DC) are likely involved in triggering an antigen-specific IEL response, the specific subset(s) responsible has yet to be identified. Toward this goal, we demonstrate a very important role for mucosal CD11b(-) CD8(+) DC in the initiation of an antigen-specific IEL in vivo. Effectively, after Encephalitozoon cuniculi infection, CD11b(-) CD8(+) DC were activated in the lamina propria (LP) and acquired the ability to process retinoic acid (RA). However, this subset did not produce interleukin 12 (IL-12) but upregulated CD103, which is essential for migration to the mesenteric lymph nodes (MLN). Interestingly, CD103(+) CD11b(-) CD8(+) DC in the MLN, in addition to processing RA, also secreted IL-12 and were responsible for gut imprinting specificity on mucosal CD8 T cells. To the best of our knowledge, this is the first report describing the importance of MLN CD103(+) CD11b(-) CD8(+) DC isolated from infected animals in the generation of an IEL response against a live pathogen.

Fast Technology Analysis Enables Identification of Species and Genotypes of Latent Microsporidia Infections in Healthy Native Cameroonians

Several enteric microsporidia species have been detected in humans and other vertebrates and their identifications at the genotype level are currently being elucidated. As advanced methods, reagents, and disposal kits for detecting and identifying pathogens become commercially available, it is important to test them in settings other than in laboratories with "state-of-the-art" equipment and well-trained staff members. In the present study, we sought to detect microsporidia DNA preserved and extracted from FTA (fast technology analysis) cards spotted with human fecal suspensions obtained from Cameroonian volunteers living in the capital city of Yaoundé to preclude the need for employing spore-concentrating protocols. Further, we tested whether amplicon nucleotide sequencing approaches could be used on small aliquots taken from the cards to elucidate the diversity of microsporidia species and strains infecting native residents. Of 196 samples analyzed, 12 (6.1%) were positive for microsporidia DNA; Enterocytozoon bieneusi (Type IV and KIN-1), Encephalitozoon cuniculi, and Encephalitozoon intestinalis were identified. These data demonstrate the utility of the FTA cards in identifying genotypes of microsporidia DNA in human fecal samples that may be applied to field testing for prevalence studies.

Effector CD8 T cell immunity in microsporidial infection: a lone defense mechanism

Microsporidia is a group of pathogens, which can pose severe risks to the immunocompromised population such as HIV-infected individuals. The expertise to diagnose these pathogens is limited and therefore their prevalence is believed to be much higher than what is currently known. In a mouse model of infections, it has been reported that CD8 T cells are the primary effector cells responsible for protecting the infected host. As the infection is acquired via per-oral route, CD8 T cells in the gut compartment apparently act as a first line of defense against the pathogens. Thus, generation of a robust CD8 T cell response that exhibits polyfunctional ability is critical for host survival. In this review, we describe the effector CD8 T cells generated during microsporidial infection and underline the factors that may be essential for the elicitation of protective immunity against this understudied but significant pathogen. Overall, this review will highlight the necessity for a better understanding of the development of the CD8 T cell response in gut associated lymphoid tissue (GALT) and provide some insights into therapies that may be used to restore defective CD8 T cell functionality in an immunocompromised situation.

Zoonotic and Potentially Host-Adapted Enterocytozoon bieneusi Genotypes in Sheep and Cattle in Northeast China and an Increasing Concern about the Zoonotic Importance of Previously Considered Ruminant-Adapted Genotypes

This study investigated fecal specimens from 489 sheep and 537 cattle in multiple cities in northeast China for the prevalence and genetic characteristics of Enterocytozoon bieneusi by PCR and sequencing of the ribosomal internal transcribed spacer. Sixty-eight sheep specimens (13.9%) and 32 cattle specimens (6.0%) were positive for E. bieneusi. Sequence polymorphisms enabled the identification of 9 known genotypes (BEB4, BEB6, CM7, CS-4, EbpC, G, I, J, and OEB1) and 11 new genotypes (NESH1 to NESH6 and NECA1 to NECA5). The genotypes formed two genetic clusters in a phylogenetic analysis, with CS-4, EbpC, G, NESH1 to NESH3, and NECA1 to NECA5 distributed in zoonotic group 1 and BEB4, BEB6, CM7, EbpI, J, OEB1, and NESH4 to NESH6 distributed in potentially host-adapted group 2. Nearly 70% of cases of E. bieneusi infections in sheep were contributed by human-pathogenic genotypes BEB6, CS-4, and EbpC, and over 80% of those in cattle were by genotypes BEB4, CS-4, EbpC, I, and J. The cooccurrence of genotypes BEB4, CS-4, EbpC, I, and J in domestic ruminants and children in northeast China and the identification of BEB6 and EbpC in humans and water in central China imply the possibility of zoonotic transmission. This study also summarizes E. bieneusi genotypes obtained from ruminants worldwide and displays their host ranges, geographical distributions, and phylogenetic relationships. The data suggest a host range expansion in some group 2 genotypes (notably BEB4, BEB6, I, and J) that were previously considered to be adapted to ruminants. We should be concerned about the increasing zoonotic importance of group 2 genotypes with low host specificity.

Encephalitozoon cuniculi infection among immunocompromised and immunocompetent humans in Egypt

BACKGROUND

Encephalitozoon cuniculi infects a wide range of homoeothermic animals, including man. Complications due to this microsporidian have been reported only in immunocompromised patients. Reports on E. cuniculi in immunocompetent humans are lacking, most probably, because it is not linked to any clinical manifestations in such hosts. The present work was carried out with the aim of studying, for the first time in Egypt, the prevalence of E. cuniculi infection of urinary tract among non-HIV immunocompromised patients and immunocompetent individuals. It tested also the influence of some factors on the risk of infection.

METHODS

Blood and urine samples were collected from 88 persons (44 non-HIV immunocompromised patients and 44 subjects as immunocompetent control group). IFAT serological assay and Weber's green modified trichrome stain (MTS) urine smears were carried out. Molecular study by PCR was also performed to detect DNA of E. cuniculi in urine samples. A full history sheet was fulfilled for each subject to test the suspected risk factors.

RESULTS

The IFAT examination confirmed the presence of antibodies against E. cuniculi in 44.3% of the human subjects. The seroprevalence of E. cuniculi was significantly higher in the immunocompromised patients compared with the immunocompetent individuals (77.3% versus 11.4%). Compared with IFAT (the gold standard), the sensitivity and specificity of Weber's green MTS smears were 69.23% and 89.80%. By using PCR, no positive cases were detected among human subjects.

CONCLUSION

A high prevalence of E. cuniculi infection in the studied individuals was noted. Although infection was found in some immunocompetent individuals, the immune status of the host remains the corner stone for occurrence of the infection.

Encephalitozoon cuniculi-Associated Equine Encephalitis: A Case Report

A case of encephalitis of unknown origin in the horse was investigated. Postmortem examination findings revealed a nonsuppurative granulomatous meningoencephalitis in the right hemisphere of the cerebral cortex. Testing for West Nile virus, equine herpes virus, equine infectious anemia, Toxoplasma gondii, Neospora caninum, and Sarcocystis neurona were negative. The horse had a titer for Encephalitozoon cuniculi, and sections from the affected area of the brain tested positive for the organism using both polymerase chain reaction (PCR) and immunohistochemistry. Amplicons generated using PCR were sequenced, and E. cuniculi genotype II was identified. This is the first case of E. cuniculi genotype II associated with encephalitis in the horse.

Epidemiology and geographical distribution of enteric protozoan infections in sydney, australia

BACKGROUND

Enteric protozoa are associated with diarrhoeal illnesses in humans; however there are no recent studies on their epidemiology and geographical distribution in Australia. This study describes the epidemiology of enteric protozoa in the state of New South Wales and incorporates spatial analysis to describe their distribution.

DESIGN AND METHODS

Laboratory and clinical records from four public hospitals in Sydney for 910 patients, who tested positive for enteric protozoa over the period January 2007 - December 2010, were identified, examined and analysed. We selected 580 cases which had residence post code data available, enabling us to examine the geographic distribution of patients, and reviewed the clinical data of 252 patients to examine possible links between protozoa, demographic and clinical features.

RESULTS

Frequently detected protozoa were Blastocystis spp. (57%), Giardia intestinalis (27%) and Dientamoeba fragilis (12%). The age distribution showed that the prevalence of protozoa decreased with age up to 24 years but increasing with age from 25 years onwards. The geographic provenance of the patients indicates that the majority of cases of Blastocystis (53.1%) are clustered in and around the Sydney City Business District, while pockets of giardiasis were identified in regional/rural areas. The distribution of cases suggests higher risk of protozoan infection may exist for some communities.

CONCLUSIONS

These findings provide useful information for policy makers to design and tailor interventions to target high risk communities. Follow-up investigation into the risk factors for giardiasis in regional/rural areas is needed. Significance for public healthThis research is significant since it provides the most recent epidemiological update on the common enteric protozoa affecting Australians. It reveals that enteric protozoa cause considerable disease burden in high risk city dwellers, and provides the evidence base for development of targeted interventions for their prevention and control in high risk populations. The prevalence of enteric protozoa in this metropolitan setting underscores that microorganisms do not respect borders and that a collaborative approach is needed to contain the global spread of infectious diseases. Incorporating spatial analysis is valuable in providing a compelling picture of the geographical distribution of these often neglected diseases. Local and State Public Health departments can use this information to support further inves-

Intrinsic TGF-β signaling promotes age-dependent CD8+ T cell polyfunctionality attrition

Advanced age is associated with immune system deficits that result in an increased susceptibility to infectious diseases; however, specific mediators of age-dependent immune dysfunction have not been fully elucidated. Here we demonstrated that aged mice exhibit poor effector CD8+ T cell polyfunctionality, primarily due to CD8+ T cell-extrinsic deficits, and that reduced CD8+ T cell polyfunctionality correlates with increased susceptibility to pathogenic diseases. In aged animals challenged with the parasite Encephalitozoon cuniculi, effector CD8+ T cell survival and polyfunctionality were suppressed by highly elevated TGF-β1. Furthermore, TGF-β depletion reduced effector CD8+ T cell apoptosis in both young and aged mice and enhanced effector CD8+ T cell polyfunctionality in aged mice. Surprisingly, intrinsic blockade of TGF-β signaling in CD8+ T cells was sufficient to rescue polyfunctionality in aged animals. Together, these data demonstrate that low levels of TGF-β1 promote apoptosis of CD8+ effector T cells and high TGF-β1 levels associated with age result in both CD8+ T cell apoptosis and an altered transcriptional profile, which correlates with loss of polyfunctionality. Furthermore, elevated TGF-β levels are observed in the elderly human population and in aged Drosophila, suggesting that TGF-β represents an evolutionarily conserved negative regulator of the immune response in aging organisms.

Genetic polymorphism and zoonotic potential of Enterocytozoon bieneusi from nonhuman primates in China

Enterocytozoon bieneusi is an important zoonotic pathogen. To assess the human-infective potential of E. bieneusi in nonhuman primates (NHPs), we examined the prevalence and genotype distribution of E. bieneusi in 23 NHP species by PCR and sequence analysis of the ribosomal internal transcribed spacer (ITS). A total of 1,386 fecal specimens from NHPs from five provinces in China were examined, and E. bieneusi was detected in 158 (11.4%) specimens from five NHP species, including cynomolgus monkey (67.7%), rhesus macaque (8.8%), Japanese macaque (33.3%), white-headed langur (13.6%), and golden snub-nosed monkey (3.5%) (P < 0.0001). The infection rates were 70.2%, 21.5%, 8.5%, 7.5%, and 5.6% in Guangdong, Yunnan, Guangxi, Henan, and Sichuan Provinces, respectively (P < 0.0001). The prevalence was significantly higher in captive (13.7%) than in free-range (5.0%) animals (P < 0.0001). Altogether, 16 ITS genotypes were observed, including nine known genotypes (IV, D, Henan V, Peru8, PigEBITS7, EbpC, Peru11, BEB6, and I) and seven new genotypes (CM1 to CM7). The common genotypes included CM1, IV, and D, which were detected in 43, 31, and 30 specimens, respectively. Phylogenetic analysis revealed that seven known genotypes (but not BEB6 and I) and four new genotypes (CM1, CM2, CM3, and CM6) belonged to the previously described group 1 with zoonotic potential. Genotypes CM5 and CM7 clustered with group 2, whereas genotype CM4 did not belong to any of the previously proposed groups. It was concluded that humans and NHPs residing in the same geographical location shared the same E. bieneusi genotypes, indicating a potential role of these animals in the zoonotic transmission of E. bieneusi.

[Intestinal parasitoses in Argentina: major causal agents found in the population and in the environment]

Intestinal parasitic diseases are widely spread in the world, with the highest prevalence in developing countries. Children are mainly affected, showing a decrease in physical and mental development, as well as the expected manifestations of the disease. This situation can be greatly enhanced in children with poor nutritional status. The World Health Organization considers intestinal parasitic diseases a major cause of morbidity, closely linked to poverty and poor personal hygiene, inappropriate handling of raw food, lack of sanitation, lack of potable water supply, and environmental fecal contamination. Some parasitic diseases are cosmopolitan while others have variable geographic distribution, due to different factors such as the presence of exclusive intermediate hosts. In the past few years, globalization allowed the spread of certain parasites from endemic to non-endemic regions. Even though people's customs influence on the frequency of certain parasites, environmental conditions are a determinant factor for parasite survival. In our country, due to the variety of soils and climatic conditions, several causative agents of these parasitoses can be found. The aim of this work was to review the literature on the intestinal parasitic agents found in Argentina in human fecal samples and its environment, as parasitic contamination constitutes a direct indicator of the infection risk by intestinal parasites.

Variability in minimal genomes: analysis of tandem repeats in the microsporidia Encephalitozoon intestinalis

Microsporidia are ubiquitous fungi with genomes that have undergone a strong reduction to the extreme cases of Encephalitozoon cuniculi and Encephalitozoon intestinalis. Genetic variability within species of the Encephalitozoon genus has been reported, with most of the studies based on the internal transcribed spacer (ITS) of the rDNA. However, in contrast to the picture of E. cuniculi and Encephalitozoon hellem, where different strains have been identified, no genetic variability has yet been observed in E. intestinalis. We have analysed tandem repeats included in putative coding sequences which could be used as polymorphic markers in E. intestinalis. Eight candidate loci (M2, M2A, M3, M5, M7, M7A, M8 and PTP1) were established and 9 E. intestinalis cultured strains from North America, South America and Europe were analysed. M2, M7 and PTP1 nucleotide sequences were identical among the different strains and the GenBank sequence. In contrast, we observed variants in 4 markers (M2A, M3, M7A and M8) which did not correspond to their respective reference sequences. The most noticeable finding was that with the M5 marker two genotypes were defined among the different strains studied, demonstrating genotypic variability of E. intestinalis. Although the diversity described is certainly not high, which can be explained by a lower chance of genetic variability in its minimal genome, we have demonstrated that polymorphisms actually exist in E. intestinalis. Epidemiological studies using this genetic marker should now be conducted to elucidate the genetic variability in E. intestinalis and improve our knowledge of the epidemiology of this microsporidia.

Microsporidia and coccidia as causes of persistence diarrhea among liver transplant children: incidence rate and species/genotypes

We determined species/genotype(s) of enteric microsporidia and coccidia causing diarrhea among 44 liver transplant children in Shiraz Nemazee hospital using acid-fast-trichrome staining and polymerase chain reaction-sequencing techniques. Enterocytozoon bieneusi (genotype D), Cryptosporidium (parvum and meleagridis) were detected in 6.81% and 11.36% of the children, respectively.

Epidemiology of Enterocytozoon bieneusi Infection in Humans

A review was conducted to examine published works that focus on the complex epidemiology of Enterocytozoon bieneusi infection in humans. Studies on the prevalence of these emerging microsporidian pathogens in humans, in developed and developing countries, the different clinical spectra of E. bieneusi intestinal infection in children, in different settings, and the risk factors associated with E. bieneusi infection have been reviewed. This paper also analyses the impact of the recent application of PCR-based molecular methods for species-specific identification and genotype differentiation has had in increasing the knowledge of the molecular epidemiology of E. bieneusi in humans. The advances in the epidemiology of E. bieneusi, in the last two decades, emphasize the importance of epidemiological control and prevention of E. bieneusi infections, from both the veterinary and human medical perspectives.

Enteric protozoa in the developed world: a public health perspective

Several enteric protozoa cause severe morbidity and mortality in both humans and animals worldwide. In developed settings, enteric protozoa are often ignored as a cause of diarrheal illness due to better hygiene conditions, and as such, very little effort is used toward laboratory diagnosis. Although these protozoa contribute to the high burden of infectious diseases, estimates of their true prevalence are sometimes affected by the lack of sensitive diagnostic techniques to detect them in clinical and environmental specimens. Despite recent advances in the epidemiology, molecular biology, and treatment of protozoan illnesses, gaps in knowledge still exist, requiring further research. There is evidence that climate-related changes will contribute to their burden due to displacement of ecosystems and human and animal populations, increases in atmospheric temperature, flooding and other environmental conditions suitable for transmission, and the need for the reuse of alternative water sources to meet growing population needs. This review discusses the common enteric protozoa from a public health perspective, highlighting their epidemiology, modes of transmission, prevention, and control. It also discusses the potential impact of climate changes on their epidemiology and the issues surrounding waterborne transmission and suggests a multidisciplinary approach to their prevention and control.

Microsporidiosis: not just in AIDS patients

PURPOSE OF REVIEW

Microsporidia have emerged as causes of opportunistic infections associated with diarrhea and wasting in AIDS patients. This review describes recent reports of microsporidiosis in HIV-infected individuals and the growing awareness of microsporidiosis in non-HIV-infected populations.

RECENT FINDINGS

Microsporidia were only rarely recognized as causes of disease in humans until the AIDS pandemic. Implementation of combination antiretroviral therapy (cART) to curtail HIV replication and restore immune status drastically reduced the occurrence of opportunistic infections, including those due to microsporidia, in HIV-infected individuals. In developing countries where cART is not always accessible, microsporidiosis continues to be problematic. Improvement of diagnostic methods over the previous 25 years led to identification of several new species of microsporidia, many of which disseminate from enteric to systemic sites of infection and contribute to some unexpected lesions. Among non-HIV-infected but immune-suppressed individuals, microsporidia have infected organ transplant recipients, children, the elderly, and patients with malignant disease and diabetes. In otherwise healthy immune-competent HIV seronegative populations, self-limiting diarrhea occurred in travelers and as a result of a foodborne outbreak associated with contaminated cucumbers. Keratitis due to microsporidiosis has become problematic and a recent longitudinal evaluation demonstrated that non-HIV-infected individuals seropositive for microsporidia who had no clinical signs continued to intermittently shed organisms in feces and urine.

SUMMARY

Greater awareness and implementation of better diagnostic methods are demonstrating that microsporidia contribute to a wide range of clinical syndromes in HIV-infected and non-HIV-infected people. As such, microsporidia should be considered in differential diagnoses if no other cause can be defined.