Screening of opportunistic Encephalitozoon intestinalis and Enterocytozoon bieneusi in immunocompromised patients in Slovakia

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.

Investigation of the presence of Enterocytozoon bieneusi and Encephalitozoon intestinalis in immunosuppressed patients with diarrhea by IFA and real time PCR methods

PURPOSE

This study aimed to investigate the frequency of Enterocytozoon bieneusi and Encephalitozoon intestinalis in patients with diarrhea in the immunosuppressed.

METHODS

Patients between the ages of 18-85 who applied to different clinics of Muş Bulanık and Bitlis State Hospitals and were referred to the microbiology or parasitology laboratory were selected for this study. A total of 200 individuals, including 88 immunosuppressed with diarrhea patients, 38 immunocompetent with diarrhea patients, 38 immunosuppressed without diarrhea patients, and 36 immunocompetent without diarrhea individuals, were included. Collected stool samples were evaluated using IFA-MAbs and real-time PCR methods to determine the frequency of E.intestinalis and E.bieneusi.

RESULTS

E. intestinalis was detected in 59 (29.5%) of 200 samples and E. bieneusi was detected in 46 (23.0%) of them. Mixed infection was detected in 16 (8%) of the positive samples. While there was no statistically significant difference between E. intestinalis positivity and gender, age, diarrhea status and immune system status, a statistically significant relationship was determined between E. bieneusi positivity and diarrhea. When the real-time PCR method was accepted as the gold standard, the sensitivity of the IFA-MAbs method in the diagnosis of E. intestinalis was 94.54%, the specificity was 97.24, the sensitivity in the diagnosis of E. bieneusi was 95.45%, and the specificity was 98.72%. The overall accuracy of the IFA-MAbs method was 96.5% for the diagnosis of E. intestinalis and 98% for the diagnosis of E. bieneusi.

CONCLUSIONS

The findings suggest that E. intestinalis and E. bieneusi should be considered in both immunosuppressed and healthy individuals with diarrhea. IFA-MAbs method can be used in addition to the real-time PCR method to diagnose E. intestinalis and E. bieneusi.

The successful treatment of Enterocytozoon bieneusi Microsporidiosis with nitazoxanide in a patient with B-ALL: A Case Report

Introduction

Enterocytozoon bieneusi (E. bieneusi) Microsporidia can cause opportunistic infections in immunocompromised patients and is also an emerging disease in these individuals. Its clinical manifestations are chronic diarrhea and severe wasting syndrome, these can be extremely debilitating and carry a significant risk of death for immunocompromised patients. Often, microsporidia cannot be confirmed immediately by routine examination and culture. Effective and available treatment options are limited for infections caused by E. bieneusi in humans. Such cases are very rare in Chinese Mainland.

Case presentation

A 47-year-old male had recurrent, profuse watery diarrhea and abdominal discomfort for more than 7 months, with a fever for 5 days. Two years earlier, he received treatment with a modified BFM-90 protocol for acute B cell lymphoblastic leukemia and is currently in the final stages of maintenance therapy with oral methotrexate and mercaptopurine. The leukemia was assessed as still in remission two months ago. PET/CT showed massive peritoneal fluid accumulation and a high uptake area in the diffused peritoneum (SUVmax 12.57), suggesting tumor invasion or microbial infections. However, broad-spectrum antibacterial therapies were ineffective. Metagenomic sequencing of plasma and peritoneal fluid showed no suggestion of the existence of a tumor but instead showed a high sequence number of DNA and RNA of the Microsporidia. His albendazole treatment failed and subsequent treatment with nitazoxanide successfully resolved the infection.

Conclusion

This case shows that we should consider the possibility of atypical pathogen infection in patients with hematologic malignancy who repeatedly develop unexplained diarrhea with wasting. mNGS can help rule out malignant neoplasms and diagnose infections. Our results suggest that nitazoxanide effectively treats E. bieneusi microsporidia infections.

Zoonotic Enterocytozoon bieneusi genotypes in free-ranging and farmed wild ungulates in Spain

Microsporidia comprises a diverse group of obligate, intracellular, and spore-forming parasites that infect a wide range of animals. Among them, Enterocytozoon bieneusi is the most frequently reported species in humans and other mammals and birds. Data on the epidemiology of E. bieneusi in wildlife is limited. Hence, E. bieneusi was investigated in eight wild ungulate species present in Spain (genera Ammotragus, Capra, Capreolus, Cervus, Dama, Ovis, Rupicapra, and Sus) by molecular methods. Faecal samples were collected from free-ranging (n = 1058) and farmed (n = 324) wild ungulates from five Spanish bioregions. The parasite was detected only in red deer (10.4%, 68/653) and wild boar (0.8%, 3/359). Enterocytozoon bieneusi infections were more common in farmed (19.4%, 63/324) than in wild (1.5%, 5/329) red deer. Eleven genotypes were identified in red deer, eight known (BEB6, BEB17, EbCar2, HLJD-V, MWC_d1, S5, Type IV, and Wildboar3) and three novel (DeerSpEb1, DeerSpEb2, and DeerSpEb3) genotypes. Mixed genotype infections were detected in 15.9% of farmed red deer. Two genotypes were identified in wild boar, a known (Wildboar3) and a novel (WildboarSpEb1) genotypes. All genotypes identified belonged to E. bieneusi zoonotic Groups 1 and 2. This study provides the most comprehensive epidemiological study of E. bieneusi in Spanish ungulates to date, representing the first evidence of the parasite in wild red deer populations worldwide. Spanish wild boars and red deer are reservoir of zoonotic genotypes of E. bieneusi and might play an underestimated role in the transmission of this microsporidian species to humans and other animals.

First Identification and Genotyping of Enterocytozoon bieneusi and Prevalence of Encephalitozoon intestinalis in Patients with Acute Diarrhea in the Republic of Korea

Encephalitozoon intestinalis and Enterocytozoon bieneusi can cause diarrhea in humans, especially severe diarrhea in immunocompromised patients. However, there have been few studies on Enc. intestinalis and Ent. bieneusi in patients with acute diarrhea in the Republic of Korea (ROK). In this study, fecal samples were collected from 1241 patients with acute diarrhea in 2020. Among these, 24 cases of Enc. intestinalis and one case of Ent. bieneusi were detected via PCR amplification of small subunit ribosomal RNA. Genotyping of the internal transcribed spacer region sequence revealed that the detected Ent. bieneusi genotype was in Group 1. This study provides the first evidence that Ent. bieneusi exists in humans in addition to animals in the ROK. To identify the causative agent, continuous monitoring of Enc. intestinalis and Ent. bieneusi is necessary for patients with acute diarrhea in the ROK.

Microsporidiosis in Humans

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

Advancement in our understanding of immune response against Encephalitozoon infection

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

Alternatives in Molecular Diagnostics of Encephalitozoon and Enterocytozoon Infections

Microsporidia are obligate intracellular pathogens that are currently considered to be most directly aligned with fungi. These fungal-related microbes cause infections in every major group of animals, both vertebrate and invertebrate, and more recently, because of AIDS, they have been identified as significant opportunistic parasites in man. The Microsporidia are ubiquitous parasites in the animal kingdom but, until recently, they have maintained relative anonymity because of the specialized nature of pathology researchers. Diagnosis of microsporidia infection from stool examination is possible and has replaced biopsy as the initial diagnostic procedure in many laboratories. These staining techniques can be difficult, however, due to the small size of the spores. The specific identification of microsporidian species has classically depended on ultrastructural examination. With the cloning of the rRNA genes from the human pathogenic microsporidia it has been possible to apply polymerase chain reaction (PCR) techniques for the diagnosis of microsporidial infection at the species and genotype level. The absence of genetic techniques for manipulating microsporidia and their complicated diagnosis hampered research. This study should provide basic insights into the development of diagnostics and the pitfalls of molecular identification of these ubiquitous intracellular pathogens that can be integrated into studies aimed at treating or controlling microsporidiosis.