Wild micromammal host spectrum of zoonotic eukaryotic parasites in Spain. Occurrence and genetic characterisation

Micromammals have historically been recognized as highly contentious species in terms of the maintenance and transmission of zoonotic pathogens to humans. Limited information is currently available on the epidemiology and potential public health significance of intestinal eukaryotes in wild micromammals. We examined 490 faecal samples, grouped into 155 pools, obtained from 11 micromammal species captured in 11 Spanish provinces for the presence of DNA from Cryptosporidium spp., Giardia duodenalis, Enterocytozoon bieneusi and Blastocystis sp. The presence of Leishmania spp. was investigated in individual spleen samples. All micromammal species investigated harboured infections by at least one eukaryotic parasite, except Apodemus flavicollis, Myodes glareolus, Sorex coronatus and Sciurus vulgaris, but the sample size for these host species was very low. Cryptosporidium spp. was the most prevalent species found (3.7%, 95% confidence interval [CI]: 2.2-5.7), followed by G. duodenalis (2.8%, 95% CI: 1.6-4.6) and E. bieneusi (2.6%, 95% CI: 1.4-4.3). All pooled faecal samples tested negative for Blastocystis sp. Leishmania infantum was identified in 0.41% (95% CI: 0.05-1.46) of the 490 individual spleen samples analysed. Sequence analyses allowed the identification of Cryptosporidium andersoni (5.9%), C. ditrichi (11.7%), C. muris (5.9%), C. parvum (5.9%), C. tyzzeri (5.9%), rat genotypes CR97 (5.9%) and W19 (5.9%), vole genotypes V (11.7%) and VII (5.9%) and Cryptosproridium spp. (35.3%) within Cryptosporidium (n = 17). Known genotypes C (66.7%) and Peru11 (25.0%) and a novel genotype (named MouseSpEb1, 8.3%) were detected within E. bieneusi (n = 12). None of the G. duodenalis-positive samples could be genotyped at the assemblage level. Molecular data indicate that wild micromammals were primarily infected by rodent-adapted species/genotypes of eukaryotic pathogens and thereby have a limited role as a source of human infections. The presence of ruminant-adapted species C. andersoni along with finding C. parvum is indicative of an overlap between domestic/peri-domestic and sylvatic transmission cycles of these agents.

Infects the Enterocytes of Adult Chinook Salmon (Oncorhynchus tshawytscha) and May Be a Sentinel of Immunosenescence

A novel Enterocytozoon infection was identified in the intestines of sexually mature Chinook salmon. While microsporidian parasites are common across a diverse range of animal hosts, this novel species is remarkable because it demonstrates biological, pathological, and genetic similarity with Enterocytozoon bieneusi, the most common causative agent of microsporidiosis in AIDS patients. There are similarities in the immune and endocrine processes of sexually mature Pacific salmon and immunocompromised humans, suggesting possible common mechanisms of susceptibility in these two highly divergent host species. The discovery of Enterocytozoon schreckii n. sp. contributes to clarifying the phylogenetic relationships within family Enterocytozoonidae. The phylogenetic and morphological features of this species support the redescription of Enterocytozoon to include Enterospora as a junior synonym. Furthermore, the discovery of this novel parasite may have important implications for conservation, as it could be a sentinel of immune suppression, disease, and prespawning mortality in threatened populations of salmonids.

IMPORTANCE In this work, we describe a new microsporidian species that infects the enterocytes of Chinook salmon. This novel pathogen is closely related to Enterocytozoon bieneusi, an opportunistic pathogen commonly found in AIDS patients and other severely immunocompromised humans. The discovery of this novel pathogen is of interest because it has only been found in sexually mature Chinook salmon, which have compromised immune systems due to the stresses of migration and maturation and which share similar pathological features with immunocompromised and senescent humans. The discovery of this novel pathogen could lead to new insights regarding how microsporidiosis relates to immunosuppression across animal hosts.

Incubation period, spore shedding duration, and symptoms of Enterocytozoon bieneusi genotype C infection in a foodborne outbreak in Denmark, 2020

Background

Microsporidia are rarely reported to cause outbreaks of diarrhea. We describe a foodborne outbreak of microsporidiosis from a workplace canteen in November 2020 in Denmark.

Methods

A probable case was defined as any person using the canteen between 4 November and 13 December 2020, reporting at least one gastrointestinal symptom, whereas a confirmed case also had an Enterocytozoon bieneusi positive stool sample. A web-based questionnaire was used to collect clinical, epidemiological, and food exposure data. We performed a retrospective cohort study and tested stool samples from affected individuals for bacterial, viral, and parasitic pathogens, including E. bieneusi.

Results

Altogether, 195 individuals completed the questionnaire. We identified 52 cases (65% male; median age 45 years [range 25–65]). Diarrhea (90%), fatigue (83%), and abdominal pain (79%) were the most commonly reported symptoms. Eight cases were laboratory-confirmed and had E. bieneusi genotype C. The incubation period was between 5 and 12 days, and polymerase chain reaction (PCR)-detectable spore shedding occurred up to 43 days after symptom onset. Disease was associated with consuming food from the workplace canteen on 4 November 2020 (relative risk [RR[, 2.8 [95% confidence interval [CI]: 1.4 – 5.4]) and lunchboxes containing open sandwiches (RR, 3.2 [95% CI: 1.4 – 7.2]) served that day.

Conclusions

This is the second documented foodborne outbreak of E. bieneusi genotype C-associated diarrhea worldwide. Epidemiological findings advocated an open sandwiches lunchbox from 4 November 2020, as a likely source. E. bieneusi may be an under-reported cause of outbreaks of diarrhea, and testing for it might be useful in foodborne outbreak investigations.

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.

Global prevalence of microsporidia infection in cats: A systematic review and meta-analysis of an emerging zoonotic pathogen

Microsporidiosis in pet and stray cats is an emerging zoonotic threat with public health significance worldwide. However, the epidemiological patterns of feline microsporidiosis is still neglected around the world. Hence, current systematic review and meta-analysis aimed at characterizing the prevalence estimates and genotypes of microsporidian parasites among cats of the world. Several databases (PubMed, Web of Science, Scopus, and Google scholar) were systematically explored to find relevant studies. Evaluation of the weighted prevalences among included studies was done using random-effects model. Totally, 30 studies (34 datasets) reported from 19 countries were included in the present work. Microsporidia infection demonstrated higher prevalence rates using microscopy 29.7 % (19.7-42.2 %), followed by serology and molecular techniques with 11 % (4.6-24.2 %) and 8.2 % (5.9-11.4 %), respectively. Moreover, molecular data showed Enterocytozoon bieneusi as the most dominant reported species with 7.4 % (5.1-10.5 %). Also, investigations (11 studies) mostly isolated D genotype among all E. bieneusi genotypes. These results highlight cats as a potential reservoir for acquisition of microsporidia infection in humans, and surveillance programs should be implemented in high-risk areas.

Molecular Diversity of Giardia duodenalis, Cryptosporidium spp. and Blastocystis sp. in Asymptomatic School Children in Leganés, Madrid (Spain)

Enteric parasites including Giardia duodenalis, Cryptosporidium spp., and to a lesser extent, Blastocystis sp. and Enterocytozoon bieneusi, are major worldwide contributors to diarrhoeal disease. Assessing their molecular frequency and diversity is important to ascertain the sources of infection, transmission dynamics, and zoonotic potential. Little molecular information is available on the genotypes of these pathogens circulating in apparently healthy children. Here, we show that asymptomatic carriage of G. duodenalis (17.4%, 95% CI: 15.5‒19.4%), Blastocystis sp. (13.0%, 95% CI: 11.4‒14.8%), and Cryptosporidium spp. (0.9%, 95% CI: 0.5‒1.5%) is common in children (1‒16 years; n = 1512) from Madrid, Spain. Our genotyping data indicate that; (i) the observed frequency and diversity of parasite genetic variants are very similar to those previously identified in Spanish clinical samples, so that the genotype alone does not predict the clinical outcome of the infection, (ii) anthroponotic transmission accounts for a large proportion of the detected cases, highlighting that good personal hygiene practices are important to minimizing the risk of infection, (iii) Blastocystis ST4 may represent a subtype of the parasite with higher pathogenic potential, and (iv) Enterocytozoon bieneusi does not represent a public health concern in healthy children.

"Enterocytozoon bieneusi and Cryptosporidium: a cross-sectional study conducted throughout Thailand"

BACKGROUND

Enterocytozoon bieneusi and Cryptosporidium spp. are prevalent zoonotic parasites associated with a high burden among children. To date only limited molecular epidemiological data on E. bieneusi and Cryptosporidium spp. in humans living in Thailand has been published.

METHODS

PCR-based tools were used to detect and characterize E. bieneusi and Cryptosporidium spp. The internal transcribed spacer (ITS) region of the rRNA gene was used to investigate E. bieneusi, and the small subunit (SSU) rRNA gene was used to investigate Cryptosporidium spp., and 697 fecal samples from villagers and school children in rural areas in Thailand were analyzed.

RESULTS

The infection rates were 2.15% (15/697) for E. bieneusi and 0.14% (1/697) for Cryptosporidium spp. The prevalence of E. bieneusi was significantly high in Loei province. Sequence analysis indicated that the Cryptosporidium isolate was C. parvum. Nine E. bieneusi genotypes were identified, EbpC, Peru12, TMH6, TMH3, TMH7, H, D, and two novel genotypes TMLH1 and TMLH2. E. bieneusi prevalence was significantly higher in male participants than in female participants, and in children aged 3-15 years than in participants aged > 15 years.

CONCLUSIONS

The prevalence, genotypes, and zoonotic potential of E. bieneusi were found to vary significantly high even in one country. Transmission routes and key animal carriers of E. bieneusi may be associated with differences in hygiene, sanitation, and cultural behaviors. Further molecular studies including longitudinal studies will be required to unveil epidemiological characteristics of these opportunistic intestinal protozoa in all over the countries.

Identification of human pathogenic Enterocytozoon bieneusi, Cyclospora cayetanensis, and Cryptosporidium parvum on the surfaces of vegetables and fruits in Henan, China

Cryptosporidium spp., Giardia duodenalis, Cyclospora cayetanensis, and Enterocytozoon bieneusi are known etiological agents of self-limiting diarrhea, chronic disorders, and severe debilitating illnesses in humans, particularly children and patients with immunodeficiency diseases. To assess the pathogen carriage status of raw vegetables and fruits and the potential transmission routes of the aforementioned parasites in Henan province, China, a total of 1099 vegetables and fruits samples (21 items) were purchased and collected from agricultural farms or open markets. Cryptosporidium spp., E. bieneusi, C. cayetanensis and G. duodenalis were screened by employing polymerase chain reaction (PCR) amplification of species-specific genes. Three kinds of human pathogenic agent (E. bieneusi, C. cayetanensis and C. parvum) were identified on the surfaces of the vegetables and fruits (3.7%, 41/1099). E. bieneusi was found in 3.5% (38/1099) of the samples, whereas C. cayetanensis and C. parvum were only identified in two (0.2%) and one (0.1%) of the vegetable and fruit samples, respectively. No G. duodenalis contamination was detected in the present study. In total, 12 different E. bieneusi ITS genotypes (eight known and four novel) were detected, of which the ten (EbpA, CM8, CHG19, EbpC, CTS3, Henan-IV, and CHV1 to CHV4) that occurred in 20 samples (20/38, 52.6%) clustered into the previously described high potential zoonotic group 1 in the phylogenetic analysis. The remaining two known genotypes (BEB8 and CD6) detected in 18 samples (18/38, 47.4%) belonged to group 2. That C. cayetanensis, C. parvum and some E. bieneusi genotypes have been reported in humans, highlights the possible risk of foodborne related disease outbreaks.

Pragmatic Combination of Available Diagnostic Tools for Optimal Detection of Intestinal Microsporidia

Diarrhea is a debilitating condition in HIV infected individuals and with the finding that almost 1/4 cases of diarrhea in HIV are due to microsporidia, there is a dire need to institute measures for its detection on a regular basis. Keeping this in mind the study aims to determine the burden of intestinal microsporidiosis in HIV seropositive patients presenting with and without diarrhea and to compare the ability of microscopy and PCR in its detection.The study group consisted of 120 patients divided into four groups HIV seropositive with/without diarrhea, and HIV seronegative with/without diarrhea. Performance of four staining techniques including Modified Trichrome, Calcofluor White, Gram Chromotrope and Quick hot Gram Chromotrope stains were evaluated against PCR in diagnosing enteric microsporidiosis from stool samples.Overall prevalence of intestinal microsporidiosis was 10.83%. The same for HIV seropositive patients with diarrhea was 23.33%, HIV seropositive patients without diarrhea and in immune-competent hosts with diarrhea was 10% each. Enterocytozoon bieneusi was found to predominate. Calcofluor white stain detected maximum microsporidia in stool samples (76.92%), followed by Modified Trichrome stain (61.5%), PCR (46.15%) and Gram Chromotrope and Quick hot Gram Chromotrope stains (38.4% each). PCR exhibited the best performance with a sensitivity and specificity of 100%. Our data suggests screening of stool samples with either Modified Trichrome or Calcofluor white stain followed by PCR confirmation thus leading to maximum detection along with speciation for complete cure.

Molecular diagnosis of human microsporidian infections

With the transformation of HIV infection from an acutely life-threatening disease into a chronic condition (as a consequence of the development of effective antiretroviral medication), the perceived clinical importance of diagnosing and treating microsporidian infections diminished, at least in industrialized countries. In locales where effective antiretroviral therapy is not available, as well as in patients with immunodeficiency for reasons other than HIV infection (e.g., following organ transplantation), and in individuals with suspected ocular microsporidiosis, diagnosing microsporidian infections remains a clinical priority. Molecular techniques can readily distinguish different species of microsporidia. At least one molecular diagnostic platform that can detect the intestinal parasites Encephalitozoon intestinalis and Enterocytozoon bieneusi is commercially available.

Genetic aspects and environmental sources of microsporidia that infect the human gastrointestinal tract

Enterocytozoon bieneusi and Encephalitozoon intestinalis are microsporidia that infect the human gastrointestinal (GI) tract. Each of these microsporidia has been shown to infect various non-human hosts (mammalian and avian), raising the possibility of inter-species transmission, for example, from such hosts to human subjects via waterborne dispersal of microsporidian spores. During the past two decades, genome sequencing has delineated more than 90 genotypes of Ent. bieneusi, and has led to the conclusion that not all the genotypes of this organism infect human subjects. Well documented in the HIV-infected population, GI tract microsporidiosis is also known to occur in immunocompetent, HIV-negative, individuals. The prevalence of HIV-associated microsporidiosis diminished following the introduction of effective anti-retroviral therapy.

First survey of Cryptosporidium, Giardia and Enterocytozoon in diarrhoeic children from Wuhan, China

Intestinal protozoan pathogens cause significant diarrhoeal diseases in children. However, to date, there has been limited genetic study of the intestinal pathogens Cryptosporidium, Giardia and Enterocytozoon in humans in China, with the exception of research in a small number of cities/provinces. In the present study, PCR-based tools were used to detect and characterise these protistan parasites from 500 children with a history of diarrhoea in Wuhan and environs, Hubei province, China. Genomic DNAs from faecal samples were screened for the particular protists by PCR utilising regions in the small subunit (SSU) of the nuclear ribosomal RNA, the 60kDa glycoprotein (gp60), the internal transcribed spacer of nuclear ribosomal DNA (ITS) and/or the triose phosphate isomerase (tpi) genes as markers. Cryptosporidium meleagridis subtype IIIb (10/500, 2.0%), Giardia duodenalis assemblage A (7/500, 1.4%) and Enterocytozoon bieneusi genotype D (1/500, 0.2%) were identified in small percentages of the 500 samples. No significant gender- or age-associated differences in the prevalence of Cryptosporidium and Giardia infections were found. Future studies might focus on the occurrence of these protists in children as well as animals, with an emphasis on Cryptosporidium meleagridis in pets and agriculturally important birds, in different parts of Hubei province.

Molecular characterization of zoonotic pathogens Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in calves in Algeria

Little is known on the identity and public health potential of Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in farm animals in Algeria. In this study, 102 fecal specimens from pre-weaned dairy calves with or without diarrhea were collected from 19 dairy farms located in 6 provinces. PCR-restriction fragment length polymorphism analysis of the small subunit rRNA gene was used to detect and differentiate Cryptosporidium spp., whereas PCR-sequence analysis of the triosephosphate isomerase gene and ribosomal internal transcribed spacer were used to detect and genotype G. duodenalis and E. bieneusi, respectively. Cryptosporidium was found in 14 specimens, among which 7 had C. parvum, 4 had C. bovis, and 3 had mixed infection of C. parvum and C. bovis or C. bovis and C. andersoni. Subtyping of C. parvum by PCR-sequence analysis of the 60kDa glycoprotein gene identified two zoonotic subtypes IIaA16G2R1 and IIaA17G3R1. G. duodenalis was found in 28 specimens, with 6 having the host-specific assemblage E, 14 having the zoonotic assemblage A (all belonging to A2 subtype), and 8 having mixed assemblages. Six known genotypes of E. bieneusi belonging to Group 2, including I, J, BEB3, BEB4, BEB6 and PtEb XI, were identified in 11 specimens. Diarrhea was mostly associated with the occurrence of C. parvum. Data from this study suggest that human-pathogenic C. parvum subtypes and G. duodenalis and E. bieneusi genotypes are common on dairy farms in Algeria.

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.

Identification of Giardia duodenalis and Enterocytozoon bieneusi in an epizoological investigation of a laboratory colony of prairie dogs, Cynomys ludovicianus

Since 2005, black-tailed prairie dogs (Cynomys ludovicianus) have been collected for use as research animals from field sites in Kansas, Colorado, and Texas. In January of 2012, Giardia trophozoites were identified by histology, thin-section electron microscopy, and immunofluorescent staining in the lumen of the small intestine and colon of a prairie dog euthanized because of extreme weight loss. With giardiasis suspected as the cause of weight loss, a survey of Giardia duodenalis in the laboratory colony of prairie dogs was initiated. Direct immunofluorescent testing of feces revealed active shedding of Giardia cysts in 40% (n=60) of animals held in the vivarium. All tested fecal samples (n=29) from animals in another holding facility where the index case originated were PCR positive for G. duodenalis with assemblages A and B identified from sequencing triosephosphate isomerase (tpi), glutamate dehydrogenase (gdh), and β-giardin (bg) genes. Both assemblages are considered zoonotic, thus the parasites in prairie dogs are potential human pathogens and indicate prairie dogs as a possible wildlife reservoir or the victims of pathogen spill-over. Molecular testing for other protozoan gastrointestinal parasites revealed no Cryptosporidium infections but identified a host-adapted Enterocytozoon bieneusi genotype group.