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Clinical Microbiology Reviews Dec 2021Microsporidia are obligate intracellular pathogens identified ∼150 years ago as the cause of pébrine, an economically important infection in silkworms. There are...
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.
Topics: Gastrointestinal Diseases; Humans; Microsporidia; Microsporidiosis; Phylogeny; Prevalence
PubMed: 34190570
DOI: 10.1128/CMR.00010-20 -
Turkiye Parazitolojii Dergisi 2013All microsporidia are obligate parasites and have no active stages outside their host cells. Microsporidia lack some typical eukaryotic characteristics. There are now... (Review)
Review
All microsporidia are obligate parasites and have no active stages outside their host cells. Microsporidia lack some typical eukaryotic characteristics. There are now over 1200 species identified in 144 genera. The most familiar stage of microsporidia is the small, highly resistant spore, the size of which differs according to the species and is often 1-10 μm. The general life cycle pattern of the microsporidia can be divided into three phases: the infective or environmental phase, the proliferative phase, and the sporogony or spore-forming phase. There are several methods for diagnosing microsporidia: light microscopic, transmission electron microscopy (TEM), immunofluorescence assays (IFA) and molecular methods. The clinical course of microsporidiosis depends on the immune status of the host and site of infection. Microsporidia can cause infections such as diarrhoea, keratitis, myositis, bronchitis and brochiolitis. Human microsporidiosis represents an important and rapidly emerging opportunistic disease, occurring mainly, but not exclusively, in severely immunocompromised patients with AIDS. The treatment of microsporidiosis is generally achieved with medications and supportive care. Depending on the site of infection and the microsporidia species involved, different medications are utilized. The most commonly used medications for microsporidiosis include albendazole and fumagillin.
Topics: Animals; Antifungal Agents; Humans; Immunocompromised Host; Life Cycle Stages; Microsporidia; Microsporidiosis; Opportunistic Infections; Spores, Fungal
PubMed: 23955911
DOI: 10.5152/tpd.2013.28 -
Journal of Clinical Microbiology Nov 2014Microsporidia are highly specialized obligate intracellular organisms that are closely related to fungi. Although traditionally associated with diarrheal illness in... (Review)
Review
Microsporidia are highly specialized obligate intracellular organisms that are closely related to fungi. Although traditionally associated with diarrheal illness in patients with AIDS, extraintestinal infections involving various organs have been reported with increasing frequency in the past decade, particularly in immunocompromised hosts. Diagnosis is usually accomplished by light microscopic identification of spores in body fluids and tissues, using a variety of stains. Transmission electron microscopy, immunofluorescence assays, or molecular methods are necessary for identification to the genus and species level. Early diagnosis is essential for preventing the significant associated morbidity and mortality of extraintestinal microsporidiosis.
Topics: Humans; Immunocompromised Host; Microbiological Techniques; Microsporidia; Microsporidiosis
PubMed: 24829239
DOI: 10.1128/JCM.00971-14 -
Current Opinion in Microbiology Aug 2015Microsporidia comprise one of the largest groups of obligate intracellular pathogens and can infect virtually all animals, but host response to these fungal-related... (Review)
Review
Microsporidia comprise one of the largest groups of obligate intracellular pathogens and can infect virtually all animals, but host response to these fungal-related microbes has been poorly understood. Several new studies of the host transcriptional response to microsporidia infection have found infection-induced regulation of genes involved in innate immunity, ubiquitylation, metabolism, and hormonal signaling. In addition, microsporidia have recently been shown to exploit host recycling endocytosis for exit from intestinal cells, and to interact with host degradation pathways. Microsporidia infection has also been shown to profoundly affect behavior in insect hosts. Altogether, these and other recent findings are providing much-needed insight into the underlying mechanisms of microsporidia interaction with host animals.
Topics: Animals; Disease Models, Animal; Host-Pathogen Interactions; Humans; Immunity, Innate; Insecta; Microsporidia; Microsporidiosis
PubMed: 25847674
DOI: 10.1016/j.mib.2015.03.006 -
Revista Chilena de Infectologia :... 2018
Topics: Microsporidia; Microsporidiosis
PubMed: 29652974
DOI: 10.4067/s0716-10182018000100073 -
Current Opinion in Infectious Diseases Oct 2006Microsporidiosis is an emerging and opportunistic infection associated with a wide range of clinical syndromes in humans. This review highlights the research on... (Review)
Review
PURPOSE OF REVIEW
Microsporidiosis is an emerging and opportunistic infection associated with a wide range of clinical syndromes in humans. This review highlights the research on microsporidiosis in humans during the previous 2 years.
RECENT FINDINGS
The reduced and compact microsporidian genome has generated much interest for better understanding the evolution of these parasites, and comparative molecular phylogenetic studies continue to support a relationship between the microsporidia and fungi. Through increased awareness and improved diagnostics, microsporidiosis has been identified in a broader range of human populations that, in addition to persons with HIV infection, includes travelers, children, organ transplant recipients, and the elderly.
SUMMARY
Effective commercial therapies for Enterocytozoon bieneusi, the most common microsporidian species identified in humans, are still lacking, making the need to develop tissue culture and small animal models increasingly urgent. Environmental transport modeling and disinfection strategies are being addressed for improving water safety. Questions still exist about whether microsporidia infections remain persistent in asymptomatic immune-competent individuals, reactivate during conditions of immune compromise, or may be transmitted to others at risk, such as during pregnancy or through organ donation. Reliable serological diagnostic methods are needed to supplement polymerase chain reaction or histochemistry when spore shedding may be sporadic.
Topics: Animals; Humans; Microsporidia; Microsporidiosis
PubMed: 16940873
DOI: 10.1097/01.qco.0000244055.46382.23 -
Clinical Microbiology Reviews Oct 1994Microsporidia are obligate intracellular spore-forming protozoal parasites belonging to the phylum Microspora. Their host range is extensive, including most... (Review)
Review
Microsporidia are obligate intracellular spore-forming protozoal parasites belonging to the phylum Microspora. Their host range is extensive, including most invertebrates and all classes of vertebrates. More than 100 microsporidial genera and almost 1,000 species have now been identified. Five genera (Enterocytozoon spp., Encephalitozoon spp., Septata spp., Pleistophora sp., and Nosema spp.) and unclassified microsporidia (referred to by the collective term Microsporidium) have been associated with human disease, which appears to manifest primarily in immunocompromised persons. The clinical manifestations of microsporidiosis are diverse and include intestinal, pulmonary, ocular, muscular, and renal disease. Among persons not infected with human immunodeficiency virus, ten cases of microsporidiosis have been documented. In human immunodeficiency virus-infected patients, on the other hand, over 400 cases of microsporidiosis have been identified, the majority attributed to Enterocytozoon bieneusi, an important cause of chronic diarrhea and wasting. Diagnosis of microsporidiosis currently depends on morphological demonstration of the organisms themselves. Initial detection of microsporidia by light microscopic examination of tissue sections and of more readily obtainable specimens such as stool, duodenal aspirates, urine, sputum, nasal discharge, bronchoalveolar lavage fluid, and conjunctival smears is now becoming routine practice. Definitive species identification is made by using the specific fluorescein-tagged antibody (immunofluorescence) technique or electron microscopy. Treatment options are limited, but symptomatic improvement of Enterocytozoon bieneusi infection may be achieved with the anthelmintic-antiprotozoal drug albendazole. Preliminary observations suggest that Septata intestinalis and Encephalitozoon infections may be cured with albendazole. Progress is being made with respect to in vitro propagation of microsporidia, which is crucial for developing antimicrosporidial drugs. Furthermore, molecular techniques are being developed for diagnostic purposes, taxonomic classification, and analysis of phylogenetic relationships of microsporidia.
Topics: Animals; HIV Infections; Humans; Microscopy, Electron; Microscopy, Electron, Scanning; Microsporida; Microsporidiosis
PubMed: 7834600
DOI: 10.1128/CMR.7.4.426 -
The Malaysian Journal of Pathology Apr 2021Disseminated microsporidiosis is a life-threatening disease resulting from the haematogenous spread of microsporidia species. The diagnosis is challenging owing to its... (Review)
Review
Disseminated microsporidiosis is a life-threatening disease resulting from the haematogenous spread of microsporidia species. The diagnosis is challenging owing to its subtle nonspecific clinical presentation, which usually reflects the underlying organ involved. Therefore, a high index of suspicion is required for early diagnosis. Besides, tools for confirmatory laboratory diagnosis are limited. Currently, there is no direct diagnostic method that can detect the infection without involving invasive procedures. Clinical confirmation of disseminated microsporidiosis is usually based on light and transmission electron microscopy of infected tissue specimens. These are then followed by species detection using polymerase chain reaction (PCR). Disseminated microsporidiosis shows the potential to be cleared up by albendazole or fumagillin if they are detected and treated early. Based on a series of case reports, this review aims to present a current update on disseminated microsporidiosis with emphasis on the clinical manifestations based on the organ system infected, diagnostic approach and treatment of this devastating condition.
Topics: Humans; Microsporidia; Microsporidiosis; Polymerase Chain Reaction
PubMed: 33903300
DOI: No ID Found -
Current Opinion in Infectious Diseases Oct 2011Microsporidia have emerged as causes of opportunistic infections associated with diarrhea and wasting in AIDS patients. This review describes recent reports of... (Review)
Review
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.
Topics: AIDS-Related Opportunistic Infections; Antiprotozoal Agents; Humans; Immunocompromised Host; Microsporidiosis
PubMed: 21844802
DOI: 10.1097/QCO.0b013e32834aa152 -
Trends in Parasitology Apr 2016Intensification of food production has the potential to drive increased disease prevalence in food plants and animals. Microsporidia are diversely distributed,... (Review)
Review
Intensification of food production has the potential to drive increased disease prevalence in food plants and animals. Microsporidia are diversely distributed, opportunistic, and density-dependent parasites infecting hosts from almost all known animal taxa. They are frequent in highly managed aquatic and terrestrial hosts, many of which are vulnerable to epizootics, and all of which are crucial for the stability of the animal-human food chain. Mass rearing and changes in global climate may exacerbate disease and more efficient transmission of parasites in stressed or immune-deficient hosts. Further, human microsporidiosis appears to be adventitious and primarily associated with an increasing community of immune-deficient individuals. Taken together, strong evidence exists for an increasing prevalence of microsporidiosis in animals and humans, and for sharing of pathogens across hosts and biomes.
Topics: Animals; Communicable Diseases, Emerging; Food Chain; Food Parasitology; Humans; Microsporidia; Microsporidiosis
PubMed: 26796229
DOI: 10.1016/j.pt.2015.12.004