A review of the development of two types of human skeletal muscle infections from microsporidia associated with pathology in invertebrates and cold-blooded vertebrates. (1/3)
Traditionally, the Microsporidia were primarily studied in insects and fish. There were only a few human cases of microsporidiosis reported until the advent of AIDS, when the number of human microsporidian infections dramatically increased and the importance of these new pathogens to medicine became evident. Over a dozen different kinds of microsporidia infecting humans have been reported. While some of these infections were identified in new genera (Enterocytozoon, Vittaforma), there were also infections identified from established genera such as Pleistophora and Encephalitozoon. The genus Pleistophora, originally erected for a species described from fish muscle, and the genus Encephalitozoon, originally described from disseminated infection in rabbits, suggested a link between human infections and animals. In the 1980's, three Pleistophora sp. infections were described from human skeletal muscle without life cycles presented. Subsequently, the genus Trachipleistophora was established for a human-infecting microsporidium with developmental differences from species of the genus Pleistophora. Thus, the existence of a true Pleistophora sp. or spp. in humans was put into question. We have demonstrated the life-cycle stages of the original Pleistophora sp. infection from human muscle, confirming the existence of a true Pleistophora species in humans, P. ronneafiei Cali et Takvorian, 2003, the first demonstrated in a mammalian host. Another human infection, caused by a parasite from invertebrates, was Brachiola algerae Lowman, Takvorian et Cali, 2000. The developmental stages of this human muscle-infecting microsporidium demonstrate morphologically what we have also confirmed by molecular means, that B. algerae, the mosquito parasite, is the causative agent of this human skeletal muscle infection. B. algerae had previously been demonstrated in humans but only in surface infections, skin and eye. The diagnostic features of B. algerae and P. ronneafiei infections in human skeletal muscle are presented. While Encephalitozoon cuniculi has been known as both an animal (mammal) and human parasite, the idea of human microsporidial infections derived from cold-blooded vertebrates and invertebrates has only been suggested by microsporidian phylogeny based on small subunit ribosomal DNA sequences but has not been appreciated. The morphological data presented here demonstrate these relationships. Additionally, water, as a link that connects microsporidial spores in the environment to potential host organisms, is diagrammatically presented. (+info)Detection and species identification of microsporidial infections using SYBR Green real-time PCR. (2/3)
(+info)Microsporidiosis in zebrafish research facilities. (3/3)
(+info)"Pleistophora" is not a term that has a widely accepted medical definition. It is a genus name in the kingdom Protista, specifically in the phylum Apicomplexa, which includes various microorganisms that can cause diseases in humans and animals. Some species of Pleistophora are known to infect fish and amphibians, causing muscle degeneration and other symptoms. However, there is no established medical definition or clinical significance for "Pleistophora" in human medicine.
Microsporidiosis is an infection caused by microscopic, single-celled parasites belonging to the phylum Microspora. These parasites are primarily intracellular and can infect various organisms, including humans. Infection typically occurs through ingestion of spores present in contaminated food, water, or soil, or through inhalation of spores. Once inside a host, the spores germinate, releasing the infective sporoplasm that invades host cells and multiplies within them.
In humans, microsporidiosis can cause various symptoms depending on the species involved and the immune status of the host. In immunocompetent individuals, it may present as self-limiting diarrhea or mild gastrointestinal disturbances. However, in immunocompromised patients (e.g., those with HIV/AIDS, organ transplants, or using immunosuppressive medications), microsporidiosis can lead to severe and chronic diarrhea, wasting, and potentially life-threatening complications affecting various organs such as the eyes, kidneys, and respiratory system.
Diagnosis of microsporidiosis typically involves detecting the parasites in stool or tissue samples using specialized staining techniques (e.g., chromotrope stains) or molecular methods (e.g., PCR). Treatment usually includes antiparasitic drugs such as albendazole, which has activity against many microsporidian species. In severe cases or when the infection involves multiple organs, additional supportive care and management of underlying immunodeficiencies may be necessary.
Microsporidia are a group of small, spore-forming, obligate intracellular parasites that were once considered to be primitive protozoans but are now classified within the fungi. They are characterized by a unique infection mechanism called "polysporous invasion," where a single spore can infect multiple host cells and produce numerous progeny spores.
Microsporidia infect a wide range of hosts, including insects, fish, birds, and mammals, including humans. In humans, microsporidiosis is an opportunistic infection that primarily affects immunocompromised individuals, such as those with HIV/AIDS, organ transplant recipients, and those undergoing chemotherapy.
The most common Microsporidia species that infect humans are Enterocytozoon bieneusi and Encephalitozoon intestinalis, which can cause gastrointestinal symptoms such as diarrhea, abdominal pain, and weight loss. Other species can infect various organs, including the eyes, muscles, and respiratory system, causing a range of clinical manifestations.
Microsporidia have a complex life cycle that involves several developmental stages, including spores, meronts, and sporonts. The spores are highly resistant to environmental stresses and can survive for long periods outside the host, facilitating their transmission. Once inside the host cell, the spore releases its infectious contents, including a coiled tubular structure called the polar filament, which penetrates the host cell membrane and injects the parasite's genetic material into the host cytoplasm. The parasite then undergoes rapid multiplication, eventually producing numerous progeny spores that are released into the environment upon host cell lysis.
Microsporidia have been identified as potential bioterrorism agents due to their high infectivity, environmental resistance, and ability to cause severe disease in immunocompromised hosts. However, there are currently no effective vaccines or specific antimicrobial therapies available for microsporidiosis, and treatment is mainly supportive, focusing on managing symptoms and improving immune function.
Pleistophora mulleri