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At least 19 recordsLinked to original sources
PubMed1997

Protozoan parasites of the intestinal tract: a review of Coccidia and Microsporida.

Ubiquitous in nature, members of the Coccidia and Microsporida are being reported with increasing frequency in the immunocompromised as well as the immunocompetent population. These protozoans are primarily waterborne, but foodborne disease has also been reported. These organisms are responsible for acute, as well as protracted, cases of watery diarrhea with various other related sequelae. The Coccidia includes three genera--Cryptospridium, Isospora, and Cyclospora. The latter two are of lesser importance in terms of morbidity and mortality. The Microsporida includes genera (Enterocytozoon, Encephalitozoon) only recently recognized as important agents of disease. Unlike the Coccidia, these organisms are more restricted to the immunocompromised population. Increased incidence and numbers of patients with prolonged diarrhea due to these forms indicate the need for increased clinical vigilance with regard to prevention, diagnosis, and treatment.

Animals↗
PubMedDate not supplied

Microfilum lutjani N. G. N. Sp. (Protozoa Microsporida), a gill parasite of the golden African snapper Lutjanus fulgens (Valenciennes, 1830) (Teleost Lutjanidae): developmental cycle and ultrastructure.

Microfilum lutjani n. g., n. sp. (Microsporida) was found on the gill filaments of Lutjanus fulgens (Teleost) inhabiting the coasts of Senegal. This microsporidium forms xenomas distinguished by the microvilli covering the plasma membrane. At all stages of development individuals have isolated nuclei and are in direct contact with the host cytoplasm. Merogony is binary and sporogony is tetrasporoblastic. The spore (4.75 x 2.60 microns) is characterized by a manubrium inserted on a laterally offset anchoring disc and extending into a very short, noncoiled polar filament (no longer than 500 nm) in the form of a hook. This type of polar filament has not been described previously in the Microsporida.

Animals↗
PubMed1993

Life cycle of a new species of Duboscqia (Microsporida: Thelohaniidae) infecting the mosquito Anopheles hilli and an intermediate copepod host, Apocyclops dengizicus.

A new species of Microsporida, Duboscqia dengihilli, was found infecting larvae of the mosquito Anopheles hilli in northern Queensland, Australia. Laboratory experiments showed that binucleate spores formed within infected female mosquitoes were responsible for transovarial transmission to the next generation. Sporogony within the larval fat body was initiated by two diplokarya, one at each end of the cell, which undergo meiosis within a single sporophorous vesicle to form 16 meiospores. These spores are responsible for horizontal transmission to the copepod Apocyclops dengizicus. The microsporidium is transmitted back to the mosquito host via uninucleate pyriform spores formed within the copepod host which are infectious to larvae of A. hilli. The meronts within larvae infected by horizontal transmission ultimately develop into the binucleate spores within adult females to complete the life cycle. Thus, the development of this microsporidium involves vertical transmission between successive mosquito generations and horizontal transmission between mosquitoes and copepods similar to the life cycles of Amblyospora and Parathelohania.

Animals↗
PubMed1998

Optimal screening and diagnosis of microsporida in tissue sections: a comparison of polarization, special stains, and molecular techniques.

With improving therapeutic protocols, confirmation of microsporidiosis has become increasingly important. We designed a study to determine the best screening method(s) for microsporidian detection in biopsy specimens. Forty-two small intestinal biopsy specimens from 31 immunocompromised patients (68% AIDS) were stained (hematoxylin-eosin [H & E], modified trichrome, Warthin-Starry, and Brown-Brenn) and polarized. Polymerase chain reaction and Southern blot assays were performed on all positive cases. Microsporida were detected in nine cases (21%) by modified trichrome (all patients with AIDS). Of these, seven were Brown-Brenn positive, and five Warthin-Starry positive. Two cases polarized on H & E and three on special stains. Four of nine positive cases were confirmed by molecular studies. We found polarization to be the least sensitive screening method. The modified trichrome was the most sensitive when screening for microsporidiosis in paraffin-embedded biopsy specimens. Furthermore, combining Brown-Brenn or Warthin-Starry with the trichrome stain helps exclude false-positive results due to granular artifacts (eg, eosinophils, Paneth cells).

Adolescent↗
PubMed2005

[The fine structure of chromatin in Paranosema grylli (Microsporida)].

Nucleosomes were found for the first time in the nuclear chromatin of Microsporida--organisms known among the smallest eukaryotes on Earth. Chromatin of Paranosema grylli sporoplasm was studied by Miller's technique. On low ionic-strength cell spreads, this chromatin was represented by 10 nm nucleosome filaments, 20 nm filaments, and "smooth" (nucleosome-free) filaments of 3-4 nm in diameter. Nucleosome filaments display structural heterogeneity seen as irregular arrangement of nucleosome particles along the filament length. Different nucleosome filaments show 13-30 nucleosomes per 1 microm with the length of linker DNA ranging from 10 to 45 nm. The present results suggest that microsporidian chromatin is weakly condensed. Only lower-order chromatin packaging levels displayed some structural peculiarities.

Chromatin↗
PubMed1995

[New parasitic diseases in man: infections caused by Microsporida and Cyclospora species].

The non-taxonomic term microsporidia relates to a group of organisms belonging to the order Microsporida of the phylum Microspora. Microsporidia are obligate intracellular spore-forming protozoa and have no metabolically active stages outside the host cell. Their host range is extensive and includes most invertebrates and all 5 classes of vertebrates. More than 100 microsporidial genera and almost 1000 species have now been identified. 5 genera (Enterocytozoon, Encephalitozoon, Septata, Pleistophora and Nosema) and unclassified microsporidia have been associated with human disease. Only 10 cases of microsporidiosis have been described among persons not infected with HIV. In contrast, microsporidia have gained increasing attention as important opportunistic pathogens in the evolving pandemic of HIV infection. Diagnosis depends on morphological demonstration of the organisms themselves. The potential sources and modes of transmission of human microsporidial infections are uncertain. The clinical manifestations of microsporidiosis are diverse and include intestinal, pulmonary, ocular, muscular, and renal disease. Preliminary observations of the possible utility of albendazole for infections due to Septata intestinalis and Encephalitozoon sp. have been reported. The success of therapy for intestinal Enterocytozoon bieneusi infection has been limited. Cyclospora sp. are recently described protozoa capable of causing diarrhea in immunocompetent and immunodeficient patients. Groups at risk for infection are children in the developing world, travellers and HIV-infected patients. Diagnosis depends on light-microscopic detection of oocysts in stool smears stained with acid-fast stains. Diarrhea is usually self-limiting. Diarrhea, however, may often last weeks to months, causing significant morbidity. Cotrimoxazole appears to be the drug of choice for treatment of Cyclospora infection.

Adult↗
PubMed1989

The effect of the microsporida Glugea stephani on the immunoglobulin levels of juvenile and adult winter flounder (Pseudopleuronectes americanus).

The microsporida Glugea stephani is an intracellular parasite that causes a decline in the serum IgM levels of both adult and juvenile winter flounder, shortly after introduction. This decline was noted in fish injected with spores or infected via an intermediary vector. The parasite also suppresses the humoral response to other antigens such as horse red blood cells. The suppression of the response to the antigen however, is related directly to the exposure time with regard to the kinetic state of the immune response. Less suppression occurred when the response was already past the initiation stage. The results implicate that the parasite may be interfering with the initiation of the response as well as at other stages. The presence of a soluble serum protein, which may contribute to this immunosuppression, was detected by electrophoresis.

Animals↗
PubMed1977

Some ultrastructural and functional aspects of the golgi àpparatus of Thelohania sp. (Microsporida) in the shrimp Pandalus jordani Rathbun.

Electron microscope observations on Thelohania sp. in the shrimp Pandalus jordani support the view that the Golgi complex in Microsporida is a "classical" one, composed of vesicular, vacuolar, and cisternal components. During development of the sporoblast, a portion of the Golgi complex is seen as an electron-dense reticulum enmeshing the core of the polar filament. Associated with the reticulum are electron-dense bodies. The reticulum and "dense bodies," reported in several previous publications, have not been well understood and have been given a variety of names. The evidence favors the view that these structures have secretory activity in which the reticulum concentrates or synthesized material, some of which takes the form of membrane-bounded granules. It is suggested that the most appropriate name for the reticulum is "reticulum golgien," and the the correct name for the "dense bodies" is the standard cytologic term, "secretion granules." The secretion granules apparently remain in the posterior part of the spore, and may be stored there for some as yet undetermined use.

Animals↗
PubMedDate not supplied

Development of Amblyospora campbelli (Microsporida: Amblyosporidae) in the mosquito Culiseta incidens (Thomson).

The complete life cycle of Amblyospora campbelli (Kellen and Wills, 1962) (Microsporida: Amblyosporidae) requires a two-host system involving the mosquito host, Culiseta incidens (Thomson), and an obligatory intermediate copepod host. The parasite has dimorphic spore development producing meiospores (haploid condition) and binucleated spores (diploid condition), either as an exclusive infection or simultaneously (within females only). This is the 1st known report of concurrent spore development within an adult mosquito host, and, therefore, shows the Amblyospora campbelli system to be uniquely different from other Amblyospora spp. cycles previously described. The significance of dimorphic spore development is discussed. In females, diplokaryotic meronts may invade oenocytes, causing a benign-type of infection. A blood-meal is required to initiate sporulation of the binucleate spore. The binucleate spore contains the sporoplasm involved in transovarial transmission. A 2nd sporulation sequence, primarily in adipose tissue, may involve both males and females. In this sequence, repeated merogonic division greatly increased the density of diplokaryotic meronts and generally involved most of the body of the host. Production of meiospores, unlike that for the binucleate spore, appeared to be spontaneous (i.e. no obligatory blood meal). Survivorship of male and female larval mosquitoes was nearly equal. Adult females spread the parasite in three ways: transovarial, transovum, and by meiospore deposition.

Animals↗
PubMed1987

Two-dimensional electrophoretic analysis of spore proteins of the Microsporida.

Microsporida are potentially useful as biological control agents for insects of economic and medical importance. Prior to their responsible use, however, an accurate and reliable means of identification to the species and subspecies level is required. Current methods used for identification are not adequate, due to variability of identifiable characters and to the occurrence of dimorphism. Recently, progress has been made in the use of biochemical characteristics to support the more traditional methods of distinguishing between morphologically similar species. We report on an improved method of characterization of microsporidan spore proteins, using 2-dimensional polyacrylamide gel electrophoresis (2D-PAGE). This method increased the number of spore polypeptides resolved from Nosema locustae spore protein extracts 2-3-fold over 1-dimensional PAGE. Also, each of the 2D-PAGE spore protein fingerprints of the species examined, namely Nosema locustae, Nosema bombycis, and Vairimorpha necatrix, were unique and differences in their spore protein composition were easily determined. The major structural proteins of Nosema locustae spores co-electrophoresed with alpha and beta tubulin from calf brain and had similar pI and molecular weight values as reported for tubulin in other species. Each species' 2D-PAGE fingerprint contained a few polypeptides that were present in relatively high concentration and these polypeptides may represent the major proteins of the structural components of the spore.

Animals↗
PubMed1994

Host range tests with Edhazardia aedis (Microsporida: Culicosporidae) against northern Nearctic mosquitoes.

Twelve species of northern Nearctic mosquitoes representing five genera (Aedes, Anopheles, Culex, Culiseta, and Psorphora) were bioassayed for susceptibility to Edhazardia aedis, an exotic, heterosporous, microsporidian parasite of the yellow fever mosquito, Aedes aegypti. Infections were achieved in Aedes atropalpus, Aedes triseriatus, and Aedes vexans following oral ingestion of uninucleate spores obtained from patently infected Ae. aegypti larvae. The microsporidium underwent normal vegetative growth and development in each unnatural mosquito host; the only differences observed were in the degree of infection. With the exception of adult oenocytes, the predominant sites of infection in Ae. triseriatus were generally similar to those in Ae. aegypti. These included the gastric caeca and muscle tissue in larvae and fat body tissue in adult females. Binucleate spores, which are normally responsible for ovarian infection and transovarial transmission in Ae. aegypti, were produced in all but one (Ae. atropalpus) susceptible host. However, E. aedis was not transmitted transovarially to larvae of the filial generation by these alternate female hosts thus indicating a high level of specificity for Ae. aegypti. Since E. aedis can not complete its normal life cycle through two successive host generations in alternate host mosquitoes, its potential as a biological control agent would appear to be limited to Ae. aegypti.

Aedes↗
PubMed1998

Phylogeny of amblyospora (Microsporida: amblyosporidae) and related genera based on small subunit ribosomal DNA data: A possible example of host parasite cospeciation.

Small subunit ribosomal RNA (SSU rRNA) gene sequences were analyzed for six species and four genera of microsporidia from mosquito hosts; Amblyospora stimuli (Aedes stimulans), Amblyospora californica (Culex tarsalis), Amblyospora sp. (Culex salinarius), Edhazardia aedis (Aedes aegypti), Culicosporella lunata (Culex pilosus), and Parathelohania anophelis (Anopheles quadrimaculatus). Comparison of these sequences to those of other microsporidia show that these sequences are longer with the SSU rRNA gene of E. aedis being the longest microsporidia sequenced to date (1447 base pairs). Parsimony, maximum likelihood, and distance methods produced identical trees, suggesting that the above microsporidian taxa, contrary to current classification schemes, form a monophyletic group. Relationships within this group are further supported by high bootstrap and decay analysis values. Based on the molecular analysis, P. anophelis is the most divergent species in this group of mosquito parasites. Amblyospora is paraphyletic with A. californica and Amblyospora sp., forming a sister taxon to a clade composed of E. aedis and A. stimuli. Culicosporella lunata comprises a sister taxon to the Amblyospora/Edhazardia clade. The pattern of host relationships on the tree provides preliminary evidence that the branching pattern seen here may indicate that host-parasite cospeciation is an important mechanism of evolution in this group.

Aedes↗
PubMed1992

Loma camerounensis sp. nov. (Protozoa:Microsporida) a parasite of Oreochromis niloticus Linnaeus, 1757 (Teleost:Cichlidae) in fish-rearing ponds in Melen, Yaoundé, Cameroon.

A new microsporidian, Loma camerounensis, was found in the Cichlidae Oreochromis niloticus from the Melen fish-rearing station in Yaoundé, Cameroon. Xenomas were located in the gut from the oesophagus to the intestine, but preferentially in the duodenum. Dimensions of the fresh spores were 3.96 x 2.16 microns. The ultrastructural study indicated the following characteristics: parasite stages arranged in a random, unstratified manner in the xenoma; merogony by multiple fission; sporogonic stages isolated within a sporophorous vesicle containing several sporoblasts and polysporoblastic sporogony. Ultimately the spores appeared to be isolated in a single vesicle, but this was a secondary phenomenon induced by the intervention of tubules that resolved in partitions of the initial sporophorous vesicle.

Animals↗
PubMed1998

Tetramicra brevifilum (Matthews & Matthews, 1980) (Microsporida: Tetramicriidae) in a new fish host, Lophius budegassa (Spinola, 1807) in Spain.

Tetramicra brevifilum, a microsporidian parasite of Scophthalmus maximus, was found in Lophius budegassa for the first time. This parasite was detected in 5 of 199 hosts captured in the coastal waters of Barcelona (Northwest Mediterranean), which enlarges the geographic distribution of this microsporidian. Affected fish did not show any external sign of disease, and cysts of T. brevifilum were found associated with the body musculature but were easily differentiated from those of Spraguea lophii, another microsporidian present in this host. A case of simultaneous infection by both T. brevifilum and S. lophii was found.

Animals↗
PubMed1992

Influence of temperature on developmental parameters of the parasite/host system Edhazardia aedis (Microsporida: Amblyosporidae) and Aedes aegypti (Diptera: Culicidae).

Larvae of Aedes aegypti, transovarially infected with Edhazardia aedis, were reared between 20 and 36 degrees C to determine the influence of temperature on the development of the parasite and the infected host. Development of the parasite was evaluated based on spore yield and size. The predicted optimum temperature for maximum spore production of E. aedis in A. aegypti was 30.8 degrees C. The results demonstrate that the E. aedis-A. aegypti system has a wide temperature tolerance; whereas spore yield will be lower at unfavorable temperatures, the host will remain infected. Additionally, spores were significantly smaller from individual reared at 34 degrees C than those reared at either 20 or 27 degrees C. Development of the infected host was evaluated based on pupal weight and time of pupation. Infected pupae were significantly larger than uninfected pupae. There was also a significant difference in the pupation rate between controls and infected A. aegypti larvae. Controls had a 50% cumulative pupation time (CPT50) of 65.7 degree days and infected individuals a CPT50 of 76.6 degree days.

Aedes↗
PubMed1992

Effect of per os Edhazardia aedis (Microsporida: Amblyosporidae) infection on Aedes aegypti mortality and body size.

Infection with Edhazardia aedis uninucleate spores had less effect on Aedes aegypti larval mortality and adult body size than did larval diet. Larval mortality averaged 60-81% in starved larvae and 2-16% in well-fed larvae. No significant amounts of larval mortality could consistently be attributed to exposure to the parasite at dosages of 1.5 x 10(3) or 1.5 x 10(5) spores/ml. Infection rates in adults surviving exposure to the parasites as larvae ranged from 30 to 59%. Infected adults had significantly smaller body sizes than uninfected adults or controls. Storage of spores in water reduced infectivity gradually over the course of 36 h. By 48 h, the spores were not able to infect mosquito larvae. Spore infectivity was eliminated by drying.

Aedes↗