[PARASITES OF THE COMMON ROACH (RUTILUS RUTILUS L.) UNDER THE IMPACT OF INDUSTRIAL POLLUTION OF A LAKE].

The consequences of man-induced transformation of Lake Kostomukshskoe (tailings dump) related to increased mineralization and entry of highly dispersed dredge material not typical for northern lakes were studied using roach parasites as the example. It was found that the roach parasite fauna has been losing rare and scant parasite species of different taxonomic groups, mainly helminthes with an indirect life cycle. Common and dominant species of myxosporidians, monogeneans, trematodes of genera Diplostomum and Tylodelphys have been preserved. The chances of survival are higher for those parasites with direct life cycle. Also the parasite species whose larvae can actively penetrate the host have been survived. The species Ligula intestinalis, Philometra rishta, Pseudocapillaria tomentosa had reported very rare. Fish are infected with these parasites by feeding of Copepoda and oligochaetes.

Examination of naturally exposed bottlenose dolphins (Tursiops truncatus) for Microsporidia, Cryptosporidium, and Giardia.

Bottlenose dolphins (Tursiops truncatus) captured in the estuarine waters off the coasts of South Carolina and Florida were examined for the presence of Microsporidia, Cryptosporidium sp., and Giardia sp. DNA extracted from feces or rectal swabs was amplified by polymerase chain reaction using parasite-specific small subunit ribosomal RNA gene primers. All positive specimens were subjected to gene sequence analysis. Of 83 dolphins, 17 were positive for Microsporidia. None was positive for Cryptosporidium or Giardia. Gene sequence data for each of the positive specimens were compared with data in GenBank. Fourteen specimens were found similar to, but not identical to, the microsporidian species Kabatana takedai, Tetramicra brevifilum, and Microgemma tinca, reported from fish, and possibly represent parasites of fish eaten by dolphins. Gene sequence data from 3 other specimens had approximately 87% similarity to Enterocytozoon bieneusi, a species known primarily to infect humans and a variety of terrestrial mammals, including livestock, companion animals, and wildlife. It is not clear if these specimens represent a species from a terrestrial source or a closely related species unique to dolphins. There were neither clinical signs nor age- or gender-related patterns apparent with the presence of these organisms.

[Microsporidiosis of the dragonfly Aeshna viridis larvae (Odonata: Aeshnidae) caused by Systenostrema alba Larsson, 1988 (Microsporida: Thelohaniidae)].

A microsporidian species producing octospores in sporophorous vesicles is found in Aeshna viridis larvae from intermittent streams situated in the vicinity of Novosibirsk City. Size of the spores measured on fresh smears was 6.9 +/- 0.09 microm x 4.1 +/- 0.08 microm (6.0-7.6 x 3.5-4.9). Each spore have single elongated nucleus and an anisofilar polar filament composed of 10-11 anterior and 10-11 posterior coils. The infection was restricted to adipose tissue. According to spore morphology the Siberian isolate can be attributed to the species Systenostrema alba described from Aeshna grandis in Sweden (Larsson, 1988). This is the first description of Microsporidia infecting Odonata from Siberia.

Microsporidiosis in mammals.

Microsporidia are small, single-celled, obligately intracellular parasites that have caused significant agricultural losses and interference with biomedical research. Interest in the microsporidia is growing, as these organisms are recognized as agents of opportunistic infections in persons with AIDS and in organ transplant recipients. Microsporidiosis is also being recognized in children and travelers, and furthermore, concern exists about the potential of zoonotic and waterborne transmission of microsporidia to humans. This article reviews the basic biology and epidemiology of microsporidiosis in mammals.

Microsporidiosis: human diseases and diagnosis.

Microsporidia are considered opportunistic pathogens in humans because they are most likely to cause diseases if the immune status of a host is such that the infection cannot be controlled. A wide spectrum of diseases has been reported among persons infected with microsporidia and different diagnostic techniques have been developed during the last decade.

Biology of microsporidian species infecting mammals.

Microsporidia (phylum Microspora) are obligate intracellular protozoan parasites that infect a wide range of vertebrate and invertebrate hosts. Over 1000 species have been classified into approximately 100 genera, and at least 13 species have been reported to infect mammals. Phylogenetically, the microsporidia are early eukaryotes because they have a true nucleus, possess prokaryote-like ribosomes, and lack mitochondria. The species that infect mammals are relatively small, measuring 2.0-7.0 microns long and 1.5-5.0 microns wide. The mature organism is the spore, which is enclosed by a chitinous coat, making it relatively resistant to the environment. Infections often occur by fecal-oral or urinary-oral transmission, although vertical transmission is quite common in the carnivores. Host cells become infected through a process of germination in which the spore propels its contents through the everting and unwinding polar filament into the host cell. The polar filament is unique to the microsporidia. With a few exceptions, microsporidiosis is typically chronic and subclinical in immunologically competent hosts. Young carnivores infected with microsporidia, however, develop severe and sometimes lethal renal disease, and immunodeficient laboratory animals (e.g. athymic and SCID mice) develop ascites and die from microsporidiosis. This review describes the morphology, life cycle, taxonomy, and host-parasite relationships of the species of microsporidia that infect mammals.

Microsporidiosis: molecular and diagnostic aspects.

The term 'microsporidia' is a nontaxonomic designation which is used to refer to a group of intracellular parasites belonging to the phylum Microspora. These eukaryotic obligate intracellular protozoans have been described infecting every major animal group, especially insects, fish and mammals. They are important agricultural parasites in commercially important insects, fish, laboratory rodents, rabbits, fur-bearing animals, and primates. There is now an increasing recognition of microsporidia as important opportunistic pathogens in persons infected with the human immunodeficiency virus (HIV). Microsporidia possess ribosomes with features resembling prokaryotes. Phylogenetic analysis of the rRNA sequence from several of the microsporidia suggests that these organisms were early branches in the eukaryotic evolutionary line. The data on these molecular phylogenetic relationships are reviewed in this paper. Inroads have recently been made into the molecular biology of these organisms and these data are also presented. 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 level. Both staining and PCR techniques for the diagnosis of microsporidia are reviewed.

Disseminated microsporidiosis especially infecting the brain, heart, and kidneys. Report of a newly recognized pansporoblastic species in two symptomatic AIDS patients.

Microsporidia have emerged as important opportunistic AIDS pathogens of the alimentary, respiratory, and urinary tracts. Although nonhuman mammalian microsporidia infections typically include encephalitis, CNS microsporidiosis has not been reported in patients with AIDS. A 33-year-old white male and an 8-year-old black girl presented with seizures and declining mental status. Central nervous system (CNS) imaging studies revealed small peripherally and diffusely enhancing lesions present for at least 2 and 4 months before death, respectively. Both patients expired despite empirical anti-toxoplasma therapy. Their brains contained innumerable soft gray matter lesions that consisted of central areas of necrosis, filled with free spores and spore-laden macrophages, surrounded by microsporidia-infected astrocytes. The complete autopsy of the child also revealed necrotizing and sclerosing cardiac and renal microsporidiosis and infection of the pancreas, thyroid, parathyroids, liver, spleen, lymph nodes, and bone marrow. Infected cells included astrocytes, cardiac myocytes, epithelium, endothelium, vascular smooth muscle cells, hepatocytes, adipocytes, Schwann cells, and macrophages. Light and electron microscopic studies revealed pansporoblastic development within thick-walled sporophorous vacuoles of parasite origin. Although most similar to Pleistophora sp and Thelohania sp, this microsporidian is different from any known species. Microsporidiosis should be considered as the possible cause of a wide range of diseases in AIDS patients, including CNS, cardiac, and renal.

Detection and identification of gastrointestinal microsporidia using non-invasive techniques.

AIMS: To detect enteric microsporidia in faecal specimens from patients with the acquired immunodeficiency syndrome (AIDS), and to identify the spores to species level without using invasive procedures. METHODS: Formalised faecal preparations were examined using a modification of the strong trichrome staining method to demonstrate microsporidian spores. Six positive specimens were prepared for electron microscopy by emulsification and separation using a 9% Ficoll gradient. RESULTS: The modified staining technique readily identified microsporidian spores. Spores of different species showed variation in size. Identification using electron microscopy was successful for five of the six positive specimens examined. It was unsuccessful for one specimen in which spores were less abundant on initial staining. CONCLUSIONS: The modified strong trichrome staining method is a useful way of detecting spores of intestinal microsporidia in faecal specimens. Variation in spore size may permit provisional identification by light microscopy. Electron microscopic examination of faecal preparations is useful for identifying spores to species level.

Cryptosporidia and microsporidia--waterborne diseases in the immunocompromised host.

Cryptosporidia and microsporidia are emerging parasitic pathogens in immunocompetent and immunocompromised individuals. Cryptosporidium infects several wild and domestic animals that excrete oocysts into the environment and contaminated water represents the major source of infection for humans. Waterborne transmission of Cryptosporidium is a major risk for humans and appropriate measures have to be taken to protect immunocompetent and immunocompromised individuals to become infected. For microsporidia, the sources and ways of transmission are not well documented. Although several animal hosts have been identified recently, the relevant reservoirs of human microsporidia are still unknown. Also, the routes of spreading are unknown. Is microsporidiosis a zoonotic disease that will be transmitted through close contact with infected animals or is contaminated surface water responsible for transmission and represents a relevant reservoir? This review is designed to give information on these two emerging intestinal parasites in a format that will be useful to clinical microbiologists, physicians interested in infectious diseases, and public health personnel.

Encephalitozoon-like microsporidia in the ticks Amblyomma cajennense and Anocentor nitens (Acari: Ixodidae).

A Encephalitozoon-like microsporidia was found in epithelial cells of the midgut and the salivary glands of Amblyomma cajennense (F.) and Anocentor nitens (Neumann) that had fed on rabbits. Ultrastructural studies demonstrated that all stages of the life cycle of the parasite occur in parasitophorous vacuoles and contain only 1 nucleus. The sporonts detach from the limiting membrane of the vacuole and divide by binary fission to produce the sporoblasts, each presenting a thickened electron-dense wall, and a primordium of a polar filament. Each spore contained a single nucleus, an electron-dense and rough exospore, an electron-lucent and thick endospore, and 5 coils of the polar tubule.

Kabataia gen. n., a new genus proposed for Microsporidium spp. infecting trunk muscles of fishes.

Based on a fine structural study, a new genus, Kabataia gen. n., is proposed for Microsporidium arthuri Lom, Dyková and Shaharom, 1990. It develops in trunk muscles of a South-East Asian freshwater fish, Pangasius sutchi. The genus has nuclei isolated throughout the cycle, merogony stages are multinucleate, sporogony proceeds in 2 steps: multinucleate sporont segments into sporoblast mother cells which produce 2 sporoblasts. Sporoblasts and early spores are characterized by a dense globule at the site of the posterior vacuole. Mature spores are of a rather variable shape. Their exospore is raised into small, irregular fields. The polaroplast is relatively small and its posterior part consists of flat vesicles with dense contents. The polar tube makes a small number (4 to 6) of turns. A congeneric species is Kabataia seriolae (Egusa, 1982) comb. nov. from cultured marine yellowtails Seriola quinqueradiata. Kabataia inflicts heavy damage on muscle tissue. The sarcoplasm within which Kabataia develops is reduced to an amorphous mass with tubule-like fibrils, microfibrils and small vesicles.

Ovipleistophora gen. n., a new genus for Pleistophora mirandellae-like microsporidia.

Based on ultrastructural study and molecular analysis, a new genus, Ovipleistophora, is established for Pleistophora mirandellae-like microsporidia from roach and ruff oocytes. Unlike Pleistophora, Ovipleistophora has a thick additional envelope around the meront. This envelope breaks open to release the cells into the host cell cytoplasm. The cells, becoming multinuclear sporogonic plasmodia, already have a surface coat that transforms into the sporont wall and eventually into the sporophorous vesicle wall. The surface coat and its transformation differ from those of Pleistophora, but bear some resemblance to those of Trachipleistophora. In Trachipleistophora the sporonts, however, do not form plasmodia, as they do in Ovipleistophora and Pleistophora. Small subunit ribosomal DNA analysis supports the establishment of the new genus and assignment of P. mirandellae from 2 different fish hosts to the same species. The same small subunit ribosomal DNA analysis lends support for transferring P. ovariae into the genus Ovipleistophora.

Small subunit ribosomal DNA phylogeny of microsporidia with particular reference to genera that infect fish.

Molecular data have proved useful in the study of microsporidia phylogeny. Previous studies have shown that there are several important differences between phylogenies based on rRNA and morphological data. In the present study, small subunit (SSU) rDNA sequences were obtained from 7 different fish-infecting microsporidia from 4 different genera (Glugea Thélohan, 1891, Loma Morrison and Sprague, 1981, Pleistophora Gurley, 1893, and Spraguea Weissenberg, 1976). The lengths of the SSU rDNA genes in these species were between 1,332 and 1,343 base pairs. Phylogenetic analysis was performed using parsimony, maximum likelihood, and Kimura 2-parameter with neighbor joining. The analyses revealed that the microsporidia could be divided into 3 major groups. With the exception of Nucleospora salmonis Hedrick, Groff, and Baxa, 1991, all the microsporidia infecting fishes occurred in the same group. The analysis showed that Pleistophora mirandellae Vaney and Conte, 1901 and Pleistophora aguillarum Hoshina, 1951 are not species of Pleistophora. Furthermore, the analysis showed that Loma is not a member of Glugeidae Thélohan, 1892.

A new Microsporidium sp. (microsporidia) from the musculature of the mountain whitefish Prosopium williamsoni from British Columbia: morphology and phylogeny.

Few microsporidia have been reported from whitefish species (subfamily Coregoninae). For the most part, these microsporidia have been incompletely described. In a survey of parasites of mountain whitefish Prosopium williamsoni collected from Kootenay Lake, British Columbia, we encountered an unusual microsporidium infecting the endomysium of the skeletal musculature. Spores were uninucleate, ovoid to pyriform, and were 5.6 (5-7) microm x 3.2 (3-4) microm with 13-16 coils in the polar filament. We describe here this organism as a new species based on its site of development and its relationship among fish microsporidia based on small subunit ribosomal DNA sequence data, i.e., our analysis showed that it is not closely related to other microsporidia for which ribosomal DNA sequence is available thus far.

Molecular detection and phylogenetic placement of a microsporidian from English sole (Pleuronectes vetulus) affected by X-cell pseudotumors.

Flatfish tissue samples exhibiting X-cell pseudotumors were tested with a number of ribosomal DNA (rDNA) general primers in polymerase chain reactions (PCRs). Microsporidian primers resulted in the amplification of an rDNA fragment and molecular phylogenetic analysis indicated that although the organism did not relate closely with any current microsporidian genera, it was most similar to Nucleospora salmonis and branched within the Enterocytozoonidae. Re-examination of the original tissues used for DNA extractions revealed the presence of putative microsporidian spores in PCR-positive samples. These observations reiterate the highly sensitive diagnostic feature of PCR, allowing detection of organisms overlooked by conventional methods and demonstrate the occurrence of rare, coinfecting organisms.

A PCR-RFLP method for the detection and species identification of human microsporidia.

From small subunit ribosomal RNA gene sequences, a pair of PCR primers were designed to amplify a portion of this gene from five species of microsporidia. The amplified fragments encompass polymorphic restriction sites for the Hphl enzyme, resulting in different restriction patterns in the different species. We tested this identification method both on cultured microsporidia and on clinical samples. On cultured microsporidia the expected amplification bands were obtained even when DNA preparations from only ten spores were analysed. On clinical samples, identification of microsporidia was obtained from crude DNA preparations. This method allows for a rapid and easy diagnosis of human microsporidioses.

[Microsporida infections in immunocompetent and immunosuppressed subjects]. / Infezioni da microsporidi in soggetti immunocompetenti ed immunodepressi.

Parasites of the phylum Microspora are obligatory intracellular protoza with a widespread host range among invertebrates and vertebrates. Species from Nosema, Encephalitozoon, Enterocytozoon and Pleistophora genera can infect immunocompetent and immunosuppressed patients. The emergency of the AIDS epidemic has recently highlighted the role of these parasites in human pathology, microsporidian species being a frequent cause of diarrhoea and ocular infections. Recent acquisitions in the taxonomy and life cycle of this parasite group, as well as pathogenesis, immunopathology, clinical aspects, diagnosis, therapy and epidemiology of human microsporidiosis are reviewed and discussed.

Microsporidial infections in humans: current practice and developments in laboratory diagnosis.

Microsporidia are small, intracellular parasites that infect a wide range of hosts, including vertebrates, invertebrates and fish. They were discovered more than a century ago. The first well documented human case, however, was not reported until 100 years later. Since the first case of intestinal microsporidiosis was reported in 1985, numerous cases of microsporidiosis have been reported in immunocompromised patients, especially those in the later stages of human immunodeficiency virus (HIV) infection. Microsporidia also have been described in various other clinical conditions, including keratoconjunctivitis, sinusitis, peritonitis and myositis. The numbers of cases reported have risen dramatically since 1985, which can be explained partly by the acquired immune deficiency syndrome (AIDS) pandemic and partly by increased laboratory awareness. Some studies have shown that up to 50% of selected AIDS patients are infected with microsporidia. Diagnosis depended initially on the use of invasive techniques, namely histological examination of biopsy material. Since then, however, there have been important advances in the detection of microsporidial spores in clinical samples. Recent developments in the diagnosis of microsporidiosis are described, including light microscopy staining methods, fluorescent staining, electron microscopy and molecular techniques.

Early experiences with microsporidia of man and mammals.

Comparative data are given of microsporidian infections in insects and mammals. Due to minute size and diffuse distribution in mammals microsporidia were recognized in vertebrates only during search for virus infections. Early infections with Encephalitozoon in rearings of laboratory animals contaminated many isolates of other protozoan infections. Old separate descriptions of microsporidia in mice, rabbits or dogs have to be reevaluated with modern methods of molecular analysis. Old cases of infection of man known now as Encephalitozoon chagasi or Encephalitozoon sp. Matsubayashi are not belonging to the genus Encephalitozoon and should be jointly studied with Nosema connori as eventually identical. With actual improvements of methods of diagnostics the net of detection of microsporidia in man should be extended on routine testing of urine, faecal samples, eye and nose biopsies and other materials including vaginal smears. The way of circulation of the infections in the host organisms must be studied.