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L’examen de Clarias pachynema Boulenger, 1903 (Clariidae), Ctenopoma petherici Günther, 1864 (Anabantidae) et Parachanna obscura (Günther, 1861) (Channidae), capturés dans le bassin du Nkam au Cameroun, a révélé la présence de deux espèces nouvelles de Myxosporidies du genre Myxidium Bütschli, 1882, toutes parasites de la vésicule biliaire. Les espèces inédites sont : Myxidium nkamensis n. sp., parasite de Clarias pachynema; M. sangei n. sp., qui forme des spores dans la paroi de la vésicule biliaire de Parachanna obscura. Deux autres espèces, Myxidium petrocephali Fomena et Bouix, 1986 et M. distichodi Kostoïngué, Faye et Toguebaye, 1998, ont été retrouvées chez des hôtes nouveaux. Leur diagnose est complétée. La liste des espèces de Myxidium parasites des poissons d’eau douce d’Afrique est donnée.

L’examen de Schilbe mystus (Linné, 1758) (Schilbeidae) et Citharinus citharus (Geoffroy Saint-Hilaire, 1809) (Citharinidae), capturés respectivement dans les bassins de la Sanaga à Edéa et de la Bénoué à Lagdo, a révélé la présence de deux espèces nouvelles de Myxosporidies appartenant au genre Thelohanellus Kudo, 1993 : Thelohanellus njinei n. sp., parasite de l’intestin de Schilbe mystus et Thelohanellus lagdoensis n. sp., parasite de l’intestin chez Citharinus citharus. Des informations complémentaires sont données sur la diagnose de Thelohanellus citharini, parasite antérieurement décrit au Tchad.

L'examen de Citharinus citharus (Geoffroy Saint-Hilaire, 1809 (Teléostéen, Citharinidae), récolté sur le fleuve Chari au Tchad, a révélé la présence de trois espèces nouvelles de Myxosporidies dont nous donnons ici la description complète : Thelohanellus taguii n. sp., parasite systémique; Myxobolus mbailaoi n. sp., parasite des opercules, de la peau et de l'intestin et Myxobolus charii n. sp., parasite de la peau.

The study of 102 teleost freshwater fishes of Sanaga basin in Cameroon revealed the presence of three myxosporean species, among which two were new. Host fishes were of three families: Centropomidae, Cichlidae and Characidae. New species were identified as Henneguya mbakaouensis sp. nov., a gill parasite of Lates niloticus and Myxobolus nounensis sp. nov. found in the kidney and spleen of Sarotherodon galilaeus and Tilapia mariae. Myxobolus hydrocyni Kostoïngue & Toguebaye, 1994, previously described in Chad, was also found in Cameroon; complementary informations were given on that parasite which seemed to be specific to its host.

The microsporidian Pleistophora senegalensis sp. nov. parasitizes the gilt-head sea bream, Sparus aurata L. The parasite is found in the intestinal wall where it forms small xenomas in the muscularis. The development cycle of this species is described by light and electron microscopy. Meronts are rounded plasmodia dividing by plasmotomy and bounded by an amorphous and very regular wall. At the onset of sporogony, sporophorous vesicles are formed by separation of the plasma membrane from the external wall which then becomes a characteristic mesh. Mature spores (4-45 × 2-37 μm) are ovoid and slightly pyriform with a large posterior vacuole. [ABSTRACT FROM AUTHOR]

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 3.96×2.16 μm. 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. [ABSTRACT FROM AUTHOR]

The study of Myxosporidia infecting Clarias pachynema Boulenger, 1903 (Clariidae), Ctenopoma petherici Günther, 1864 (Anabantidae) and Parachanna obscura (Günther, 1861) (Channidae) from the basin of Nkam in Cameroon, revealed the presence of two new species of Myxosporidia of the genus Myxidium Bütschli, 1882, all found in the gall bladder of their hosts. These new species were: Myxidium nkamensis n. sp., found in Clarias pachynema and M. sangei n. sp. found in the gall bladder wall of Parachanna obscura. Two other species, Myxidium petrocephali Fomena and Bouix, 1986 and M. distichodi Kostoïngué, Faye and Toguebaye, 1998 were found in new hosts. The list of Myxidium species parasitizing African fresh water fishes is given.

The study of Citharinus citharus (Geoffroy Saint-Hilaire, 1809) (Teleost, Citharinidae) captured in the Chari river in Chad revealed the presence of three new myxosporidian which are described in the present paper: Thelohanellus taguii sp. nov., a systematic parasite; Myxobolus mbailaoi sp. nov., which affects operculum, skin and intestine, Myxobolus charii sp. nov., a parasite of the skin.

The cytology of a new microsporean parasite Microsporidium epithelialis sp. n. from the intestinal epithelial cells of the freshwater oligochaete Tubifex sp. (Tubificidae) is described. The microsporean occurred together with an actinosporean of the genus Triactinomyxon, which was found between the epithelial cells. The merogonic and sporogonic stages (mature spores included) of the microsporean parasite are monokaryotic. An individual sporophorous vesicle surrounds each spore. The fixed and stained spore has an average dimension of 1.9-2.5 x 0.9-1.2 microm. The spores are oval with a characteristic surface layer, showing ornamentation-like projections, which are in close contact to the exospore. A short polar filament forming three to four coils traverses the polaroplast with two lamellar layers. The ultrastructure and other characteristic features of this microsporean parasite are distinct from those of the microsporean species described so far from oligochaetes.

Background: In the past 25 years the United Arab Emirates (UAE) have experienced a socioeconomic boom. The once nomadic Bedouin population of Al Ain, in the emirate of Abu Dhabi, now lives in modern air-conditioned accommodation, and huge desalination plants have allowed afforestation and farming., Objective: To evidence responsible airborne allergens in an UAE population., Patients and Methods: 263 UAE Nationals who attended Tawam Hospital (Al Ain, UAE) with a respiratory disease suspected of being of allergic origin, were submitted to SPT and RAST. The choice of pollinic allergens was made in accordance with the local flora and market availability. All patients were SPTed with at least the same battery of 15 pollinic and indoor allergens. Most patients were submitted to at least 4 RAST, viz Cynodon dactylon, Salsola kali, Prosopis juliflora and Dermatophagoides pteronyssinus., Results: 71.8% patients were positive for at least one allergen. Pollen accounted for 61.6% of positive patients, with 45.2% positive to chenopodiaceae, 33% to gramineae and 23.5% to P. juliflora. Indoor allergens were positive in 30.4% of patients with 17.9% positive to D. pteronyssinus and D. farinae, 11% to Blatella germanica, 8.3% to Cat fur, 4.9% to Goat hair, 0.7% to Rat hair and Mouse hair and 1.5% to Candida albicans., Conclusion: Pollen was the prominent allergen. There is room, however, for further epidemiological studies possibly with new extracts and RAST specifically designed after the species of the Gulf region.

The microsporidia Enterocytozoon bieneusi is reported in 10-30% of those infected with the human immunodeficiency virus. The parasite appears to be a cause of gastralgia, malabsorption, and diarrhea. A Western blot technique using another microsporidian species, Glugea atherinae, has demonstrated an antigenic similarity between this parasite and E. bieneusi. Preliminary results show the variability of the antigenic profiles obtained from the sera of immunodeficient patients infected with E. bieneusi and also of the cross-reactivity to Glugea sp. antigens of some sera from patients with cryptosporidiosis. The origin of this cross-reactivity is undetermined. The possibility of coinfection with undetected microsporidia is not excluded. These results raise questions concerning the interpretation of serologic data and of the potential immunodiagnostic value of microsporidian antigens.

Ultrastructural study of Myxidium giardi showed that pluricellularity is maintained by the formation of septate desmosomes. The polar capsule is formed from helicoidal depositions of banded material in the initial vacuole. This process makes possible not only the formation of the rigid capsular body but also of the flexible polar filament which is evaginable and reversed in the capsule. The special feature of the genus Myxidium is the ornamentation of the valvogenic cells of the spores in the form of longitudinal ribs. An ultrastructural study showed that the morphogenesis of this cell relief in Myxidium giardi involves a special process based on the development of fusiform macrovesicles whose bases are connected to a cytoskeleton formed of special microtubules 14 nm in diameter. The latter seem to determine the future rigidity of the valvar epicyte., (Copyright © 1993 Gustav Fischer Verlag · Stuttgart · Jena · New York. Published by Elsevier GmbH.. All rights reserved.)

High death rates have been recorded in populations of Pinctada margaritifera (natural or reared stocks) in atolls in the Tuamotu Archipelago (French Polynesia). An histological study of the oysters from the concerned areas revealed the occurrence of a protist of which ultrastructural features correspond to those of Gregarinea. It is still premature to establish a link between the presence of the Gregarine and recent deaths of pearl oysters.

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.

The life cycle of the microsporidian parasite of Galerucella luteola (Chrysomelidae, Coleoptera) was investigated by optical and electron microscopy. All stages were diplokaryotic and apansporoblastic. Sporogony was disporous. Spores were oval, elongated and measured 4.95 × 2.89 μm with a lamellar polaroplast and 7-9 coils of polar filament. These ultrastructural features indicate that this microsporidian is a Nosema. We have named it Nosema galerucellae n. sp., (Copyright © 1989 Gustav Fischer Verlag, Stuttgart. Published by Elsevier GmbH.. All rights reserved.)

Glugea stephani forms xenomas in the intestinal wall and in several organs of the flounder Platichthys flesus in the Languedoc's ponds. Four characteristic stages are recognised in the development of these xenomas: reinforcement of the wall and maintenance of the host-parasite equilibrium, inflammation, granulomaformation, cicatrisation. The role of the polymorph neutrophiles is essential, first because it harbours the sporoplasm and then because it contributes to the destruction of the spores. The entire phenomenon is described at the ultrastructure level.

Macrophages of 1+ rainbow trout are parasitised by an unknown protozoan. An ultrastructural study permits to associate it with the genus Dermocystidium described in many fishes. This protozoan is characterized by a large vacuole of mitochondrial origin and by concentric structured bodies.