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A globule frequently refractory, appearing blue, pale blue, or white with Giemsa stain, is characteristic of the intraerythrocytic stages of the type species and of most of the other species included at present in the sub-genus Novyella. This globule is absent from the other Plasmodium sub-genera. An ultrastructural study has been performed on schizogonic stages of Plasmodium merulae from the blood of the blackbird, Turdus merula. In section the globule contains a finely granular substance suggesting a condensed or coagulated substance. It differs distinctly from a classical food vacuole by denser contents, and show in some sections (19, 23) a peripheral opaque rim with a radial arrangement of ribosomes. Except for the presence of the globule, in other details P. merulae do not diverge from the ultrastructure common to the intraerythrocytic stages of avian Plasmodium.

Examination of blood smears obtained from raptors trapped while on migration at Eilat, Israel, demonstrated Plasmodium infection in Accipiter brevipes and Buteo buteo. The following species are described, from A. brevipes: Plasmodium alloelongatum n. sp., P. accipiteris n. sp. and from B. buteo: P. buteonis n. sp. and Plasmodium sp. for which we lack sufficient data for adequate species description. Overall prevalence of infection with Plasmodium spp. was very low: among 38 examined A. brevipes 5 % and among 56 B. buteo 3.6 %.

Testudo graeca tortoises were collected in the northern and southern Golan Heights (Israeli occupied territory of south Syria), and various locations in Israel and Palestine. Hyalomma aegyptium ticks were found only on Golan Height tortoises, and only the tortoises and ticks from the northern Golan Heights were infected with Hemolivia mauritanica. Tortoises became infected after ingesting infected ticks. Male ticks carrying sporocysts, which remain attached to tortoises for extended durations, apparently served as the source for dissemination of new infections among tortoises. Sporogenesis followed the pattern observed in the two other known species of Hemolivia, though there was some evident variation in fine-structural detail. The sutural slit detected in the H. mauritanica mature sporocyst wall was reminiscent of the suture characteristic of Coccidia of heterothermic vertebrate hosts; it could be a common ancestral character for both hemogregarines and Coccidia.

Specimens of Hepatozoon-infected Boa constrictor constrictor were obtained from localities in Pará State, north Brazil. Gametocytes in erythrocytes of the peripheral blood measured 10 x 2.5-16.2 x 3.7 µm. They were similar to those described as Haemogregarina terzii by Sambon & Seligmann (1907) in B. c. constrictor, in that they did not distort the infected erythrocyte, and their dimensions approximated those given by Carini (1947). Lungs and liver of infected snakes contained actively dividing meronts of a single type, and cysts containing two to six cystozoites were also present in the liver. Our initial feeding of Culex quinquefasciatus on infected snakes consistently resulted in a heavy death-rate of the engorged mosquitoes, with only a few surviving till the 9th day post feeding. These contained numerous oocysts which were undivided or in early stages of division. A fifth and final experiment, however, provided a few mosquitoes surviving up to 21 days post infection (dpi), and these contained fully sporulated oocysts measuring 190-200 µm in diameter and containing over 60 sporocysts of 19-30 µm in diameter. The number of sporozoites in each sporocyst was estimated as approximately 50. The nature of the parasite's sporogonic cycle in the mosquito thus justifies inclusion of this haemogregarine in the genus Hepatozoon. Two wild-caught specimens of the lizard Tropidurus torquatus were fed with mosquitoes containing fully developed oocysts (21 dpi). When sacrificed, three months later, large numbers of dizoic, tetrazoic and hexazoic cysts were demonstrated in their livers. Cystozoites released from these cysts were shown to possess a conspicuous refractile body.

Laboratory rats fed sporocysts of Sarcocystis singaporensis (Zaman & Colley, 1975) Zaman & Colley, 1976 originating from Singapore were euthanized 22, 23, 33 and 80 days later. Sporocysts were extracted from feces of either naturally or laboratory-infected Python reticulatus. Electron microscopically examined tongue and esophageal muscles yielded images of successive developing stages of sarcocysts. The primary wall evolved from a continuous thin layer into folds and later, into villar protrusions. At all stages the wall was interrupted by pinocytotic-like indentations. Young sarcocysts contained only metrocytes, they divided by endodyogeny into daughter metrocytes. The first bradyzoites appeared only 33 d.p.i. Sarcocysts by 80 d.p.i. were enclosed in a fully differentiated primary wall and contained almost entirely bradyzoites.

Hepatozoon kisrae n. sp. was found infecting a starred lizard at a site in southeastern Samaria, Palestine. These lizards were also hosts to the ixodid tick Hyolomma cf. aegyptium, which was demonstrated to be the vector of this hemogregarine. Hepatozoon and tick infections occurred in lizards within a very restricted locality; at a second site, nearby, ticks occurred without Hepatozoon infection. Micro- and macromeronts occurred mainly in the lungs, while cyst-like merogonic stages, mainly dizoic, occurred in the liver. Mature intraerythrocytic gametocytes were stout and encapsulated. Development from oocysts to sporocysts took place in the tick hemocoel, and was examined by transmission electron microscopy. Lizards were successfully infected when fed on sporocyst-infected ticks or viscera of infected lizards. Ticks become infected when fed on infected lizards; sporogony was complete when the ticks reached adult stage, over 40 days after initial attachment.

Plasmodium kentropyxi n.sp. is described in the teiid lizard Kentropyx calcarata from north Brazil. Young asexual stages and gametocytes are at first polar in the erythrocyte but with elongation, move to a lateral position. Largest meronts seen contained from 30-40 nuclei and conspicuous greenish-black pigment granules located in a distinct vacuole. With growth the gametocytes eventually assume a smooth, curved cylindrical shape, with evenly rounded ends. Pigment is scattered or concentrated around a conspicuous vacuole which is slowly developed as the gametocytes mature. Mature male parasites measured 11.8 x 4.0 μm (9.6 x 4.2 - 13.2 x 3.6 μm), shape-index 2.9 (2.2 - 5.0), and females 13.5 x 4.5 μm (12.0 x 4.5 - 15.0 x 4.8 μm), shape-index 3.0 (2.2 - 3.8). Some larger meronts may slightly enlarge the erythrocyte, but most asexual stages and the mature gametocytes rarely do so. A second, P. tropiduri-like parasite encountered in K. calcarata possessed small rounded or fan-shaped meronts producing from 4-14 merozoites, and spherical to subspherical gametocytes of approximately 6.0 x 5.0 μm. The parasite was consistently polar in its position in the erythrocyte.

Examined fish of the genus Baryancistrus (Loricaridae) from Rio Xingu in central amazonian Brazil were found infected with extrasporogonic stages of Sphaerospora sp. (Myxosporea) in the blood and sporogonic stages in the glomeruli with the resulting escape of the sporogony products into the renal tubules, apparently when the mesangial tissue in the Bowman's capsule collapsed. Spores were seen evacuating via the urinary tubules. Blood stages were initially 2.1 x 2.8 to 2.8 x 2.8 μm in size, and when fully differentiated reached 5.6 x 5.6 - 5.6 x 7.0 μm; in blood smears they were 11.2 x 8.4 to 14 x 8.4 μm. Bisporoblasts in the glomerular taft were 9.8 x 7.0 μm, premature spores were 5.6 x 4.2 - 5.6 μm.

Sarcocysts in muscles of the teiid lizard Ameiva ameivafrom north Brazil were fed to the colubrid snake Mastigodryas bifossatus, the faeces of which had been shown to be devoid of coccidial oocysts or sporocysts. When necropsied 16 days later the snake was shown to have developed a massive intestinal infection of Sarcocystis. Mature sporocysts from another, naturally infected M. bifossatus were fed to juvenile specimens of A. ameiva in which no sarcocysts could be detected in tail muscle biopsies. When examined 30 and 47 days later they had very large numbers of sarcocysts in their tail and tongue muscles. The parasite is given the name of Sarcocystis ameivamastigodryasi n. sp. An ultrastructural study has been made of the sarcocyst and of the parasite's sporulation in the lamina propria of the snake: the latter provides details of the wall formation process in developing sporocysts. Attempts to infect a specimen of the boid Boa constrictor constrictor by feeding it with infected Ameivafailed, suggesting that sporocysts previously recorded in genera of the family Boidae may be those of a different species of Sarcocystis.

Three, 4-month old reticulated pythons (Python reticulatus) hatched from eggs laid by a newly caught female from Singapore Island, were fed on muscles of Sarcocystis singaporensis infected Rattus rattus caught in Singapore. Snakes were sacrificed five, six and eight days later. The infected tissues were studied by transmission electron microscope. The present communication summarizes findings on macrogamont and oocyst stages. In the premature stages, rough endoplasmic reticulum consolidate into a large rectangular array; the electron-dense wall-forming-like bodies reveal a laminar structure. Macrogamont parasitophorous vacuoles became filled with granular matrix and electron-dense strands, which later on consolidate into a coat around the fertilized zygote. The oocyst wall is constructed from several formed membranes combined with deposited substance. All development to the sporulated oocyst stage occurs in the mucosal epithelium.

The ixodid tick Ixodes granulosus Supino 1897 was found infesting Rattus rattus in Semakau island, one of the small offshore islands fringing Singapore to the south. None of the examined R. rattus from the other islands fringing Singapore, or from Singapore island were found infested. Ixodes granulatus occurs, however, on Singapore island on Rattus annandalei, resident of undisturbed forested habitats. We speculate that invading black rats in Semakau replaced autochthonous sylvatic rodent population and contracted their associate tick population.

The ultrastructure is described of the meronts, microgamonts and young oocyst stages of Isospora hemidactyli of the gecko Hemidactylus mabouia from Belém, PA, north Brazil. The endogenous stages all develop in the nucleus of the gut epithelial cells. The nucleus remains intact up to the latest stages of the parasite's development, but degenerates by the time the oocyst appears. Merogonic division appears to be asynchronous, and some of the differentiated merozoites contained more than one nucleus. Microgamonts conform in structure with those of other eimeriids. Some of the type 2 wall-forming bodies disintegrate into smaller globules and ground substance of lower density.

Focuses on the detection of branchiomycosis in an amazonian fish, Baryancistrus sp. of Order Loricariidae. Detection of Branchiomyces-like hyphae in three out of seven Baryancistrus sp.; Restriction of fungal infection to small regions in the gills and extended beyond the vascular system; Hyphae description; Segmentation of the plasmodia into smaller, multinucleated and uninucleated bodies in the sporulation process.

The complex interactions between parasites, hosts and the environment are influenced by the stability of the ecosystem. Heteroxenous parasites, with complex, multiple-host life cycles, can persist only in habitats where the full range of their required hosts are present. Conversely, in impoverished environments such as those impacted by environmental stress, monoxenous species that have simple, single-host life cycles are likely to predominate. In the present study, we analyzed the ratio between heteroxenous and monoxenous (H/M) parasites as well as parasite species richness (SH/SM) and species diversity in rabbitfish ( Siganus rivulatus) collected from several sites in the Red Sea. The rabbitfish is a Suez Canal immigrant, well established in the eastern Mediterranean, and fish were also collected from a site on the Mediterranean coast of Israel. Separate treatment of the micro- and macroparasite components of the rabbitfish parasite communities in the Red Sea suggested that macroparasites only – monogenea and gut parasites – were better indicators than the parasite community as a whole. Quantification of macroparasites is accurate, saves time and effort, produces more accurate data and better differentiates between sites. Higher H/M ratios and SH/SM ratios were found in the rabbitfish collected at the ecologically stable habitat of the coral reef compared to rabbitfish from sandy habitat or mariculture-impacted sandy habitat. The results of the study emphasized the negative impacts of cage mariculture on the environment. The rabbitfish collected near the mariculture farms supported the poorest and least diverse parasite communities of all sampled sites, with virtual depletion of heteroxenous species, and even reduction of gill monogenean infections on the hosts. When results from the Mediterranean sites were compared with those of the Red Sea, the data showed full representation of monoxenous parasites (all but one of Red Sea origin), while heteroxenous species were completely absent. We may therefore regard the Mediterranean as a simulation model for a severely environmentally deteriorated, impoverished habitat, in which all or part of the intermediate host species have been depleted, enabling survival of the monoxenous parasite species only. Parasitological investigations were supplemented by testing the activity of cytochrome P 450- dependent mono-oxygenase EROD as a measure of exposure, and lysosomal stability as a measure of toxic effect in the liver of rabbitfish. The results underline the parasitological findings, showing that fish caught at the impacted sandy beach location in the Red Sea have significantly higher EROD activity and a decreased membrane stability compared with animals from the coral reef. In comparison, EROD activity values in rabbitfish from the Mediterranean Sea were double, while lysosomal membrane stability was half that measured at the most impacted Red Sea location. [ABSTRACT FROM AUTHOR]

An integrated biological effect monitoring concept has been tested in flounder ( Platichthys flesus L.) from four locations with different anthropogenic impact in the German Bight. During 3 years of sampling, biomarkers at all levels of biological organisation from the molecular to the ecosystem level were applied and tested on 742 individual fish of body lengths between 18 and 25 cm. At the ecosystem level, the fish were taken as a habitat for the parasite assemblage. The hypothesis was that changes in the environment might lead to changes in the species diversity of parasites and in the infection intensity of single species, as well as between heteroxenic and monoxenic parasite species (H/M ratio). At the molecular level, activity of the CYP1A-dependent monooxygenase ethoxyresorufin O-deethylase (EROD) was used as a biomarker of exposure. At the subcellular level, the integrity of lysosomal membranes in hepatocytes was taken as an indicator of non-specific acute and chronic toxic effects. Both biomarkers are recommended by the ICES Advisory Committee on the Marine Environment for the application in biological effects monitoring programmes. In addition, neutral lipid content in the liver was used as a marker for pathologically induced fat accumulation. In the same individual fish, a new method for the measurement of macrophage aggregate activity in the liver was tested for its application and reliability in reflecting immunosuppression. Tests were accompanied by chemical analysis of standard organochlorine and heavy metal residues in flounder tissue. A total of 33 parasite species were found. As an indicator species, the mean abundance of Trichodina sp. reflected best the pollution gradient observed with highest infection intensity at the most polluted location. Species diversity was significantly higher in fish caught near the reference site and significantly lower in fish from the polluted Elbe estuary. The use of the heteroxenous/monoxenous species ratio as a marker was not useful at the locations investigated because of the dominance of heteroxenous species at all habitats. Since EROD activity and macrophage aggregate activity were dependent on sex and maturity of female flounder, only male fish were taken into consideration for the integrated evaluation of data. All biochemical and histochemical tests were able to reflect accurately the site-specific differences, as well as an observed pollution event at the end of 1995 as determined by chemical analyses. The correlation analysis revealed a connection not only between the single parasitological and biochemical parameters but also within these groups. The non-specific immune response and Trichodina infection intensity were correlated with all other parameters, leading to the assumption that these may serve as links between the lowest and the highest levels of biological organisation. The simultaneous use of metabolic and parasitological results facilitated the interpretation of the observed variations of the data and the distinction between natural variation and pollution-mediated effects. [ABSTRACT FROM AUTHOR]

A lymphocystis infection is described from aquarium-held snakeskin gourami, Trichogaster pectoralis (Regan). The cytoplasm of the hypertrophic cells revealed virus particles of extended hexagonal profiles with thin two-layered capsids. Subsequent examination of the fish 4 months later revealed hypertrophic cells showing varying degrees of collapse and degradation. The virus particles loading such cells were of regular hexagonal profiles with thick three-layered capsids. [ABSTRACT FROM AUTHOR]

Epitheliocystis infections in the gills of carp from Israel and Portugal occurred in lining epithelial cells as well as mucus and chloride cells. Ultrastructural studies of infected cells revealed several morphological forms of epitheliocystis showing the existence of a pleomorphic developmental cycle. The following stages were observed: chlamydia-like round cells (RC), non-dividing round cells (NRC) and bullet-shaped small cells (SC). All these were identical in shape to RC and SC described from epitheliocystis of other fish, The rickettsia-like cells (PLC and ILC) which occur in epitheliocystis from other fish species and produce the SC were absent in carp epitheliocystis and instead the RC were seen transforming into SC. Transformation to SC, however, occurred at any stage of the developmental process, even before the replication potential of the RC was exhausted, i.e. before reaching the NRC stage. [ABSTRACT FROM AUTHOR]

This article presents a study related to A Chloromyxum-like myxosporean infection in the stomach of cultured Spams aurata. Heavy infection by a myxosporean tentatively identified as Chloromyxum sp. was recovered in two out of 500 histologically studied juvenile S. aurata. Parasites were found only in the stomach, being absent from other segments of the digestive tract and associated tissues. In the cardiac region of the stomach infection was limited to the gastric mucosa lining the surface and the pits, but was absent from the secretory epithelium lining the fundic glands.

The article presents information on Kudoa infection in the glomeruli of cultured Spams aurata L. specimens from the Station Biologique Marine, Séte, France. Infection of Kudoa sp. was recovered throughout the peritoneum and the mesenteries of a reared S. aurata at the Mariculture Laboratory of the Israel Oceanographic and Limnologic Research, Eilat, Israel. This 245 mm long, 3-year old fish was reared from fry collected in Bardawil lagoon, Mediterranean coast of Sinai. It represents the only case of infection found in 2000 autopsied and 1500 histologically examined cultured S. aurata in Eilat since 1974. These included hatchery-born fish as well as those reared from wild fry.

The article reports on the occurrence of lymphocystis virus infections in the Gulf of Aqaba, Red Sea. Sparus aurata L. has been cultured in the Gulf of Aqaba by the Mariculture Laboratory of the Israel Oceanographic and Limnological Research since 1973. The prevailing water temperatures in the Gulf water range annually from 23 to 26 degrees C and the salinity is about 40%. Maintenance offish in high densities, frequent handling, netting and transfer, which always results in minor injuries and abrasions to fish skin, could undoubtedly promote transmission of the virus and at the same time stress the fish, hence reducing their tolerance to infection.

The existence of a pleomorphic development cycle is demonstrated in epitheliocystis organisms obtained from fish of the following families: Sparidae, Sparus aurata L.; Mugilidae, Liza ramada (Risso), Liza aurata (Risso) and Mugil cephalus L.; Cichlidae, Tilapia mossambica (Peters) and Tilapia aurea x nilotica; and Serranidae, Dicentrarchus labrax L. Ultrastructure of the successive developmental stages, primary long cells, intermediate long cells and small cells are described as well as the division process between stages. An additional stage, the round cell, was found in infected chloride cells. The affinities between epitheliocystis organisms and known chlamydial organisms of vertebrates and invertebrates are discussed. [ABSTRACT FROM AUTHOR]

Ulteastructural study of epitlieliocystis organisms from gills of Sparus aurata (L.) and Liza ramada (Risso) revealed in each fish a new form of the organism which differed from epitheliocystis organisms previously described. In their size range, the presence of a plasma membrane, a trilaminated cell wall and a central nucleoid, these organisms resembled chlamydial organisms (PLT). However they differed from them in the following respects: in both species several morphological forms were recognized; hyphae or mycelium-like forms and individual units, not comparable to any of the successive units described for Chlamydia organisms. Both organisms were contained within an inclusion in the host cell, but in epitheliocysts from S. aurata apparently intracytoplasmic forms were also observed. Ultra-structural studies of the cytoplasmic wall of the epitheliocystis inclusion in S. aurata suggest that the epitheliocystis cyst remains contained in a single unruptured hypertrophied cell, while in L. ramada the final cyst is formed through the coalescence of several epithelial cells. [ABSTRACT FROM AUTHOR]

Cysts containing coccidian merozoites, tentatively identified as hemogregarines, are described from muscles of juvenile Liza subviridis Valenciennes 1836 (Mugilidae) in the Gulf of Aqaba, Red Sea. Cysts consisted of aggregates of infected macrophage-like cells bound by a fibroblast envelope. Up to 20 merozoites were present in each infected cell histological section. Ultrastructural study revealed merozoites with structural similarities to previously described species of Haemogregarina. The encysted merozoites are suggested to be a dormant stage, acquired and transmitted through predation or necrophagy among nonspecific host fish. [ABSTRACT FROM AUTHOR]

Over a period of 11 months, eight samples of Pirenella conica were taken at each of three sites of a mangrove lagoon in Sinai. Infection with larval trematodes, especially of Heterophyidae, was highest at the site within the mangrove thicket with a breeding colony of reef herons, the supposed definitive hosts of the Heterophyidae. The lowest frequency of infection was recorded from a tide-pool on the broad sand-flats surrounding the lagoon, where there was a great variation in the abundance of snails and xiphidiocercariae were more common than heterophyid cercariae. Predation from fish or other molluscs did not appear to be an important factor at either of these two sites. In all three sites, double infections of Heterophyidae and trematodes with xiphidiocercariae as well as of Heterophyidae and Echinostomatidae occurred less frequently than theoretically expected, but there was no competitive exclusion between Echinostomatidae and xiphidiocercariae. [ABSTRACT FROM AUTHOR]