Interactions between the intestinal cestode Polyonchobothrium clarias (Pseudophyllidea: Ptychobothriidae) from the African sharptooth catfish Clarias gariepinus and heavy metal pollutants in an aquatic environment in Egypt.

In an aquatic environment, there is a profound and inverse relationship between environmental quality and disease status of fish. Parasites are one of the most serious limiting factors in aquaculture. Therefore, the present investigation was carried out during the period of February-December 2014 to determine the parasitic infections in the African sharptooth catfish Clarias gariepinus, relative to the capability of internal parasites to accumulate heavy metals. Up to 100 catfish were examined for gastrointestinal helminths and 38% of fish were found to be infected with the cestode Polyonchobothrium clarias. The morphology of this parasite species, based on light and scanning electron microscopy, revealed that the adult worm was characterized by a rectangular scolex measuring 0.43-0.58 (0.49 ± 0.1) mm long and 0.15-0.21 (0.19 ± 0.1) mm wide, with a flat to slightly raised rostellum armed with a crown with two semicircles each bearing 13-15 hooks, followed by immature, mature and gravid proglottids which were about 29-55 (45), 16-30 (24) and 15-39 (28) in number, respectively. The mature proglottid contained a single set of genitalia in which medullary testes measured 0.09-0.13 (0.11 ± 0.01) mm long and 0.05-0.08 (0.06 ± 0.01) mm wide; a bi-lobed ovary was situated near the posterior margin of the proglottid, extending laterally up to the longitudinal excretory canals; the tubular uterus arose from the ootype up to the anterior margin of the proglottid; and vitelline follicles were cortical. The greater portion of the gravid proglottid was occupied by a uterus filled with unoperculate and embryonated eggs. Chemical analysis confirmed that the concentrations of heavy metals (Zn, Cu, Mn, Cd, Ni and Pb) accumulated in P. clarias were higher than in fish tissues and values recommended by FAO/WHO, with the exception of Zn, which was found to be higher in fish kidneys than in the cestode. This supports the hypothesis that cestodes of fish can be regarded as useful bioindicators when evaluating the environmental pollution of aquatic ecosystems by heavy metals.

Five new myxosporean species (Myxozoa: Myxosporea) infecting the Nile tilapia Oreochromis niloticus in Bahr Shebin, Nile Tributary, Nile Delta, Egypt.

Five new myxosporean species belonging to three different genera were described from the Nile tilapia Oreochromis niloticus in Bahr Shebin, Nile Tributary, Nile Delta, Egypt. These species are: Zschokkella nilei sp. n., Ortholinea africanus sp. n., Triangula egyptica sp. n., Myxobolus fomenai sp. n., and Myxobolus branchiophilus sp. n. Morphometry, light microscopy, and hand drawing of mature spores and plasmodia were presented for each species.

Four new species of Ceratomyxa Thelohan 1892 (Myxozoa: Myxosporea: Ceratomyxidae) infecting the gallbladder of some Red Sea fishes.

Four new Ceratomyxa species were described from the gallbladder of four Red Sea fishes at Suez and Hurghada, Egypt. These species are Ceratomyxa bassoni sp. n. from Plectorhinchus gaterinus (Forsskal 1775) at Suez and Hurghada, Ceratomyxa entzerothi sp. n. from Valamugil seheli (Forsskal 1775) at Suez and Hurghada, Ceratomyxa swaisi sp. n. from Saurida undosquamis (Richardson 1848) at Suez only and Ceratomyxa hurghadensis sp. n. from Fistularia commersonii Ruppell 1838 at Hurghada only. Their taxonomic affinities to other species are discussed.

Light and electron microscopic studies on Kudoa pagrusi sp. n. (Myxosporea: Multivalvulida) infecting the heart of sea bream Pagrus pagrus (L.) from the Red Sea.

A new multivalvulid species, Kudoa pagrusi sp. n., was described from the sea bream Pagrus pagrus. The cysts were oval to ellipsoidal and restricted to the cardiac muscles. The mean spore measurements were 7.0 microm in length and 6.4 microm in width as well as in thickness, while the mean polar capsule measurements were 3.7 microm in length and 1.5 microm in width. The ultrastructural features of the present species proved that the spore have four polar capsules with four shell valves that are the main criteria for genus Kudoa.

Zschokkella helmii n. sp. (Myxozoa: Myxosporea), a new parasite of marbled spinefoot Siganus rivulatus (Forsskal 1775), Red Sea, Egypt: light and transmission electron microscopy.

Zschokkella helmii n. sp., a new parasite of Siganus rivulatus from the Red Sea, Egypt, was described using light and transmission electron microscopy. However, the infection was severe; single "histozoic" plasmodium was encountered in the gallbladder wall. Spores are ellipsoid with 9-11 valvar striations. Spore mean length is 10.8 microm (10.0-11.0), while the spore mean width is 7.5 microm (7.0-8.0). Polar capsules are nearly round with a diameter of 2.2 microm (2.0-3.0) and have five filaments. Ultrastructure of the plasmodial wall and sporogenesis of the present species followed the usual pattern valid for most studied myxosporean species.

Microscopic study on Sarcocystis moulei from sheep and goats in Saudi Arabia.

The present investigation revealed that the role of natural infection with Sarcocystis in sheep was 84% in Niemy, 76% in Najdy, 89% in Sawakny sheep and 77% in goats slaughtered in Riyadh, Saudi Arabia. The distribution of infection among the examined organs was varied from the sheep strain to goats. Recorded muscle cysts were macroscopic 8-18% (mean 13.5%) and microscopic 73-85% (mean 79%). Macroscopic cysts were usually detected on the oesophagus. EM showed an ultrastructural similarities in the cyst walls and their parasite contents (metrocytes and merozoites) for all macroscopic cysts examined from sheep and goats. These were also enclosed by a secondary cyst wall. The primary cyst wall had many cauliflower-like protrusions supported by many fibellar structures, while the ground substance underneath them contained many dark, dense granules and usually extended into the cyst cavity dividing it into many compartments containing the parasites. The cyst parasites were the peripheral globular to spherical metrocytes, which were divided by endodyogeny and the central banana-shaped merozoites. Both metrocytes and merozoites had all characteristics of the Apicomplexa. Experimental transmission of Sarcocystis to the definitive host, revealed that kittens were the only suitable final host. Thus, gamogony and zygote formation (fertilization) occurred 2-8 days post infection (p.i.) while sporulation took place within this final host 13-15 days p.i., where sporocysts were passed within faeces of infected kittens at that time. Also, the study indicated that the prepatent period was 13-15 days, while the patent period was 37-42 days.

Lead concentrations in Hymenolepis diminuta adults and Taenia taeniaeformis larvae compared to their rat hosts (Rattus norvegicus) sampled from the city of Cairo, Egypt.

Concentrations of lead, determined by electrothermal atomic absorption spectrometry, were compared between the cestodes Hymenolepis diminuta and Taenia taeniaeformis and its host rat (Rattus norvegicus). Rats were sampled at 2 sites, which differed in respect to lead pollution as quantified from road dust, adjacent to the city of Cairo, Egypt. Comparing lead levels among host tissues and the parasites the significantly highest accumulation was found in H. diminuta, followed by rat kidney and larvae of T. taeniaeformis. Calculation of bioconcentration factors showed that H. diminuta contained 36-, 29-, 6- and 6-fold higher lead levels than intestinal wall, liver, kidney and larvae of T. taeniaeformis, at the more polluted site. At the less contaminated site lead bioconcentration factors for H. diminuta were found to be 87, 87 and 11 referred to intestine, liver and kidney of the host. Due to a high variability of the lead concentrations in H. diminuta it was not possible to indicate differences in metal pollution between both sampling sites. This variability may be influenced by different age structures of cestode infrapopulations. It is likely that younger worms contain lower metal levels than older worms due to a shorter exposure period. Thus, it is necessary to standardize the sampling of worms which should be used for indication purposes. Due to a lack of adequate sentinel species in terrestrial habitats more studies are required to validate and standardize the use of helminths as accumulation bioindicators in order to obtain mean values with low standard deviations. The host-parasite system rat-H. diminuta appears to be a useful and promising bioindication system at least for lead in urban ecosystems as rats as well as the tapeworm are globally distributed and easily accessible.

Histopathological and ultrastructural studies of Henneguya suprabranchiae Landsberg, 1987 (Myxosporea: Myxobolidae) parasitizing the suprabranchial organ of the freshwater catfish Clarias gariepinus Burchell, 1822 in Egypt.

Serious loss in the length and weight of the economically important catfish Clarias gariepinus was caused by a high intensity of infestation with Henneguya suprabranchiae, parasites which infect the hyaline cartilage of the suprabranchial organ of fish. Fish were collected from three different localities: the River Nile in the Cairo and Giza provinces, some Giza markets and agricultural drains in Kalyubia province. All harbored cysts at the tips of the secondary bronchioles. These measured between 1.5 and 5 mm in length. The plasmodia of these parasites contained generative cells with immature pansporoblasts at the periphery and mature spores occupying the center. The mature spores were mostly elongate fusiform and had two identical, parallel elongate polar capsules. Each capsule contained a polar filament coiled eight times. There was an iodinophilous vacuole within the sporoplasm. The shell valves extended posteriorly to form two caudal processes. New histopathological lesions caused by these parasites, which are cited to be pathogenic, were studied. Plasmodium growth on the bronchioles was pathogenic. The continuous mass growth of plasmodium in the colony led to pressure on the host cartilaginous tissue which was subsequently compressed. Moreover, this compression induced severe atrophy as well as damage to and destruction of the endothelial lining of the hyaline cartilage. The whole bronchiole tissue was shown to be sloughing and necrotic at the site of infection. In addition, the blood vessels lining the epithelia of the bronchiole were dilated, particularly when large plasmodia were present. A high intensity of infection with several plasmodia may cause a disturbance in the respiratory process of the infected catfish, leading to asphyxia and subsequently to weight loss. In addition, new ultrastructural data on the generative cells, sporogenesis, capsulogenesis, valvogenesis and spore maturation of H. suprabranchiae are presented.

Studies on Eimeria species naturally infecting Gerbillus pyramidum (1) Exogenous stages.

Exogenous stages of two new Eimerian species, naturally infecting the Egyptian gerbil Gerbillus pyramidum were described and diagnosed in the present study. (1) The subspherical type of oocysts was 20 x 17 microns (length x width) in average. These are colourless and enveloped within an even double-layered oocyst wall. Sporulated oocysts containing four sporocysts each averaged in 10 x 8 microns, and a small spherical oocyst residual body was also observed. This type is termed Eimeria pyramidi after the species name of its host. (2) The second type of oocysts was elongated in shape measured congruent to 21 x 16 microns. These are colourless and enclosed within smooth double layered oocyst wall. Sporulated oocysts of this type were lacking oocyst residual bodies. This type is termed Eimeria gerbilli after the generic name of its host. Both types of described oocysts lack micropyle and polar cap.

Endodyogony and cyst formation of Sarcocystis gongyli (Trinci 1911) from the skink Chalcides ocellatus.

The heteroxenous life cycle of S. gongyli comprising both the skink Chalcides ocellatus (intermediate host) and the snake Spalerosophis diadema, herewith the process of cyst formation was followed by means of light and electron microscopy after experimental infection. Following migration of the merozoites to muscle fibres, they changed into globular metrocytes, meanwhile a parasitophorous vacuole enclosing them. As development proceeded the wall of the parasitophorous vacuole is thickened in the form of striated protrusions as well as the metrocytes underwent endodyogony producing large numbers of banana-shaped merozoites in the centre of the cyst. Mature microscopic sarcocyst appeared at 120 days p.i, and these were characterized by presence of stalky leaf-like protrusions in their primary cyst wall. Asexual multiplication of metrocytes occurred through endodyogony in which always the mother metrocyte produced two opposite merozoites.

Electron microscopic study on macrogametogenesis of Eimeria labbeana infecting the Egyptian wild doves and host-parasite relationship.

The development of macrogametes of Eimeria labbeana was studied by electron microscopy in the epithelial cells of the villi at 96 hrs. post-infection. Appearance of young macrogamonts was characterized by the loss of the architecture of the apicomplexa (polar ring, rhoptries, micronemes, conoid, subpellicular microtubules), while the pellicle became only one unit membrane. This was associated by the formation of wall forming bodies II then I. Moreover, the mitochondria, endoplasmic reticulum and Golgi were increased in the cytoplasm. Amylopectin granules as well as lipid globules were greatly increased in mature macrogametes. Host cell reaction due to infection included enlargement and deformation of infected cells, hypertrophy of their nuclei, swollen and degeneration of mitochondria, endoplasmic reticulum and vacuolation of ground cytoplasm. These changes occur in both cells with and without parasite.

Life cycle of Hepatozoon mehlhorni sp. nov. in the viper Echis carinatus and the mosquito Culex pipiens.

Hepatozoon mehlhori sp. nov. and its developmental stages from the tissues of the Egyptian viper Echis carinatus and the mosquito Culex pipiens are described. The erythrocytic parasites were differentiated into the small form (trophozoite) measuring 14.5 +/- 0.6 x 4 +/- 0.12 micron and the mature form (gametocyte) measuring 17.2 +/- 1.6 x 5.4 +/- 0.5 micron. Merogony took place in the pulmonary endothelial cells and in the parenchyma cells of the liver and spleen of the infected vipers. Two types of meront were found. The large meronts (macromeronts) were 30.2 +/- 1.73 x 22.6 +/- 1.2 microns in size and yielded 16-40 (average, 28) micromerozoites measuring 17.2 +/- 0.7 x 5 +/- 0.15 microns. The small meronts (micromeronts) measured 18.2 +/- 0.6 x 13.5 +/- 0.5 microns and yielded 2-14 (average, 8) macromerozoites that were 15.1 +/- 0.12 x 6.2 +/- 0.8 microns in size. After syzygy in the haemocoel of the mosquito, the microgamont produced four uniflagellate microgametes (6.4 +/- 0.3 x 4.5 +/- 0.5 microns in size, with a short flagellum measuring 3.2 +/- 0.1 microns); on the 3rd day post-infection (p.i.)., one of these fertilized the macrogamete, giving rise to the zygote. The oocyst developed from the zygote on the 5th day p.i. and measured 135 +/- 2.6 x 120 +/- 1.8 microns. About 11-60 (average, 35) sporoblasts were formed by centripetal invaginations from each oocyst on the 8th day p.i. and developed into sporocysts on the 14th day p.i. Inside each sporocyst, 5-12 (average, 8) sporozoites, each measuring 12.6 +/- 1.2 x 4.1 +/- 0.3 microns, developed on the 16th day p.i. According to the above-mentioned characteristics the parasite was recorded as being a new species and was named Hepatozoon mehlhorni. Experimental transmission was accomplished by i.p. inoculation of the infectious stages (sporozoites) into uninfected vipers and led to the appearance of blood stages at 4-6 weeks p.i.

Endogenous stages of Eimeria arvicanthi infecting the field rat Arvicanthis niloticus niloticus from Egypt.

The endogenous stages of Eimeria arvicanthi were studied after experimental infection with pure strain in the rat Arvicanthis n. niloticus. The prepatent period was 5 days, while the patent period extended to the 11th day p.i. Two asexual generations were determined in the epithelial cells of the upper part of the colon, while the sexual one was found in the crypts of Lieberkühn. Schizonts of the 1st generation were found 60 hrs p.i., measuring 9 X 4 microns and contained 4-8 merozoites, however those of the 2nd generation were found at 96 hrs p.i., measured 14 X 10 microns and contained 8-12 merozoites. Gamonts were firstly recorded at 108 hrs p.i., after growth they differentiated and gave rise to gametes. Macrogametes were 19 X 17 microns with large nuclei and wall-forming bodies in their cytoplasm. Microgamonts (14 X 11 microns) were irregular in shape and after many nuclear divisions produce many microgametes. Eimeria arvicanthi was pathogenic and about 60% of the experimentally infected rats with 3-5 X 10(5) sporulated oocysts were died till the 9th day p.i.