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The oocapt of Paramphistomum cervi has a narrow constriction followed by a wide lumen with a thickened wall and is surrounded by several unicellular flask-shaped gland cells opening into the lumen. The oocapt gland cells are filled with granules, the size and number of which vary in the body cells and its duct. Histochemical studies have shown that the oocapt gland cells secrete mainly mucoproteins but a few lipoprotein and phospholipid granules have also been observed. The passage of the oocyte through the lumen of the oocapt, appears to stimulate the oocapt gland cells to release their secretion which seems to be involved in transport of the oocyte through the oviduct.

The ovary in 4-week-old worms contains undifferentiated germ cells. The oogonial differentiation, together with the appearance of some PAS-positive material in the ooplasm occurs in the ovary of 8-week-old worms. The ovary of 16-week-old worms contains only oogonia and oocytes and no germ cells. In adult worms, the oocytes reach the pachytene stage and further development is arrested at this stage. Nucleolar fragmentation and subsequent transport of nuclei to the ooplasm have been observed. The ooplasm contains nutritive material rich in proteins, carbohydrates and lipids. Its amount varies with different stages of oogenesis. The localization of various phosphatases and dehydrogenases was studied during oogenesis and their functional significance was discussed.

The life cycle of Paramphistomum leydeni Näsmark, 1937, is carried out in the laboratory. Adults were obtained from the rumen of a naturally infected Bos taurus in Czechoslovakia. Laboratory-reared Planorbis planorbis experimentally infected shed the first cercariae two months after exposure to miracidia. Argentophilic structures in miracidia and cercariae are described. In miracidia, these structures are similar to those previously described from species of Paramphistomum: P. togolense, P. phillerouxi, P. daubneyi, P. microbothrium. They differ, however, from those of Calicophoron calicophorum. In cercariae, argentophilic structures have some features in common with those of the species of Paramphistomum mentioned above, especially at the levels CII and AM V, but the very peculiar acetabular chaetotaxy allows us to distinguish P. leydeni from these species. Thus, each species can easily be differentiated from the related species; moreover the genus Paramphistomum as characterized by Näsmark (1937) appears to be justified.

The activity and properties of malate dehydrogenase (MDH; EC 1.1.1.37) and of "malic" enzyme (EC 1.1.1.40) in cytosole of the trematode C. ijimai were determined. The activity of MDH directed to oxaloacetate formation was shown to be 14 times and maximum velocity 13 times lower than that of the reverse reaction. The apparent KM was one order higher in the direct reaction. This confirms the possibility of glycolytic pathway in C. ijimai via CO2 fixation into phosphoenolpyruvate to form oxaloacatate which is readily eliminated by active MDH. The presence of "malic" enzyme in C. ijimai testifies to the occurrence of different pathways of succinate formation in this species.

Experiments were carried out with the preparation Nilsan (oxiclozanide + levamizal) in the treatment of sheep with Fasciola, Dictyocaulus, and Trichostrongylus infection. The trials involved a total of 2782 sheep on two sheep-breeding farms, constituting 15 flocks. The liveweight of the adult animals ranged from 40 to 60 kg, and that of the year-old female ones--from 40 to 45 kg. The daily ration on the two farms did not differ essentially from that offered to the animals in the past 2-3 years. It was found that at the rate of 22 to 28 cm3 per head Nilsan produced 76.67 to 96.67 percent effect against Paramphistomum infection, 100 percent effect against Dictyocaulus infection, 73.37 to 90.00 percent effect against Trichostrongylus infection, and 23.34 to 83.34 percent effect against Dicrocelium infection. The application of an ex tempore combination of oxiclozanide and levamizal to sheep at the rate of 24 cm3 per head produced 86.67 to 100 percent effect against Paramphistomum, 96.67 to 100 percent effect against Dictyocaulus, 86.67 to 96.67 percent effect against Trichostrongylus, and 46.67 to 86.67 percent effect against Dicrocelium. The experimental sheep produced 16.41 to 37.40 per cent more wool, 0.85 to 35.09 per cent more milk, and 8 to 12 per cent more weight gain.

The formation of the egg mass in the ootype, containing the oocyte, vitelline cells, numerous spermatozoa and Mehlis’ gland secretion marks the beginning of eggshell formation. Mehlis’ gland cells pour their lipoprotein secretion into the ootype; this secretion forms a thin template around the egg mass and upon this template the shell globules are deposited. Eggshell formation begins in the proximal uterus and is completed in the middle uterus. The eggshells are devoid of phenols and phenolase indicating that hardening is not by quinone tanning. The eggshells contain keratin and are stabilized by disulphide linkages.

SUMMARY: Controlled trials were used to assess the efficacy of various anthelmintics against immature and adult paramphistomes in 75 experimentally or naturally infected sheep. Albendazole (20 mg/kg), praziquantel (10 mg/kg), nitroxynil (10 mg/kg) triclabendazole (10 and 100 mg/kg), profenophos (25 mg/kg) and netobimin (15 mg/kg) had little or no activity against adult or immature fluke. Niclosamide at 100 mg/kg had high efficacy (99%) against intestinal fluke but none against adult fluke. A 2- tertiary-butyl benzthiazole compound (CGA 72630) at 25 mg/kg and resorantel at 65 mg/kg had very high efficacy against both adult and immature fluke in the rumen and small intestine respectively. The efficacy of other anthelmintics which have been used against paramphistomes in sheep is reviewed.

Contrary to common belief, Gastrodiscus aegyptiacus can be pathogenic to horses. History of cases of a particular stud, necropsy findings, diagnosis, and successful treatment with hexachlorophene and with dichlorvos are recorded. The presence of eggs can be established by a special flotation technique.

Scanning electron microscopy (SEM) was used to study the topographical features of untreated Gigantocotyle explanatum. The topographical effects of mebendazole, fenbendazole, metrifonate and oxyclozanide on whole worms maintained in vitro were compared by SEM. All the drugs used in the present study damage the body surface, but the nature and degree of damage varied in each case. Abrasion of surface papillae, formation of lesions and peeling of the tegumental syncytium were common effects of all four anthelmintics. Some drugs caused smoothing of the tegumental surface whereas others produced a wrinkled appearance. Oxyclozanide was the most effective and mebendazole the least because the degree of surface damage produced by the drugs was in the order: oxyclozanide > metrifonate > fenbendazole > mebendazole. The surface papillae apparently represent distinct target sites for the action of certain anthelmintics.

Survival of immature and mature stages of Paramphistomum cervi , collected from the intestine and the rumen of sheep has been studied in in vitro using Tyrode's, Hank's, Eagle's, Stephenson's saline and Hedon—Fleig media. Twenty-five ml quantities of carbon dioxide (CO 2 )-rich Hedon—Fleig solution at pH 6.7, at 37°C supported the maximum survival of 5 worms of both immature and mature flukes for periods of 9 and 10 days, respectively. Alterations to the pH of the medium, the incubation temperature and the number of worms significantly affected the period of their in vitro survival. The tissues of immature and mature worms did not show any marked histological and histochemical change until 24 h of in vitro survival in Hedon—Fleig solution when the testes of adult worms started undergoing degeneration. There was a progressive depletion of stored lipids and carbohydrates in the parenchymatous tissue during the course of in vitro survival. After the second day of in vitro maintenance, the maturation of the worms' vitelline follicles was affected, and thereafter they started to degenerate. On Day 4, degeneration of some gastrodermal cells, and a ruptured body wall were observed in some worms. Though the degenerative changes in the tissues of worms appeared at 24 h and continued to increase during in vitro maintenance, the worms survived for 9–10 days.

Experiments have shown that developmental period of eggs of P. petrowi under humid conditions depends directly on temperature. At 30 C their development is over in 8, at 26-27 C in 14 and at 18.5 C in 40 days. Under natural conditions at daily average temperature of 17.5 C the hatching of miracidia occurred in 52 days. Intermediate host of this trematode in a zone of park deer breeding is a freshwater mollusc of the family Planorbidae, Anisus minusculus. The development of parthenites in the intermediate host at 11 to 22 C completes within 83 days.

Intestinal paramphistomiosis was diagnosed in a bull and cow with severe diarrhea and weight loss, and subsequent investigation suggested that the infection was transmitted from American bison (Bison bison). The rumen fluke, Paramphistomum microbothrioides, was recovered from the rumen of 3 bison on the farm or origin. Single operculate eggs of P microbothrioides measuring 130 x 69 micrometers were recovered from the feces of the bull, from 9 of 10 bison, and from 3 of 9 other beef cattle. Snails of the genera Physa and Helisoma were collected at the farm of origin. Ostertagiosis and paratuberculosis were considered in the differential diagnosis but were ruled out on the basis of fecal, plasma, and mucosal tests. In view of the lack of approved drugs for treatment of paramphistomes in the United States, treatment was attempted with an 8 times normal dose of thiabendazole (528 mg/kg). Advice was given on grazing management strategies designed to reduce exposure of susceptible cattle to metacercariae, and the owner was advised to drain a large snail habitat.

In 6 week-old Paramphistomum cervi, vitelline cells appear in the form of a few scattered cells, present below the body wall which divide mitotically to form vitelline follicles in 8 week-old worms. Small shell globules appear first in 10 week-old worms, the number and size of which continue to increase till the worm becomes adult. In the latter the vitelline follicles contain stem cells, immature, maturing and mature vitelline cells, which differ due to the distribution of shell globules as well as their histochemical nature. The shell globules are keratin in nature. The vitelline cells showed activities of various phosphatases but did not show the presence of any of the dehydrogenases studied.

Morphological and histochemical changes accompanying testicular development and spermatogenesis have been described in the ruminal trematode Paramphistomum cervi during the course of its infection in sheep. Small testes of 4-week-old worms contain a few primordial germ cells. Spermatogonial cells appear first in 6-week-old worms and increase in number by the 10th week when the testes become large and follicular. Mature spermatozoa appear in the testes of 16-week-old worms. General pattern of spermatogenesis is the same as described for other trematodes, i.e. a single spermatogonium gives rise to 32 spermatozoa. Cytophore is formed at secondary spermatogonial stage. Various spermatogenic stages contain proteins, glycogen and phospholipids, however, the amount of phospholipids decreases as the maturation proceeds. The mature spermatozoa stain strongly with PAS. The enucleated residual mass contains HgBB-positive proteins and lipid granules. The morphological and cytochemical changes occurring during various spermatogenic stages have been correlated with corresponding histoenzymological changes in the cytoplasm. Frequency of spermatogenesis has been worked out which indicates that the transformation of secondary spermatogonia into spermatids is relatively fast as compared to transformation of primary spermatogonia into secondary spermatogonia and stages of spermateleosis.

1. Haemoglobin content of two trematodes, Fasciola gigantica collected from the bile ducts and Cotylophoron indicum from the reticulum of buffaloes has been investigated spectroscopically and by “alkaline haematin” method.

The whole life cycle of Paramphistomum microbothrium Fischoeder, 1901, found in cattle of Kenya, East Africa, has been established experimentally.In laboratory conditions, the eggs hatched miracidia on the 14th to 16th day, if they were kept in water at a temperature of 26–28° C.In a snail, Bulinus alluaudi (Dautzenberg), kept at the temperature of 18–20° C., the miracidium developed into a sporocyst, the elongated body of which, containing young rediae, reached a length of 3·6 mm. in about 2 weeks.The first rediae which emerged from a sporocyst were observed on the 14th day, and on the 20th day the first generation rediae began to produce second-generation rediae. From the 28th day onward the first-generation parent rediae ceased to produce daughter rediae and began to develop cercariae only. This period of production of cercariae by the redia lasted about 30 days, and when the life of the first-generation rediae drew to its close, the old rediae developed a few daughter rediae again.Cercariae began to emerge from the first-generation rediae 30 days after exposure of the snail to miracidia. The cercariae left the parent redia in a very immature state and further development occurred in the liver of the snail. The emergence of cercariae from the infected snail began on the 43rd day after exposure to miracidia. Shortly after emerging from the snail, the cercariae attached themselves to vegetation and encysted.Development of rediae of the second, third, fourth and apparently more successive generations followed an identical course to that outlined for the rediae of the first generation. As a result the successive generations of rediae maintain the infection going in an intermediate host and the infected snails were continually shedding cercariae as long as they lived. In the laboratory experiments the life span of some of the infected snails exceeded a year.In cattle infected experimentally P. microbothrium reached maturity and began passing out the eggs about a 100 days after the encysted cercariae were fed to the animals.

Observations were made on the biology of Cotylophoron cotylophum in respect of the hatching of miracidia, infection of the intermediary mollusc, emergence and encystment of cercariae, and on the pathogenicity of the parasite. It was noted that miracidia of this parasite hatch in 15 days at a temperature of 28-30°C. At a lower or higher temperature than this hatching is delayed. When the miracidia are mature a sudden fall in temperature hastens their hatching. Darkness has no adverse effect on hatching. These miracidia show a marked attraction towards Indoplanorbis exustus, which are proven to be the intermediary molluscs of this amphistome. At room temperature, ranging between 21-24°C. during the day and 18-21°C. at night, sporocysts develop within the snails in about 24 hours and on the 4th day rediae are seen developing inside the sporocysts.

1. The surface area body weight relationship in C. cotylophoron and G. crumenifer has been determined.

Calicophoron calicophorum was recorded in domestic cattle from the East Kimberley district of Western Australia. No other species of paramphistomes were found. The significance ofC. calicophorum as a probable cause of poor productivity in beef cattle in tropical Northern Australia is discussed.

Paramphistomumi sukari n.sp. from the reticulum of cattle in the Kenya Highlands (East Africa) is described. An intermediate snail host of P. sukari was shown to be Biophalaria pfeifferi (Krauss).

The development of Paramphistomum sukari Dinnik in a snail host is described with the emphasis laid on the succession of redial generation.The sporocyst gives birth to about twenty to thirty rediae. These rediae of the first generation commence with the production of daughter rediae then enter the second phase of their productivity during which they produce cercariae. The daughter rediae, or the rediae of the second generation, repeat these two phases during their lives, commencing with redial production and after that changing to the production to cercariae. Both the first- and second-generation rediae are able to produce a few daughter rediae at the end of their life. There is evidence that the subsequent generations of rediae are also able to give birth to daughter rediae and cercariae.As a result the successive generations of rediae maintain the infection in an intermediate host for a long time, probably as long as the infected snail can survive.

Background Rumen flukes parasitize the rumen and reticulum of ruminants, causing paramphistomiasis. Over the years, there has been considerable debate as to whether Paramphistomum leydeni and Paramphistomum cervi are the same or distant species. Methods In the present study, the complete mitochondrial (mt) genome of P. leydeni was amplified using PCR-based sequencing and compared with that of P. cervi. The second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) of P. leydeni specimens (n = 6) and P. cervi specimens (n = 8) was amplified and then sequenced. Phylogenetic relationship of the concatenated amino acid sequence data for 12 protein-coding genes of the two rumen flukes and selected members of Trematoda was evaluated using Bayesian inference (BI). Results The complete mt genome of P. leydeni was 14,050 bp in size. Significant nucleotide difference between the P. leydeni mt genome and that of P. cervi (14.7%) was observed. For genetic divergence in ITS-2, sequence difference between P. leydeni and P. cervi was 3.1%, while no sequence variation was detected within each of them. Phylogenetic analysis indicated that P. leydeni and P. cervi are closely-related but distinct rumen flukes. Conclusions Results of the present study support the proposal that P. leydeni and P. cervi represent two distinct valid species. The mt genome sequences of P. leydeni provide plentiful resources of mitochondrial markers, which can be combined with nuclear markers, for further comparative studies of the biology of P. leydeni and its congeners from China and other countries. Electronic supplementary material The online version of this article (doi:10.1186/s13071-015-0823-4) contains supplementary material, which is available to authorized users.

On a decouvert que, dans la famille des Paramphistomatidae (Trematodes), la coquille de l'∄uf, transparente et sans couleur, est une keratine-type de scleroproteine, constituee de disulphide en chaInes (-S-S-). On sait que chez d'autres trematodes, la coquille d'ceuf, d'une couleur ambree, est une proteine de quinone.