Showing papers in "Parasitology Research in 1980"
TL;DR: The fine structure of the tegument of three trematode species, Schistosoma mansoni, Dicrocoelium dendriticum, and Fasciola hepatica, was studied by means of light scanning and transmission electron microscopy after in vitro exposure to 0, 1,10, and 100 μg/ml of the anthelmintic praziquantel for 5, 15, 30, and 60 min.
Abstract: The fine structure of the tegument of three trematode species,Schistosoma mansoni, Dicrocoelium dendriticum, andFasciola hepatica, was studied by means of light scanning (SEM) and transmission electron microscopy (TEM) after in vitro exposure to 0, 1,10, and 100 μg/ml of the anthelmintic praziquantel for 5, 15, 30, and 60 min. InS. mansoni andD. dendriticum the resulting vacuolization of the tegument was confined to numerous small areas scattered all over the surface of the parasites and this finally led to the disruption of the apical tegumental layer. No changes were found in the tegument ofF. hepatica after treatment with praziquantel.
171 citations
TL;DR: It is concluded that the observed gigantism of infected snails is more likely to have a nutritional rather than endocrine origin, rather than a switch in nutrient supply from reproduction to somatic tissue growth and parasite growth.
Abstract: The shells of Lymnaea truncatula infected with the larval stages of Fasciola hepatica were significantly longer than those of comparable uninfected controls. The dry mass (tissue, shell + parasite) of the same infected snails, 56 days after infection, was approximately twice that of the controls (tissue + shell). The increased mass of infected snails was not due to a disproportionate increase in shell weight relative to tissues. Infected snails maintained at 20 degrees C had virtually ceased egg production by 21 days post-infection whereas control snails continued to lay eggs steadily for the duration of the experiment. The dry mass of snail tissue plus the cumulative dry weight of eggs produced was taken as an indication of the ability of control snails to generate biomass. Similarly the tissue mass plus cumulative egg weight and parasite weight was taken as an indication of the ability of the infected snails to generate biomass. The control and infected snails were not significantly different in this respect indicating that the gigantism of infected snails could be the result of a switch in nutrient supply from reproduction to somatic tissue growth and parasite growth. Castration was brought about 17-21 days after infection as a result of the direct consumption of the ovotestis by a proportion of the redial population. In a separate experiment it was demonstrated that a population of infected snails maintained at 20 degrees C survived as long as a similar group of control snails. The findings with this host-parasite system are discussed in relation to possible mechanisms causing castration and gigantism in other digene-snail interactions, and in relation to parasitic castration in other groups. It is concluded that the observed gigantism of infected snails is more likely to have a nutritional rather than endocrine origin.
94 citations
92 citations
TL;DR: It is concluded that the occurrence of HP- and LP-infections indicates differences in reproductive capacity of the parasite.
Abstract: The effects of exposure of juvenileLymnaea stagnalis to one, two or, four miracidia ofTrichobilharzia ocellata on the following parameters were studied: infection rate, length of prepatent period, production of cercariae, growth and ovipository activity of the snails, and the weights of their accessory sex organs. An infection rate of 100% was established with all miracidial doses. Mortality of the snails was low in all experimental groups. In cercarial production high-(HP) and low-productive (LP) infections could be distinguished. An increase in miracidial dose at exposure results in an increase in the number of snails with HP-infections and decreases the length of the prepatent period of these infections. Snails with HP-infections grow faster than controls after day 14 post-exposure and show giant growth, while the accessory sex organs remain very small. The snails show hardly any ovipository activity. In all snails with HP-infections these effects are observed independent of the miracidial dose at exposure. Snails with LP-infections demonstrate no signs of gigantism, their accessory sex organs are almost identical to those of controls, and the snails show ovipository activity. It is concluded that the occurrence of HP- and LP-infections indicates differences in reproductive capacity of the parasite. HP-infections can only develop when the parasites can adjust the host to their requirements at an early stage of the infection.
87 citations
TL;DR: Children of T. taeniaeformis developed identical tegumental lesions after contact with praziquantel whether incubated in vitro or treated in vivo, while the wall of the bladder containing the larva remained unaffected and the cyst wall with its germinative layer were unaffected.
Abstract: AdultHymenolepis diminuta, H. microstoma, H. nana, Echinococcus multilocularis, andTaenia (Hydatigera)taeniaeformis have been exposed in vitro in media containing 0.1 to 100 μg praziquantel/ml. Already after 5 min characteristic tegumental lesions, that were restricted to the growth zone of the neck region, were recognized using both scanning and transmission electron microscopy. Within the tegument numerous vacuoles were formed that released their contents to the exterior and finally caused destruction of the tegument. Proglottides of the central or posterior strobilar portions were never damaged. Larvae ofT. taeniaeformis (cysticerci) andE. multilocularis (alveolar cysts) were studied employing the same methods both after in vitro exposure to and after in vivo treatment of their hosts with praziquantel. Strobilocerci ofT. taeniaeformis developed identical tegumental lesions after contact with praziquantel whether incubated in vitro or treated in vivo. The wall of the bladder containing the larva remained unaffected. Evaginated protoscolices ofE. multilocularis were damaged by in vitro contact with praziquantel while invaginated protoscolices remained intact. After in vivo exposure there were some fully developed evaginated and damaged protoscolices whereas all invaginated protoscolices and the cyst wall with its germinative layer were unaffected.
69 citations
TL;DR: Long-term alternations between two temperature levels resulted in prepatent periods corresponding exactly to the proportional time-temperature products, however, slight accelerations of up to 7% and more could be observed when the prepatency began in a period of high temperature.
Abstract: Laboratory experiments have permitted the quantification of the developmental times (prepatent periods) ofSchistosoma mansoni in the snail over the whole possible range of constant temperatures. The basis relationship is satisfactorily described by a hyperbola of the formulay=268/(x−14.2),y being the minimum time from miracidial infection to cercariae shedding (in days)x the mean temperature, and 14.2 the theoretical temperature threshold (in °C). Cercariae production takes place within the limits of +16°C and 35°C, the number of cercariae being low and the mortality of snails high at the extreme values.
59 citations
TL;DR: Ultrastructural observations on adult Proteocephalus tidswelli revealed a marked microtrichial polymorphism, suggesting that microtriches are involved in a diversity of functions, and possible functional activities are discussed.
Abstract: Ultrastructural observations on adult Proteocephalus tidswelli revealed a marked microtrichial polymorphism Structural and dimensional variations of microtriches between different regions of the strobila and scolex, as well as within the same region, were observed The authors suggest that microtriches are involved in a diversity of functions, and possible functional activities are discussed
58 citations
TL;DR: Five species of the genusBulinus andPhysa acuta were found to be highly susceptible as second intermediate host snails, whereas three species ofThe genusBiomphalaria, Planorbarius corneus (Rabat),Lymnaea natalensis (Egypt), andHelisoma duryi (Florida) all had a lower degree of susceptibility.
Abstract: Moderate freezing, desiccation, and pH levels of 5 and 6 killed theEchinostoma liei egg immediately or after only partial development, and increasing salinity levels above 3.79‰ and temperatures of 33°C and 35°C reduced the developmental potential. Temperatures of 6°C and 8°C and maintenance of eggs in mouse faeces arrested the development of the egg, and increasing temperatures decreased the time of development from 40 days at 18°C to nine days at 35°C. Maintenance of unembryonated eggs for 14 weeks in faeces at 12°C and 22°C and for 20 weeks in filtered pond water at 4°C allowed a subsequent normal development, while embryonated eggs maintained at 4°C only retained an unchanged hatchability for three weeks. A miracidium/snail density of 10∶10 in 18 litres of water gave rise to an average level of parasitisation of 21%. Increasing miracidium/snail densities gave rise to increasing levels of parasitisation but to a level less than expected. The first intermediate host spectrum ofE. liei was shown to be restricted to the genusBiomphalaria, but species variability in susceptibility within the genus and differences in survival of infected susceptible species was also demonstrated to exist.B. glabrata (Puerto Rico and St. Lucia),B. alexandrina (Qalyub), andB. pfeifferi (Malumfashi) were found to be susceptible, whileB. camerunensis (Kinshasa) was almost refractory. Increasing size ofB. glabrata (Puerto Rico) resulted in increasing daily cercarial production, but resistance to infection with increasing snail size was also demonstrated to exist.E. liei cercarial infectivity to the second intermediate host snail and the subsequent metacercarial infectivity to the mouse was found to be independent of the species of the first intermediate host and of the age of the infection inB. glabrata (Puerto Rico) for up to at least 6 1/2 weeks after the end of the prepatent period. No obvious peak in cercarial shedding from the host snail occurred during the day. Five species of the genusBulinus andPhysa acuta (Egypt) were found to be highly susceptible as second intermediate host snails, whereas three species of the genusBiomphalaria, Planorbarius corneus (Rabat),Lymnaea natalensis (Egypt), andHelisoma duryi (Florida) all had a lower degree of susceptibility. On the other hand,E. liei metacercarial infectivity to the mouse was independent of the species and size of the second intermediate host snail. Also, the infectivity of metacercariae encysted on snail mucus, in snails harbouring patent redial infections, and in clean second intermediate host snails was comparable. Metacercarial infectivity remained unchanged for at least 12 and 18 weeks, respectively, when encysted in livingB. glabrata (Puerto Rico) or when maintained in freshwater at 4°C. Metacercariae in dead decayingB. glabrata remained unharmed for one week, followed by a loss of infectivity after 4 1/2 weeks, while the infectivity of metacercariae maintained in freshwater with snail debris at 22°C declined for four weeks, followed by a loss in infectivity after five weeks.
56 citations
TL;DR: The dwarf tapeworm,Hymenolepis nana, was studied by means of scanning and transmission electron microscopy after in vitro exposure to 1, 10, and 100 μg/ml of the anthelmintic praziquantel (Droncit®) for 5, 15, 30, and 60 min, which led to the disruption of the syncytial layer in the apical region of the tegument.
Abstract: The dwarf tapeworm,Hymenolepis nana, was studied by means of scanning and transmission electron microscopy after in vitro exposure to 1, 10, and 100 μg/ml of the anthelmintic praziquantel (Droncit®) for 5, 15, 30, and 60 min. The resulting vacuolization of the tegument was exclusively confined to the neck region of the tapeworms and was already observed after treatment for 5 min with 1 μg/ml. This vacuolization finally led to the disruption of the syncytial layer in the apical region of the tegument. The tegumental microtriches and the surface coat remained unaffected. Proglottids of the middle or posterior regions of the worms never showed destruction.
52 citations
TL;DR: The study of dividing and non-dividing tetrathyridia using electron microscopy shows that the mode of multiplication by antero-posterior fission of these larvae is due to a particular tissue which is called the ‘apical massif’, a part of the tegumental syncytium.
Abstract: The study of dividing and non-dividing tetrathyridia using electron microscopy shows that the mode of multiplication by antero-posterior fission of these larvae is due to a particular tissue which is called the ‘apical massif’. The apical massif is a part of the tegumental syncytium. It is located at the top of the scolex. It represents a polynucleated cell mass which has cytomorphogenetic power. During asexual multiplication, it differentiates into tegumental syncytium, sub-tegumental muscles, glycogen-storing parenchyma cells, and other cell types. Parts of it remain undifferentiated. The hypothetic origin of the apical massif is discussed.
49 citations
TL;DR: The peptidergic and aminergic neurons in adult Diphyllobothrium dendriticum were studied by light and electron microscopy, combined with fluorescence histochemistry (Falck-Hillarp method for biogenic amines) to indicate a possible interdependence between the two types of neurons.
Abstract: The peptidergic and aminergic neurons in adultDiphyllobothrium dendriticum were studied by light and electron microscopy, combined with fluorescence histochemistry (Falck-Hillarp method for biogenic amines). The peptidergic neurons, regarded as presumptive neurosecretory cells, are located close to the central as well as the peripheral nervous system. These neurons are characterized by their large electron-dense granules. They have very long processes extending to the musculature and the basement membrane of the tegument. The aminergic neurons show the fluorescence characteristic of 5-hydroxytryptamine and contain small dense-core granules. They are located in the brain commissure and along the main nerve cords. Fine nerves reach the muscular and subtegumental layers. Their distribution thus parallels that of the peptidergic neurons, indicating a possible interdependence between the two types of neurons.
TL;DR: It is suggested that either the secretion of gonadotrophic hormones or the response of their targets is reduced by humoral effects of the parasites.
Abstract: Juvenile specimens ofLymnaea stagnalis were exposed to 0 or 4 miracidia ofTrichobilharzia ocellata. Highly productive infections developed in all infected snails. Qualitative and/or quantitative light microscopic observations were performed at various intervals between day 0 and 83 post exposure (p.e.). Gonadal maturation started between day 4 and 7 p.e. in all snails, but in infected animals gonadal growth was retarded considerably after day 7 and was blocked from day 19 onwards. This resulted in very small gonads (10% of the volumes of those of controls on day 83 p.e.) in infected snails, in which however, gametogenesis was initially normal. Due to the small gonad volume gamete production was highly reduced. From day 33 onwards spermatogenesis appeared to be inhibited and around day 83 oocyte maturation seemed to be impaired. The accessory sex organs (ASO) of infected snails showed a similar reduced growth. The cellular differentiation and production of secretory granules in these small ASO was normal albeit delayed in both the male and female organs. The severe reduction in growth of the gonad and the ASO started in the presence of immature primary sporocysts, the later effects on gametogenesis were simultaneous with the production of massive numbers of cercariae. These results are discussed in view of the available data on the endocrine control of reproduction inL. stagnalis. It is suggested that either the secretion of gonadotrophic hormones or the response of their targets is reduced by humoral effects of the parasites.
TL;DR: The distribution of larvae was found to be overdispersed statistically and in general much greater numbers of L3s were recovered during the rainy season, and there was a tendency for larvae to be confined to the surface/topsoil.
Abstract: Observations have been made over a 15-month period on the frequency distribution of human faecal deposits and infective larvae ofNecator americanus in a hookworm endemic area. The agestructure of infective larvae in a field population and their vertical distribution in soils were determined. These studies were undertaken to examine the hypothesis that hookworm transmission in the tropics is discontinuous and limited mainly to the rainy season. The distribution of larvae was found to be overdispersed statistically and in general much greater numbers of L3s were recovered during the rainy season. The degree of overdispersion was also reduced during this season, and there was a tendency for larvae to be confined to the surface/topsoil. The implications of these findings have been discussed in relation to human hookworm parasitism in endemic areas of the tropics.
TL;DR: In this paper, the dimensions and histologic features of the larval cyst mass (LCM) were determined at three days, at weekly intervals for 12 weeks, and at 22 weeks postinfection.
Abstract: C57L/J male mice were infected subcutaneously in their left flank with 10 cysts ofEchinococcus multilocularis. The dimensions and histologic features of the larval cyst mass (LCM) were determined at three days, at weekly intervals for 12 weeks, and at 22 weeks postinfection. The LCM doubled its size between 3 and 12 weeks, and at 22 weeks it was five times larger than at three weeks. During the proliferative phase, the LCM was infiltrated massively by neutrophils, macrophages, and progenitors of the plasma cell series. The first two cell types were found firmly bound to the laminated layer of both intact and degenerating cysts, whereas plasma cells colonized the fibrohistiocytic corona and the interlacunar stroma harboring individual cysts. By 22 weeks, the proliferation of the cysts had ceased and histologically the LCM consisted of fibrous and fibrohistiocytic stroma, thick-walled fertile and sterile brood capsules, and predominantly plasmacytic and histiocytic infiltrates. In addition to exogenous budding evidence has been presented also suggesting the role of free germinal cells in the histogenesis of LCM. Regulation of cyst proliferation in susceptible hosts is discussed with reference to antibody-dependent cell mediated cytotoxicity with nonlymphoid inflammatory cells.
TL;DR: Developments in the tegumental structure of the daughter sporocyst include the formation of microvillus-like projections, a surface coat, spines, and a basement membrane.
Abstract: The development of the mother sporocyst and the differentiation of the daughter sporocyst ofSchistosoma mansoni inBiomphalaria pfeifferi are described. The tegumental structure of the mother sporocyst, consisting of an outer layer connected to internally situated nucleated cell bodies, forms extensions which enwrap the germinal cells. The parenchyma cells, in which the germinal cells were embedded before, degenerate. When daughter sporocyst embryos develop from germinal cells they are enveloped by a primitive epithelium which is formed by fusion of the extensions of the tegumental structure of the mother sporocyst. Somatic cells located peripherally in the developing daughter sporocyst expand and coalesce beneath the primitive epithelium to form the future outer layer of the tegumental structure of the daughter sporocyst. The primitive epithelium degenerates, the newlyformed layer looses its nuclei, and becomes connected to internally situated nucleated cell bodies. Further developments in the tegumental structure of the daughter sporocyst include the formation of microvillus-like projections, a surface coat, spines, and a basement membrane.
TL;DR: It has been shown that during the attachment of the head region, these sacs are everted to expose the enclosed microvilli and duct openings and secretions S1 and S2 are extruded.
Abstract: The light microscope and the transmission electron microscope have revealed that the anterior adhesive apparatus ofDactylogyrus amphibothrium and that ofD. hemiamphibothrium are similar and composed of three kinds of gland cell, one producing rod-shaped bodies (secretion S1), one producing spherical bodies (S2), and the third producing electronlucent vesicles (S3). In the cytoplasm of Gl gland cells each rod-shaped body is enclosed by a single layer of microtubules but no microtubules are associated with S2 and S3 bodies. The possible functions of these microtubules are discussed. The ducts which extend anteriorly from all three kinds of gland cell coverge on and open into six adhesive sacs, situated ventrally on the distal extremities of the head lobes. Each adhesive sac is supplied with at least one gland duct from each type of gland cell and is lined by a special tegument bearing dense microvilli and a few cilia which may have a sensory function. It has been shown that during the attachment of the head region, these sacs are everted to expose the enclosed microvilli and duct openings and secretions S1 and S2 are extruded.
TL;DR: It was concluded that irradiation had selected an avirulent parasite population in Hereford steers after injecting Babesia bovis parasites attenuated by 35 krads gamma irradiation and parasites not exposed to irradiation.
Abstract: Babesia bovis parasites attenuated by 35 krads γ irradiation and parasites not exposed to irradiation, were injected into intact 2-year-old Hereford steers. All five animals receiving non-irradiated blood died but the five animals which received irradiated blood were only mildly affected.
TL;DR: This is the first reported in vitro test directed against the parasitic stages of a nematode that is capable of detecting reliably the activity of a wide range of anthelmintics including thiophanate and all the benzimidazoles.
Abstract: A new in vitro test suitable for the large scale screening of chemical compounds for anthelmintic activity is described. The test which utilizes the fourth larval and adult stages ofNippostrongylus brasiliensis in a medium capable of supporting the growth and development of the parasite, detects selectively those compounds which possess either broad spectrum anthelmintic or specific anti-trichostrongyle activity. The screen is easy to operate requiring only minute quantities of experimental compound. It renders fully reproducible results which furthermore can be interpreted objectively. This is the first reported in vitro test directed against the parasitic stages of a nematode that is capable of detecting reliably the activity of a wide range of anthelmintics including thiophanate and all the benzimidazoles.
TL;DR: The structure of the outer “membranes” surrounding the salivary gland appeared similar to, and often actually part of, the basement membrane of the gland cells and were found to enclose large numbers of multinuleate “giant form” trypanosomes, whose significance is as yet unknown, but could perhaps represent a stage in the life cycle of the parasite where genetic interchange could take place.
Abstract: Ultrastructural studies of the mechanism of penetration of the salivary gland of the reduviid bugRhodnius prolixus byTrypanosoma rangeli showed that trypanosomes from the haemocoele penetrate the outer “membranes” of the gland flagellum foremost, disrupting the inner layers, to pass between the muscle cells to reach the gland cell basement membrane. This latter is also penetrated flagellum foremost, the parasite invaginating the gland cell plasmalemma beneath, to create a vacuole in which the trypanosome crosses the gland cells to reach the central lumen, often only losing its containing vacuole just before leaving the cell.
TL;DR: Differences in number and localization of the larvae, and hypothetical mechanisms how they could influence the behavior of their hosts are discussed.
Abstract: Cerebral larvae ofDicrocoelium dendriticum andD. hospes and the brains of infected ants were studied. Morphologic differences of the freed larvae could not be found, but there were evident differences in number and localization of the cerebral stages. Ants infected withD. dendriticum usually showed one “Hirnwurm” while in the majority of the ants infected withD. hospes two larvae were found.
TL;DR: Compared with fish on a restricted diet alone, parasitism plus dietary restriction also reduced survival; however, the combination of cadmium exposure and restricted diet did not and a possible explanation for this finding is proposed.
Abstract: The effects on the three-spined stickleback, (Gasterosteus aculeatus L.), of various combinations of stresses due to parasitism bySchistocephalus solidus, dietary restriction, and exposure to cadmium (0.032 mg l−1) were investigated. Sticklebacks exposed to a combination of all three stressors died first with a median period of survival significantly shorter than that for fish subjected to fewer stressors. Compared with fish on a restricted diet alone, parasitism plus dietary restriction also reduced survival; however, the combination of cadmium exposure and restricted diet did not. A possible explanation for this finding is proposed.
TL;DR: Sixteen species of terrestrial gastropods, collected at Tromsöya, northern Norway, were experimentally brought into contact with first stage larvae of Elaphostrongylus rangiferi, a parasite causing neurological disorders in reindeer, and no obvious relationship between the degree of tissue reactions and susceptibility to infection was found.
Abstract: Sixteen species of terrestrial gastropods, collected at Tromsoya, northern Norway, were experimentally brought into contact with first stage larvae ofElaphostrongylus rangiferi, a parasite causing neurological disorders in reindeer,Rangifer tarandus (L.). All species were susceptible to infection but there were considerable variations in incidence and intensity of infections and in the development of the nematode in the different gastropod species. InDiscus ruderatus, Arion silvaticus, Deroceras laeve, Euconulus fulvus, andTrichia hispida, development to infective third stage larvae took about 20 days at 20°C. InSuccinea pfeifferi, Deroceras reticulatum andArianta arbustorum development was somewhat slower. InCochlicopa lubrica, Arion subfuscus, A. hortensis, Vitrina pellucida, Nesovitrea spp., andClausilia bidentata, only small numbers of larvae developed and at a very slow rate. InVertigo lilljeborgi andPunctum pygmaeum, the larvae did not develop. Growth in length ofE. rangiferi inD. ruderatus was rapid and continuous up to the second molt (about 15 days postinfection). Thereafter there was a slower growth rate. Tissue reactions against the infection were observed in eleven of the gastropod species. No obvious relationship between the degree of tissue reactions and susceptibility to infection was found.
TL;DR: The test was not found to be reliable in individual animals with natural infections when compared with sera from cattle naturally infected withF.
Abstract: A “crude” antigen prepared from the strobilate stage ofTaenia saginata was tested for its suitability in the peroxidase microenzyme-linked immunosorbent assay (ELISA) for the diagnosis ofT. saginata cysticercosis in cattle. Sera were tested from laboratory and pasture-reared calves experimentally infected withT. saginata as well as from cattle naturally infected by grazing on pasture irrigated with sewage effluent. The specificity of the “diagnostic” antigen was assessed using sera from laboratory-reared cattle with monospecific infections ofT. saginata, T. hydatigena, Fasciola hepatica, or gastro-intestinal nematodes, and natural infections ofF. hepatica. Cross-reactions occurred in sera from all heterologous infections but the highest level occurred in cattle experimentally or naturally infected withF. hepatica. Clear diagnostic antibody levels were found in cattle experimentally infected withT. saginata but the test was not found to be reliable in individual animals with natural infections when compared with sera from cattle naturally infected withF. hepatica. On a group or herd basis ELISA using “crude” antigen and taking the mean absorbance values, could be useful as an indicator of a high prevalence rate ofT. saginata cysticercosis.
TL;DR: Rat erythrocytes infected with Fasmodium berghei were disrupted by gentle passage of Coneanavalin A (ConA) agglutinated cells through a 100 mesh stainless steel grid and the combination of the two techniques produces a high yield of intact free parasites suitable for physiological or immunological studies.
Abstract: Rat erythrocytes infected with Plasmodium berghei were disrupted by gentle passage of Concanavalin A (Con A) agglutinated cells through a 100 mesh stainless steel grid. The free parasites were separated from cell debris, unbroken infected cells, and from uninfected rat erythrocytes on a Percoll gradient. The parasites remained morphologically intact, metabolically active, and infective to mice. The parasites were observed by light and electron microscopy. The incorporation of 3H-isoleucine and 3H-hypoxanthine was compared in intact and infected cells, and the infectivity was measured by the injection of parasites into susceptible mice. It seems that the combination of the two techniques used, produces a high yield of intact free parasites suitable for physiological or immunological studies.
TL;DR: The results forE.
Abstract: The ability of three treatment schedules of mebendazole to kill well-established hydatid cysts was studied. Pregnant sheep, naturally infected with Echinococcus granulosus and/or Taenia hydatigena, were treated daily with mebendazole at a dose rate of 50 mg/kg body weight for either five days, one month, or three months. At autopsy, seven months after the commencement of treatment, no evidence was found that the 5-day treatment schedule had any damaging effect on E. granulosus cysts. The effects of the one month treatment were equivocal. There was evidence of a damaging effect from the 3-month treatment schedule and protoscoleces were not infective to dogs. No T. hydatigena cysts survived the 1- and 3-month treatments, but organisms from the 5-day treatment were infective to dogs. These results for E. granulosus in sheep suggest that long-term treatment with mebendazole may be required in hydatid disease in man. The results obtained for T. hydatigena in sheep are discussed in relation to the treatment of cysticercosis from T. solium in man. Mebendazole showed no untoward effect on the sheep or their lambs.
TL;DR: The differences in findings concerning intestinal lesions and forms of the disease (from acute to chronic to latent) are explained by differences in the virulence of different parasite strains and by Differences in inherent host resistance.
Abstract: Using light and electron microscopy, we studied the ultrastructure of Spironucleus muris (syn. Hexamita muris) from spontaneously and experimentally infected normal and athymic mice. Kinetosomes and cytoskeletal fibers arranged in two-fold rotational symmetry are similar to the species Spironucleus elegans from amphibians. Taxonomic proposals and a possible evolutionary scheme for diplomonad genera accepted at the last International Congress of Parasitology are given. The genus Hexamita should be divided into two new genera: Hexamita (usually free-living) and Spironucleus (exclusively parasitic). We consider previous descriptions of hexamitiasis in rodents as dealing with spironucleosis. We distinguish a fresh and an old cyst of the parasite on the basis of structure, light refraction, location in the host, and infectivity. The transition from a fresh to an old cyst parallels the dessication of feces. The trophozoites can damage the microvilli and penetrate into the epithelium. We explain the differences in findings concerning intestinal lesions and forms of the disease (from acute to chronic to latent) by differences in the virulence of different parasite strains and by differences in inherent host resistance.
TL;DR: It is suggested that the anti-oncospheral antibody response could be associated with protective or “functional” antibody.
Abstract: Using a peroxidase micro-enzyme--linked--immunosorbent assay (ELISA) method anti-oncospheral antibodies were demonstrated in sera from four lambs after primary and challenge infections with Taenia ovis or T. hydatigena. Antibodies assayed using homologous oncospheral antigen (OA) reached a peak by 3-4 weeks after primary infection and at 1-3 weeks post-challenge infection, but waned to pre-infective, "background" levels by 8-12 weeks after each infection. Antibodies assayed against antigens in strobilar or cystic larval extracts persisted for long periods after the initial infections and exhibited different kinetics of response from those demonstrated against OA. These antibodies showed increased levels after challenge infection. Oncospheral antigens did not seem to be species specific although they appeared to elicit a stage-specific response. It is suggested that the anti-oncospheral antibody response could be associated with protective or "functional" antibody.
TL;DR: The microanatomic arrangement of the muscular, nervous, and excretory systems as well as the organization of the tegument are described for the rostellum of Hymenolepis diminuta, which includes a single bilateral pair of ganglia which provide motor innervation of the anterior canal.
Abstract: The microanatomic arrangement of the muscular, nervous, and excretory systems as well as the organization of the tegument are described for the rostellum ofHymenolepis diminuta. An inner circular and an outer longitudinal layer of muscle comprise the rostellar capsule, delimiting the rostellum from the scolex proper. A similar muscular arrangement surrounds an apical invagination of the rostellar tegument, the anterior canal. Elements of the excretory and nervous systems enter the rostellum basally through a discontinuous region of the capsule. Although excretory canals extend into the rostellum, flame cells and their associated collecting ducts are absent. The rostellar nervous system is comprised of a single bilateral pair of ganglia, which provide motor innervation of the anterior canal, and the circular muscles of the rostellar capsule; it also receives dendrites from apical uniciliate sensory receptors. The tegument lining the anterior canal and covering the apical rostellum is syncytial and continuous with the tegument of the scolex proper. Twelve to 15 cytons are radially arranged around the anterior canal. They stain selectively with paraldehyde-fuchsin between days 3 and 35 postinfection, but are clearly tegumental, not neurosecretory elements. The appearance of ovoid granules in the rostellar tegumentary cytons coincides with the onset of fuchsinophilia, but the granules persist despite the subsequent loss of this staining characteristic. Intact granules are secreted into the lumen of the anterior canal, although their function has not been ascertained.
TL;DR: The application submitted by Professor Frenkel and his colleagues will nevertheless be published in the Bulletin of Zoological Nomenclature so that the Commission can deliver a ruling on it before the new edition of the code has appeared.
Abstract: The availability or non-availability of a name is a question of historical fact. A name once made available under theInternational Code of Zoological Nomenclature can be rendered unavailable only by use of the plenary powers of the Commission. The question whether a name is anomen dubium or not is a matter of taxonomic judgement. The difficulty with the Sarcocystinae discussed by Frenkel et al. (1979) stems from the fact that, under the present provisions of theCode, it is not possible to designate for the species concerned types that will serve any useful function. The Commission is now considering changes to theCode proposed to remedy this defect in a general, legislative way. It will not, as a matter of general practice, entertain proposals for the suppression of names merely because they are considered to benomina dubia. The application submitted by Professor Frenkel and his colleagues will nevertheless be published in the Bulletin of Zoological Nomenclature so that the Commission can, if necessary, deliver a ruling on it before the new edition of theCode has appeared.
TL;DR: The haemolytic activity of serum complement was measured in cattle during acute Babesia bovis infection and factors such as protease secretion by the parasites, antigenantibody reactions, and the release of haemoglobin were implicated as causes of the decline.
Abstract: The haemolytic activity of serum complement was measured in cattle during acute Babesia bovis infection. The level fell significantly on day 5 post infection (p.i.) and was not detectable by day 10 p.i. After clinical recovery between days 15 and 20 p.i. haemolytic activity was again detected in serum and gradually returned to the pre-infection level. The components of both classical and alternative pathways were involved in complement depletion and factors such as protease secretion by the parasites, antigen-antibody reactions, and the release of haemoglobin were implicated as causes of the decline. The absence of complement activity during the acute phase of the disease may interfere with immune mechanisms at a critical time for the host.