Showing papers in "Parasitology in 1965"
TL;DR: Smithers and Terry as discussed by the authors described techniques which are rapid and do not require great skill in their performance, and in their hands they have given very consistent results, in this respect they believe that these techniques have advantages over others which are currently practised.
Abstract: At present many laboratories throughout the world are studying the chemotherapy and immunology of Schistosoma mansoni in laboratory hosts. Many workers judge the success or failure of their attempts to cure or immunize these hosts from the ratio of the number of living adult worms recovered to the number of infecting cercariae. This ratio is affected, however, not only by the efficacy of any treatment, but also by the methods used to infect the animals and to recover the worms. If these methods result in widely varying worm recoveries amongst the animals in any experimental group, then small but significant effects of treatment might well be missed. Alternatively, such large experimental groups must be used that the work becomes tedious to perform and depends upon the availability of a great deal of technical assistance. This paper describes techniques which are rapid and do not require great skill in their performance. More important, in our hands they have given very consistent results. In this respect, particularly, we believe that these techniques have advantages over others which are currently practised.The techniques described here are those which were used in other investigations reported in this journal (Smithers & Terry, 1965a, b).The strain of S. mansoni used throughout this work was isolated in Puerto Rico and was obtained through the courtesy of Dr W. B. DeWitt of the National Institutes of Health. The parasite is maintained in an albino strain of Australorbis glabratus (Newton, 1955). Snails are exposed individually to ten miracidia overnight at 27 °C.
1,332 citations
TL;DR: Findings on naturally acquired resistance to Schistosoma mansoni in the rhesus monkey are reported, which are likely to be applicable in others.
Abstract: In recent years there has been a steadily growing interest in the immunology of schistosomiasis. Much work has been carried out using a variety of experimental hosts and many attempts have been made to vaccinate these hosts against schistosomes, both by exposing them to irradiated cercariae and by injecting them with various antigens derived from the parasites. These attempts have been attended by varying degrees of success. The ultimate object of much of this work has been its possible application to the disease in man. We believe, however, that work of this kind cannot really be profitably undertaken unless there already exists a sound understanding of the basic host-parasite relations between the schistosomes and their hosts. This knowledge is essential in order to decide whether a finding in one host is likely to be applicable in others. With this idea in mind, we report here our findings on naturally acquired resistance to Schistosoma mansoni in the rhesus monkey.
94 citations
TL;DR: The results of faecal worm-egg counts performed on alternative days, and of differential worm counts carried out on animals slaughtered at crucial times during the course of infection, showed that retardation of development at the 4th larval stage occurred in the group 3 infections and was the major effect of control of the parasitic burden as mentioned in this paper.
Abstract: Two groups of sheep born and raised worm-free were dosed with 3000 infective Haemonchus contortus larvae. Group 1 were each given a single dose of infective larvae on day 0 while the group 3 animals were dosed with 100 infective larvae per day for 30 consecutive days. The results of faecal worm-egg counts performed on alternative days, and of differential worm counts carried out on animals slaughtered at crucial times during the course of infection, showed that retardation of development at the 4th larval stage occurred in the group 3 infections and was the major effect of control of the parasitic burden. There was no evidence that egg production per female was affected. Three animals of the nineteen infected in group 1 died during the course of the experiment owing to the pathogenic effects of the worm burden. Deaths did not occur among the animals of group 3. This finding was correlated with the observation that haematocrit levels were consistently lower among the animals of group 1 than among those of group 3. The results are interpreted in terms of the theory of threshold behaviour of the immunological response to parasitic infection. We are greatly indebted to Dr D. F. Stewart for his interest and constructive criticism during the course of these studies, and to Mr E. Teleki and Misses Helen Giller and Lindy Stothart for their valuable technical assistance.
93 citations
TL;DR: The effects of parasitism by five species of larval Digenea on the digestive gland cells of Littorina saxatilis (Olivi) subsp. tenebrosa (Montagu) were investigated by comparing histochemically stained cells in healthy, starved and parasitized animals as discussed by the authors.
Abstract: The effects of parasitism by five species of larval Digenea on the digestive gland cells of Littorina saxatilis (Olivi) subsp. tenebrosa (Montagu) were investigated by comparing histochemically stained cells in healthy, starved and parasitized animals.Two distinct effects were apparent: (a) The germinal sacs compress the walls of the digestive gland tubules and block the lumen. Since food cannot pass this block, digestive gland cells behind undergo starvation autolysis. (b) In digestive gland tubules not cut off from their food supply, glucose, glycogen, glycoproteins and lipid food storage globules are reduced and there is a compensatory increase in the number of food vacuoles in the digestive cells; an increase in glucose but a decrease in glycogen in the visceral haemocoel; and an increase in the number of secretory cells, perhaps in order to eliminate the parasite's excretory products from the visceral haemocoel.
84 citations
TL;DR: The cyst wall which encloses the metacercaria of Fasciola hepatica consists of four major layers, one of which is further divisible into three sublayers, the relative importance of these resistant layers in providing protection against desiccation, toxic substances and attack by other organisms is discussed.
Abstract: The cyst wall which encloses the metacercaria of Fasciola hepatica consists of four major layers, one of which is further divisible into three sublayers. These layers are numbered I to IV, the first being the external layer. Layers I and II form the outer cyst which may be separated from the inner cyst formed from layers III and IV.Layer I, the thick incomplete external layer, covers the metacercaria dorsally and laterally. It is composed of tanned protein.Layer II is a thin fibrous layer closely adherent to the inner surface of layer I and is composed of mucoprotein and acid mucopolysaccharide.Layer III is made up of three separate sublayers, the relative widths of which vary in different regions of the cyst. In general IIIa consists of mucoprotein, IIIb of acid mucopolysaccharide and IIIc of neutral mucopolysaccharide.In the dorsal and lateral regions, layer IV appears to be formed of lamellae held in a protein–lipid matrix. The lamellae are composed of protein stabilized by disulphide linkages.In the ventral region of layer IV there is a thickened mucopolysaccharide area, the ventral plug, through which the metacercaria excysts.The relative importance of these resistant layers in providing protection against desiccation, toxic substances and attack by other organisms is discussed.This work was carried out during the tenure of a Commonwealth Post Graduate Scholarship. The author is grateful to Professor J. D. Smyth and Dr J. A. Clegg for advice and encouragement during the course of this work and in preparation of the manuscript.
70 citations
TL;DR: In this paper, it was shown that immunity to N. brasiliensis in rats is stimulated primarily by the adult worms and not only on adult worms but also on larvae in a challenge infection.
Abstract: Immunity to N. brasiliensis in rats is stimulated primarily by the adult worms. An initial infection consisting solely of adult worms terminated at the same time as an infection consisting of all the parasitic stages.Immunity is not stage specific. Immunity stimulated by adult worms acts not only on adult stages inhibiting their reproduction but also inhibits the development to maturity of larvae in a challenge infection.Rats infected solely with female adult worms, whether egg producing or sterile, are more resistant to reinfection than rats infected with male worms only.Immunity stimulated by a single normal infection lasts a long time but it does not depend on the persistence of adult worms in the intestine of the rats.This work was done during the tenure of a Commonwealth Scholarship awarded by the Association of Commonwealth Universities.
67 citations
TL;DR: The small intestine of rats was divided into twenty sections in a reproducible manner in order to study the distribution of Nippostrongylus brasiliensis by stretching it under a tension of 5g in adrenaline saline, finding fourth-stage larvae were found chiefly in the sections that were later most heavily parasitized by adult worms.
Abstract: The small intestine of rats was divided into twenty sections in a reproducible manner in order to study the distribution of Nippostrongylus brasiliensis by stretching it under a tension of 5g in adrenaline saline. A small but significant difference between the distribution of parasites in male and female rats was observed. As larvae had virtually ceased to reach the intestine by the fifth day all changes in distribution after that day were due to movements of the established adult population. Up to the twelfth day of a primary infestation the majority of the worms were found between the third and tenth sections, the population mode being in the fifth or sixth section. After the thirteenth day the number of worms in this region fell sharply. The female worms had not ceased from egg-laying by the time most of the worms were being rejected. The posterior half of the small intestine, i.e. the eleventh to twentieth sections, was not heavily parasitized, many of the worms seen being in passage to the anus. The first section was not parasitized until the seventh day, but thereafter remained parasitized until long after worms had disappeared from the more posterior sections. The relative number of male worms present increased as the infestation aged. Throughout the experiment the relative number of male worms present at the anterior end of the smaller intestine was higher than that at the posterior. Fourth-stage larvae were found chiefly in the sections that were later most heavily parasitized by adult worms.
64 citations
TL;DR: The present work has been undertaken in order to establish whether the immune response in the albino rat is at all similar to that in the rhesus monkey (Smithers & Terry, 1965 b ).
Abstract: The host–parasite relationships of Schistosoma mansoni in the albino rat have been studied recently by Ritchie, Garson & Knight (1963) and by Sadun & Bruce (1964). The general findings of these and other workers are that, in rats, the worms are always stunted, although they may pair and non-viable eggs may be found in the liver. The worms remain in the liver and seldom, if ever, migrate to the mesenteries. Ritchie et al. (1963) found that the majority of the worms were eliminated between the 4th and 8th week after infection; this is much sooner than in other experimental hosts. Sadun & Bruce (1964) suggest that rats are particularly suitable and convenient for studies on acquired resistance to S. mansoni ; this suggestion is based mainly on the grounds that acquired resistance is more easily demonstrated in animals which show a relatively great degree of innate resistance. The present work has been undertaken in order to establish whether the immune response in the albino rat is at all similar to that in the rhesus monkey (Smithers & Terry, 1965 b ). Two features of the host–parasite system have been studied in detail; the elimination of the worms which follows an initial infection and a comparison of the development of acquired resistance following exposure to X-irradiated cercariae with that following exposure to normal cercariae. A Puerto-Rican strain of S. mansoni , and Sprague–Dawley rats weighing 100–200 g, were used in all experiments. The methods of exposing the rats percutaneously to infection and the recovery of the worms by perfusion have been fully described (Smithers & Terry, 1965 a ).
64 citations
TL;DR: The British host, the brown trout, has been intensively studied for many years and it was thought that this would be of advantage in attempting to relate any seasonal fluctuations in the parasite population to the biology of the host.
Abstract: Relatively little is known of the way in which the populations of monogenean parasites are related to the behaviour and physiology of their hosts or how such populations vary in composition over the year. Bychowsky (1957, trans. Hargis, 1961, p. 108) has described the results of studies upon six different fish hosts and parasites, while Llewellyn (1962) has studied two other species of Monogenea living on one host species. In all these investigations, the various ecological factors which influence the life cycles of the parasites have been determined.Dogiel, Petrushevski & Polyanski (1961, p. 14) referred to a previous population study of Discocotyle sagittata on a host Coregonus lavaretus in Lake Ladoga, Russia. The parasite was said to breed in July and August, while in September broods of young and old parasites overlapped. The large individuals disappeared in October and November and this ‘death of the older generation’ was taken to indicate that the parasites had a life span of only one year.The only relevant work available when the present study was commenced was the population study of the monogeneans Gastrocotyle trachuri and Pseudaxine trachuri by Llewellyn and as this concerned a marine host, it was of obvious interest to investigate the population dynamics of a parasite of a freshwater fish. Discocotyle sagittata was chosen because the biology of the British host, the brown trout (a different host from that in the Russian study of Discocotyle), has been intensively studied for many years. It was thought that this would be of advantage in attempting to relate any seasonal fluctuations in the parasite population to the biology of the host.
57 citations
TL;DR: The cuticle of adults of Nippostrongylus brasiliensis has been described using histological, histochemical and ultrastructural techniques in this paper, and the structure of the cuticle has been shown to have three layers: an outer triple-layered membrane; a single cortical layer; a fluid-filled layer which is traversed by numerous collagen fibrils; struts which support the fourteen longitudinal ridges; two fibre layers, each layer apparently containing three layers of fibres; and a basement lamella.
Abstract: The cuticle of adults of Nippostrongylus brasiliensis has been described using histological, histochemical and ultrastructural techniques.The cuticle has the following layers: an outer triple-layered membrane; a single cortical layer; a fluid-filled layer which is traversed by numerous collagen fibrils; struts which support the fourteen longitudinal ridges of the cuticle and which are suspended by collagen fibrils in the fluid-filled layer; two fibre layers, each layer apparently containing three layers of fibres; and a basement lamella.The fluid-filled layer contains haemoglobin and esterase.The muscles of the body wall are attached to either the basement lamella or to the fibre layers of the cuticle.The mitochondria of the hypodermis are of normal appearance.The longitudinal ridges of the cuticle appear to abrade the microvilli of the intestinal cells of the host.Possible functions of the cuticle are discussed.I wish to thank Dr P. Tate, in whose department this work was done, for helpful suggestions and criticism at all stages of this work, and Mr A. Page for technical assistance. I also wish to thank Professor Boyd for permission to use the electron microscope in the Department of Anatomy.
54 citations
TL;DR: Ogilvie et al. as discussed by the authors showed that daily treatment with 2 mg cortisone acetate throughout five immunizing infections and continued during the challenge infection increased the number of worms in the intestine and had a marked effect on the cellular response in the skin and lungs.
Abstract: Acquired resistance to some nematode parasites can be suppressed by daily administration of cortisone acetate to the host. Cortisone treatment completely suppressed previously acquired resistance of mice to Trichinella spiralis (Coker, 1956) and suppressed, at least partially, the acquisition of resistance to T. spiralis by rats during initial infection (Markell & Lewis, 1957).A previous report (Weinstein, 1955) suggested cortisone acetate treatment was less effective in the suppression of acquired resistance of rats to Nippostrongylus brasiliensis. Weinstein showed that daily treatment with 2 mg cortisone acetate throughout five immunizing infections and continued during the challenge infection increased the number of worms in the intestine and had a marked effect on the cellular response in the skin and lungs. However, there was no significant effect when daily cortisone treatment commenced only on the fifth day before the challenge infection. This result suggested that acquisition of immunity to N. brasiliensis was partially overcome by cortisone treatment, but the same level of drug treatment had no effect on immunity already acquired.In the experiments reported here, previously acquired resistance to N. brasiliensis was suppressed completely and the initiation of immunity stopped, either completely or at a very early stage, by treatment with the cortisone derivatives prednisolone or betamethasone. The complete suspension of all manifestations of acquired resistance obtained by treatment with these drugs was used to investigate the fate of larvae migrating in an immune host.The rats and strain of parasite, and the methods of handling them, have been described previously (Ogilvie, 1965).
TL;DR: Leptocotyle minor is a monogenean parasite specialized for living on the denticlecovered skin of the dogfish Scyliorhinus canicula and possesses six haptoral spicules which may be homologues of the marginal hooks of other monogeneans, but theseSpicules disappear early in postoncomiracidial development.
Abstract: Leptocotyle minor is a monogenean parasite specialized for living on the denticlecovered skin of the dogfish Scyliorhinus canicula. Each adult parasite attaches itself to the outer surface of a single denticle. Small postlarvae are found on the inner surfaces of the denticles. The denticles have hard enamel on both inner and outer exposed surfaces. Haptoral hooks, such as are present in other monogenean oncomiracidia, would be unable to penetrate this hard surface and are absent in postlarval and adult parasites which attach themselves by cement. The oncomiracidium possesses six haptoral spicules which may be homologues of the marginal hooks of other monogeneans, but these spicules disappear early in postoncomiracidial development.Adult parasites feed on the host's epidermis which lies between the denticles. The position of small postlarvae on the inner surfaces of the denticles enables them to reach the epidermis for feeding purposes. Growth then permits young parasites to migrate away from the epidermis on to the outer surfaces of the denticles.Adult parasites move from one denticle to another in a leech-like manner, and copulation occurs between parasites which meet as a result of these movements.I am grateful to the Director and Staff of the Plymouth Laboratory for their hospitality and particularly to Mr J. E. Green for his interest and co-operation.
TL;DR: The results showed that the level of worm counts attained on secondary infection with the parasite was much reduced compared with the counts recorded following initial infection, and the relative fecundities of parasite populations which developed in individual hosts following challenge infection, ranked in magnitude in an order which was similar to that established followingInitial infection.
Abstract: The present studies were designed to characterize the response of sheep infected with N. spathiger to challenge infection with the same species.The results showed that: (1) the level of worm counts attained on secondary infection with the parasite was much reduced compared with the counts recorded following initial infection; (2) the relative fecundities of parasite populations which developed in individual hosts following challenge infection, ranked in magnitude in an order which was similar to that established following initial infection; (3) as fecundity was highly correlated with the number of egg-laying females and the number of males and females was nearly equal in individual specimens, it was concluded that worm burdens were also ranked for individual animals on primary infection and following challenge; and (4) the animals of the control group remained as susceptible as the animals of groups 1 and 3 at the time of their primary infection; consequently, in the absence of previous immunological experience due to infection, there was no apparent change in susceptibility of the animals due to an effect of age during the course of the 17 weeks of the experiment.We are greatly indebted to Dr Michael Tallis, Division of Mathematical Statistics, C.S.I.R.O., for advice and assistance with the statistical analyses, and to Dr D. F. Stewart for his interest and constructive criticism during the course of these studies. Our thanks are also due to Mr E. Teleki and Misses Helen Giller and Lindy Stothart for their valuable technical assistance.
TL;DR: The establishment of reproducible differences in infections of hosts at the sub-specific level provides basic information for investigation of factors which influence penetration and maturation and which are thus involved in host specificity and innate resistance in closely related animals.
Abstract: Penetration and maturation of Schistosoma mansoni were compared in four strains of mice under controlled conditions, with the C3H as the reference strain. Differences were observed in (1) average numbers of cercariae penetrating, (2) percentage of individual mice penetrated by at least 90% of the available cercariae, (3) worm burdens, (4) maturation of penetrants, and (5) consistency of mice with reference to these characteristics. Criteria 2, 4 and 5 have not been evaluated in this way before.Best average penetration (47%), greatest consistency, and highest percentage of samples with at least 90% of the cercariae penetrating were in mice of the C3H strain (85%). Of the other strains the Swiss albino strain most resembled strain C3H. Beige and hairless mice were comparatively resistant to penetration since only 60 and 30% respectively of these hosts had at least 90% of the cercariae penetrating. Hairless mice gave the best average worm recovery (23%) and parasite maturation (53%) and beige the poorest (15 and 34%). Mice of the Swiss and beige strains were highly variable in terms of parasite maturation.The establishment of reproducible differences in infections of hosts at the sub-specific level provides basic information for investigation of factors which influence penetration and maturation and which are thus involved in host specificity and innate resistance in closely related animals.The authors are grateful to Dr Margaret Deringer, National Cancer Institute, National Institutes of Health, for the hairless mice and to Mildred Walters, Naval Medical Research Institute, for assistance in the production of cercariae.
TL;DR: In this article, a simple cylindroid pharynx of Ascaris lumbricoides has been shown to be characterized by a pharyngo-intestinal valve which is composed of two sets of valves.
Abstract: The simple cylindroid pharynx of Ascaris lumbricoides has been shown to be characterized by a pharyngo-intestinal valve which is composed of two sets of valves. This is the only valve structure in the pharynx of this nematode. The pharynges of Oxyuris equi, Aplectana brevicaudata and Panagrellus silusiae have a series of valve structures along the lengths of the organs. All these types have a valve at the anterior end of the corpus, corrugated ‘valves’ in the posterior bulb, and pharyngo-intestinal valves. A valve between the corpus and the isthmus has been shown in Oxyuris.In all the nematodes studied the pharyngo-intestinal valve is characterized by an overlapping of the muscle fibres associated with the valve and the main musculature of the pharynx that immediately precedes them. It has been suggested that the pharyngo-intestinal valves of the types studied may have evolved from the type of valve found in the Enoplina.The marginal tissues of the pharynx of Ascaris lumbricoides have been shown to be composed of three types of tissues. It has been suggested that the marginal tissues have a suspensory and skeletal function. The suspensory strands subserve the first function, while the investing strands and the associated fibrous layer provide a longitudinal skeletal structure in the pharynx. In Oxyuris no fibrous layer is associated with the marginal tissues.I would like to thank Professor J. E. Harris and Dr H. D. Crofton for their help and criticism during the course of this work, which was carried out during the tenure of a Postgraduate Studentship awarded by the Agricultural Research Council.
TL;DR: The specific composition of the parasitic helminth fauna of wild ruminants in Britain has not been examined for 30 years, and the series of surveys to be described were undertaken to provide data on this aspect of helminths epidemiology as discussed by the authors.
Abstract: The specific composition of the parasitic helminth fauna of wild ruminants in Britain has not been examined for 30 years, and the series of surveys to be described were undertaken to provide data on this aspect of helminth epidemiology. With the increase in interest in conservation of wild stock, and especially ruminants, in recent years, information on the epidemiology of their helminth infections is an essential adjunct to any schemes for their protection and husbandry.The common roe deer, Capreolus capreolus capreolus, is distributed throughout Europe and Asia, the other subspecies, G. c. pygargus, the Siberian roe, G. c. bedfordi, the Manchurian roe, and C. c. melanotis, the Szechwan roe, being limited in range. It is indigenous to Britain, and over the centuries its populations have undergone great numerical fluctuations. Though at one time nearly extinct in England except in the counties on the Scottish marches it appears at present to be in a period of resurgence, and the range is extending from dense foci in the south and south-east to join the northern population. It has always been numerous in mainland Scotland and a few of the Western Isles, but is extinct in Wales and Ireland (Whitehead, 1964). The roe is the smallest of our indigenous deer and differs from the others in its breeding habits, not forming herds, but grouping as family units of buck, doe and offspring. On the mainland of Europe, however, herding does take place, and a limited migration has even been observed in Russian roe (Flerov, 1952). Its habitat is essentially woodland, but it grazes open areas to some extent and, not-withstanding its timid character, lives in close proximity to man in agricultural and even in urban areas.
TL;DR: Protein quality appears not to be a factor in growth of H. diminuta, and replacement of all the protein of the diet by carbohydrate resulted in greater development of the worm, while replacement of casein by fat had no effect on worm development, indicating that removal of protein is not a significant factor, whereas addition of carbohydrate is effective.
Abstract: The dry weight and nitrogen content of Hymenolepis diminuta were studied after a period of 15 days‘ growth in rats receiving different diets. The special diets were fed during the last 7 days of this period, that is, while the major part of growth is occurring but before shedding proglottids.Replacement of all the protein (casein) of the diet by carbohydrate resulted in greater development of the worm. However, replacement of casein by fat had no effect on worm development, indicating that removal of protein is not a significant factor, whereas addition of carbohydrate is effective.Since exchange of casein by the nutritionally incomplete protein zein did not affect worm development significantly, protein quality appears not to be a factor in growth of H. diminuta.The addition of tryptophan and lysine to the meal containing zein, in order to raise its nutritional value to that of casein, did not influence the growth of the parasite. However, the feeding of the same amounts of these two amino acids at times other than those of giving zein depressed the growth of the parasite. This was not due to type of protein (zein) fed in the rest of the diet, since a similar phenomenon occurs when casein is the dietary protein, or when a protein-free diet rich in carbohydrate is given. Addition of these amino acids, singly, either to diets containing protein or deficient in protein, had significant actions on worm growth, which was sometimes stimulated and in other circumstances reduced.The nitrogen balance of the host was unaffected by the worm burden.We are deeply indebted to Dr C. A. Hopkins for providing facilities, for infection of rats with the cestode, and for his helpful advice. Miss M. Cowan provided skilled technical assistance during the feeding of the animals and analysis of the host and parasite tissues. One of us (D.F.M.) gratefully acknowledges the Award of a Commonwealth Bursary from the Royal Society and the Nuffield Foundation.
TL;DR: The development of Archigetes limnodrili in species of Limnodrilus is described, and the life-history discussed with particular reference to the phenomenon of progenesis.
Abstract: The development of Archigetes limnodrili in species of Limnodrilus is described. There is no free-living larva and eggs are ingested by the tubificids. Growth and development is completed within the body cavity of the annelid, and egg liberation is accomplished by release of the parasite and decay of its body. Breeding of A. limnodrili takes place throughout the year. In the localities investigated there was no evidence that a fish host was required in the life-cycle. Progenesis was the only type of development encountered in Britain. A. limnodrili exhibits an unusual degree of host specificity, being found only in species of Limnodrilus . It is suggested that this is due to differences in the composition of the coelom or intestine of Limnodrilus compared to other genera. The degree of infection in all localities is very low, and shows no regular seasonal variation. There is no similarity in the seasonal changes in different localities. The relationship between the host and parasite is a stable one, and there is little mutual damage. Factors contributing to this stability are discussed. The development of A. limnodrili is compared with that of other species of Archigetes , and the life-history discussed with particular reference to the phenomenon of progenesis. I wish to thank Professor R. J. Pumphrey in whose Department this work was carried out, and Dr J. C. Chubb for his constant advice and criticism. I also wish to thank Dr K. H. Mann and the University of Reading for provision of specimens and permitting me the use of their facilities. The work was carried out during the tenure of a Nature Conservancy Research Studentship.
TL;DR: A study of the distribution of the antigens in F. hepatica at various stages of development, and in the liver and spleen of experimentally infected rats using globulins labelled with fluorescein isothiocyanate is described.
Abstract: The results are described of a study of the distribution of the antigens in F. hepatica at various stages of development, and in the liver and spleen of experimentally infected rats using globulins labelled with fluorescein isothiocyanate, from rats and sheep infected with F. hepatica . Possible uses of this technique in aiding the diagnosis of fascioliasis are indicated. I wish to thank Dr A. W. J. Broome for a supply of the metacercariae of F. hepatica , and Dr J. S. S. Lowe who kindly isolated and labelled the globulins with fluorescein isothiocyanate. Miss Enid Eccleston gave valuable technical assistance.
TL;DR: The genus Acanthobothrium van Beneden, 1850, seems to be in a state of slight confusion due, possibly, to some inadequate descriptions which have led to subsequent misidentifications of some of the species.
Abstract: The genus Acanthobothrium van Beneden, 1850, seems to be in a state of slight confusion due, possibly, to some inadequate descriptions which have led to subsequent misidentifications of some of the species. The type species A. coronatum was first recorded and very briefly described by Rudolphi (1819) as Bothriocephalus coronatus from ‘ Squali stellaris, Squali squatinus and Torpedinis marmoratae “. Since then specimens have been assigned to this species which probably belong elsewhere; the list of synonyms and the host records are extensive. Baer (1948) divided the species of the genus into two groups, namely, those parasitic in sharks and those in rays. This seems to be a reasonable distinction as specificity is very marked in cestodes and especially in those of elasmobranchs. It was thought that a detailed study of the type species, presented here, would be a useful preliminary to a consideration of the genus as a whole. Specimens of A. coronatum were obtained from the spiral valve of Scyliorhinus stellaris (L.) caught in Cardigan Bay in July 1956 and at Plymouth in August 1958 and August and September 1959. The number of worms, complete with scoleces varied from 6 to 10 per fish and in one instance 14. Many fragments of two to three proglottids and many individual proglottids were also present. The scoleces were attached in the first turn of the spiral valve and the strobila adhered feebly along the whole length, sometimes as far back as the rectal gland, leaving on removal a distinct groove in the mucosa.
TL;DR: Schistocephalus plerocercoids in the weight range 2-200mg F.W. were cultured in various media, including 25% horse serum, 0.5% yeast extract, 0·65% glucose and Hanks's saline at pH 7·1, 21°C, 95% air +5% CO2.
Abstract: Schistocephalus plerocercoids in the weight range 2–200mg F.W. recovered from the perivisceral cavity of Gasterosteus aculeatus were cultured in various media. In a medium composed of 25% horse serum, 0·5% yeast extract, 0·65% glucose and Hanks's saline at pH 7·1, 21°C, 95% air +5% CO2, dry weight increases of up to 500% were recorded in 8 days. The specific growth rate of large plerocercoids was only one-tenth of the rate observed in small plerocercoids. A plerocercoid of double the weight of another had approximately half the specific growth rate.Worms after 8 days cultivation were found to have only slightly higher than normal glycogen and water content, and to be able to mature when heated to 40°C. However, the rate of growth slowed to zero by the 24th day in culture at 21°C. Electron microscopic examination showed a ‘deposit’ formed over the microvilli, thin at 8 days but dense after 21 days.The in vivo glycogen and water content of plerocercoids from 3–300 mg F.W. was determined. Glycogen rose from 24% in plerocercoids of 10mg F. W. to 50–55% in plerocercoids over 80mg F. W. The water content was found to mimic precisely this change, falling from 82% to a plateau of 67–69%.We wish to thank Professor Gareth Owen for permission to use the photograph shown in the Plate and for his help while using the electron microscope. It is also a pleasure to thank Miss Patricia Grant for her technical assistance.
TL;DR: It is suggested from the observations made on the birds of the reserve, from the results of infecting domestic ducks and from a consideration of the list of final hosts of the parasite, that there exist strains of P. minutus, adapted to development in different species of birds.
Abstract: Observations are described on Polymorphus minutus in its final and intermediate hosts from a wildfowl reserve in Kent. The appearance of the parasite in the reserve followed the alteration of the course of the River Darent, an operation which created a suitable habitat for the intermediate host, Gammarus pulex.The parasite has been found to occupy the same region of the intestine in the Mallard as in domestic ducks, but it occupies a more anterior region in the Tufted Duck. Worms of varying age have been shown to be present in natural infections of wildfowl.P. minutus and a cestode, Dicranotaenia coronula, appear to compete for attachment sites in the intestine of Mallard. This competition may be a factor which causes the attachment zone of P. minutus to be extended anteriorly.The presence of the parasite in the reserve appears to be causing the population of G. pulex to decrease.It is suggested from the observations made on the birds of the reserve, from the results of infecting domestic ducks and from a consideration of the list of final hosts of the parasite, that there exist strains of P. minutus, adapted to development in different species of birds.We wish to thank Dr P. Tate for helpful discussions, and Dr I. C. Williams, Department of Zoology, University of Hull, for the identification of the cestodes and criticism of the manuscript. Thanks are also due to Drs J. M. and D. L. Harrison, Mr G. Wallis and Mr A. Meikle for assistance with the population studies and the collection of some of the material.
TL;DR: It is suggested that ticks may have become reinfected from the non-bovine hosts, a possibility supported by the finding of B. bigemina in blood smears from two of the sheep.
Abstract: The failure of Boophilus microplus to be cleansed of Babesia bigemina while the ticks were growing on non-bovine hosts, as well as the infection of the non-bovine hosts, was demonstrated in experiments in which infected ticks were released on a number of sheep, a goat and a horse. Seven of ten batches of ticks, collected from six non-bovine hosts, retained their babesia-infection. Blood subinoculated into cattle from seven of nine sheep and from the horse showed that these animals carried B. bigemina whilst the ticks were feeding on them. This suggested that ticks may have become reinfected from the non-bovine hosts, a possibility supported by the finding of B. bigemina in blood smears from two of the sheep. This work was performed at the Animal Research Institute, Yeerongpilly, and in the Department of Parasitology, University of Queensland, and supported by funds from both organizations. I am indebted to Mr G. D. Daly for technical assistance, to Professor J. F. A. Sprent and Dr H. M. D. Hoyte for their interest and help.
TL;DR: In the testis of a young animal, primary, secondary and tertiary spermatogonia are present as mentioned in this paper, and they undergo a complicated series of changes to transform into spermatozoa during spermateleosis.
Abstract: While some variation of detail may be found in different species of the hermaphroditic Digenea, the process of spermatogenesis conforms to a common plan throughout the group. There is divergence of opinion concerning the interpretation of the structure of the ripe spermatozoon.In the testis of a young animal, primary, secondary and tertiary spermatogonia are present. The tertiary spermatogonia divide to give a group of eight primary spermatocytes that undergo the first division of the meiotic phase to form sixteen secondary spermatocytes. As a result of the second division of the meiotic phase, the sixteen secondary spermatocytes give a group of thirty-two spermatids that through a complicated series of changes are transformed into spermatozoa. During spermateleosis much of the cytoplasm of the late spermatid is sloughed off.Recent research, including the application of the Feulgen technique, the examination of living material, and electron microscopy, supports the view that the ripe spermatozoon is composed of an elongate head, and a flagellum. The head, with the exception of its external sheaths, consists of nuclear material.The flagellum of the sperm of Fasciola hepatica is Feulgen-negative and is composed of a proximal and a distal region. Its proximal part is provided with two axial filaments, a middle fibril and an external sheath. The axial filaments and the middle fibril are continued into the distal region where the external sheath appears to be absent. The external sheath of the flagellum of the sperm of Haematoloechus ( = Ostiolum) medioplexus is said to be composed of thirty-six fibrils. Claims that the flagellum of some digeneans contains a centriole, a middle-piece, and mitochondria have not so far been substantiated by means of electron microscopy.
TL;DR: Recently some parasites were reported which suggested that the Hapalidae could be considered primitive monkeys of the superfamily Ceboidea rather than specialized, but it was then stressed that the suggestion must be tentative because few parasite records were available, however, two further samples of pin-worms from HAPalidae have now become available which support this suggestion.
Abstract: The Oxyuridae parasitic in Primates have a restricted host range with, in the wild, one species of parasite characteristic of one genus of host (Inglis, 1961). Under such conditions one would expect the hosts and their parasites to show parallel evolutionary trends. While this is not established in detail there is a broad correlation between the trends that can be established in the morphology of the parasites and the phylogenies of the hosts (Inglis, 1965).Recently some parasites were reported which suggested that the Hapalidae could be considered primitive monkeys of the superfamily Ceboidea rather than specialized (Inglis & Dunn, 1964), but it was then stressed that, because few parasite records were available, the suggestion must be tentative. However, two further samples of pin-worms from Hapalidae have now become available which also support this suggestion. One sample is from Oedipomidas oedipus (reported by Menschel & Stroh (1963) as Enterobius minutus) and the other is from Callimico goeldii. Both samples represent new species which are described below.The specimens from C. goeldii are particularly interesting because they represent a species which is clearly con-generic with those from the Hapalidae that have been studied. This suggests that Callimico should be referred to the family Hapalidae rather than to the family Cebidae or even, as is suggested by some authors, to a distinct family Callimiconidae.Both the new species are referable to the genus Trypanoxyuris and the opportunity is taken to publish an illustration of the lateral view of the male tail of Trypanoxyuris callithricis (Fig. 1).