bluuebunny/crossref_metadata_2025 huggingface dataset:
Some observations of Fasciola hepatica L. during feeding operations in the hepatic parenchyma of the mouse, with notes on the nature of liver damage in this host
Authors: Dawes Ben
Published: June 2009

During the early stages of infections of mice with Fasciola hepatica (6–11 days) the young flukes feed almost exclusively on hepatic cells which the oral sucker and the pharynx have broken down into a kind of homogenate containing Kupffer cells, invading leucocytes and some erythrocytes. As the flukes increase in size liver damage also increases in amount because of the larger burrows which are made. In some instances this does not adversely affect the host but in many infections excessive liver damage produces critical conditions which threaten the life of the host and its parasites. A comparison of the lesions produced in infections lasting 17–25 days with lesions produced after only 6–7 days has shown that the former, unlike the latter, are not due entirely to the feeding activities of the fluke. In short-term infections the inflammatory reaction produces the characteristic effects which are concerned with the healing of fluke tracts, but in older infections this reaction appears to be much more violent and tremendous leucocytic infiltrations break down apparently normal hepatic parenchyma and convert the terminal part of the burrow into a pool containing enormous numbers of invading leucocytes, broken hepatic cells and blood. These are the conditions which prevail at the onset of the critical period, when flukes have their growth inhibited as if by nutritional deficiencies. Some hosts are able to survive the critical period and nurture well-grown flukes for long periods, and may be able to obviate the critical conditions. It is suggested that the excessive damage which occurs in many instances during the critical period is not due to the feeding activities of the larger flukes but is a consequence of less restrained or even unrestrained inflammatory reactions which may lead to more serious pathogenic effects bordering on malignancy. This may be related to differences in the time spent by flukes in the hepatic parenchyma, early entry into the biliary system obviating these effects, late entry facilitating them.
Three new species of Myxosoma (Protozoa: Myxosporidia) from East African freshwater fish
Authors: Baker J. R.
Published: June 2009

1. Three new species of Myxosoma (Sporozoa, Cnidosporidia, Myxosporidia) are described from freshwater fish of the genus Tilapia in East Africa.

2. Two of these, M. heterospora and M. brachyspora spp.nov., inhabit the abdominal viscera: the former was found in 41 of 43 fish examined, while the latter was less common. The third species, M. homeospora sp.nov., produces small oval or circular ‘cysts’ in the subdermal muscle and was found in two very young fish only. Spores resembling those of the first two species were also found in one Haplochromis sp.

3. The spores of M. heterospora are roughly ellipsoidal but are very variable in shape, and range from 8·5–17·0 μ in length and 6·3–11·0 μ in breadth; the two anterior polar capsules measure from 2·0–9·5 by 1·5–3·5 μ. Those of M. brachyspora are flattened antero-posteriorly, measuring from 7·0–7·5 μ long and 12·0–13·5 μ broad; their polar capsules are from 2·5–3·8 by 2·3–2·5 μ in size. M. homeospora has ovoid spores with the anterior end narrowed, measuring from 13·5–17·0 by 8·5–11·0 μ; the polar capsules measure 4·0–6·0 by 2·0–4·0 μ.

4. It is suggested that M. heterospora, at least, is pathogenic and may play a considerable part in reducing the availability of fish as food in this part of Africa.

5. A check-list is given of all species of the genus Myxosoma.

I thank Mr R. S. A. Beauchamp (then Director of E.A.F.R.O.) and his staff, also Mr G. Bowser (Manager of TUFMAC), for facilities and assistance in the examination of fish; also Dr G. D. Fryer and Dr D. J. Garrod for sending material to me in London, and Dr P. H. Greenwood for supplying the Haplochromis and checking the names of fish; also Messrs G. D. Lomax and P. E. Nesbitt for the preparation of sections. This work was commenced while I was employed at the East African Trypanosomiasis Research Organization.
The evolutionary biology of molecular parasites
Authors: Nee S. , Smith J. Maynard
Published: June 2009

A parasite can be considered to be the device of a nucleic acid which allows it to exploit the gene products of other nucleic acid–the host organisms. In this view, all parasites are ‘molecular parasites’. But it is interesting to restrict our attention to nucleic acids which do not encode organisms, as these live in a purely molecular world which lacks emergent features such as fangs and ovipositors. Viruses and transposons are molecular parasites in this sense. Most viral nucleic acids do code for some proteins, such as replicases and the protein shell in which they travel between their cellular oases. Some, however, do not even have a shell and code for nothing at all–these are the ‘viroids’ (Reisner & Gross, 1985), the smallest parasites in the world.
Parasites, desiderata lists and the paradox of the organism
Authors: Dawkins R.
Published: June 2009

Eavesdrop morning coffee at any major centre of evolutionary theory today, and you will find ‘parasite’ to be one of the commonest words in the language. Parasites are touted as prime movers in the evolution of sex, promising the final solution to that problem of problems, the puzzle that led G. C. Williams to proclaim in 1975 ‘a kind of crisis’ at hand in evolutionary biology (Hamilton, 1980; Tooby, 1982; Seger & Hamilton, 1988). Parasites seem to offer a plausible justification for the otherwise futile effort females put into choosing among posturing males (Hamilton & Zuk, 1982; but see Read, 1990). Frequency-dependent selection exerted by parasites is, according to one admittedly minority view, largely responsible for the high levels of diversity found in gene pools (Clarke, 1979). One might even extrapolate to a time when the entire metazoan body could come to be seen as a gigantic adaptation against microscopic pathogens.
Evolutionary aspects of transmitter molecules, their receptors and channels
Authors: Walker R. J. , Holden-Dye L.
Published: June 2009

Classical transmitters are present in all phyla that have been studied; however, our detailed understanding of the process of neurotransmission in these phyla is patchy and has centred on those neurotransmitter receptor mechanisms which are amenable to study with the tools available at the time, for example, high-affinity ligands, tissues with high density of receptor protein, suitable electrophysio-logical recording systems. Studies also clearly show that many neurones exhibit co-localization of classical transmitters and neuropeptides. However, the physiological implications of this co-localization have yet to be elucidated in the vast majority of examples.

The application of molecular biological techniques to the study of neurotransmitter receptors (to date mainly in vertebrates) is contributing to our understanding of the evolution of these proteins. Striking similarities in the structure of ligand-gated receptors have been revealed. Thus, although ligand-gated receptors differ markedly in terms of the endogenous ligands they recognize and the ion channels that they gate, the structural similarities suggest a strong evolutionary relationship. Pharmacological differences also exist between receptors that recognize the same neurotransmitter but in different phyla, and this may also be exploited to further the understanding of structure-function relationships for receptors. Thus, for instance, some invertebrate GABA receptors are similar to mammalian GABAareceptors but lack a modulatory site operated by benzodiazepines. Knowledge of the structure and subunit composition of these receptors and comparison with those that have already been elucidated for the mammalian nervous system might indicate the functional importance of certain amino acid residues or receptor subunits. These differences could also be exploited in the development of new agents to control agrochemical pests and parasites of medical importance.

The study of the pharmacology of receptor proteins for neurotransmitters in invertebrates, together with the application of biochemical and molecular biological techniques to elucidate the structure of these molecules, is now gathering momentum. For certain receptors, e.g. the nicotinic receptor, we can expect to have fundamental information on the function of this receptor at the molecular level in both invertebrates and vertebrates in the near future.
Two species of Nematoda (Spirurida: Spiruridae) from Australian dasyurids
Authors: Mawson Patricia M.
Published: June 2009

Cylicospirura heydoni (Baylis) is redescribed, from what is assumed to be paratype material (Queensland) and from Dasyurus quoll (Tasmania) and Dasyurops maculatus (N.S. Wales). Cyathospirura dasyuridis, sp.nov., is described from the same host spp., from N.S.W. and Tasmania.

Some specimens and some intact nodules were sent by Mr Green of Queen's Museum, Launceston, Tasmania. Skinned animals were given to me for dissection by Mr Peter Aitken, Curator of Mammals, at the South Australian Museum. To both of these collectors I am most grateful.

Types of the new species will be deposited in the South Australian Museum.
Death of schistosome cercariae during penetration of the skin
Authors: Clegg J. A. , Smithers S. R.
Published: June 2009

A large percentage of the cercariae ofSchistosoma mansonidie while penetrating the abdominal skin of rats or mice but relatively few cercariae die in the skin of hamsters.

Comparison of hamsters and mice infected from the same pool of cercariae showed that the higher percentage of cercariae recovered as adult worms from hamsters than from mice was due to the lower percentage of cercariae which died during penetration of hamster skin.

In similar comparisons of rats with mice the lower percentage of adult worms recovered from rats was not entirely accounted for by the higher percentage of cercariae which died in rat skin. Losses of schistosomula at later stages of development are apparently higher in rats than in mice.

Cercariae die within 10 min after beginning to penetrate the skin of mice. At this stage the cercariae, which are now termed schistosomula, are attempting to penetrate the Malpighian layer of the epidermis. Five minutes later many schistosomula have entered the dermis.

The cause of death of cercariae has not been determined. It is not related to the development of sensitivity to water which accompanies the transition from cercaria to schistosomulum. Sensitivity to water appears much sooner after penetration in some cercariae than in others; even after 30 min in the skin some cercariae can tolerate a return to water.

In rats, hyper-immunized by a series of infections with cercariae through the abdominal skin, the percentage of challenging cercariae which die in the abdominal skin shows a slight increase over controls. No further mortality of schistosomula occurs during the next 24 h.

Age resistance to infection withS. mansonicould not be demonstrated in comparisons of young mice (1 month) with old mice (1 year) of the Parkes and CBA strain.

We should like to thank Dr F. Hawking for performing the skin biopsies on the dogs and Mrs P. Clark and Miss J. Marsh for their excellent technical assistance.
The development of the adhesive organs of some diplectanid, tetraonchid and dactylogyrid gill parasites (Monogenea)
Authors: Kearn G. C.
Published: June 2009

The adhesive organs of diplectanid, tetraonchid and dactylogyrid monogeneans develop in very similar ways indicating that all these gill parasites are closely related to each other. The oncomiracidia make initial contact with the general body skin or the lining of the buccal cavity to which they attach themselves by 14 or 16 ventrally orientated marginal hooklets. The growing parasites then find their way to the gills which call for a different kind of adhesive apparatus. In order to anchor itself between two of the host's secondary gill lamellae, two pairs of the parasite's marginal hooklets migrate to the dorsal surface of the haptor and two of the four developing hamuli rotate so that they also point dorsally.

In diplectanids the hamuli are assisted by accessory friction pads (squamodiscs) which develop on the surface of the body anterior to the hooks.

In dactylogyrids the ventral hamuli do not develop and are represented in the adult only by small spicules. In contrast the marginal hooklets grow during larval development and become important adult attachment organs, together with the dorsal hamuli.

Adults of Tetraonchus monenteron feed on the epidermis covering the gills.

I am most grateful to the Director and Staff of the Laboratory of the Marine Biological Association at Plymouth and particularly to Mr J. E. Green for help and hospitality. I would also like to express my thanks to the East Suffolk and Norfolk River Authority and particularly to the Fishery Superintendent, Mr E. Q. Bitton, and to Mr D. Leary, for supplying me with freshwater fishes.
Identification and quantification of rodent malaria strains and species using gene probes
Authors: Snounou G. , Bourne T. , Jarra W. , Viriyakosol S. , Brown K. N.
Published: June 2009

A DNA probe PCsv4 and a subclone thereof PCsv4.1, hybridize specifically to rodent malaria DNA. DNA purified from a small volume (10 μ1) of infected mouse blood was used to determine the composition of the parasite population present. The hybridization signal following PCsv4 probing of slot-blotted DNA correlated directly with parasitaemia. The hybridization pattern and Intensity, resulting from probing restriction enzyme digested and Southern-blotted genomic DNA, determined the identity of the infecting parasite line(s), and provided a semi-quantitative measure of parasite burden. Fifteen parasite lines representative of all fourPlasmodiumspecies infecting rodents can be differentiated in this way.
Mathematical modelling and theory for estimating the basic reproduction number of canine leishmaniasis
Authors: Hasibeder G. , Dye C. , Carpenter J.
Published: June 2009

The paper describes a mathematical model for canine leishmaniasis and presents formulae which can be used to estimate the basic reproduction number,R0. The primary concern has been to devise methods of estimation which make best use of those data most easily obtained by fieldwork, e.g. surveys of prevalence in dog (by age) and sandfly populations. A range of formulae are offered which are more or less demanding of data, and which consequently give more or less precise estimates ofR0. They include methods for assessing the influence onR0of heterogeneous biting rates of sandflies on dogs, in which the essence of heterogeneous transmission can be captured merely by measuring relative rather than absolute contact rates.
Vegetation structure influences the burden of immature Ixodes dammini on its main host, Peromyscus leucopus
Authors: Adler G. H. , Telford S. R. , Wilson M. L. , Spielman A.
Published: June 2009

To determine whether the relative abundance of immature Ixodes dammini (the vector of Lyme disease and human babesiosis) is related to habitat structure, we examined tick burdens on their main host, the white-footed mouse (Peromyscus leucopus), in 4 structurally diverse sites on Great Island, Massachusetts, USA. Vegetation structure at each site was quantified with respect to 25 habitat variables. Principal components analysis was used to reduce this set of habitat variables to seven new and orthogonal variables. Immature tick abundance varied widely among grids. Regression analysis of tick burdens on the habitat principal components showed that larval burdens were related strongly to the density of woody vegetation and negatively to herbaceous vegetation. Nymphal burdens were related negatively to herbaceous vegetation, but the relationship was not as strong as in the case of larvae. An experimental reduction in the abundance of white-tailed deer (Odocoileus virginianus), the main host of adult ticks, substantially reduced tick burdens and altered their relationships to habitat structure. Nymphal burdens were unrelated to habitat structure following deer removal. Manipulating habitat structure may have utility as a control strategy against this important vector.
Trichinellastrain, pig race and other parasitic infections as factors in the reliability of ELISA for the detection of swine trichinellosis
Authors: Serrano F. , Pérez E. , Reina D. , Navarrete I.
Published: June 2009

An enzyme-linked immunosorbent assay (ELISA) using crude worm extracts (CWE) and mixtures of these as antigens of five Spanish isolates (P, C, B1, B2 and W) was developed for detecting homologous and heterologous experimental infections with these isolates between – 14 and 82 days post-infection (p.i.) in white and Iberian pigs. A total of 243 pigs (Ilberian or cross-bred with this race) with numerous parasitic infections were also screened for the presence of antibodies to a mixture of CWE of C, B1 and B2 isolate. The test showed a specificity of 93·1–98·9% depending on the cut-off values and a maximum sensitivity of 92·8–100% between days 34 and 82 p.i. A low grade of infectivity was shown in the T3 isolates compared to the T1 isolates (P, C, B1 and B2) but high cross-reactions were observed between all the isolates with minor differences between P and W isolates. The highest antibody response was found in P infections and the lowest in pigs infected with the W isolate. A clear association between the presence of several parasitic infections and false positive reactions was not found, but an important relation was shown between high background levels and the Iberian race in experimentally and conventionally raised pigs
Variation in responsiveness toTrichinella spiralisinfection in inbred rat strains
Authors: Bell R. G.
Published: June 2009

An analysis of interstrain variation between 12 inbred and 4 congenic rat strains in the expression of immunity againstTrichinella spiralisis reported. All rat strains expressed strong rapid expulsion which resulted in the elimination of 88–98% of a challenge infection of muscle larvae. In contrast, substantial interstrain variation in the rate of adult worm expulsion in the primary infection as evident. By day 10 after infection, BUF and YO strains had < 50 worms left in the intestine whereas BI and WKA strain rats had barely begun rejection, with approximately 1000 worms present in the gut for both strains. All other rat strains fell within these extremes in a continuous gradation. There was no clustering of rat strains into phenotypic groups with comparable worm burdens as seen with mice. The number of muscle larvae that established after the primary infection showed less variation than had adult worm burden in the primary infection and there was only a weak correlation of muscle larvae burden with numbers of intestinal adults present at 10 days. Comparison of MHC matched or MHC-disparate rat strains on a PVG background suggested that non-MHC genes determined the principal adult worm rejection characteristics of a given strain. The absence of phenotypic variation in the expression of rapid expulsion in rats reinforces the biological distinction between rat rapid expulsion and the ‘rapid expulsion’ defined for mice
Comparative prevalences of Ascaris lumbricoides, Trichuris trichiura and hookworm infections and the prospects for combined control
Authors: Booth M. , Bundy D. A. P.
Published: June 2009

Programmes to control Ascaris lumbricoides, Trichuris trichiura and hookworm infections have often been targeted at each infection separately, but the advent of benign and broad-spectrum anthelmintics suggests that combined control ma be feasible. The extent to which the infections co-occur in communities will determine the need for, and potential benefits of, such a combined approach. This paper examines the comparative distribution of the three geohelminths in different geographical areas and shows that A. lumbricoides and T. trichiura have closely related distributions, while hookworm infection is largely independent of the other two. These results indicate that many communities are at risk of disease from infection by more than one species of helminth. The similar distributions and epidemiological characteristics of A. lumbricoides and T. trichiura suggest that simultaneous control of these two parasites by the same strategy would be feasible and highly beneficial to communities. Multiple species control strategies which aim to control hookworm infection may require a more complicated protocol with more precise locality targeting.
Comparative studies on the biology and morphology ofEchinococcus granulosusfrom domestic livestock, moose and reindeer
Authors: Sweatman G. K. , Williams R. J.
Published: June 2009

1. As an intermediate host of the hydatid tapeworm in boreal North America, the moose is of relatively greater importance than other indigenous cervids (white-tailed deer, wapiti, barren-ground caribou) primarily because of a higher rate of infection in different individuals and the fertility of the hydatid cysts.

2. The European reindeer introduced into north-western Canada is of considerable importance as an intermediate host where it occurs locally.

3. Timber wolves are the important definitive hosts; no infections occurred naturally or were produced experimentally in the bobcat, Canada lynx, raccoon, fisher, marten, striped skunk or European ferret.

4. A description using biological and morphological criteria is presented forEchinococcus granulosus granulosusin dogs, sheep and other domestic animals,E. g. borealissubsp.nov. in timber wolves, moose and other cervids indigenous to North America, andE. g. canadensisWebster and Cameron, 1961, in dogs and reindeer introduced into north-western Canada from Laplandic Norway.

5. The rate of cystic growth, scolex production, infectability of timber wolves and dogs and prepatent period are similar for all three subspecies.

6.E. g. borealisreached a gravid state in experimental red foxes (Vulpes fulva).

7. Hydatid cysts developed only rarely in sheep fed eggs ofE. g. borealisorE. g. canadensis.

8. Eggs ofE. g. granulosusproduced only one viable hydatid cyst in a series of experimental red deer (Cervus elaphus) and fallow deer (Dama dama).

9.E. g. granulosus, E. g. borealisandE. g. canadensisare morphologically distinct, the most distinctive characters occur inE. g. canadensis.

10. Besides the above andE. multilocularis, other species inEchinococcusare little known. Those recognized as being currently valid areE. lycaontis, E. ortleppi, E. felidis, E. cameroni, E. oligarthrus, E. cruziand possiblyE. patagonicus.

The writers wish to thank Sir Charles Hercus and the other members of the Hydatid Research Committee for their interest and encouragement in the present study. Valuable discussion in the early stages of this work was had with Prof. A. M. Fallis, Director, Department of Parasitology, Ontario Research Foundation. Much of the field work was done with various members of the Ontario Research Foundation; Institute of Parasitology, McGill University; Canada Department of Agriculture; and Canada Department of Northern Affairs and Natural Resources, to whom we extend our thanks. Norwegian material was kindly provided by Dr Sven Skjenneberg, Statens Veterinaera Laboratorium for Nord-Norge. Technical assistance was provided by Messrs G. D. Page, D. V. Weston, Miss L. A. Duncan and Mrs B. R. Clarke.
Opposite influences of host anaemia on blood feeding rate and fecundity of mosquitoes
Authors: Shieh J.-N. , Rossignol P. A.
Published: June 2009

We tested a theoretical model based on the physics of capillary flow and confirmed that anaemia accelerates blood intake in the yellow-fever mosquito, Aedes aegypti (L.). We also investigated the influence of anaemic blood on egg production of mosquitoes and found that it has a negative influence on fecundity. Based strictly on egg production and the physics of fluid intake, we propose that although anaemia associated with blood-borne parasites may be detrimental to mosquitoes that can engorge to repletion in one session, it may be beneficial to those interrupted before repletion because the greater quantity of the bloodmeal may compensate for its lower quality. Epidemiological consequences are discussed but require further inquiry.
The ENZYMEBA test: detection of intestinal Entamoeba histolytica infection by immuno-enzymatic detection of histolysain
Authors: Luaces A. L. , Picó T. , Barrett A. J.
Published: June 2009

We describe a new, improved test for the detection of intestinal infection by Entamoeba histolytica. The test depends upon immunoadsorption of the E. histolytica cysteine proteinase, histolysain, from faecal samples, and subsequent visual detection of the enzyme by a colour reaction. With samples from 200 volunteers, results agreed closely with those obtained by the conventional microscopic technique, and there were no false positive reactions with samples containing other parasites. The test is suitable for use either in the laboratory or in the field.
Purification and characterization of a 47 kDa protease fromSchistosoma mansonicercarial secretion
Authors: Chavez-Olortegui C. , Resende M. , Tavares C. A. P.
Published: June 2009

Fractionation ofSchistosoma mansonicercariae gland secretion on a Sephadex G-150 column followed by a Superose-12 column in an FPLC system, isolated a 47 kDa protease which migrated as a single band on SDS–PAGE gels. A monoclonal antibody (MAb) was produced which recognizes only the 47 kDa protease, and an immuno-affinity column with the MAb was used to isolate the protease. The 47 kDa protease showed activity on several macromolecules such as elastin and collagen type VI besides gelatin and casein. This suggests that this enzyme can be one of the enzymes that might facilitate invasion of the cercariae through host skin. The optimal pH of the protease against the synthetic substrate, Ac-Phe-Arg-Nan, in Tris–HCI buffer was 10. Experiments with protease inhibitors indicate that the purified enzyme is a serine protease.
Restriction fragment length polymorphisms within the ribosomal DNA repeat unit of British entomopathogenic nematodes (Rhabditida: Steinernematidae)
Authors: Reid A. P. , Hominick W. M.
Published: June 2009

Genomic DNA extracted from entomopathogenic nematodes isolated from 89 soil samples taken throughout the United Kingdom was hybridized with the ribosomal DNA clone from Caenorhabditis elegans (pCe7). When the DNA was digested with EcoR I and Hind III in a double digest, 5 distinct RFLP (restriction fragment length polymorphism) types were observed. While the prevalence of the 5 types was not equal, no correlation with geographical location, soil type or habitat could be detected. Subsequent hybridizations of total genomic DNA from the various RFLP types divided them into 2 groups. The most prevalent group, identified as Steinernema feltiae ( = bibionis), contained 2 of the RFLP types (Al and A2). The other group contained the remaining 3 RFLP types (B1, B2 and B3). Although similar to S. feltiae ( = bibionis), the members of the B-types can be distinguished from this species on morphological grounds and preliminary crossbreeding experiments have demonstrated that the 2 groups are reproductively isolated.
The influence of temperature on the succession of redial and cercarial generations of Fasciola gigantica in a snail host
Authors: Dinnik J. A. , Diknik N. N.
Published: June 2009

Experiments on the larval development of Fasciola gigantica carried out under natural conditions have shown that at temperatures of 16° C. or less the rediae did not produce cercariae. The first-generation rediae, developed from the sporocyst, and all the rediae of subsequent generations produced only daughter rediae and did not change over to the production of cercariae as long as the low temperatures of the cold season lasted.

As soon as the cold season ended and the temperature of the water in the aquaria containing the infected snails rose to a mean maximum of 20° C. all the rediae switched from redial to cercarial production.
Epidemiology of nematode infections of Soay sheep (Ovis ariesL.) on St Kilda
Authors: Gulland F. M. D. , Fox M.
Published: June 2009

The epidemiology of nematode infections of Soay sheep on the island of St Kilda over a period of 2 years (August 1988–August 1990) spanning a host population crash is described. Infective larvae (L3) levels on pasture were high (2422±365 L3/kg D.M. grass in midsummer 1988) when host population density was high, decreasing after the sheep population declined by 70% in early 1989 (601 ±14 L3/kg D.M. in midsummer 1989). The availability of infective larvae to sheep increased during the winter of 1988–1989, probably as a result of concentration of existing larvae on grass as vegetation was destroyed by bad weather and overgrazing. Increased availability of pre-parasitic stages was accompanied by a marked increased in faecal egg counts from sheep of all ages and both sexes. Prevalence and intensity of infection (faecal egg counts) were higher in males than females throughout the 2-year study (χ2= 208.3,P< 0.005 andF1.2000= 304,P< 0.001 respectively), except during the lambing periods, and decreased with age in both sexes. Changes in prevalence and intensity of strongyle infections were associated with changes in host population density. Prevalence and intensity ofDictyocaulus filarialarvae in faeces increased during the host population crash. Infection intensity decreased with age (F1.203= 44.02,P< 0.001) and was higher in males than females (F1.203= 13.45,P< 0.001).
Effects of qinghaosu (artemisinin) and its derivatives on experimental cutaneous leishmaniasis
Authors: Yang D. M. , Liew F. Y.
Published: June 2009

We have investigated the effect of qinghaosu (QHS, artemisinin) and its derivatives onLeishmania majorreplicationin vitroand on the disease development in mice infected withL. major. Artemisinin is effective against promastigotesin vitro, with an ED50(50% effective dose) at 7.5 × 10−7m. Both artemisinin and artemether are leishmanicidal for amastigotes in infected murine macrophagesin vitro, with ED50at 3 × 10−5m and 3 × 10−6m respectively. These compounds have no effect on the viability of macrophages or on the phytohaemaglutinin-induced proliferation of normal spleen cells, even at 10−4m. BALB/c mice infected in the footpad withL. majordeveloped significantly smaller lesions and parasite loads when treated with the compounds. Intra-lesion injection of the compounds was the most effective route. The intramuscular and oral routes were also effective; however, intravenous injection with artesunate was not effective.
The recruitment of mast cells, exclusively of the mucosal phenotype, into granulomatous lesions caused by the pentastomid parasitePorocephalus crotali: recruitment is irrespective of site
Authors: McHardy P. , Riley J. , Huntley J. F.
Published: June 2009

Adults of the porocephalid pentastomidPorocephalus crotaliinfect the lung of rattlesnake definitive hosts and larvae develop in rat intermediate hosts. In the latter, nymphs encyst within a variety of tissue sites (commonly abdominal fat bodies and lungs) and each becomes the focus of an eosinophilic granuloma. From an early stage in infections, granulomas become increasingly infiltrated by mast cells which, using conventional histology and paired immunofluorescence against mast cell proteases, appear to be exclusively of the mucosal phenotype. Mucosal mast cells are concentrated along the dorsal region of the parasite and in a plug of tissue containing degenerating cuticles within independent granulomas, which is located between its head and tail. ELISAs against the rat mast cell proteases I and II (RMCP I and II), extracted from abdominal fat, lung, spleen, liver and kidney granulomas at various intervals post-infection, reveal a substantially elevated concentration of RMCP II in all lesions. In fat, concentrations increase up to about 100 days post-infection, at which time moulting ceases and inflammatory responses subside. RMCP II was scarcely detectable in matched control tissues. Unlike infections with certain nematode parasites, where enteric mucosal mast cells secrete RMCP II systemically, concentrations of RMCP II in the serum of infected rats were significantly reduced when compared with age-matched uninfected controls. These results confirm thatP. crotalican selectively recruit mucosal mast cells to a variety of tissue sites, most of which are non-mucosal. Possible mechanisms are discussed.
Vaccination of merino lambs against haemonchosis with membrane-associated proteins from the adult parasite
Authors: Munn E. A. , Smith T. S. , Grahama M. , Greenwood C. A. , Tavernor A. S. , Coetzee G.
Published: June 2009

Groups of South African, farm-reared merino lambs about 4 months old were vaccinated with extracts of adult Haemonchus contortus enriched with H11, an integral membrane protein from the parasite's intestinal microvilli, or with proteins soluble in Tween 20. The lambs were challenged with 5000 infective 3rd-stage larvae. Compared to the adjuvant-injected controls, lambs vaccinated with 350 μg/kg liveweight of the H11-enriched extract showed an 89% reduction in parasite egg production and an 88% reduction in total worm burden at post-mortem 35 days post-challenge. The H11-enriched extract contained some protein also present in the Tween 20 extract. Lambs vaccinated with 600 μg/kg of protein soluble in Tween 20 showed a 40% reduction in faecal egg counts and 51% reduction in total worm numbers 35 days post-challenge. Animals injected with 20 μg/kg of a sub-fraction containing H11 obtained from the H11 extract, showed a 71% reduction in egg output and total worm numbers.
Immunoelectron microscopical studies of regulatory peptides in the nervous system of the monogenean parasite, Diclidophora merlangi
Authors: Brennan G. P. , Halton D. W. , Maule A. G. , Shaw C. , Johnston C. F. , Moore S. , Fairweather I.
Published: June 2009

Specific antisera, directed against the highly conserved C-terminal hexapeptide amide of mammalian pancreatic poly-peptide (PP) and the invertebrate peptide FMRFamide, have been used in conjunction with post-embedding, IgG-conjugated colloidal gold immunostaining to demonstrate peptide immunoreactivity at subcellular level in the nervous system of adult Diclidophora merlangi. Gold labelling revealed that immunoreactivity for PP and FMRFamide was localized exclusively in dense-cored vesicles occupying the majority of axons in the central nervous system. Double-labelling demonstrated an apparent co-localization of PP and FMRFamide in the same dense-cored vesicles. Antigen pre-absorption experiments indicated cross-reactivity of the two antisera as unlikely, and that some if not all of the PP/FMRFamide immunostaining in the parasite was due to a neuropeptide F-like peptide.
The expulsion of Echinostoma trivolvis: worm kinetics and intestinal cytopathology in conventional and congenitally athymic BALB/c mice
Authors: Fujino T. , Fried B. , Tada I.
Published: June 2009

The infectivity and distribution of Echinostoma trivolvis were studied in male, conventional and congenitally athymic nude mice, each infected with 30 metacercarial cysts. In conventional mice, worm recoveries at 6 and 8 days post-exposure were58·3 and 54·0%, respectively. Worm recovery declined to 44·0% by day 10, to 4·3% by day 13, and 0% by day 17. In athymic mice, worm recoveries at 6 and 8 days post-exposure were 61·7 and 36·3%, respectively. Worm recovery declined to 27·7% by day 10, to 0·7% by day 13, and 0% by day 17. The distribution of worms demonstrated a posteriad migration over time in both groups. Kinetic changes in the number of goblet and mucosal mast cells in the upper ileum of mice infected with E. trivolvis were examined. In conventional mice, the number of goblet cells increased rapidly to reach a peak at day 13 and then declined gradually. The number of goblet cells in athymic mice also increased to reach a peak at day 13, and then declined rapidly. However, the number of goblet cells in athymic mice was always less than that inconventional mice. The mast cell number in infected conventional mice increased rapidly to reach a peak at day 17 and then declined. There was no increase in the mast cell number of infected athymic mice throughout the experiment. Whereas common pathological changes occurred in the intestines of both mice groups infected with echinostomes some ultrastructural differences were observed in the gut epithelial cells of conventional versus athymic mice.
Immunocytochemical demonstration of neuropeptides in the central nervous system of the roundworm, Ascaris suum (Nematoda: Ascaroidea)
Authors: Brownlee D. J. A. , Fairweather I. , Johnston C. F. , Smart D. , Shaw C. , Halton D. W.
Published: June 2009

The localization and distribution of neuropeptides in the central nervous system of the pig roundworm, Ascaris suum, have been determined by an indirect immunofluorescence technique in conjunction with confocal microscopy. Antisera to 25 vertebrate peptides and two invertebrate peptides were used to screen the worm for immunoreactivity (IR). Immuno-staining was obtained with antisera to pancreatic polypeptide (PP), peptide YY (PYY), neuropeptide Y (NPY), gastrin, cholecystokinin (CCK), substance P (SP), atrial natriuretic peptide (ANP), salmon gonadotropin-releasing hormone (SGnRH), mammalian gonadotropin-releasing hormone (MGnRH), chromogranin A (CGA) and FMRFamide. The most extensive patterns of IR occurred with antisera to PYY, FMRFamide and gastrin. IR was evident in nerve cells and fibres in the ganglia associated with the anterior nerve ring and in the main nerve cords and their commissures; IR to FMRFamide also occurred in the posterior nerve ring. Immunostaining for the other peptides was confined to the nerve cords, with the number of immunoreactive nerve fibres varying from peptide to peptide.
The Wellcome Trust Lecture: Infection and disease in lymphatic filariasis: an immunological perspective
Authors: OtteSen E. A.
Published: June 2009

The basic tenet of the immunological perspective of fuiarial disease is that differential immune responsiveness among individuals exposed to infection results in the different clinical manifestations that develop. The mechanisms involved in this differential responsiveness appear to reflect different T-cell cytokine response patterns. Asymptomatic patients with the clinically silent presentation of ‘asymptomatic microfilaraemia’, who have been previously described as being ‘immunosuppressed’ with respect to their generating pro-inflammatory (Th1-type) immune responses to parasite antigen, are now recognized to be fully responsive to parasite antigen but to produce cytokines and mediators that have primarily anti-inflammatory (Th2-like) effects. Studies with immunodeficient mice have indicated the existence of two alternative pathways to the development of lymphatic pathology: one dependent on the induction of inflammatory reactions by the host immune response, the other entirely independent of the immune system and reflecting the direct actions of the parasite or its products on the lymphatics. As histopathology of affected human lymphatics is consistent with this hypothesis, it may be that the lymphatic pathology seen normally in the amicrofilaraemic, highly immunoresponsive infected patients derives from inflammation induced by immune responses to parasite antigen, whereas the lymphatic pathology sometimes seen coexisting with the ‘immunosuppressed’ state of asymptomatic microfilaraemia actually reflects lymphatic damage that is not immunologically mediated. Though little information exists about the ‘natural history’ of lymphatic filariasis, there is no evidence for an inevitable progression from one clinical form to another. Instead, there appears to be a definite plasticity in the response that depends on prior (? pre-natal) and current exposure to the parasite as well as on the immunomodulatory effects it induces. This plasticity does not appear to be complete, however, as there is no evidence that a chronically infected host who has developed strong pro-inflammatory immune responses can subsequently become sufficiently ‘down-regulated’ to support an asymptomatic microfilaraemia type of infection. Another possible constraint to the plasticity of the clinical and immunological responses may be the genetic determination of certain unusual syndromes, such as tropical pulmonary eosinophilia or TPE, though this hypothesis remains to be proven.
Immuno-epidemiology of human geohelminthiasis: ecological and immunological determinants of worm burden
Authors: Bundy D. A. P. , Medley G. F.
Published: June 2009

The morbidity and transmission dynamics of geohelminthiases are determined by the patterns of infection intensity in the community. Understanding the determinants of these patterns requires a combination of field, laboratory and theoretical study. Studies of age-specific reinfection, and of the phenomenon of predisposition, indicate that the major determinant of convex age-intensity profiles and of heterogeneity in infection intensity is the rate of establishment of infection, rather than the rate of adult worm mortality. The rate of establishment is, in turn, determined by exposure to, and protection from, infection. The evidence indicates that exposure, at least to the orally-transmitted geohelminths, varies with age and is highly heterogeneous between hosts. The immune response in geohelminthiasis is vigorous, parasite-specific, hetero geneous between hosts, and both age and infection dose dependent, but has yet to be convincingly shown to be protective. Since the immune response is itself a function of exposure, unravelling the interaction between ecology and immunology as determinants of geohelminth worm burden will require simultaneous assessment of both processes via immuno epidemiological study.
Food-borne bacterial infections
Authors: Lacey R. W.
Published: June 2009

The number of episodes of diseases caused by bacterial contamination of food has shown a real increase by about threefold in the last decade in the U.K. The numbers for 1992 are estimated to be 2 million. The causes are multifactorial and complex, and 4 representative pathogens are reviewed. The main increase in diseases due to salmonella has been caused bySalmonella enteritidis, especially from eggs. The commonest bacterial food pathogen is Campylobacter, which causes an illness with specific season peaks in May and June. This may be related to the activities of birds and mammals. Both these bacteria cause common diseases that are rarely fatal. In contrast, Listeria andE. coliare ubiquitous but rarely produce disease; however, the consequences of any such illness are often dire. Procedures and techniques are available for the control of most of these diseases, but society does not seem determined to implement them.
Filariasis: nutritional interactions in human and animal hosts
Authors: Storey D. M.
Published: June 2009

Vector-borne nematodes of the Order Filarioidea produce chronic, debilitating human infections which are usually non-fatal but are associated with a high degree of severe morbidity. Weight loss often accompanies infection and is probably a consequence of the increased energy cost associated with filarial fever, lymphangitis and lymphadenitis. In onchocerciasis, weight loss is associated with heavy worm loads as assessed by abundant nodules and large numbers of skin microfilariae. Experimental infections using rodent filariae have confirmed these observations and have also shown that low protein diets render hosts more susceptible to infection; nevertheless, parasite growth and embryogenesis is retarded in stunted female worms from protein deficient animals. In the absence of appropriate evidence, studies of experimental filariasis suggest that human protein-energy malnutrition may delay the development of stage-specific acquired immunity with a corresponding prolongation of patency. Epidemiological and experimental evidence shows that filarial nematodes acquire certain nutrients directly from their hosts. Of major importance in this respect is vitamin A which is taken up preferentially by human and rodent filariae; in humans, symptoms of hypovitaminosis A often accompany infection and could be an aggravating factor in onchocerciasis. Filariae also appear to require other specific nutrients such as iodine, thiamine and pyridoxine; dietary levels of these nutrients affect the host-parasite relationships in filariasis and pyridoxine seems to be of particular importance in this respect. Filarial parasites obviously compete with their hosts for available nutrients and, in the real world, human filariasis is often associated with a deterioration in the plane of nutrition of infected individuals.
Nutritional and physiological consequences of tumour glycolysis
Authors: Dills W. L.
Published: June 2009

A frequent characteristic of many malignant tumours is an increase in anaerobic glycolysis, that is the conversion of glucose to lactate, when compared to normal tissues. The causes of this intensification involve changes in enzyme and glucose transporter levels, shifts of the isoenzyme patterns in the cancer cells to those similar to foetal tissues and a breakdown in the normal control mechanisms, most notably the Pasteur effect. The host must adapt, with a corresponding increase in gluconeogenesis. This change, along with other adaptations made by the host, eventually results in the syndrome known as cancer cachexia, which is characterized by anorexia and depletion and redistribution of the host energy stores. In some ways many malignant tumours behave much like parasites, drawing upon the host for nutrients such as glucose and returning waste products such as lactate to the host for recycling or disposal. This cycling of glucose and lactate between host and tumour has been the target for a number of proposed and tested treatments, with regard to the possible inhibition of tumour growth and/or possible prevention of some or all of the cachectic effects. Some of these suggested treatments have reached the point of clinical testing and show promise for continued research.
Characterization of phosphoglycan-containing secretory products ofLeishmania
Authors: Ilg T. , Stierhof Y.-D. , Wiese M. , McConville M. J. , Overath P.
Published: June 2009

This article presents an overview on phosphoglycan-containing components secreted by the insect and mammalian stages of several species ofLeishmania, the causative agents of leishmaniasis in the Old and New World. Firstly, promastigotes of all three species considered,L. mexicana, L. donovaniandL. major, shed lipophosphoglycan (LPG) into the culture medium possibly by release of micelles from the cell surface. Like the cell-associated LPG, culture supernatant LPG is arhphiphilic and composed of a lysoalkylphosphatidylinositol-phosphosaccharide core connected to species-specific phosphosaccharide repeats and oligosaccharide caps. Secondly, all three species release hydrophilic phosphoglycan. Thirdly, all three species appear to secrete proteins covalently modified by phosphosaccharide repeats and oligosaccharide caps. In the case of promastigotes ofL. mexicana, these components are organized as two filamentous polymers released from the flagellar pocket: the secreted acid phosphatase (sAP) composed of a 100 kDa phosphoglycoprotein and a protein- containing high-molecular-weight-phosphoglycan (proteo-HMWPG) and fibrous networks likewise composed of phosphoglycan possibly linked to protein. Structural analyses and gene cloning suggest that the parasites can covalently modify protein regions rich in serine and threonine residues by the attachment of phosphosaccharide repeats capped by oligosaccharides. We propose that the networks formedin vitrocorrespond to fibrous material previously demonstrated in the digestive tract of infected sandflies. In the case ofL. donovani, the sAP is also modified by phosphoglycans but contains neither proteo-HMWPG nor does it aggregate to filaments. Finally,L. mexicanaamastigotes release proteo-HMWPG via the flagellar pocket into the parasitophorous vacuole of infected macrophages. This material appears to be released into the tissue of the infected mammal upon rupture of infected macrophages during lesion development. This secretory product may contribute to the pathology of lesion development.