bluuebunny/crossref_metadata_2025 huggingface dataset:
The epidemiology of Nematodirus battus – is it changing?
Authors: Thomas D. Rh.
Published: June 2009

Natural populations of 3rd-stage Nematodirus battus larvae were present on pastures in North Wales throughout the year; highest numbers were present in late spring, with smaller peaks occurring in autumn. Inter-site variation was observed in the timing and magnitude of these peaks. Hatching on experimental plots occurred 2 months to 2 years following deposition of eggs. Intraspecific and inter-site variation occurred in the timing, and inter-site variation occurred in the magnitude, of the mass hatch on upland and lowland experimental plots. Arrested 4th-stage N. battus were recovered from Welsh Mountain lambs. Percentage arrest and number of arrested worms was greatest during winter and early spring. The prevalence and intensity of N. battus infection in 1-, 2- and 3-year-old Welsh Mountain ewes was low. The plasticity exhibited in the parasite's life-history is discussed in relation to potential changes in the epidemiology of nematodiriasis.
Expression of LPG and GP63 by different developmental stages ofLeishmania majorin the sandflyPhlebotomus papatasi
Authors: Davies C. R. , Cooper A. M. , Peacock C. , Lane R. P. , Blackwell J. M.
Published: June 2009

Development and forward migration ofLeishmaniaparasites in the sandfly gut is accompanied by morphological transformation to highly motile, non-dividing ‘metacyclic’ forms. Previous studiesin vitrohave demonstrated that this metacyclogenesis is associated with developmentally regulated changes in expression of two major surface glycoconjugates ofLeishmania, the lipophosphoglycan (LPG) and the glycoprotein protease GP63. Studies presented here are the first to examinein situthe changes in expression of these two important surface molecules which occur during amastigote-initiated development ofL. majorin its natural vectorPhlebotomus papatasi. Immunocytochemical analysis using a GP63-specific monoclonal (3.8). and others recognizing metacyclic-specific (3F12) and common (WIC79.3) epitopes of LPG on logarithmic and metacyclic promastigotes, demonstrates: (1) clear expression of LPG and GP63 from 2 and 7 days post-bloodfeeding, respectively; (2) developmental modification of the LPG molecule as parasites undergo forward migration and morphological changes associated with metacyclogenesis; and (3) striking deposition of large amounts of parasite-free excreted LPG on/in the epithelial cells of the gut wall.
Identification of midgut trypanolysin and trypanoagglutinin in Glossina palpalis sspp. (Diptera: Glossinidae)
Authors: Stiles J. K. , Ingram G. A. , Wallbanks K. R. , Molyneux D. H. , Maudlin I. , Welburn S.
Published: June 2009

A midgut trypanolysin and an agglutinin from Glossina palpalis subspecies were isolated and partially characterized using anion-exchange chromatography and polyacrylamide gel electrophoresis. FPLC fractions of midgut extracts of Glossina palpalis palpalis caused agglutination and lysis of two trypanosome species (Trypanosoma congolense and Trypanosoma brucei brucei). although Glossina palpalis gambiensis caused only agglutination. The trypanolysin and agglutinin were active only in the posterior midguts, were heat labile above 50%C, had a periodic cycle of ‘activity’ in response to bloodmeal intake and were not affected by protease inhibitors or trypsin but were inactivated by pronase. The lytic substance contained two proteins with approximate molecular weights (Mr) of 12000 and 10000 Da respectively. The agglutinin had an approximate Mr of 67000 Da. Gamma-irradiation of the two subspecies caused a temporary inhibition of trypanolytic and agglutinin activities in midgut extracts.
A monoclonal-based IgM capture ELISA for detection of antibodies to 22 and 41 kDa membrane antigens ofToxoplasma gondii
Authors: Wee J. L. K. , Ho L. C. , Yap E. H. , Singh M.
Published: June 2009

A murine monoclonal antibody which reacts to 22 and 41 kDaToxoplasma gondiisurface antigens was employed in an IgM capture enzyme-linked immunosorbent assay (ELISA). A total of 125 patients' sera were tested in the monoclonal-based assay. When compared with a commercial ELISA test (Abbott Toxo-M EIA) which uses polyclonal anti-T. gondiiantibodies, good correlation (Pearsons coefficientr= 0.91) was observed. The specificity of the assay was studied by testing a panel of control sera obtained from healthy individuals and blood transfusion donors; all sera gave negative results. Serum samples positive forT. gondiiantibodies were treated with 2-mercaptoethanol (2-ME) to demonstrate the specificity of the test for IgM antibodies. Reactivity of these sera was lost after the treatment. The test is not subject to interference by rheumatoid factor as sera positive for rheumatoid factor were negative in the assay. Reproducibility was good with the coefficients of variation for within-day tests below 10% and not exceeding 18% for day-to-day tests. The monoclonal-based assay is simple to perform and appears to be a viable test for diagnosis ofT. gondiiinfection.
Immunoepidemiology of Ascaris lumbricoides: relationships between antibody specificities, exposure and infection in a human community
Authors: Haswell-Elkins M. R. , Leonard H. , Kennedy M. W. , Elkins D. B. , Maizels R. M.
Published: June 2009

The serum antibody responses of 124 people naturally exposed to Ascaris lumbricoides infection were analysed by immunoprecipitation of radio-isotope labelled 3rd- and 4th-stage larval Ascaris suum excretory and secretory antigens (L3/4 ES). Profiles of antigens recognized were visualized by polyacrylamide gel electrophoresis (SDS–PAGE), and the band intensities of the 12 major precipitated antigens were individually scored. Most subjects were seropositive, but considerable variation was observed in the amount of total and individual ES antigens precipitated. The sex- and age-related profiles of antibody levels followed similar patterns to those of egg output. In addition, total antibody scores of individuals were closely correlated (r = 0.47–0.52) with their eggs per gram of faeces (e.p.g.) collected 4 months after blood samples were taken. These findings suggest that antibody levels against larval ES antigens reflect recent exposure and are consistent with the hypothesis that establishment of adult worms is proportional to the number of larvae that recently migrated through the lung.
Sequential development of the immune response in rainbow trout [Oncorhynchus mykiss (Walbaum, 1792)] to experimental plerocercoid infections of Diphyllobothrium dendriticum (Nitzsch, 1824)
Authors: Sharp G. J. E. , Pike A. W. , Secombes C. J.
Published: June 2009

Development of the inflammatory response of rainbow trout to experimental infections with Diphyllobothrium dendriticum plerocercoids is described using light and electron microscopy. The cellular response to plerocercoids occurred within 2 weeks post-infection (p.i.). This was followed by an increase in leucocyte numbers during weeks 3–6 p.i., with full encapsulation of plerocercoids by week 6 p.i. Neutrophils were the first leucocytes to engage the developing plerocercoid, followed by large influxes of macrophages which transformed into epithelioid cells. With longer times p.i. the accumulation of different leucocyte types increased, and a blood vascular network developed. Full development of the composite cyst was characterized by fibroplasia, particularly at the periphery of the cyst, and the subsequent deposition of a collagenous tissue matrix. Enzyme-linked immunosorbent assay (ELISA) examination of serum samples taken over the 20 week period showed that specific anti-D. dendriticum antibody titres were first detected at 5 weeks p.i. and increased to a maximum by 11 weeks p.i.
Detection ofTrypanosoma congolenseandTrypanosoma bruceisubspecies by DNA amplification using the polymerase chain reaction
Authors: Moser D. R. , Cook G. A. , Ochs Diane E. , Bailey Cheryl P. , McKane Melissa R. , Donelson J. E.
Published: June 2009

The nuclear DNA ofTrypanosoma congolensecontains a family of highly conserved 369 base pair (bp) repeats. The sequences of three cloned copies of these repeats were determined. An unrelated family of 177 bp repeats has previously been shown to occur in the nuclear DNA ofTrypanosoma brucei brucei(Sloofet al.1983a). Oligonucleotides were synthesized which prime the specific amplification of each of these repetitive DNAs by the polymerase chain reaction (PCR). Amplification of 10% of the DNA in a single parasite ofT. congolenseorT. bruceispp. produced sufficient amplified product to be visible as a band in an agarose gel stained with ethidium bromide. This level of detection, which does not depend on the use of radioactivity, is about 100 times more sensitive than previous detection methods based on radioactive DNA probes. The oligonucleotides did not prime the amplification of DNA sequences in other trypanosome species nor inLeishmania, mouse or human DNAs. Amplification of DNA from the blood of animals infected withT. congolenseand/orT. bruceispp. permitted the identification of parasite levels far below that detectable by microscopic inspection. Since PCR amplification can be conducted on a large number of samples simultaneously, it is ideally suited for large-scale studies on the prevalence of African trypanosomes in both mammalian blood and insect vectors.
Infective juvenile formation in the insect parasitic nematodeSteinernema feltiae
Authors: Popiel Irene , Grove Donna L. , Friedman M. J.
Published: June 2009

Steinernematid nematodes form a developmentally arrested infective juvenile (IJ) stage at the second moult, when conditions inside the insect host are no longer suitable for further reproduction. In a liquid culture micro-assay two environmental cues were shown to influence the formation ofSteinernema feltiaeIJs. High nematode population density induced IJ formation, suggesting the presence of a nematode pheromone. Bacterial food and soluble nutrients acted competitively to reduce the frequency of IJ formation. Frequency of IJ formation was greatest when lst-stage juveniles were subjected to IJ-inducing conditions. The optimum temperature range for the IJ induction response was 25–30°C. These findings suggest that maximal IJ production in large-scale liquid culture will depend on the correct balance of nematode population density and nutrient availability at the peak of egg hatching.
Epidemiology and immunology of Necator americanus infection in a community in Papua New Guinea: humoral responses to excretory-secretory and cuticular collagen antigens
Authors: Pritchard D. I. , Quinnell R. J. , Slater A. F. G. , McKean P. G. , Dale D. D. S. , Raiko A. , Keymer A. E.
Published: June 2009

Baseline data from an immuno-epidemiological study of hookworm infection in a rural village in Madang Province, Papua New Guinea are reported. Necator americanus was found to be the commonest helminth infection, with a prevalence of near 100% and intensity of 40 worms per host in adults. Enterobius vermicularis, Ascaris lumbricoides and Trichuris trichiura were also present, at prevalences of 53, 10 and 3% respectively; Ancylostoma duodenale was absent. The frequency distribution of N. americanus was highly over-dispersed, and was well described by a negative binomial distribution with aggregation parameter, k, of 0·370. Intensity of infection was significantly related to host age, but did not differ between the sexes. Haemoglobin levels and haematocrit values were indicative of anaemia in the community, but were unrelated to hookworm infection. Levels of antibodies (IgG, IgA and 1gM combined) against adult Necator cuticular collagen and excretory-secretory (ES) products were determined.
Effects of cyclophosphamide and dexamethasone on mast cell populations inHymenolepis microstoma-infected mice
Authors: Novak M. , Buchannan L. G. , Howlader H.
Published: June 2009

Antineoplastic cyclophosphamide (CY) significantly reduced the survival and the weight ofHymenolepis microstomain mice. Corticosteroid dexamethasone (DEX), on the other hand, did not influence the worm survival and the worms in DEX-treated mice became significantly heavier. Both immunosuppressants abolishedH. microstoma-induced bile duct hypertrophy and submucous enteritis and lowered the number of mast cells (MC) in these regions. CY appeared to be more effective in depleting the bile duct MC whereas DEX seemed to affect more the duodenal MC population.
In vitrocytoadherence ofPlasmodium falciparum-infected erythrocytes to melanoma cells: factors affecting adhesion
Authors: Sherman I. W. , Valdez Esther
Published: June 2009

A reproducible and standardized assay for measuring the cytoadherence of knobbyPlasmodium falciparum-infected red cells to amelanotic melanoma cells was developed. Adhesion was dependent on temperature, haematocrit, and parasitaemia. Addition of EDTA to the binding medium reduced adhesion. Removal of protease-sensitive molecules on the surface of the infected cell abolished cytoadherence, whereas removal of carbohydrate residues by treatment of cells with neuraminidase or galactosidase promoted adhesion. Calcium, magnesium, fibrinogen or fibronectin in the medium had no effect on adhesion nor was there any enhancement of adhesion by pre-loading infected cells with calcium. Serum was essential for good adhesion. Adhesion was species specific for target cells; human endothelial or amelanotic melanoma cells were suitable target cells whereas bovine cells were not. The amelanotic melanoma cell could be formalin-fixed and still retain its adhesion properties. The binding properties of formalin-fixed amelanotic melanoma cells were not identical to those of endothelial or unfixed target cells.
Chloroquine containing liposomes in the chemotherapy of murine malaria
Authors: Peeters P. A. M. , Huiskamp Caroline W. E. M. , Eling W. M. C. , Crommelin D. J. A.
Published: June 2009

In this study, the advantage of the use of chloroquine (CQ) containing liposomes (lipCQ) over free CQ in the chemotherapy of murine malaria (Plasmodium berghei) was demonstrated. The maximum permissible dose per intraperitoneal injection was 0·8 and 10 mg for CQ and lipCQ, respectively. An increase in therapeutic and prophylactic efficacy of lipCQ in comparison with free CQ at a 0·8 mg CQ dose level was found. It was possible to obtain 100% efficacy (injection at day 5 after infection; parasitaemia 4–8%) with one single intraperitoneal injection of 6 mg lipCQ. Moreover, the ability to increase the doses of CQ per injection after liposome encapsulation allowed successful treatment of infections with CQ-resistantPlasmodium bergheiwhich could not be cured by a 7-day course with the maximum tolerable dose of free CQ of 0·8 mg/mouse/day.
Changes in nematode antigens recognized by monoclonal antibodies during early infections of soya beans with the cyst nematode Heterodera glycines
Authors: Atkinson H. J. , Harris P. D.
Published: June 2009

The invasion and establishment of Heterodera glycines has been studied for 0–120 h after addition to host roots using a synchronized infection system. A high degree of synchrony in development was noted, with juvenile nematodes reaching their feeding sites adjacent to the root endodermis and discharging their subventral pharyngeal glands by 24 h post-invasion (p.i.). The moult to the 3rd-stage juvenile occurred approximately 89 h after entry to the root. Using an enzyme-linked immunosorbent assay with monoclonal antibodies (MAbs) whose tissue specificities had already been defined by immuno-cytochemistry, it was found that MAbs recognizing intestinal lipid droplets and granules showed a major increase in reactivity 18–24 h p.i. before declining by 39 h p.i. In contrast, the reactivity of two MAbs recognizing adult cuticle increased significantly only after 89 h p.i., following the second moult. MAbs to the two subventral pharyngeal gland cells showed a variety of patterns of changing reactivity during the experiment. One increased within 24 h of invasion before declining whereas a second fell without any initial rise. Two further MAbs specific for the subventral glands initially declined but showed a secondary increase in reactivity after 72 h and could be detected in adult females. This pattern was also seen in a MAb specific for the dorsal pharyngeal gland cell. These changes are discussed in the context of events taking place following invasion, with particular reference to the initiation and maintenance of a feeding syncytium by the developing nematode.
Detection of a carrier state in Theileria parva-infected cattle by the polymerase chain reaction
Authors: Bishop R. , Sohanpal B. , Kariuki D. P. , Young A. S. , Nene V. , Baylis H. , Allsopp B. A. , Spooner P. R. , Dolan T. T. , Morzaria S. P.
Published: June 2009

Two sets of oligonucleotide primers, one derived from a repetitive sequence and the other from the gene encoding a 67 kDa sporozoite antigen of Theileria parva, were used to amplify parasite DNA from the blood of T. parva-infected carrier cattle using the polymerase chain reaction (PCR). PCR amplification products were obtained from 15 carrier cattle infected with one of 4 different T. parva stocks. Successful amplifications were performed using DNA from 2 cattle infected with T. p. parva Pemba Mnarani, 10 cattle infected with T. p. parva Marikebuni, 2 cattle infected with T. p. bovis Boleni and 1 animal infected with T. p. lawrencei 7014. No amplification products were obtained from any of 7 cattle which had been infected with the T. p. parva Muguga stock. A synthetic oligonucleotide, which hybridized specifically to T. p. parva Marikebuni DNA among 6 T. parva stocks tested, was designed using sequence data from within the region of the T. parva genome amplified by the repetitive sequence primers. The oligonucleotide was used to probe PCR products and to increase the sensitivity and specificity of carrier animal detection. Southern blot analysis using a T. parva repetitive sequence probe demonstrated the existence of restriction fragment length polymorphisms between parasites isolated from T. p. parva Marikebuni-infected carrier cattle. The use of the PCR and other methods of carrier animal detection are discussed.
Host specificity, host location and dispersal: experimental conclusions from freshwater mites (Unionicolaspp.) parasitizing unionid mussels
Authors: Barbara Downes J.
Published: June 2009

Parasites with low host specificity are predicted to search for hosts in ways less specific than highly host-specific species. They may also be better dispersers. Unionicolan mites that parasitize mussels are positively phototactic, with some species becoming negatively phototactic when host substances are present. This response has been interpreted as an aid to host location and occurs in species where adult mites have a relatively permanent association with hosts. Three species ofUnionicola(Unionicolidae: Acari) that differ in host specificity co-occur in freshwater mussels (Unionidae) in St Mark's River in north Florida.
Effect of Praziquantel treatment on lung-stage larvae ofSchistosoma mansoni in vivo
Authors: Flisser Ana , McLaren Diane J.
Published: June 2009

Mice infected heavily withSchistosoma mansonicercariae were treated 6 days later with Praziquantel and the parasites studied 1 h post-treatment. Immunofluorescence experiments showed that parasite surface antigens became available for labelling in larvae harvested from Praziquantel-treated mice, but not from untreated mice. Red blood cell antigens acquired from the host were localized on all lung worms studied. The distribution of each set of antigens, as revealed by fluorescence-labelling was, however, quite different. The lungs of heavily infected, drug-treated mice, exhibited severe haemorrhages which occurred in a dose-dependent manner. Fewer haemorrhages were found when heavily infected mice were treated simultaneously with Praziquantel and Aprotinin, a proteinase inhibitor. These results indicate that Praziquantel treatmentin vivoinduces the exposure of parasite antigens on lung-stage worms and may cause the release of parasite-derived enzymes which induce haemorrhages in the lung tissue of the host.
Immunocytochemical demonstration of neuropeptides in the nervous system of the liver fluke, Fasciola hepatica (Trematoda, Digenea)
Authors: Magee R. M. , Fairweather I. , Johnston C. F. , Halton D. W. , Shaw C.
Published: June 2009

The localization and distribution of neuropeptides in the nervous system of the liver fluke, Fasciola hepatica at different stages in the development of the adult fluke have been determined by an indirect immunofluorescence technique, using antisera to 19 vertebrate peptides and the invertebrate neuropeptide, FMRFamide. Positive immunoreactivity was obtained with antisera to pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), substance P (SP) and FMRFamide. Cell bodies and nerve fibres immunoreactive to the 4 peptides are present in the anterior ganglia and the 3 pairs of longitudinal nerve cords and their commissures in the central nervous system. In the peripheral nervous system, immunoreactivity occurs in the nerve plexuses supplying the subtegumental musculature, the oral and ventral suckers, and the muscular lining of the male and female reproductive ducts, including the ootype, uterus, cirrus pouch and gonopore. Cells displaying immunoreactivity to PYY and FMRFamide lie amongst the Mehlis' gland cells that surround the ootype. Processes from these cells extend into the wall of the ootype. One group of PP-immunoreactive cells occurs at the junction of the vitelline and ovovitelline ducts, whilst another group is situated at the entrance to the uterus from the ootype. The results are discussed in relation to the possible roles of the peptides in the neurophysiology and egg production of the fluke.
Translation in a reticulocyte cell-free system of RNA isolated from blood and culture forms of Trypanosoma brucei
Authors: Eggitt M. J. , Tappenden L. , Brown K. N.
Published: June 2009

RNA with messenger activity has been extracted from both blood and culture (insect mid–gut) forms of Trypanosoma brucei and translated in a reticulocyte cell–free system. The products of this cell–free system have been compared, and many common polypeptides demonstrated. A major polypeptide of 58000–65000 molecular weight was made when both blood and culture from RNA was added to the cell–free system.

Antiserum raised against purified variant antigen from a cloned variant (MIAG 099) was used to detect specific products of this system. A major polypeptide of approximately 58000–65000 molecular weight was precipitated when the homologous trypanosome (MIAG 099) blood form RNA was used in the cell–free system. No such polypeptide was precipitated when RNA from a heterologous strain culture or blood form was used in the system. Competition experiments, in which excess purified variant antigen was added after incubation but before addition of specific antiserum, confirmed that the polypeptide of 58000–65000 molecular weight is the variant antigen.

Poly(A)–containing RNA from trypanosomes was shown to contain the mRNA for the variant antigen.
Human malaria infectiousness measured by age-specific sporozoite rates in Anopheles gambiae in Tanzania
Authors: Lines J. D. , Wilkes T. J. , Lyimo E. O.
Published: June 2009

In an area of holoendemic malaria in Northern Tanzania, Anopheles gambiae s.l. females were age-graded by Polovodova's method and dissected for sporozoites. Age-specific sporozoite rates implied that mosquitoes acquired new infections at all ages. The extrinsic period lasted just over 3 gonotrophic cycles (9–11 days). Very high sporozoite rates in the oldest females implied the absence or rarity of genetic refractoriness to infection. A method is described for estimating the proportion of bloodmeals which result in mosquito infection. This method makes relatively few assumptions about mosquito behaviour, and could be useful for evaluating transmission-blocking interventions. Overall, it is estimated that about 21% of meals are infectious. This is much higher than previous estimates derived either from experimental mosquito feeding studies or from similar age-grading data collected from the same area in 1962. Various alternative explanations are considered, and it is concluded that there has been a 2.5-fold increase in human infectiousness in the last 25 years. This is partly attributable to suppression of human infectiousness by widespread chloroquine usage during the 1960s, followed by removal of this effect by drug resistance. It is argued that chloroquine would be expected to select for increased infectivity in the parasite, and this may also have contributed to the observed increase.
In vitrocultivation ofTrypanosoma congolensebloodstream forms in the absence of feeder cell layers
Authors: Hirumi H. , Hirumi K.
Published: June 2009

Bloodstream forms ofTrypanosoma congolense(2 clones: ILNat3·1 and IL3000, and 4 stocks: IL2079, IL2466, IL3266 and CP-81) were continuously cultivatedin vitroat 34–36 °C in the absence of feeder cell layers, using HMI-93 medium which was modified from Iscove's modified Dulbecco's MEM (Flow Laboratories, Irvine, Scotland). The modification was done by supplementing the medium with 0·05 mM bathocuproine sulphonate, 1·5 mM L-cysteine, 0·5 mM hypoxanthine, 0·12 mM 2-mercaptoethanol, 1 mM sodium pyruvate, 0·16 mM thymidine, 20% (v/v) heat-inactivated young goat serum and 5% (v/v) Serum Plus™ (Hazleton Biologics, Lenaxa, KS, USA). Trypanosomes obtained from two different sources were used to initiate primary cultures: (1) metacyclic forms which were producedin vitroat 27 °C, and (2) bloodstream forms obtained from Balb/c mice which had been infected with the bloodstream forms transformedin vitrofrom the metacyclic forms. Metacyclic forms placed in 25 cm2T-type (T-25) flasks rapidly attached to the bottom of the flasks and transformed to bloodstream forms during the initial 24 h and continued to proliferate. The bloodstream forms isolated from the infected mouse blood by means of diethylaminoethyl cellulose (DE52) column chromatography also continued to proliferate in the flasks. Cultures were maintained by replacing the medium every 24 h. Every 4–5 days, the attached bloodstream forms were resuspended in fresh medium by gentle pipetting and then were subcultured. The method was further simplified by initiating primary cultures directly with 10 μl of the tail blood of infected mice in 24-well culture plates and then by subcultivating either in wells or in T-25 flasks. The shortest population doubling time, 9 h, was achieved by seeding subcultures with 106bloodstream forms/ml. The bloodstream forms propagated in this system were morphologically similar to those seen in infected mouse blood, they were covered with a surface coat as examined by electron microscopy and they were infective to mice.
The epidemiology of Schistosoma spindale Montgomery, 1906 in cattle in Sri Lanka
Authors: De Bont J. , Vercruysse J. , Van Aken D. , Southgate V. R. , Rollinson D. , Moncrieff C.
Published: June 2009

During 1988 and 1989, the mesenteric veins of 901 cattle were examined for the presence of schistosomes at the Kandy slaughterhouse (Sri Lanka). The overall prevalence of infection was 31·2%. Animals younger than 2 years were less infected (21·3%) than those older than 5 years (47·9%). Based on the number of paired worms counted, three intensities of infection were recognized: low (1–20 pairs), moderate (21–100 pairs) and heavy (> 100 pairs). Intensities increased with the age of the animals but remained low (average 10 worm pairs). The worm burden increased by approximately 20% for each step in age group. The number of miracidia/100 g faeces was measured in 85 animals of all age groups and intensities of infection; 77% of the samples contained less than 100 miracidia. Miracidia counts decreased with age; moderately and heavily infected animals in each age group had the highest and the lowest counts, respectively. This may be due to a host immune response. The results raise questions on the sensitivity of faecal egg counts as a diagnostic method for visceral schistosomiasis in cattle.
Membrane structure and function of malaria parasites and the infected erythrocyte
Authors: Sherman Irwin W.
Published: June 2009

According to the World Health Organization the global estimate of malaria is over 200 million infections, the majority of which are caused by the most life-threatening species,Plasmodium falciparum(Report of the Steering Committees of the Scientific Working Groups on Malaria, World Health Organization, June 1983). The causative agent of the disease, the malarial parasite, requires two hosts: a blood-sucking mosquito and a blood-containing vertebrate. Commonly, infection of the vertebrate begins when an infected mosquito bites a suitable vertebrate and injects minute sporozoites into the bloodstream. Within 30 mm the introduced sporozoites leave the bloodstream and enter parenchymal cells of the liver (mammals) or endothelial cells (birds). In these sites the parasite undergoes asexual multiplication (= exo-erythrocytic schizogony) producing daughter progeny called merozoites. The exo-erythrocytic merozoites are released from the tissues into the circulation where they invade red blood cells. Within an erythrocyte the merozoite undergoes asexual multiplication (= erythrocytic schizogony) producing a substantial number of merozoites. The erythrocyte lyses, merozoites are released, and invasion of another erythrocyte may then take place. The synchronous rupture of the red cell and merozoite release is marked by the periodic fever–chill cycles so characteristic of the malarial infection. Some merozoites continue to reinvade other erythrocytes and multiply by asexual means, whereas others enter erythrocytes and differentiate into sexual stages, male or female gametocytes. When a suitable mosquito feeds on an infected vertebrate gametocytes are ingested and the sexual cycle of development is initiated. In the mosquito stomach the gametocytes transform into gametes, fertilization takes place, the resultant worm-like zygote penetrates the cells of the mosquito gut and comes to lie on the outer surface of the stomach. Here each zygote forms a cyst-like body, the oocyst, within which thousands of sporozoites are produced by asexual multiplication. When the swollen oocysts burst, sporozoites are freed and these make their way to the salivary gland. At the next blood feeding the mosquito injects the infective sporozoites and the life-cycle is completed.
Use of chick embryo infections for the study of drug resistance in Eimeria tenella
Authors: Chapman H. D.
Published: June 2009

The activity of 12 anticoccidial drugs against an embryo-adapted strain of Eimeria tenella has been investigated. After seven and five serial passages respectively, in the presence of drug, resistance was developed to methyl benzoquate and buquinolate. A strain of E. tenella made resistant by exposure to drugs in chickens was resistant to the same drugs when evaluated in infections of chick embryos. This relatively simple technique would appear to offer advantages over existing methods for the study of drug resistance.
Acquired immunity toSchistosoma mansoniin the rat: measurement of immunity by the lung recovery technique
Authors: Perez Hilda , Clegg J. A. , Smithers S. R.
Published: June 2009

Acquired immunity toSchistosoma mansoniin the rat can be assayed by the recovery of a proportion of the schistosomula of a challenge infection from the lungs 5 days after the challenge has been given. The recoveries from immune rats, which are significantly less than those from control animals, demonstrate that a proportion of a challenge infection is killed in the lungs or at an earlier point in the pathway of migration.

Immunity in the Sprague–Dawley rat can first be shown by the lung recovery technique 3 weeks after an immunizing exposure of 500 cercariae. Immunity reaches a peak between weeks 6 and 7 but then declines to zero by week 12. The PVG inbred Hooded rat shows a similar but delayed development and decline of immunity. When the lung recovery technique shows immunity to be declining, hepatic perfusion demonstrates that immunity to reinfection is partially retained, indicating that at this stage the challenge is killed after the first 5 days.

Re-exposure of rats in which immunity has declined induces an anamnestic lung recovery response. There appears to be a relationship between spontaneous cure and the decline of immunity. A factor in the serum of infected rats which kills young schistosomula in culture develops in parallel with immunity, but high titres of this factor are maintained during the decline of immunity.
Functional bursting by the dracunculoid nematodePhilonema oncorhynchi
Authors: Lewis J. W. , Jones D. R. , Adams J. R.
Published: June 2009

Using biomedical techniques experimental determinations of the hydrostatic pressure in the pseudocoel of adult femalePhilonema oncorhynchiindicated that the rate of increase in pressure (dP/dT) and absolute pressure values (cm/H2O) shown by bursting worms in distilled water are correlated with the diameter of the nematode. At bursting pressures, wall tension in a wide size range of worms was virtually identical, indicating that the bursting process is independent of muscular contraction. That the generation of the hydrostatic pressure was an osmotic phenomenon was confirmed by measuringdP/dTin prelarvigerous and larvigerous female worms subjected to different concentrations of sodium chloride, ranging from 89 to 800 m-osmol/kg, and also to a variety of solutions of similar osmolarity (155–175 m-osmol/kg),e.g.magnesium sulphate, urea, potassium chloride, sodium chloride and sucrose. The overall rate of uptake was faster in the larger worms but, per unit surface area, small worms had an uptake rate three times that of the large individuals.

The prediction that the body wall of femaleP. oncorhynchiis permeable to ions such as Na+ was confirmed using radiolabelled22Na and by bringing about changes in the osmolarity of worms subjected, for 5 min periods, to hyperosmotic solutions of sodium chloride and sucrose. The survival ofP. oncorhynchiin the body cavity of sockeye salmon,Oncorhynchus nerka, is dependent upon the permeable nature of the body wall ofP. oncorhynchiallowing the worm to function as an ‘osmometer', because as the anadromousO. nerkaenters fresh water, the osmolarity of its blood plasma is known to decrease by about 15%. At the time of spawning in Cultus Lake, British Columbia, the body fluids of both femaleP. oncorhynchiandO. nerkaare isosmotic, indicating that the worms are able to equilibrate to the above changes and at the same time preventing premature bursting in the body cavity of its host. However, osmotic invasion of water must occur far quicker than ionic exchange since complete release of larvae does take place when female worms pass out into the redd along with the eggs of the fish and burst.
On the infracommunity structure of adult cestodes in freshwater fishes
Authors: Andersen K. I. , Valtonen E. T.
Published: June 2009

The distribution–co-occurrence and exchange of adult cestode species in two fish communities (the Bothnian Bay and Lake Yli-Kitka both in Finland) was studied. Coexistence of two or more mature cestode species in the same fish host population was zero for all fish species studied (33) except pike in the Bothnian Bay and whitefish in the lake. It was found that 60% of the fish species studied in the Bothnian Bay and 80% of the fish species studied from Lake Yli-Kitka harboured only 1 mature cestode species. Exchange of adult cestode species between the different fish species in these two fish communities was found to be as rare as coexistence. The infra-community structure of adult cestodes in freshwater fish thus turned out to be markedly different from what is known to be the situation in birds. The evolutionary explanation behind the differences is discussed.
Molecular identity of a major antigen ofSchistosoma mansoniwhich cross-reacts withTrichinella spiralisandFasciola hepatica
Authors: Aronstein W. S. , Lewis S. A. , Norden A. P. , Dalton J. P. , Strand M.
Published: June 2009

A glycoprotein cross-reactive amongSchistosoma mansoni, Trichinella spiralisandFasciola hepaticawas identified and characterized by use of monoclonal antibodies prepared againstS. mansoniglycoproteins. Four monoclonal antibodies recognized the same antigen which was one of the majorS. mansoniglycoproteins precipitated by sera of hosts infected with eitherS. mansoniorT. spiralis. This antigen was expressed inS. mansonicercariae, adult male and female worms, and eggs, and inS. haematobiumbut not inS. japonicum. Radio-immunoprecipitation and partial proteolytic digest mapping showed that the monoclonal antibodies each recognized a unique epitope. These epitopes were heat labile, sensitive to chaotropic agents, but resistant to reduction and alkylation or digestion with glycosidases, indicating that the recognition sites were amino acids and not carbohydrates. Epitopes recognized by the four monoclonal antibodies were expressed inF. hepatica, whereas only two were expressed inT. spiralis. Analysis by immunofluorescence microscopy showed that the antigen was expressed inS. mansoniin the parenchymal tissue and on the surface of the dorsal tubercles; in matureF. hepaticain the parenchymal tissue, vitelline glands and eggs; in immatureF. hepaticaonly in the parenchymal tissue and in larvalT. spiralisin the hypodermis.
Diversity of reproductive behaviour in platyhelminth parasites: insemination in some benedeniine (capsalid) monogeneans
Authors: Kearn G. C. , Whittington I. D.
Published: June 2009

Considerable diversity has been found in the reproductive behaviour of benedeniine (capsalid) monogenean parasites. Mating has been observed in Benedenia sp. 1 from the gills of Lutjanus carponatatus; externally attached spermatophores are not involved and parasites indulge in mutual cross-insemination with intromission. In contrast, there is evidence of spermatophore involvement in Benedenia sp. 2 from the fins of Lethrinus miniatus; mating was not observed but an individual was found carrying an external ovoid spermatophore attached by a stalk lodged in the vagina. In specimens of Benedeniella macrocolpa and B. posterocolpa, in which the male reproductive system was functional and the female system not fully developed, the everted cirrus was seen to be lodged in the parasite's own uterus, with, in some individuals, the tip of the cirrus inside the ootype. This is the first time that the copulatory organ has been observed inside the female reproductive tract of the same individual, not just in benedeniines but in monogeneans in general, and is also the first demonstration that monogeneans are capable of self-insemination via the uterine route.
Factors generating aggregation of Heligmosomoides polygyrus (Nematoda) in laboratory mice
Authors: Tanguay G. V. , Scott M. E.
Published: June 2009

The importance of host heterogeneity in generating aggregation was investigated using Heligmosomoides polygyrus (Nematoda) in laboratory mice. Parameters of infection were compared between inbred and outbred mice, between primary and challenge infection protocols, and between gavage and natural exposure protocols, to investigate the relative effects of innate resistance, acquired resistance and behaviour, respectively. Heterogeneity in acquired resistance was identified as the most consistent factor leading to variability and aggregation of H. polygyrus numbers in mice. This hypothesis was supported in two experiments where groups of mice did not develop resistance to challenge infection (use of certain inbred strains of mice and immunosuppression with corticosteroids in the drinking water) and where variability in worm numbers after the challenge infection was comparable with that after the primary infection. Heterogeneity in host behaviour, particularly in behaviours enhancing skin contact with larvae, also was associated with increased heterogeneity in worm burden, though not as consistently as heterogeneity in acquired resistance. Surprisingly, worm burdens were not more variable in outbred compared with inbred mice. Our data suggest that the relative contributions of innate resistance, acquired resistance and behaviour in generating variable worm burdens are likely to vary spatially and temporally.
Role of small mammals in the epidemiology of toxocariasis
Authors: Dubinský P. , Havasiová-Reiterová K. , Peťko B. , Hovorka I. , Tomašovičová O.
Published: June 2009

Studies were conducted on the role of small mammals in maintaining toxocariasis foci in urban, rural and montane biotopes. The lowest relative density of small mammals was recorded in the urban locality and the highest in the rural and montane localities. Anti-Toxocaraantibodies were most frequently detected in synanthropic and hemisynanthropic speciesMus musculus, Apodemus agrariusandMicromys minutus– 32·0, 30·4 and 25·0%, respectively. The highest seropositivity was found in small mammals from the urban and rural localities – 22·2 and 21·6%, respectively.Toxocara caniswas most prevalent in urban stray dogs (75·0%) and least prevalent in foxes from the montane locality (7·0%). The prevalence ofToxocara catiin cats at the urban, rural and montane localities was 66·2, 65·2 and 76·9%, respectively. In clinically healthy human populations, the highest seroprevalence was detected in the rural locality (14·0%). Children of the same area were 3 times more seropositive (12·9%) than those from the urban and montane localities (4·3 and 4·0%). Our studies suggest an important role for small mammals as paratenic hosts – reservoirs ofToxocaralarvae – in maintaining toxocariasis foci. In this respect toxocariasis may be classified as an anthropopurgic focal zoonosis.
Schistosoma mansoni: an ultrastructural examination of pulmonary migration
Authors: Crabtree Jean E. , Wilson R. A.
Published: June 2009

The migration of schistosomula through the lungs of mice has been investigated at the ultrastructural level. On Days 4 and 7 post-infection schistosomula were located only within the vasculature. Newly arrived Day 4 schistosomula were highly convoluted and completely occluded vessels measuring approximately 15–25μm in diameter. By Day 7 parasites were located in pulmonary capillaries, often causing considerable distension. The subtegumentary fibrous interstitial layer was absent in elongated lung schistosomula. The minimum diameter of such parasites was 8μm, and their tegument was usually unridged and flattened against the vascular endothelium, thus resulting in close apposition of endothelial and tegumental membranes. The tight fit of schistosomula in the pulmonary capillaries implies that migration through them is both a strenuous and slow process. The migratory delay in the lungs after arrival from the skin occurs because dimensional changes are necessary for successful capillary migration.
Protein analysis ofTheileria sergenti/buffeli/orientalispiroplasms by two-dimensional polyacrylamide gel electrophoresis
Authors: Sugimoto C. , Kawazu S. , Kamio T. , Fujisaki K.
Published: June 2009

Proteins of the piroplasms ofTheileria sergenti, T. buffeliandT. orientaliswere analysed by two-dimensional polyacrylamide gel electrophoresis. Protein spot patterns ofT. buffeliandT. orientaliswere identical except for a few minor proteins, whereas spot patterns of twoT. sergentistocks were differentiated from those ofT. buffeliandT. orientalisby a characteristic set of proteins including a major protein of molecular weight 33–34 kDa. This result indicates that JapaneseT. sergentican be phenotypically distinguishable from European and AustraliaTheileriaspecies;T. orientalisandT. buffeli.
Estimation of heritability of susceptibility to infection withTheileria parvain the tickRhipicephalus appendiculatus
Authors: Young A. S. , Dolan T. T. , Mwakima F. N. , Ochanda H. , Mwaura S. N. , Njihia G. M. , Muthoni M. W. , Dolan R. B.
Published: June 2009

Heritability of susceptibility to infection withTheileria parvawas estimated from full sib families ofRhipicephalus appendiculatusticks. Male and female ticks of 2 stocks were mated singly. Nineteen full sib families of the Muguga stock and 17 full sib families of the Kiambu stock were obtained. Nymphae of these families were fed on cattle infected withT. parvaso that the ticks became replete on days 16 and 17 after infection when the blood was parasitaemic with intraerythrocytic piroplasms. TheT. parvainfections were assessed in the resultant adult ticks of each full sib group and the abundance of infection, the number of salivary gland acini infected/tick, was found to be the most useful parameter for analysis. Estimates of heritability of the susceptibility to infection withT. parvafor the Kiambu and the Muguga tick stocks were 0·24 and 0·26 respectively. Using only the data from ticks which fed on day 16, the heritability estimates were 0·39 for the Kiambu stock and 0·59 for the Muguga stock. These results indicate that tick lines of high or low susceptibility forT. parvainfection could be produced through selection.
Discrimination between Gyrodactylus salaris, G. derjavini and G. truttae (Platyhelminthes: Monogenea) using restriction fragment length polymorphisms and an oligonucleotide probe within the small subunit ribosomal RNA gene
Authors: Cunningham C. O. , McGillivray D. M. , MacKenzie K. , Melvin W. T.
Published: June 2009

The small subunit ribosomal RNA (srRNA) gene was amplified from Gyrodactylus salaris using the polymerase chain reaction (PCR), cloned, and the complete gene sequence of 1966 bp determined. The V4 region of the srRNA gene was identified and amplified from single specimens of G. salaris, G. derjavini and G. truttae. Comparison of the V4 sequences from these three species revealed sequence differences from which restriction fragment length polymorphisms (RFLPs) were predicted and an oligonucleotide probe (GsV4) specific to G. salaris designed. Digestion of the amplified V4 region of the srRNA gene with Hae III and either Alw I, BstY I, Dde I or Mbo I provided a means of discriminating between G. salaris, G. derjavini and G. truttae. The GsV4 probe was used to detect the srRNA gene from G. salaris in Southern and dot blots of the amplified V4 region. The nucleotide sequences reported in this paper have been submitted to the EMBL Data Library under accession numbers Z26942 (G. salaris), Z35128 (G. derjavini) and Z35129 (G. truttae).
Ultrastructural immunolocalization of two circulating egg antigens in miracidia ofSchistosoma mansoni
Authors: Bogers J. J. P. M. , Nibbeling H. A. M. , Singh S. Kumar , Deelder A. M. , Van Marck E. A. E.
Published: June 2009

In the present study ultrastructural immunocytochemical techniques have been used to localize the cells producing two soluble egg antigens present in the hatching fluid ofSchistosoma mansoni, using two recently described monoclonal antibodies (MAbs). In the miracidium ofS. mansoni, the one apical and the two lateral unicellular glands showed immunoreactivity for the egg antigens, using a post-embedding immunogold technique. Immunoreactivity was associated with the contents of vesicles for both the MAbs, although the intravesicular distribution was not identical. This difference in ultrastructural staining pattern provides additional evidence that the two MAbs are binding with different epitopes of the same antigen or with different antigens altogether. The finding of free unbound label around the embedded miracidium is consistent with secretion having been released from the glands.