bluuebunny/crossref_metadata_2025 huggingface dataset:
Epidemiology of canine leishmaniasis: a comparative serological study of dogs and foxes in Amazon Brazil
Authors: Courtenay O. , Macdonald D. W. , Lainson R. , Shaw J. J. , Dyes C.
Published: June 2009

The paper describes a longitudinal field study of canine leishmaniasis in sympatric domestic dog and crab-eating fox (Cerdocyon thous) populations. Dogs were studied in house-to-house surveys, and foxes were studied by live-trapping and radio-telemetry. Because serological tests (IFAT in this case) for leishmaniasis are often of uncertain sensitivity and specificity, we draw conclusions comparatively. Both cross-sectional (age–prevalence) and longitudinal analyses indicate that incidence in dogs was highest in the dry season. Seasonal changes in the age–prevalence relationship for dogs suggest that serological conversion and recovery rates decline with prior exposure to infection, where ‘recovery’ may be due to loss of a positive antibody titre or death from leishmaniasis. The mean incidence in dogs was higher in the rural than in the urban population and higher in hunting dogs than pet dogs. Cross-sectional and longitudinal analyses of fox serological data suggest that foxes remain positive for longer than dogs on average, either because detectable antibody is more persistent or because they experience a lower mortality rate due to leishmaniasis.
The FMRFamide-like neuropeptide AF2 (Ascaris suum) is present in the free-living nematode,Panagrellus redivivus(Nematoda, Rhabditida)
Authors: Maule A. G. , Shaw C. , Bowman J. W. , Halton D. W. , Thompson D. P. , Geary T. G. , Thim L.
Published: June 2009

Available primary structural information suggests that the FMRFamide-related peptides (FaRPs) from parasitic and free-living nematodes are different, and that free-living forms may not represent appropriate models for the study of the neurochemistry of parasitic forms in the laboratory. However, here we report the isolation and unequivocal identification of AF2 (originally isolated from the parasite,Ascaris suum) from acidified alcoholic extracts of the free-living species,Panagrellus redivivus. While reverse-phase HPLC analysis of extracts revealed FMRFamide-immunoreactivity to be highly heterogeneous, AF2 was the predominant FMRFamide-immunoreactive peptide present (at least 26 pmol/g wet weight of worms). This peptide was also the major immunoreactant identified by an antiserum raised to the conserved C- terminal hexapeptide amide of mammalian pancreatic polypeptide (PP), which has been used previously to isolate neuropeptide F (NPF). These observations were confirmed by radioimmunoassay and chromatographic fractionation of an acidified alcoholic extract ofA. suumheads. The FMRFamide-related peptides present in a nematode extract may be highly dependent on the extraction medium employed, and these data would suggest that this complement of neuropeptides may not be as different between parasitic and free-living nematodes as initial studies have suggested. Finally, all of the evidence suggests that NPF is not present in nematodes and that the PP-immunoreactant previously demonstrated immunochemically is probably AF2.
Elevated agglutination titres in plasma of Biomphalaria glabrata exposed to Echinostoma paraensei: characterization and functional relevance of a trematode-induced response
Authors: Loker E. S. , Couch L. , Hertel L. A.
Published: June 2009

Production of elevated haemolymph agglutination titres by Biomphalaria glabrata following exposure to Echinostoma paraensei miracidia was investigated, to characterize this parasite-induced response and to understand its functional relevance. Both the dose of infection (1, 10 or 100 miracidia per snail) or the number of separate exposures to infection (between one and three, over a 4 or 8 day interval) were varied, and assuming a threshold dosage (10 miracidia per snail or higher) was exceeded, titres of juvenile snails peaked at 8–16 times the values for unexposed control snails, regardless of the exposure regimen. Adult snails, which are relatively refractory to infection, have slightly higher resting titres than juveniles, but exhibit only a 2- to 4-fold increase in titre following exposure. Juveniles exposed to infection but lacking demonstrable infection had lower titres than snails with confirmed infections. Exposure to infection increased heterogeneity of plasma agglutinins and provoked production of unique specificities not found in unexposed snails. However, the overall pattern of agglutination responses for snails with successfully developed parasites did not differ from those in which parasite development was unsuccessful. Agglutinating activity was inhibitable by several different monosaccharides, although plasma from infected snails was relatively unaffected by N-acetyl-glucosamine or N-acetyl-galactosamine. Wounding of snails provoked no change in plasma agglutination activity. As the highest agglutination titres were produced in snails with successfully developing parasites and agglutinin composition did not differ between snails with successful or unsuccessful parasites, the functional relevance of the response remains enigmatic. The production of unique agglutinins following exposure deserves additional study.
Effects of Schistosoma haematobium infection on reproductive success and male outcrossing ability in the simultaneous hermaphrodite, Bulinus truncatus (Gastropoda: Planorbidae)
Authors: Schrag S. J. , Rollinson D.
Published: June 2009

The schistosome intermediate snail host, Bulinus truncatus (Mollusca: Planorbidae), has two reproductive (phally) morphs. Both aphallics and euphallics can self-fertilize, but aphallics cannot donate sperm because they do not develop a functional penis and prostate. This study investigated the interactions between phally and fitness consequences of Schistosoma haematobium infection in B. truncatus. Snails which developed patent infections produced 26% fewer eggs than controls and 35% fewer eggs than exposed snails which did not develop infections. This reduction was due to a lower lifetime production of egg masses and a smaller mean number of eggs/mass in infected snails relative to control or exposed snails. However, there was no evidence of increased mortality in infected snails. Contrary to reports of fecundity compensation in other intermediate host snails, egg production post-exposure during the pre-patent period did not increase relative to that of controls in either infected or exposed snails. Phally did not influence susceptibility to infection or length of the prepatent period. Furthermore, lifetime egg, egg mass and hatchling production, as well as mean eggs/mass and number of hatchlings reaching maturity, did not differ significantly between aphallics and euphallics within control or exposed experimental groups. However, within the infected group euphallics produced 38% fewer eggs, smaller egg masses, and fewer hatchlings reaching maturity than aphallics, supporting the prediction of a cost to the growth and maintenance of a full male tract. This cost was detectable only when snails were under the stress of infection. The proportion of euphallic offspring produced did not differ across experimental groups. We discuss these results in light of alternative host strategies to minimize fitness costs of infection.
Interactions between infections with Eimeria spp. and Trichinella spiralis in inbred mice
Authors: Roses M. E. , Wakelin D. , Hesketh P.
Published: June 2009

Parasitological and immunological interactions between Eimeria vermiformis or E. pragensis and Trichinella spiralis were investigated during concurrent infections in NIH, BALB/c and B10.G inbred mice. The establishment of T. spiralis was unaffected by the presence of either coccidium, but expulsion of adult worms was delayed significantly in mice infected with E. vermiformis; E. pragensis did not have this effect. Replication of E. vermiformis was enhanced in concurrent infections with T. spiralis, but that of E. pragensis was reduced. Specific immune responses to each parasite were unaffected in mice infected with T. spiralis and E. pragensis, but levels of some responses were reduced when T. spiralis and E. vermiformis were combined. Thus both in vitro antigen-induced proliferation of mesenteric lymph node cells (MLNC) and intestinal mastocytosis were lower than in singly infected mice. Mitogen (Con A) responsiveness of MLNC was not affected in mice infected with T. spiralis and E. vermiformis, and cells from these mice were capable of transferring protective immunity to the nematode in naive recipients. Injection of monoclonal antibody to interferon gamma, a major component of the cytokine response to E. vermiformis, did not prevent delay of worm expulsion in concurrent infections. The results are discussed in terms of possible interactions between the T helper cell subsets or the inflammatory components of the responses induced by each parasite.
Identification of the dominant cyst antigens ofToxoplasma gondii
Authors: Woodison G. , Smith J. E.
Published: June 2009

Brain cysts from three strains ofToxoplasma gondiiwere purified and analysed by SDS-PAGE and immunoblotting. Western blot analysis revealed the presence of major cyst/bradyzoite antigens atMr25000, 36000 and 67000 common to all strains and recognized by many individual sera. There was also evidence of strain variation in cyst antigens with, for example, antigens atMr88000, 28000 and 26000 unique to the 17025 strain. There was some overlap in the molecular weight of cyst and tachyzoite antigens, but the major tachyzoite surface antigen (P30) could not be detected in brain cysts.
Regulation ofTrypanosoma cruziinfectivity by alpha- and beta-adrenergic agonists: desensitization produced by prolonged treatments or increasing agonist concentrations
Authors: Ayala A. , Kierszenbaum F.
Published: June 2009

We previously reported that blood forms ofTrypanosoma cruziexpress alpha- and beta-adrenergic receptors and that binding of specific agonists to these receptors modifies the infective capacity of the parasitein vitro. The present study has revealed that the inhibitory effect of the beta-adrenergic agonist L-isoproterenol and the stimulatory effect of the alpha-adrenergic agonist L-phenylephrine are not produced when the parasite is subjected to prolonged exposure to otherwise effective doses of these agonists or when supraoptimal doses of these agonists are used. We refer to these phenomena as ‘desensitization’ because of their analogy with vertebrate cells becoming desensitized by prolonged exposure to, or relatively high concentrations of, adrenergic agonists. At a constant agonist concentration,T. cruzidesensitization was time-dependent and, when the time of parasite treatment with the agonists was not changed, the higher concentrations of the agonist tested were the most effective in producing desensitization. The reduced infectivity resulting from treatment with optimal doses of L-isoproterenol was accompanied by elevated levels of cyclic adenosine mono- phosphate (cAMP) which were not detectable when L-isoproterenol concentrations producing desensitization were used. This finding implicated cAMP as a likely second signal in the inhibitory mechanisms of this agonist. No significant change in cAMP was detectable in parasites treated with L-phenylephrine, leaving open the question about how optimal doses of this alpha-adrenergic agonist enhanceT. cruziinfectivity. Parasite responsiveness to alpha- and beta-adrenergic agonists as well as the desensitization effects define a system which regulates infectivity and could be modified at the host tissue level by naturally occurring agonists.
Differential diagnosis of Taenia saginata and Taenia solium with DNA probes
Authors: Harrison L. J. S. , Delgado J. , Parkhouse R. M. E.
Published: June 2009

A size selected genomic DNA library was constructed using DNA extracted from Taenia saginata. The DNA was digested using the restriction enzyme EcoR1 under star conditions and the 2–4 kbase fraction, selected following sucrose density-gradient separation, was cloned in the bacteriophage λgt 10. A panel of cestode DNAs including Taenia saginata, Taenia solium, Taenia taeniaeformis, Taenia crassiceps, Echinococcus granulosus and DNAs of bovine, porcine and human origin were used in conjunction with hybridization analysis to identify two recombinant bacteriophages. The first probe, designated HDP1, reacted specifically with T. saginata DNA. The second, designated HDP2, reacted with DNA from both T. saginata and T. solium but not the other DNA samples and thus provided a general reagent for positive identification of fragments of Taenia spp. proglottides of human faecal origin. If used in conjunction the two DNA probes allow positive identification of T. saginata. In the clinical situation it is important to be able to distinguish T. saginata and T. solium infections and DNA probes such as these may be useful in such differentiation.
Transmission of Theileria parva to cattle by Rhipicephalus appendiculatus adults fed as nymphae in vitro on infected blood through an artificial membrane
Authors: Waladde S. M. , Young A. S. , Ochieng' S. A. , Mwaura S. N. , Mwakima F. N.
Published: June 2009

A technique is described for the efficient feeding of Rhipicephalus appendiculatus nymphae on cattle blood through an artificial membrane bearing tactile and olfactory stimuli. The effect of four anticoagulation methods on the feeding of nymphae was compared and heparinized blood was found to be the most efficacious, followed by defibrinated blood. Blood treated with acid citrate dextrose (ACD) or ethylenediamine tetraacetate (EDTA) inhibited nymphal feeding. Nymphae fed on heparinized and defibrinated blood obtained engorgement weights within the range of ticks fed on mammalian hosts and they subsequently moulted and fed normally as adults and produced viable eggs. Nymphae fed on membranes using either defibrinated or heparinized blood infected with Theileria parva piroplasms developed salivary gland infections as adult ticks and transmitted East Coast fever (ECF) to susceptible cattle. There were indications that T. parva-infected defibrinated blood was not as infective to the feeding nymphae as the infected heparinized blood. When T. parva-infected heparinized blood was used to feed nymphae through membranes in two experiments, it was found that the infections in the resultant adult ticks could be comparable to those of nymphae fed on donor cattle, but were usually lower. The membrane feeding technique will enable the study of factors affecting the tick and T. parva transmission without the complication of host/T. parva interactions and could be useful for both tick maintenance and Theileria parasite isolation and maintenance.
Echinococcus multilocularis: molecular and immunochemical characterization of diagnostic antigen II/3-10
Authors: Felleisen R. , Gottstein B.
Published: June 2009

A recombinantEchinococcus multilocularisantigen (II/3–10), which had previously been shown to exhibit immunodiagnostic characteristics highly specific for human alveolar echinococcosis, and the corresponding native parasite antigen, were further characterized with immunochemical and molecular biological methods. Immunoblot analysis using a polyclonal antiserum raised in rabbits against the recombinant protein, and subsequent Northern hybridization analysis, revealed that the native antigen was expressed byE. multilocularisat the adult as well as at the metacestode stage. In metacestodes, the antigen was shown by using indirect immunofluorescence and the same antiserum to be localized within the germinal layer and membrane structures of developing protoscolices. Electrophoretic analyses revealed remarkable differences in the apparent molecular weight of the antigen under reducing and non-reducing conditions. In further immunoblot analyses, anti-II/3–10 antibodies identified the corresponding epitopes on bands with identicalMrin allE. multilocularisisolates investigated (European, Asian and North American). By Southern hybridization analyses of the respective gene, phylogenetically related sequences were shown to be present in other helminth species such asE. granulosusand severalTaeniaspp. In the same respect, immunoblotting revealed that anti-II/3–10 antibodies reacted with antigens of differentMrfrom variousE. granulosusisolates and some other cestode species, indicating the presence of shared and thus potentially cross-reacting epitopes. The relevance of these findings for the immunodiagnostic performance of the recombinant antigen is discussed.
The influence of host blood on infection rates in Glossina morsitans sspp. infected with Trypanosoma congolense, T. brucei and T. simiae
Authors: Mihok S. , Olubayo R. O. , Darji N. , Zweygarth E.
Published: June 2009

Trypanosoma congolense, T. brucei and T. simiae isolated from wild-caught Glossina pallidipes were fed to laboratory-reared G. morsitans centralis and G. m. morsitans to determine the effect of host blood at the time of the infective feed on infection rates. Bloodstream forms of trypanosomes were membrane-fed to flies either neat, or mixed with blood from cows, goats, pigs, buffalo, eland, waterbuck and oryx. The use of different bloods for the infective feed resulted in differences in infection rates that were repeatable for both tsetse subspecies and most parasite stocks. Goat, and to a lesser extent, pig blood facilitated infection, producing high infection rates at low parasitaemias. Blood from cows and the wildlife species produced low infection rates, with eland blood producing the lowest. Addition of D(+)-glucosamine (an inhibitor of tsetse midgut lectin) increased infection rates in most cases. These results indicate the presence of species-specific factors in blood that affect trypanosome survival in tsetse. In certain hosts, factors actually appear to promote infection. The nature of these factors and how they might interact with midgut lectins and proteases are discussed.
Comparative electron microscope studies on the epidermis of the blood living juvenile and gill living adult stages of Amphibdella flavolineata (Monogenea) from the electric ray Torpedo nobiliana
Authors: Lyons Kathleen M.
Published: June 2009

The covering layer of Amphibdella flavolineata has been found to be a syncytial cytoplasmic epidermis bearing scattered microvilli and connecting with parenchymally situated ‘cell’ bodies or cytons by means of conspicuous, microtubulelined cell processes. There was no evidence from a comparison of the covering epidermis of the juvenile blood living form and that of the gill living adult that this layer in the juvenile was especially modified for life in the host blood system.The epidermis of adult and juvenile worms was found to be remarkably similar, the main difference being that that of the adult was slightly thicker and bears longer microvilli. Apart from some lamellate bodies of doubtful significance, the inclusions found in the epidermis of adult and juvenile forms were also very similar.The outer epidermis of the juvenile monogenean was found to be quite different from that of Schistosoma mansoni in that it is not permeated by incursive channels and contains many more mitochondria than the epidermis of the digenean. The epidermal cell bodies of Amphibdella tend to have electron-lucent areas especially in the ‘ apical cell’ regions leading to the cell processes that connect with the outer layer. Electron-dense granules secreted by the epidermal cells accumulate in these ‘clear’ regions before being transferred to the outer layer. There is some slight evidence that these electron-lucent regions may have contained glycogen. The epidermal ‘cell’ bodies of the juvenile tend to be multinucleate, whilst those of the adult are usually uninucleate.

Thanks are due to the Director and staff of the Marine Biological Laboratory, Plymouth for providing accommodation and material. The assistance of Mr George Best of the Plymouth Laboratory and Mr Harry Edge of King's College London Botany Department, who maintain the microscopes used in this work, is especially appreciated.
A comparison of multiplication rates in primary and challenge infections ofTrypanosoma bruceibloodstream forms
Authors: McLintock L. M. L. , Turner C. M. R. , Vickerman K.
Published: June 2009

The hypothesis that division ofTrypanosoma bruceislender bloodstream forms is dependent upon the availability of a host-derived growth factor has been tested by superimposing challenge doses of slender-form trypanosomes onto preexisting infections at a time during the primary infection when stumpy forms predominated. The challenge populations grew in the doubly-infected mice indicating that depletion of a putative growth factor by the expanding population of the primary infection had not prevented division of the trypanosomes although slight reductions in multiplication rates were observed. This effect was independent of the variable antigen type (VAT) of the trypanosomes and of their stock of origin.
Hymenolepis diminuta: changes in intestinal morphology and the enterochromaffin cell population associated with infection in male C57 mice
Authors: Mckay D. M. , Halton D. W. , Johnston C. F. , Fairweather I. , Shaw C.
Published: June 2009

Mean villus height, crypt depth and the number of 5-HT-positive enterochromaffin (EC) cells have been examined in two regions of the small intestine (20–30° and 60–70° distance from the pylorus) of male, 6 to 8-week-old, C57 mice following a 5-cysticercoid infection of the rat tapeworm,Hymenolepis diminuta. Test mice and sham-infected controls were autopsied 0, 4, 8, 10, 14 and 28 days post-primary infection (p-1°-i) and 2, 4, 5, 7 and 14 days post-secondary infection (p-2°-i), administered 28 days p-1°-i. Morphometric analysis revealed a statistically significant increase in crypt depth in the 60–70°ointestine region in infected mice during both primary and secondary infections; no significant deviation from the control was observed for villus height in infected mice. Statistical analysis showed a significant increase in the number of 5-HT-positive EC cells in infected mice. This response occurred in the lower portion of the intestine on days 10-p-1°-i and 5-p-2°-i, and was not due to increased mucosal surface area in this region. Results are discussed with reference to murine cestode rejection and the possible involvement therein of the neuroendocrine system.
Population dynamics in echinococcosis and cysticercosis: regulation ofTaenia hydatigenaandT. ovisin lambs through passively transferred immunity
Authors: Gemmell M. A. , Lawson J. R. , Roberts M. G. , Griffin J. F. T.
Published: June 2009

A comparison has been made of the interactions between passively transferred and actively acquired immunity in regulating populations ofTaenia hydatigenaandT. ovis.When ewes were grazed prior to parturition under a high infection pressure, immunity was transferred to their offspring for up to 8 weeks. A qualititative difference between the species was the destruction of larvalT. ovisprior to their establishment (‘pre-encystment immunity’) and that ofT. hydatigenaafter they had become established (‘post-encystment immunity’) in the challenged lambs. The major difference in terms of population regulation between the two parasites was that infection occurred withT. hydatigenabut not withT. ovisin those lambs reared from birth for 16 weeks under high infection pressure. Passive, like active immunity, is a density-dependent constraint. It plays an important role in the population regulation ofT. ovis, but not ofT. hydatigena. This is discussed in terms of transmission in the natural environment, an hypothesis on humoral protection and the need to elucidate pathways of protection when immunization schedules are being evaluated for controlling the taeniid zoonoses.
Differences in the parasite infections in three-spined sticklebacks (Gasterosteus aculeatusL.) of different sex, age and size
Authors: Pennycuick Linda
Published: June 2009

A population ofGasterosteus aculeatusfrom Priddy pool in Somerset was infected with three species of parasites:Schistocephalus solidus,Diplostomum gasterosteiandEchinorhynchus clavula.The variations in the incidence and intensity of the infections with the sex, age and size of the sticklebacks are described.

The infections with the three parasites were very similar in male and female sticklebacks. The weights ofSchistocephaluswere greater in the females, however;the mean weight of the plerocercoids was larger suggesting that they grew more rapidly in female fish.

TheSchistocephalusinfection increased in small fish, under 1 year of age, but in older larger ones the infection decreased. These changes can be related both to the feeding habits of the fish and to the weight relationships of host and parasite.It was found that the weight ofSchistocephalusdid not greatly exceed that of the fish, and also that the combined weight of fish plusSchistocephaluswas rarely greater than 3 g. Therefore the proportional weight ofSchistocephalus, or parasite index, was lower in sticklebacks heavier than about 1·5 g.

TheDiplostomumandEchinorhynchusinfections both increased with age and size of fish, but the largest sticklebacks were not the most heavily infected. These increases can be related to the feeding habits of the fish in the case ofEchinorhynchusand to accumulation with time in the case ofDiplostomum.

In all three species the largest and oldest fish were not the most heavily infected.It is suggested that the old fish are becoming senile and are therefore less able to support large parasite burdens.

I am very grateful to Dr H. D. Crofton for his constant advice and encouragement during this study, and to Dr R. A. Avery for useful discussions. This work was supported by a Science Research Council research studentship and by a NATO studentship.
The biology of Clavella uncinata (Muller) (Crustacea: Copepoda)
Authors: Shotter R. A.
Published: June 2009

Clavella uncinata (Muller) (Crustacea: copepoda) was found infesting 24% of 1352 whiting Odontogadus merlangus (L.) examined from the North Irish sea.A study of the dimensions of the adult female and a comparison of the morphology of copepodid larvae from the Clavella of whiting and pollack Pollachius pollachius (L.) suggests that the Clavella from these gadoids are all one species. Observations on the process of feeding and histochemical analysis of the gut contents indicate that the parasites feed by browsing on the superficial tissues of the whiting and that the mouthparts are used more for the gathering of food towards the mouth than for cutting. Observations show that the hatching of eggs and the behaviour of the nauplii are remarkably similar to these functions in free-living copepods. Examination of Clavella from adult and young whiting, and from living specimens kept alive on the fish, suggests that there are definite cycles of development, that the eggs take about 21 days to mature and that adult Clavella has a life span of no more than 6 months.

I would like to thank the Masters and crews of the R.V. Cuma and R.V. Silver Spray and the staff of the Marine Biological Station, Port Erin for their help in the collection of material. I am especially grateful to Mr D. J. Slinn who guided me throughout this work and to Mr R. Moore for his technical assistance.
The structure and development of the protozoonHistomonas meleagridisin the male reproductive tract of its intermediate host,Heterakis gallinarum(Nematoda)
Authors: Lee D. L.
Published: June 2009

The ultrastructure and development ofHistomonas meleagridisin the reproductive tract of maleHeterakis gallinarumhas been described. In the testis the protozoon is a relatively large amoeboid organism which lies between the epithelial cells of the testis and the spermatogonia, spermatocytes and spermatids. It is similar in appearance to the invasive stage which is found in the final host and like the invasive stage, it also feeds upon the host cells by phagocytosis. In the vas deferens the protozoon lies between the host cells, where it is much smaller than the stages in the testis but still amoeboid, and inside the cells of the vas deferens.Intracellular stages are much smaller than the other stages, are rounded in appearance and cause little or no damage to the host cell. They are similar to the stages found in oocytes of the female nematode. The possible role of the male nematode in the life cycle of the protozoon is discussed.

I wish to thank Mrs B. Fisher for technical assistance and Mr B. Carter for assistance with the photography.
An artificial feeding technique for Glossina
Authors: Moloo S. K.
Published: June 2009

An apparatus for the artificial feeding of tsetse has been described. Fresh defibrinated blood at 36 °C is circulated with a peristaltic pump through feeding capsules. The efficiency of the method has been compared with that of the Cockings' method and with the live host feeding. The flies exposed to feeding on this apparatus showed significantly higher feeding frequency than those allowed to feed on the Cockings' apparatus. Compared with the live host feeding, the feeding frequency for circulating blood method was slightly lower but the difference was not significant. Once the fly is induced to feed, it would in most cases complete engorgement unless disturbed. The rate of crop emptying in flies fed by the Cockings' method was abnormally slower as compared to those fed on the circulating blood. The present study indicates that for the successful artificial feeding of tsetse, it is essential to circulate the blood and regulate the temperature of the medium and the feeding surface to approximately 36 °C.

I wish to thank Mr S. B. Kutuza for technical help, and the Director of E.A.T.R.O. for permission to publish this work.
Trypanosoma congolense: the distribution of enzymic variants in East and West Africa
Authors: Gashumba J. K. , Baker Rose D. , Godfrey D. G.
Published: June 2009

A total of 114 stocks of Trypanosoma congolense originating from Kenya, Uganda, Tanzania, Zambia and Sudan, but including, for comparison, stocks from The Gambia, Liberia, Ivory Coast, Nigeria and Cameroun, were compared by isoenzyme electrophoresis for 6 enzymes. The zymodemes were grouped, both from a dendrogram and using a cladistic method, after calculating the dissimilarity, or distance, between profiles. Previous observations are broadly confirmed, the zymodemes clustering separately according to geographical origin and ecological zone. Thus, one group was composed almost entirely of East African stocks, and another of stocks from both East and West Africa, although each group was of savanna origin. A third group was composed of stocks from the humid, rain-forest zones of West Africa, and was particularly characterized by isoenzyme variants of superoxide dismutase and glucose-phosphate isomerase. Two stocks from the Kenyan coast formed a markedly separate group, which may be taxonomically distinct.
Patterns in helminth communities in freshwater fish in Great Britain: alternative strategies for colonization
Authors: Esch G. W. , Kennedy C. R. , Bush A. O. , Aho J. M.
Published: June 2009

Examples of the apparently stochastic nature of freshwater fish helminth communities illustrating the erratic and unpredictable occurrence and distribution of many species are provided for six species of fish from several localities throughout Britain. By focussing on parasite colonization strategies two categories of helminths are recognized: autogenic species which mature in fish and allogenic species which mature in vertebrates other than fish and have a greater colonization potential and ability. Three groups of fish are distinguished: salmonids, in which helminth communities are generally dominated by autogenic species which are also responsible for most of the similarity within and between localities; cyprinids, in which they are dominated by allogenic species which are also responsible for most of the similarity within and between localities; and anguillids, whose helminth communities exhibit intermediate features with neither category consistently dominating nor providing a clear pattern of similarity. Recognition and appreciation of the different colonization strategies of autogenic and allogenic helminths in respect of host vagility and ability to cross land or sea barriers and break down habitat isolation, and their period of residence in a locality, whether transient or permanent, provides an understanding of, and explanation for, the observed patchy spatial distribution of many helminths. Comparison with other parts of the world indicates that colonization is a major determinant of helminth community structure.
An investigation of hookworm infection and reinfection following mass anthelmintic treatment in the South Indian fishing community of Vairavankuppam
Authors: Haswell-Elkins Melissa R. , Elkins D. B. , Manjula K. , Michael E. , Anderson R. M.
Published: June 2009

Hookworm infections, as assessed by counting worms expelled following anthelmintic treatment and by egg output, were found to be of low prevalence and intensity in a South Indian fishing community. The initial overall prevalence of infection in the community was 43%, and the average burden was estimated at 2·2 hookworms per person. The age profiles of prevalence and intensity differed between males and females, with the latter harbouring significantly higher levels of infection. Children of both sexes under 10 years of age rarely harboured hookworms. Treatment with pyrantel pamoate was estimated to be 91% effective in clearing hookworm infections. Egg counts made on stools collected during an 11-month period of reinfection indicated that female patients became reinfected soon after treatment, while little hookworm egg excretion was observed in males during the observation period following treatment. Females acquired a significantly higher number of worms during the reinfection period compared with males, although the average burden in females reached only 28% of the initial, pre-treatment level. The hookworm population consisted of predominantly Necator americanus, and less than 10% of Ancylostoma duodenale. The parasites were highly aggregated within the host population with 10% of the community harbouring over 65% of the total hookworms. Low values of the negative binomial aggregation parameter, k, (indicating extreme over-dispersion) were recorded in groups stratified by age and sex. Highly significant positive correlations were observed between the initial (pre-treatment) and reinfection worm burdens of female (but not of male) patients. It is suggested that occupational practices related to walking through areas contaminated with hookworm larvae play an important role in generating the observed patterns of infection within this community.
The ultrastructure of the scolex–neck syncytium, neck cells and frontal gland cells of Caryophyllaeus laticeps (Caryophyllidea: Cestoda)
Authors: Sylvia Richards K. , Arme C.
Published: June 2009

The syncytium of the scolex and neck regions of Caryophyllaeus laticeps differs from that of the remainder of the body in a number of ways. The microtriches have short shafts and lamellated spines and the surface cytoplasm is characterized by numerous elongated granules, occasional lipid-like bodies and, in the scolex region, is penetrated by ducts from the frontal glands. The elongated granules arise from the tegumentary neck cells and pass into the syncytium via narrow cell processes possessing extensions of the neck cell microtubule system. The granules have a peripheral sub-structure of regularly spaced electron-lucent areas. Evidence suggests that the granular material becomes more diffuse before extrusion. The spherical, lipid-like bodies also arise from the neck cells, but extrusion from the syncytium was not observed. Homology of the neck cells with the tegumentary cells of the rest of the body is discussed. The frontal glands are restricted to the scolex apex and secrete spherical or sub-spherical, homogeneous granules. The cells, with microtubule-lined ducts, open to the surface via pores which possess an electron-dense ring at which point the microtubule system terminates. Sensory bulbs are also present and will be described in a subsequent communication. The inter-relationships of the gland distribution, scolex morphology and host pathology are discussed.
Nutritional aspects of Ascaris infection in young protein-deficient pigs
Authors: Forsum E. , Nesheim M. C. , Crompton D. W. T.
Published: June 2009

Experiments were carried out to investigate the effects of Ascaris suum infection on the growth, food intake, nitrogen and fat utilization and intestinal function of young pigs receiving diets low in protein. An infection procedure was developed which provided relatively uniform and heavy infections in pigs under study. Ascaris-infected pigs showed statistically significant reduction in growth rate and food intake compared to uninfected controls. The reduction in growth rate was observed after the A. suum were mature and eggs were observed in the faeces of pigs. The degree of growth retardation was significantly correlated with worm burden. Infected pigs showed no consistent reduction in nitrogen and total solids digestibility compared to controls but fat digestion was reduced. The infected pigs showed reduced nitrogen retention compared to uninfected controls. Ascaris-infected pigs had heavier intestinal tracts with increased size of the tunica muscularis. Lactase activity in mucosa from infected pigs was significantly lower than in controls, whereas no consistent effect was observed in mucosal sucrase and maltase activity. When Ascaris-infected pigs were given an oral lactose load, blood glucose levels rose less than in control pigs, suggesting that the infection resulted in impaired lactose tolerance.
Schistosoma mansonihost–parasite relationship: interaction of contrapsin with adult worms
Authors: Modha J. , Doenhoff M. J.
Published: June 2009

Contrapsin, a serine protease inhibitor (serpin) present in mouse serum, was compared with that found in adultSchistosoma mansoniworm homogenates, which although immunologically identical to contrapsin in mouse serum, had a higher molecular weight in Western blotting. Immunolocalization studies demonstrated parasite-associated contrapsin on the surface and interstitial cells of adult male worms. After extraction of these parasites with Triton X-114, contrapsin was found in the aqueous phase of the detergent, suggesting it is unlikely to be an integral membrane protein. Treatment of adult worms with deoxycholate resulted in a change in the electrophoretic behaviour of worm-derived contrapsin. Parallel studies with trypsin suggested this was due to interaction of the serpin with a protease. Using porcine pancreatic trypsin as a model for a putative schistosome protease reacting with contrapsin, we have shown that trypsin, following complex formation with contrapsin, loses immunogenicity. Thus, when contrapsin–trypsin complexes were used as immunogen, the resulting antisera contained antibodies to contrapsin and contrapsin–trypsin complexes only, and none to native trypsin. Thus, epitopes characterizing native trypsin were presumably either masked following complex formation with contrapsin, or their processing and presentation to antigen presenting cells was suppressed, so that an antibody response was not mounted against them. These observations encourage speculation thatS. mansonimay be elaborating an immune evasion strategy whereby immunologically sensitive proteases are first complexed with host serpins, which would render them immunogenically inert, and then cleared from the circulation by the host's reticulo-endothelial system. In this way the immune system would be unable to ‘see’ sensitive parasite proteases sufficiently to mount a response against the parasite.
Localization of parasite antigens inCryptosporidium parvum-infected epithelial cells using monoclonal antibodies
Authors: McDonald V. , McCrossan M. V. , Petry F.
Published: June 2009

An immunogold ultrastructural study was made ofCryptosporidium parvum-infected intestinal cells from SCID mice to locate parasite antigens recognized by monoclonal antibodies raised against sporozoite or oocyst wall antigens. The results suggested that these antigens were present in more than one life-cycle stage and demonstrated that the intracellular parasite modified the parasitophorous vacuole membrane and villous membrane surrounding the parasite. In an immuno-fluorescence antibody test monoclonal antibody (MAb) IB5 reacted with the oocyst wall, MAb 2C3 with the whole sporozoite and MAb 2B2 with the sporozoite surface. Western and dot-blot studies demonstrated that different carbohydrate epitopes were recognized by the respective sporozoite-reactive antibodies. In the ultrastructural examination MAb 1B5 reacted with macro- and microgametocytes as well as the oocyst wall. In the macrogametocyte MAb 1B5 recognized the large electron-dense bodies characteristic of this stage and, in some parasites, the parasitophorous vacuole and the parasite pellicle. The sporozoite-reactive MAbs were able to bind to all developmental stages. These antibodies recognized the parasite cytoplasm and, additionally, MAb 2B2 produced substantial labelling of the parasite membrane. Significantly, both these antibodies also detected antigen in the parasitophorous vacuole membrane and, to a lesser extent, the villous membrane surrounding the parasite.
Karyotype plasticity in NeotropicalLeishmania: an index for measuring genomic distance amongL. (V.) peruvianaandL. (V.) braziliensispopulations
Authors: Dujardin J. C. , Dujardin J. P. , Tibayrenc M. , Timperman G. , De Doncker S. , Jacquet D. , Arevalo J. , Llanos-Cuentas A. , Guerra H. , Bermudez H. , Hamers R. , Le Ray D.
Published: June 2009

A method for phenetic analysis of karyotype data has been developed forLeishmaniapopulations. Measurement of size difference between chromosomes recognized by a given DNA probe in different isolates led to the formulation of a Chromosome Size Difference Index (CSDI). The method was applied to phenetic analysis of 4 sets of chromosomes – each set being recognized by a different probe – in 37L. (Viannia) peruvianaisolates sampled along a North–South transect through the Peruvian Andes and, in 11L. (V.) braziliensisisolates from the Amazonian forest (Peru, Bolivia and Brazil). Karyotype variability was better accounted for by CSDI than by a method based on disjunctive encoding of karyotype data. CSDI evidenced the nature of relationships betweenL. braziliensisandL. peruvianaand it provided a coherent picture of geographical and genomic differentiation among parasite populations. The latter did cluster according to their geographical origin.L. braziliensiswas found karyotypically more homogeneous thanL. peruviana. WithinL. peruviana, Northern populations were closer toL. braziliensisthan to SouthernL. peruvianapopulations. The validity of karyotypic populations, or karyodemes, was sustained.
Schistosoma mansoni: patterns of codon usage and bias
Authors: Ellis J. T. , Morrison D. A.
Published: June 2009

Codon usage and bias has been examined in 20 genes ofSchistosoma mansoni. Significant heterogeneity was detected in the patterns of codon usage and bias among genes by metric multidimensional scaling and three general indictors of bias (GC3S, Ncand B). In keeping with observations on sporozoan parasites, codon usage bias was observed to be dependent on the overall base composition of the genes analysed, which in turn was reflected in the types of codons that were over or under-represented in the sequences.
Intestinal migration in the life-cycle of Pseudodiplorchis americanus (Monogenea)
Authors: Tinsley R. C. , Jackson Helen C.
Published: June 2009

Adults of Pseudodiplorchis americanus occur in the host's urinary bladder, the typical habitat of polystomatid monogeneans in amphibians. However, larvae which invade the respiratory tract via the nostrils then migrate to the bladder through the stomach and intestine, a route which is without precedent amongst monogeneans. Parasite transmission is correlated with the spawning of the desert toad Scaphiopus couchii (June/July in Arizona, USA) and the gut migration, which takes as little as 5 min, occurs after 26 days post-infection (p.i.). Migration occurs during the host's feeding season, and therefore the parasites normally encounter maximum digestive activity along their path. Worms transferred experimentally from respiratory tract to the digestive fluids in the gut are killed within 60 s. However, natural migration is stimulated by an unidentified host factor which triggers protective adaptations, enabling parasite survival for up to 4 h in these lethal conditions. Without this essential stimulus, migration may be delayed for over 1 year and juveniles remaining in the respiratory tract undergo no development beyond that reached at 4 weeks p.i. Rapid reproductive development is resumed immediately after migration, leading to maturation around 1 month later and progressive accumulation of embryos in utero in preparation for transmission during the next summer's rains.
Ovarian tissue in juvenile palaeacanthocephalans: Corynosoma semerme, C. strumosum and Echinorhynchus gadi
Authors: Peura Raija , Valtonen E. Tellervo , Crompton D. W. T.
Published: June 2009

The structure of the ovarian tissue in juvenile Corynosoma semerme and C. strumosum from a fish paratenic host and in the cystacanth stage of Echinorhynchus gadi from an amphipod intermediate host was investigated by means of transmission electron microscopy. The species were obtained from hosts living in the Baltic Sea. The observations indicate that ovarian development was more advanced in cystacanths of E. gadi than in juveniles of C. semerme and C. strumosum. Free ovaries were present in E. gadi with an obvious supporting syncytium and surface microvilli. The biological significance of the different stages of ovarian development in these species is discussed briefly in relation to either reproductive strategies and host specificity in definitive hosts or to the attainment of infectivity by cystacanths in intermediate hosts.
Permeability changes in the egg-shell of hookworms during development and eclosion
Authors: Matthews B. E.
Published: June 2009

The development and hatching ofAncylostoma ceylanicumandAncylostoma tubaeformeeggs in a range of potentially inimical solutions has been examined using time-lapse video micro-recording techniques. In all compounds tested the larvae developed to the active pretzel stage. The inception of activity resulted in an increase in shell permeability to water and small molecules. In anthelmintics of molecular weight (Mr) 400 development continued normally until about the time that control eggs hatched, when there was a marked decrease in larval activity and eclosion did not occur. The addition of a lowMrsurface-active agent potentiated the effect of the anthelmintic and caused larval activity to be lost earlier. The calcium inhibitor lanthanum chloride affected larval development rather than eclosion. LargeMrcompounds did not affect either development or hatching and the results suggest that the egg-shell may act as a form of sieve, allowing the essential oxygen to reach the developing larva while excluding large potentially dangerous molecules. No appreciable differences were found between the two species of hookworm examined.