bluuebunny/crossref_metadata_2025 huggingface dataset:
Transstadial transmission of Theileria annulata through common ixodid ticks infesting Indian cattle
Authors: Bhattacharyulu Y. , Chaudhri R. P. , Gill B. S.
Published: June 2009

Transstadial transmission of Theileria annulata with Hyalomma anatolicum anatolicum, H. dromedarii and H. marginatum isaaci, and Haemaphysalis bispinosa, Rhipicephalus haemaphysaloides haema-physaloides and Boophilus microplus was determined.

It was found that the infection was successfully transmitted by H. a. anatolicum from larva to nymph and nymph to adult in all attempts. When larvae were fed on an infected calf the succeeding adults transmitted the infection when the intervening nymphs fed on a rabbit (nonsusceptible host) but not when fed on a calf (susceptible host). Infective adult ticks transmitted the parasite during the first 24 h of feeding on a calf. When the feeding was interrupted after 24 h, and the tick transferred to another calf, the infection was transmitted to the latter as well.

H. dromedarii successfully transmitted the infection from larva to nymph and from nymph to adult.

Larvae of H. marginatum isaaci did not feed on calves but the infection was successfully transmitted from nymph to adult.

Haemaphysalis bispinosa, Rhipicephalus h. haemaphysaloides and Boophilus microplus did not transmit Th. annulata from larva to nymph to adult.
Genetic control of immune responses to parasites: immunity to Trichuris muris in inbred and random-bred strains of mice
Authors: Wakelin P.
Published: June 2009

A comparison has been made of the responses of random-bred CFLP and inbred NIH mice to infection with Trichuris muris. Random-bred mice showed greater variation in worm burdens and less uniformity in worm expulsion. Irradiation prior to infection reduced variation, but did not increase the mean level of infection above that shown by the most susceptible unirradiated mice. In NIH mice, however, irradiation raised the level of infection in all mice. The factors responsible for variation between CFLP mice and for the level of infection in NIH mice came into play after the fifth day of infection and were inactivated by cortisone acetate. It is suggested that these factors are immunologically mediated and under direct genetic control. Uniformity of infection and expulsion in NIH mice is therefore seen as a consequence of genetic uniformity; variability in CFLP mice as a consequence of genetic variation.

The time of worm expulsion was found to differ markedly between inbred strains of mice. Hybrid progeny showed the expulsion time characteristic of the parental strain with the most rapid expulsion; greater resistance was therefore inherited as a dominant characteristic. The genetic control of immunity to T. muris is discussed in the context of the antibody- and cell-mediated components of the expulsion process.
Carbon dioxide fixation in trypanosomatids
Authors: Klein R. A. , Linstead D. J. , Wheeler M. V.
Published: June 2009

Fixation of carbon dioxide has been demonstrated for extracts fromCrithidia fasciculata, Trypanosoma megaandTrypanosoma brucei bruceibloodstream and culture forms. The enzymes involved in this fixation were found to be ADP-stimulated phosphoenolpyruvate carboxykinase (E.C. 4. 1. 1. 32), ‘malic’ enzyme (E.C. 1. 1. 138–40) and pyruvate carboxylase (E. 0. 6. 4. 1. 1). The subcellular localization of these enzymes has been investigated in all three organisms. Products of short and long term fixation experiments were separated and identified.

The importance of carboxylation reactions is discussed in relation to the maintenance of oxidized and reduced coenzyme levels.
In vitro suppression of segmentation in Echinococcus multilocularis with morphological transformation of protoscoleces into monozoic adults
Authors: Smyth J. D. , Davies Zena
Published: June 2009

When protoscoleces of Echinococcus multilocularis were cultured in vitro, under axenic conditions in either monophasic or diphasic media, segmentation was suppressed in most organisms, some 70–80% of which developed into unsegmented, monozoic forms with a complete set of sexually mature male and female genitalia. The most striking feature of monozoic worms was the large lateral swelling produced by the cirrus sac the effect being to produce organisms with an unusual asymmetric shape. Worms which did not become monozoic either (a) underwent some somatic growth, developed two sets of genitalia and became ‘pseudosogmented’, i.e. with the inter-proglottid membranes absent or poorly defined, or (b) became vesicular or abnormal. The mechanisms which could be involved in the suppression of somatic growth and the induction of the monozoic condition, are examined in terms of cell lineage. The possible significance of these results in understanding the evolution of the cestodes is discussed.
Population biology ofBothriocephalus rarusThomas (1937) in the red-spotted newt,Notophthalmus viridescensRaf
Authors: Jarroll E. L.
Published: June 2009

The distribution and abundance of the cestodeBothriocephalus rarusinfecting red-spotted newts,Notophthalmus viridescens, were studied for over 1 year in an artificial pond in West Virginia, USA.Macrocyclops aterandMesocyclops edaxwere found to harbourB. rarusprocercoids experimentally, andM. aterwas confirmed as a natural intermediate host for this cestode. The recruitment ofB. rarusby newts coincided with the peak density ofM. ater, indicating thatB. rarusmay have adapted itself to the copepod life-cycle to increase the probability of successful parasite transmission. Infection was more frequent and of higher intensity in larval newts. The observed frequency distribution of cestodes in all segments of the newt population closely fits the negative binomial. The data indicated seasonal cycles in population structure, intensity of infection, maturation and reproduction. Recruitment of worms by adult newts occurred in June, July and August, at the time when the density of adult worms decreased.
Redescriptions of Eimeria irresidua Kessel & Jankiewicz, 1931 and E. flavescens Marotel & Guilhon, 1941 from the domestic rabbit
Authors: Norton C. C. , Catchpole Janet , Joyner L. P.
Published: June 2009

Eimeria flavescens and E. irresidua from the domestic rabbit are redescribed. The relatively smaller ovoidal oocysts of E. flavescens which measure on average 31·7 × 21·4 μm, possess a wide micropyle at the broad end. First-generation schizonts of this species develop deep in the glands of the lower small intestine. Merozoites migrate to the caecum and colon where second, third and fourth-generation schizonts develop in the superficial epithelium followed by the fifth-generation schizonts and gametocytes which form in the glands. In young Dutch rabbits E. flavescens is very pathogenic; low doses of oocysts produce a severe enteritis with high mortality and morbidity. The larger, broadly ellipsoidal oocysts of E. irresidua measure on average 38·4 × 23·2 μm and often possess a very small cryptic oocyst residuum. The endogenous stages develop in the small intestine only; first-generation schizonts in the glands and second-generation schizonts in the lamina propria whilst third and fourth-generation schizonts and gametocytes develop in the villous epithelium. E. irresidua is not pathogenic in young Dutch rabbits; even heavy infections produce only a transient pause in weight gain.
Studies on heterologous resistance betweenSchistosoma mansoniandFasciola hepaticain inbred rats
Authors: Ford M. J. , Taylor M. G. , McHugh S. M. , Wilson R. A. , Hughes D. L.
Published: June 2009

Fischer rats infected withFasciola hepaticashowed significant resistance toSchistosoma mansonichallenge, and vice versa, whereas immunization with 20 Krad-irradiatedS. mansonicercariae failed to protect againstF. hepaticachallenge, but did protect against homologous challenge. When groups of rats received intraperitoneal implants of newly excysted juvenile flukes, 20- to 22-day-old juveniles, or 8- to 10-week-old flukes, none was significantly protected againstS. mansonichallenge, whereas juvenile implants did protect against homologousF. hepaticachallenge. In passive transfer experiments in rats, serum fromF. hepatica-infected rats or rabbits protected recipients against homologous, but not heterologous challenge, and serum from rats vaccinated with 20 Krad-irradiatedS. mansonicercariae protected recipients against homologous, but not heterologous challenge. These experiments provide evidence that the mechanisms involved in homologous and heterologous resistance are different, the latter lacking immunological specificity. Microsphere injections inF. hepatica-infected rats demonstrated ‘shunting’ from the portal system to the systemic circulation. If migrating schistosomula are also ‘shunted’ inFasciola-infected rats, this, rather than immunologically specific effector mechanisms, might explain their failure to establish in the portal system.
Reduction of niridazole by metronidazole resistant and susceptible strains ofTrichomonas vaginalis
Authors: Yarlett N. , Rowlands C. C. , Yarlett Nuriza C. , Evans J. C. , Lloyd D.
Published: June 2009

The inhibitory effect of niridazole on hydrogen production by metronidazole-resistant (CDC-85) and susceptible (Cl-NIH)Trichomonas vaginalisstrains was investigated. The results show that niridazole is more effective than metronidazole in inhibiting hydrogen production by the resistant isolate. In CDC-85 aerobic inhibition requires a 4-fold increase in metronidazole concentration compared with that required anaerobically, but the corresponding factor for niridazole is only 1·5-fold. Reduction of the drug by a hydrogenosome-enriched preparation gave rise to a multiline electron spin resonance detectable signal, which is due to a nitrogen-centred radical.
Trichinella spiralis: immunocytochemical localization of surface and intracellular antigens using monoclonal antibody probes
Authors: McLaren Diane J. , Ortega-Pierres Guadalupe , Parkhouse R. M. E.
Published: June 2009

A panel of immunologically and biochemically defined monoclonal antibody probes has been used in conjunction with immunocytochemical techniques to localize target antigens in sections of different life-cycle stages ofTrichinella spiralis. Monoclonals that immunoprecipitate surface components from adult worms, show reactivity with the surface but not with internal tissues of sectioned parasites. Reagents that immunoprecipitate radio-isotope labelled stage-specific surface components of muscle-stage larvae, however, react with the stichosome and gut lining of sectioned larvae, as well as with the surface. Monoclonal antibody probes that do not stain the surfaces of live, intact muscle larvae in immunofluorescence assays, but which immunoprecipitate solubilized surface glycoproteins, also show reactivity with cuticular and stichosomal antigens of sectioned larvae. The more powerful resolution provided by electron microscopy has localized the surface antigens to the epicuticle and the intestinal antigens to the brush-border microvilli. Of particular interest was the finding that antigens of muscle-stage larvae, known to confer protection upon recipient mice, also exist in the stichosome of adult parasites. This observation may shed some light on the fact that mice immunized with antigens from muscle-stage larvae show, in addition to reduced muscle larva burden, accelerated expulsion of adult worms. The implications of these data for stage specificity of immune responses to trichinosis are discussed.
Effects of anti-thymocyte serum on the eosinophil and lysophospholipase responses in mice infected withTrichinella spiralis
Authors: Adewusi K. , Goven A. J.
Published: June 2009

Anti-thymocyte serum (ATS) was administered to CD-1 mice infected with 100Trichinella spiralislarvae and its effects on intestinal lysophospholipase (EC 3.1.1.5) activity, peripheral blood lymphocytes and bone marrow, peripheral blood and intestinal eosinophilia were assayed in the same experimental animal. The ATS caused a significant suppression of both the tissue lysophospholipase response and eosinophilia, in all three compartments, when compared to the values found in infected mice that were either treated with normal rabbit serum (NRS) or untreated. The suppressed eosinophil response and reduced lysophospholipase activity demonstrated a close temporal relation throughout the experiment. These findings support the hypothesis that helminth parasite-induced eosinophilia is the cause of increased lysophospholipase activity present in parasitized tissue and that the responses are thymus cell dependent.
Insect viruses as control agents
Authors: Payne C. C.
Published: June 2009

Virus diseases have been reported from more than 800 species of insects and mites. Isolates of the baculovirus and cytoplasmic polyhedrosis virus groups have biological properties which should lead to their successful use as microbial control agents in integrated pest management programmes. These viruses infect the larval stages of many lepidopterous and hymenopterous pests, producing a chronic or lethal infection and the release of large quantities of relatively stable infective inclusion bodies (IBs). The IBs serve as the means by which the viruses are transmitted and persist outside the host. Younger larvae are more susceptible to infection than older stages, and this difference influences the timing of application and doses of virus needed for practical pest control. The high degree of host specificity of many isolates reduces their potential ecological hazard but also limits their use, particularly on crops where a complex of pests is established. Environmental persistence is also a limiting factor as virus is rapidly inactivated by ultra-violet light even when contained within IBs. The viruses persist for longer periods when transmitted within the host population, a feature of virus infections restricted to the insect gut.

The practical use of insect viruses in horticulture and agriculture does not utilize their full epizootic potential, but takes advantage of their high pathogenicity and specificity. The baculoviruses of codling moth, andHeliothisspp. provide satisfactory pest control, but for their most cost-effective use it is important to determine the minimum dosage rates of virus required. It is encouraging that studies of the virus control ofPierisspp. have suggested that control achieved by the insecticidal use of a virus can be closely predicted from information on dosage-mortality responses, larval feeding rates and virus persistence. The stability of forest and grassland, and their high economic thresholds makes them ideal candidates for longer-term control. Viruses of the coconut rhinoceros beetle and european spruce sawfly provide examples of classical biological control where the viruses persist for long periods, are efficiently transmitted and act as natural regulators of their hosts. Virus control of pasture, and some forest, pests may be possible by manipulating enzootic viruses without the need for direct control measures. More frequently insecticidal applications are needed, providing control of limited duration which requires periodic ‘topping-up’.

Few viruses are commercially-available; their selectivity and often small potential market, may limit industrial interest. However, improvements in virus production, formulation and a better understanding of virus epizootiology should lead to an increasing role for this group of insect pathogens in biological control.
Current status of nematodes for the biological control of insects
Authors: Petersen J. J.
Published: June 2009

This review highlights published research on the principal entomogenous nematodes that have potential as biological control agents of insects. The life-cycles and status of promising members of the families Allantonematidae, Diplogasteridae, Heterorhabditidae, Mermithidae, Neotylenchidae, Rhabditidae, Sphaerulariidae, Steinernematidae and Tetradonematidae are discussed. Emphasis is placed on attempts to control insect populations with these nematodes. Mass propagation of the Steinernematidae and Mermithidae are also discussed, including currentin vivoandin vitrorearing systems. A number of these nematodes show promise as biological control agents but commercial development has been slow because of environmental limitations, host specificity and inherent problems associated with manipulation of living organisms. Although some of these nematodes have been considered for commercial preparation, it appears that they will remain ‘on the shelf’ until the need for such biological control provides small businesses with the incentive to make them available for general use.
Fungi as biological control agents of arthropods of agricultural and medical importance
Authors: Hall R. A. , Papierok B.
Published: June 2009

There are many species of fungi attacking terrestrial and aquatic insects of agricultural and medical importance. Of these, few species have received much attention with a view to their use as biological control agents. The mechanisms of infection have been comparatively well studied, although many questions remain to be answered. The knowledge so far obtained has shed some light on the reasons for host specificity. Temperature, above all relative humidity, and their interactions are the most important physical factors influencing infection of terrestrial insects by entomopathogenic fungi and these are discussed in relation to epizootiological events. In aquatic environments, temperature, salinity and organic pollution are the important factors. In addition to these physical factors, numerous biotic factors at the level of the insect and the fungal pathogen influence both infection and spread of disease in insect populations. The complexity of the interactions of the biotic and abiotic factors makes it extremely difficult to study the influence of any one of these. Virulence of fungal pathogens and its measurement are discussed, together with the shortcomings of present bioassay systems; virtually no laboratory bioassay system exists which has been designed to yield data meaningful in the field. Mass-production techniques are described as are their inherent problems and those of formulation and storage. Finally, the achievements of fungal control of insects in the field are reviewed. Thus far, several species are mass-produced and are in widespread use, two of which,Verticillium lecaniiandHirsutella thompsonii, have been commercialized. More studies, ecological, fundamental and developmental are required in this field to realize fully the potential of other candidate fungi.
Parasitoids as biological control agents – a fundamental approach
Authors: Waage J. K. , Hassell M. P.
Published: June 2009

This review begins with a description of the parasitoid life-style and the ecological and evolutionary factors which generate the remarkable diversity of insect parasitoids. We then describe the various ways that parasitoids have been used in the biological control of insect pests, and survey their success to date. The use of parasitoids remains largely an art, aided by past experience of success and failure. A more fundamental approach, involving basic research and theory, has not as yet contributed significantly to practical biological control. We explore the potential for such a science of parasitoid use and review basic research on parasitoid ecology and evolution which is of particular relevance to biological control. Mathematical models are used to identify and examine those parasitoid and host attributes which lead to successful biological control. Factors such as parasitoid foraging behaviour, fecundity, larval survival and sex ratio are shown to be important in influencing the depression of host populations and/or the stability of host–parasitoid interactions after depression. Multiple release is discussed and a model for inundative release of parasitoids is explored.
Evolutionary implications of Leishmania amastigotes in circulating blood cells of lizards
Authors: Telford S. R.
Published: June 2009

Amastigotes of 2 Leishmania species are reported from the Pakistani lizards Teratoscincus scincus (Gekkonidae) and Agama agilis (Agamidae) collected in western Baluchistan and north-central Sind, respectively. Parasites were seen only in blood cells, primarily within thrombocytes, and were detected on smears of peripheral blood. Slides made at 3-day intervals for 38 days from an infected hatchling T. scincus demonstrated an increase with time in the mean number of amastigotes/infected thrombocyte. No evidence of an infection focus in fixed cells of the viscera was found. It is suggested, in view of reports of amastigotes in circulating blood cells of hosts belonging to 5 genera, collected in 5 countries from India to France, that saurian Leishmania may behave simply as parasites of circulating blood cells, thus illustrating an early stage in the adaptation of leishmanias to the vertebrate host.
An experimental study of the effects of Nosema eurytremae (Microsporida: Nosematidae) on the liver fluke Fasciola hepatica
Authors: Canning Elizabeth U. , Higby G. C. , Nicholas J. P.
Published: June 2009

A microsporidian parasite, Nosema eurytremae, was fed to Lymnaea trunculata infected with Fasciola hepatica. Microsporidian infection of the snail was always light, though spores were present in all tissues, but the rediae became heavily infected in the parenchyma. The proportion of infected rediae increased with time and was especially high in ageing infections. Although rediae were only lightly infected when examined before cercarial release began, the infections became progressively heavier, so that towards the end of the life of the snails a high proportion of rediae were totally destroyed and contained no cercariae. Cercarial output was significantly depressed over a long period of active shedding by snails which had been hyperinfected with 1 × 10 6 spores and some of the liberated cercariae were themselves infected.
Acid phosphatase activity demonstrated by intact Angiostrongylus cantonensis with special reference to its function
Authors: Maki Jun , Yanagisawa Toshio
Published: June 2009

Intact Angiostrongylus cantonensis is able to hydrolyse glucose-phosphate esters, mononucleotides and p-nitrophenyl phosphate as well as β-glycerophosphate in vitro. Reciprocal inhibition studies suggest that the hydrolysis of such substrates is due to a non-specific phosphomonoesterase. Molybdate ions, which exert no effect on either the uptake of glucose or the production of lactate, inhibit the hydrolysis of glucose-1- phosphate in the external medium and simultaneously lower the production of lactate by the intact worms in vitro.
The development of the metacercaria of Maritrema linguilla Jäg., 1908 (Digenea: Microphallidae) in the intermediate host, Ligia oceanica (L.)
Authors: Benjamin L. R. , James B. L.
Published: June 2009

The first two phases in the growth of Maritrema linguilla in Ligia oceanica, which occur in unencysted specimens in the pleopod sinuses, from day 0 to day 28 post-infection (p.i.), include a 3-fold increase in size, an enormous increase in the relative size of the excretory bladder, metamorphosis of papilliform extensions of the tegument into microvilli and development of single pointed spines and cystogenous gland cells. The third phase, from day 29 to day 38 p.i., following migration to the dorsal haemocoel, includes production of 3 cyst wall layers, the loss of single pointed spines and a considerable decrease in the relative size of the excretory bladder. The fourth phase from day 39 to day 42 p.i., involves a further increase in body size and the formation of digitiform spines. The fifth, sixth and final phases from day 43 to day 120 p.i. first include the completion of the last two cyst wall layers and then an increase in body size and development of the digestive, excretory and reproductive systems to almost adult dimensions but sperm, ova, vitelline globules and eggs are produced only in the final host.
Enzyme polymorphism and the identity of Trypanosoma brucei gambiense
Authors: Godfrey D. G. , Scott Catherine M. , Gibson Wendy C. , Mehlitz D. , Zillmann U.
Published: June 2009

Thirty-two isolates from man in known areas of Gambian trypanosomiasis, in the Sudan, Kenya, Zaire, Nigeria, Ivory Coast, Burkina Faso, Liberia and Senegal, were examined by isoenzyme electrophoresis of 11 enzymes. Comparisons were also made with our previously published results on 23 other stocks of similar origins, which had been examined in the same manner. All those stocks of low initial virulence to laboratory rodents, which thus conform to the accepted view of the behaviour of Trypanosoma brucei gambiense can be identified by characteristic combinations of enzyme patterns, especially certain aminotransferase markers. A limited study of superoxide dismutase polymorphism suggested a further marker of value. The isolates of high initial virulence to rodents, which are thus behaviourally akin to T. b. rhodesiense, did not share these characteristics. We conclude that there exists a homogeneous group of trypanosomes of wide dispersion throughout tropical Africa, characterized by certain isoenzyme combinations and low initial virulence to rodents, which corresponds to the classical concept of T. b. gambiense. The features of limited antigenic repertoire, high resistance to normal human serum and restriction fragment length polymorphisms of the genes for certain variant surface glycoproteins also appear to be characteristic of this group.
Experimental infection of laboratory rats with Corynosoma semerme (Acanthocephala)
Authors: Valtonen E. Tellervo , Helle Eero
Published: June 2009

Ten albino rats injected with hydrocortisone were infected with 36–66 cystacanths of Corynosoma semerme in order to study the course of infection in a warm-blooded animal. Surveys were carried out 2, 5, 8, 14, 18, 21 and 28 days after infection. Recovery decreased from 60% after 2–5 days to 22% after 28 days. The proportion of males dropped markedly before the 8th day of infection. The worms were concentrated in the latter half of the intestine, the males being in a more anterior location on average. The males matured between the 2nd and 5th day of infection. Disintegrated ovaries were observed in some of the 2-day-old females, but mature free ovaries were seen only in 5-day-old females. By the 14th day many females contained fully developed eggs, but it was only after the 18th day that the number of eggs increased considerably. Male worms were not encountered in the 4-week-old infection. The females were longer than the males. In the present study, experimental infections are compared with other acanthocephalan infections in both birds and mammals.
An unusual structural organization to the gut of a digenetic trematode, Fellodistomum fellis
Authors: Halton D. W.
Published: June 2009

An ultrastructural examination of Fellodistomum fellis has revealed that the caecal lining consists of 2 distinct components: (a) cup-shaped digestive cells and (b) a pleomorphic layer of cytoplasm which supports and separates individual digestive cells. The digestive cells sequester host blood components within apical pockets formed by lamellated extensions of the cell surface, and undergo asynchronous, cyclical transformations in morphology associated with extracellular digestion and with the extrusion to the gut lumen of pigmented digestive residues. Histochemical tests and elemental analysis of the pigment suggest that it is a ferripor-phyrin, haematin. In the anterior portion of the caecum the supporting cytoplasmic layer is in continuity with the oesophageal tegument and snares the same ultrastructure. It is concluded that the digestive cells are supported by an extension of the foregut tegument.
Genetic control of resistance to infection with Nematospiroides dubius in mice: selection of high and low immune responder populations of mice
Authors: Sitepu P. , Dobson C.
Published: June 2009

F1, Quackenbush (Q) × Wild (W) Mus musculus were assayed and selected for their level of immunity to secondary infections with 100 Nematospiroides dubius using faecal parasite egg counts. A significant positive linear correlation was found between the number of parasite eggs voided in the faeces and the number of N. dubius recovered after secondary infections in mice. Selection for immunity was not influenced by the conformation of the mice. High (H) and low (L) responder colonies together with a randomly (Rd) bred colony of mice were established over 5 generations. Adaptive immunity was more efficacious in protecting female than male mice and appeared to be controlled by a few dominant genes; the heritability (h2) of the trait was estimated at 0·56 for the parental stock and 0·55 for the F5 Rd colony and the realized heritability was 0·49. Higher anti-N. dubius antibody titres were detected in H than L mice. H mice harboured fewer and less fecund parasites than Rd colony mice; L mice had more worms with greater fecundities than Rd mice. The levels of primary infection in H and L mice related to the levels developed after secondary infection from F4. This suggested at least partial linkage of genes controlling innate with genes controlling adaptive immunity against N. dubius.
Population dynamics ofAngiostrongylus cantonensisduring primary infections in rats
Authors: Kwong Yong Weng , Dobson Colin
Published: June 2009

About 35 ofAngiostrongylus cantonensislarvae became patent adults irrespective of the dose used to establish primary infections in laboratory rats. Worm growth and fecundity was depressed in infections from high compared with low doses of infective larvae. Rats infected with up to 50A. cantonensislarvae survived infection better than rats given greater numbers of larvae. The biology ofA. cantonensissurviving in laboratory rats from single infections with 50 larvae for over a year was studied. Stable worm numbers and fecundity were established 90 days after infection but the worms continued to grow until the experiment was terminated.
Coevolution of hosts and parasites
Authors: Anderson R. M. , May R. M.
Published: June 2009

The coevolution of parasites and their hosts has both general biological interest and practical implications in agricultural, veterinary and medical fields. Surprisingly, most medical, parasitological and ecological texts dismiss the subject with unsupported statements to the effect that ‘successful’ parasite species evolve to be harmless to their hosts. Recently, however, several people have explored theoretical aspects of the population genetics of host-parasite associations; these authors conclude that such associations may be responsible for much of the genetic diversity found within natural populations, from blood group polymorphisms (Haldane, 1949) to protein polymorphisms in general (Clarke, 1975, 1976) and to histocompatibility systems (Duncan, Wakeland & Klein, 1980). It has also been argued that pathogens may constitute the selective force responsible for the evolution and maintenance of sexual reproduction in animal and plant species (Jaenike, 1978; Hamilton, 1980, 1981, 1982; Bremermann, 1980).
Sodium azide preservation of faecal specimens for Kato analysis
Authors: Bundy D. A. P. , Foreman J. D. M. , Golden M. H. N.
Published: June 2009

The modified Kato technique has the advantages of reproducibility, simplicity and economy: the disadvantage is that it cannot be used in conjunction with traditional faecal preservatives. Sodium azide has been evaluated as a preservative for human faeces for subsequent Kato analysis. More than 400 faecal samples (from normal and malnourished children, and from mixed-age participants in a field survey of the Turks and Caicos Islands) were each mixed with 2–5 mg of sodium azide powder and stored in 2 or 4 ml autoanalyser cups at ambient tropical temperature. At intervals up to 30 weeks, aliquots were prepared for Kato analysis.Trichuris trichiura, Ascaris lumbricoidesandNecator americanuseggs were well preserved without degenerative or developmental changes in morphology. Quantitative analyses of 18 samples indicated that the mean egg count/sample did not change significantly after storage for 1, 2, 4, 8, 12 and 16 weeks in preservative. The use of azide preservative extends the applications of the Kato technique to field and clinical studies in which delays may occur between specimen collection and examination. The direct costs of azide preservation are substantially lower than for traditional methods and the preserved specimens are more compact and resistant to leakage.
Rate ofLeishmania-induced skin-lesion development in rodents depends on the site of inoculation
Authors: Kirkpatrick C. E. , Nolan T. J. , Farrell J. P.
Published: June 2009

Regional differences in the response of mice to infection with three strains of dermotropicLeishmaniaspp. were shown for skin covering the trunk. Lesions tended to appear earlier and to grow more rapidly on sites over the caudal half of the body than the cranial half, and caudal lesions were more likely than cranial ones to result in metastatic disease in susceptible strains of mice. Site-related variations in lesion development were observed in different strains of mice as well as in golden hamsters. The effect of these regional differences on the development of some parasite-specific, immunological reactions was examined, as were parasite thermosensitivity and location-related variations in host skin temperature as possible explanations.
ExperimentalEchinococcus granulosusinfection in mice: immunocytochemical analysis of lymphocyte populations in local lymphoid infections during early infection
Authors: Riley Eleanor M. , Dixon J. B.
Published: June 2009

The influence of subcutaneous infection with protoscoleces ofEchinococcus granulosuson the distribution of lymphocyte subsets in draining lymph nodes has been evaluated by immunocytochemical labelling of lymphocyte surface antigens. These studies reveal marked expansion of paracortical Thy-1 +, Lyt-1 + cells and moderate proliferation of surface immunoglobulin-bearing B-cells immediately after infection. The Lyt-1 +:Lyt-2 + ratio decreases rapidly during the first 21 days post-infection and remains below unity until at least 12 weeks post-infection due to severe depletion of Lyt-1 + cells in draining lymph nodes and a significant increase in the percentage of Lyt-2 + cells. The potential role of these Lyt-1 ∓, 2 + (putative T-suppressor) cells in regulation of the anti-parasite immune response and mediation of generalized immunosuppression is discussed in the light of evidence of inhibition of anti-parasite immunity in infected mice.
Features of amino acid metabolism inMoniliformis moniliformis(Acanthocephala)in vitro
Authors: Ward P. F. V. , Crompton D. W. T.
Published: June 2009

Experiments to investigate the metabolism of glycine, L-glutamic acid and L-aspartic acid byMoniliformis moniliformiswere carried out by incubating adult worms aerobically for 3 h at 37°C in Tyrode's solution containing either [U-14C]glycine, L-[U-14C]glutamic acid, L-[U-14C]aspartic acid or L-[4-14C]aspartic acid. Much of the glycine and glutamic acid was absorbed by the worms, but little of either was metabolized. Aspartic acid was readily taken up and metabolized. After incubating with L[U-14C]aspartic acid, most radioactivity was found in ethanol and a volatile compound, presumed to be carbon dioxide, with smaller amounts in lactate, alanine, acetate, malate, glucose and succinate. After incubating with L-[4-14C]aspartic acid, most radioactivity was found in lactate and the presumed CO2with small amounts in alanine, malate and succinate. No radioactivity was found associated with ethanol or acetate. Possible metabolic pathways and suggestions for a relationship between the metabolism of aspartate with that of alanine and serine in this parasite are discussed.
Schistosoma mansoni: host antigen occurrence on worms recovered from laboratory vertebrate animals
Authors: Coelho P. M. Z. , Gazzinelli G. , Pellegrino J.
Published: June 2009

By transferringSchistosoma mansoni(12 to 14-day-old worms) from one host into the peritoneal cavity of a host of a different species, it was possible to demonstrate that worms grown in rats, hamsters,Mastomys natalensisandCebusmonkeys were rejected by recipient animals previously immunized against red blood cells of the donor hosts. These results suggest that host-like antigens are acquired byS. mansoniin all hosts. The transfer of worms into the peritoneal cavity has proved to be a simple and convenient method for studying the presence of host antigens inS. mansoni.
Uptake of purine bases and nucleosides in African trypanosomes
Authors: James Dinah M. , Born G. V. R.
Published: June 2009

Uptake of radioactively labelled purine bases and nucleosides by suspensions ofTrypanosoma bruceiandTrypanosoma congolensein bicine buffer was determined at 37 °C. WithT. brucei, the rate of uptake of adenosine was much greater than that of the other compounds tested, the uptake of which decreased in the order adenine, inosine, guanosine and hypoxanthine. WithT. brucei, adenosine uptake increased with concentration in a manner suggesting two mechanisms, one with high and the other with low affinity for adenosine. The uptake of adenine increased with concentration only up to about 1·5 µM while the uptake of guanosine increased little with concentration and that of inosine and hypoxanthine not at all. In both species adenosine strongly inhibited the uptake of both of the other nucleosides and of both purine bases. InT. brucei, guanosine and inosine caused small increases in adenosine uptake which was, however, inhibited by them inT. congolense. InT. brucei, each of the purine bases adenine and hypoxanthine inhibited its own uptake maximally but that of each other less effectively. Hypoxanthine was more effective than adenine in inhibiting the uptake of the nucleosides guanosine and inosine, but neither base effected marked inhibition of adenosine uptake. The uptake of adenosine byT. bruceiwas inhibited by dipyridamole and its analogue, compound RA–233, strongly at 100µM and slightly at 10 µM. The other dipyridamole analogues, VK–744 and VK–774, were ineffective.
The life-cycle ofEimeria cernaeLevine and Ivens, 1965 in the bank vole,Clethrionomys glareolus
Authors: Lewis D. C. , Ball S. J.
Published: June 2009

Eimeria cernaeis recorded for the first time in England and the life-cycle is described in experimentally infected bank-voles (Clethrionomys glareolus). The pre-patent period was 6 days and the patent period was 4–6 days. Oocysts were ellipsoidal in shape and measured 20·2 × 15·9 μm. Sporocysts, measuring 11·5 μm long and 6·8 μm wide, possessed a small stieda body and contained a mass of granular sporocyst residuum. The endogenous stages developed in the epithelial cells of the colon and rectum. Three generations of schizonts were found. The lst-generation schizont seen at 48 h post-infection (p.i.) contained up to 8 merozoites, the 2nd-generation schizont seen at 72 h p.i. had a mean number of 16 (12–20) merozoites and the 3rd-generation schizont at 96 h p.i. had a mean of 18 (14–21) merozoites. Gamogonic stages were present from 96 to 120 h p.i. in the rectum only.
Parasite-induced susceptibility to predation in diplostomiasis
Authors: Brassard P. , Rau M. E. , Curtis M. A.
Published: June 2009

Guppies (Lebistes reticulatis) exposed to doses as low as 25 cercariae of Diplostomum spathaceum for 30 min were consistently and significantly more susceptible to predation by brook trout (Salvelinus fontinalis) than uninfected controls. The increase in susceptibility to predation was correlated with a marked decrease in the activity of infected fish.
Suppression ofTrypanosoma congolense, T. vivaxandT. bruceiinfection rates in tsetse flies maintained on goats immunized with uncoated forms of trypanosomes grownin vitro
Authors: Murray M. , Hirumi H. , Moloo S. K.
Published: June 2009

Significant suppression in the incidence of cyclical development ofTrypanosonia congolense, T. vivaxandT. bruceioccurred inGlossina morsitans centralismaintained on goats immunized within vitro-propagated uncoated forms ofT. congolense, T. vivaxandT. brucei, respectively. This was observed when tsetse given aT. congolense-infected feed were subsequently maintained on uninfected immunized goats and also when uninfected tsetse were fed on immunized goats infected withT. congolense, T. vivaxandT. brucei. Suppression of infection rates in tsetse was trypanosome species specific, but was independent of the trypanosome stock used for immunization of goats. These findings were reflected in antibody responses to uncoated trypanosomes, as measured by immunofluorescence and the solid-phase immuno radiometric binding assay. Thus, antibody from goats immunized with uncoated trypano somes of one species exhibited minimal reactivity with uncoated forms of other species of trypanosomes, but showed high levels of activity with uncoated forms of the same or unrelated stocks of the same species. However, in view of the range of hosts upon which tsetse feed, it is open to question whether the use of a vaccine which suppresses trypanosome infection rates in tsetse would have any significant effect in the field.
Biochemical surface components ofBrugia pahangimicrofilariae
Authors: Sayers G. , Mackenzie C. D. , Denham D. A.
Published: June 2009

The sheath and cuticle of microfilariae ofBrugia pahangiwere examined by electron microscopy and the presence of various proteins, carbohydrate and enzymes sought. The epicuticle of microfilariae consists of a pentalaminate structure (24·0 ± 1·4 nm), a cortex (13·7 ± 3·6 nm) and a basal zone (27·8 ±4·8 nm) which is often banded in appearance. The pentalaminate layers are not continuous at the base of the interannular grooves. The sheath and the epicuticle ofB. pahangistained positively with concanavalin A and saccharated iron oxide. The sheath of approximately 50% of microfilariae showed activity for acid phosphatase, 5′ nucleotidase and peroxidase, but not for ATPases, alkaline phosphatase or esterase. No enzymes were detected in the epicuticle although the cortex and basal layers of the cuticle did show enzymic activity. Structures beneath the cuticle in the main body of the worms contained considerable enzymic activity. Microfilariae directly isolated from the blood of infected cats were found by immunochemical means to carry serum proteins on their sheaths but not on their cuticles. These studies extend the definition of the outer structures of microfilariae and confirm that they significantly differ in morphology and enzyme content from typical mammalian cell membranes.
Morphological and adhesive changes to cultured chick kidney cells following parasitization withEimeria tenella(Protozoa: Coccidia)
Authors: Urquhart Catriona
Published: June 2009

Cultured adult chick kidney (CK) cells inoculated with sporozoites ofEimeria tenellashowed progressive alterations in their morphological and adhesive characteristics. Scanning electron microscopy (SEM) showed that during a 3-day period following the inoculation of parasites there was a gradual loss of contact between the cells. Initially, the cells remained connected by long cytoplasmic bridges but with the breakdown of these, the cells began to round up, losing complete contact with each other and remaining attached to the substratum by means of retraction fibres. By 3 days many cells had completely detached. The factors inducing these alterations were transmissable via the medium as the alterations were mimicked by non-parasitized cells in co-culture with parasitized cells. Studies with the reflection interference microscope (RIM) showed that the changes were accompanied by an increase in the cell-substrate separation distance and the loss of focal contacts. These changes were not effected by substances transmissable via the medium. Parasitized cells showed enhanced agglutination with Concanavalin A (Con A) which could be eliminated by pre-fixation. The possibility that changes to the host cell indicate a rearrangement of cytoskeletal apparatus is discussed.
Comparison between spring and autumn infection by Corynosoma (Acanthocephala) in the ringed seal Pusa hispida in the Bothnian Bay of the Baltic Sea
Authors: Helle Eero , Valtonen E. Tellervo
Published: June 2009

Corynosoma spp. (Acanthocephala) infection in ringed seals (Pusa hispida) is compared in spring and in autumn in the Bothnian Bay, northern Baltic Sea. The material consists of more than 13400 specimens: 7590 from the intestines of 13 seals captured in April and May 1978 and 5850 from 29 seals captured in October and November.

Corynosoma strumosum infection had approximately the same intensity in spring and autumn (mean 76 and 66 individuals/infected seal, maxmum 313 and 324 individuals, respectively). C. semerme specimens, on the other hand, were 37 times more numerous in spring than in autumn (504 compared with 136/infected seal, maximum 1700 and 1230 individuals, respectively). The ratio of C. strumosum to C. semerme was 1:6·3 in spring and 1:2·0 in autumn, as calculated from the total material. Corynosoma infection was more recent on average in spring than in autumn, as judged both from the proportion of males and immature females and from the distribution of C. semerme in the intestine. The feeding habits of the ringed seals and the rate of development of Corynosoma infection are discussed.
Fasciola hepatica: development of the tegument of normal and γ-irradiated flukes during infection in rats and mice
Authors: Burden D. J. , Bland A. P. , Hughes D. L. , Hammet N. C.
Published: June 2009

Rats and mice were infected with either normal metacercariae or metacercariae γ-irradiated at 3 krad. or 4 krad. Flukes were recovered at various times after infection and their teguments examined using a transmission electron microscope. In normal flukes, the secretory granules TO, Tl and T2 were all seen during tegumental development. The teguments of flukes from mice developed faster than the corresponding teguments in rats. TO granules were present from day 0 to day 10 post-infection (p.i.) in mouse flukes and from day 0 to day 14 p.i. in rat flukes. Tl granules first appeared in mouse flukes by day 4 p.i. but not until day 8 p.i. in rat flukes. T2 granules were seen in mouse flukes 2 days p.i. but not before 6 days p.i. in rat flukes. γ-Irradiation at 4 krad prevented normal tegumental development in flukes from both rats and mice. TO granules were present at all times in flukes from either host. Tl granules were produced in mouse flukes but their appearance was delayed until day 6 p.i. No significant production of T2 granules occurred in flukes from either host. Parasite survival was also affected by γ-irradiation and none of the flukes reached maturity. Flukes from rats died between 10 and 21 days p.i and flukes from mice died between 14 and 28 days p.i. γ-Irradiation of metacercariae at 3 krad. had an extremely variable effect on subsequent tegumental development in both rats and mice. Some flukes developed normally, some showed development associated with γ-irradiation at 4 krad, whilst some showed intermediate development.