bluuebunny/crossref_metadata_2025 huggingface dataset:
The distribution of faecal nematode egg counts in Scottish Blackface lambs following natural, predominantly Ostertagia circumcincta infection
Authors: Stear M. J. , Bairden K. , Duncan J. L. , Gettinby G. , McKellar Q. A. , Murray M. , Wallace D. S.
Published: June 2009

Faecal samples were taken in 2 consecutive years from Scottish Blackface lambs on a commercial farm in central Scotland to examine variation among lambs in the number of nematode eggs in their faeces. Samples were taken at intervals of 4 weeks from 1 to 5 months of age. Lambs were treated with a broad-spectrum anthelmintic at each sample date. Ewes and lambs were naturally infected by grazing pasture contaminated with mixed, predominantly Ostertagia circumcincta, nematode species. The ewes were removed from the lambs when the lambs were three months old. Only 3 of the 6 sets of samples taken prior to removal of the ewes fitted a negative binomial distribution but all sets of samples taken after this did so. The mean and the variance differed with the month and year of sampling. The amount of variation among lambs increased as the lambs grew from 3 to 5 months of age, possibly because of heterogeneity in the rate of development of protective responses. Counts taken in August and September, when the lambs were 4 and 5 months of age, were positively correlated with each other. In contrast, counts taken at 1 or 2 months of age were negatively correlated with counts taken when the lambs were 3–5 months old. Sex, date of birth, sire and dam were all associated with variation in faecal egg counts but the size and significance of their influence was dependent upon the date when faecal samples were taken. Four factors: sire, dam, sex and year accounted for over two-thirds of the variation among older lambs in faecal egg counts.
Immunity to tapeworms: intraspecific cross-protective interactions betweenHymenolepis citelli, H. diminutaandH. microstomain mice
Authors: Alghali Sidi T. O. , Grencis R. K.
Published: June 2009

Interactions between tapeworm species in a single host offer intriguing opportunities for immunological studies that attempt to identify the mechanism(s) underlying protection against cestode infections. Mice that are immunized againstHymenolepis citelliinfections were shown to be refractory to subsequentH. diminutachallenge infections. The reciprocity of the response was also demonstrated, although the protection recorded forH. diminutawhen mice are sensitized withH. citelliis weaker than that observed when mice are primed withH. diminutaagainstH. citellichallenge.H. citelliwas also shown to be expelled simultaneously during the rejection phase ofH. diminutain concurrent infections, indicating the susceptibility of the former tapeworm to the rejection mechanism initiated by the latter.H. microstomaimmunized mice were shown to be strongly protected against heterologousH. citellichallenge. However, mice primed againstH. citelliwere not as strongly protected againstH. microstomachallenge infections: a statistically significant protection was obtained only after a 12-cysticercoidH. citelliprimary infection, although a 6-cyst infection did stunt the growth ofH. microstomachallenge worms. It is presently suggested that the cross-protective responses observed in the study betweenH. citelli, H. diminutaandH. microstomamay have emanated from a specific immunological cross-reactivity due to the sharing of similar immunogens.
Patterns of haemozoin accumulation in tissue
Authors: Sullivan A. D. , Ittarat I. , Meshnick S. R.
Published: June 2009

A sensitive fluorometric method for assaying malarial pigment, haemozoin, has been developed and used to determine the haemozoin content of blood and tissue samples.Plasmodium falciparumrings and trophozoites were found to contain 23 and 339 ng haemozoin/106parasitized red blood cells (PRBCs), respectively. UnsynchronizedPlasmodium bergheiNK65 or ANKA parasites from infected mice contained 27 and 61 ng haemozoin/106PRBCs, respectively. An exponential accumulation of haemozoin within 18 days after infection was demonstrated in liver and spleen tissue, representing up to 0·2% of the tissue by wet weight by day 18. Histology indicated that the accumulation occurred predominantly in the tissue monocytes. In the brain, the levels of haemozoin after 8 days of infection were considerably lower than they were in the liver or spleen, and most of the pigment appeared to be that present inside parasitized red blood cells. CBA/Ca mice infected withP. bergheiANKA (a cerebral malaria model) had significantly higher amounts of haemozoin in the brain than did ICR mice infected withP. bergheiNK65. Thus, haemozoin levels in tissue increase with the duration of infection, and its presence may be associated with cerebral pathology.
Susceptibility ofBrugia malayiandOnchocerca lienalismicrofilariae to nitric oxide and hydrogen peroxide in cell-free culture and from IFNγ-activated macrophages
Authors: Taylor M. J. , Cross H. F. , Mohammed A. A. , Trees A. J. , Bianco A. E.
Published: June 2009

The susceptibility ofBrugia malayiandOnchocerca lienalismicrofilariae to H2O2and NO either in cell-free culture or from IFNγ-activated macrophages was examined. In cell-free culture,O. lienalismicrofilariae were highly susceptible to H2O2induced toxicity, exhibiting rapid reductions in motility and viability. The addition of exogenous catalase abrogated H2O2-induced killing. In contrast,B. malayimicrofilariae were relatively resistant to H2O2, with concentrations as high as 50 μM having no effect on motility or viability. On exposure to NO, both species showed reductions in motility within 5–30 min, but longer was required to see effects on the viability of microfilariae. Parasites incubated with IFNγ-activated macrophages also exhibited marked reductions in motility and viability. In cultures withB. malayiand activated macrophages, inhibition of these effects was achieved by the addition of eitherL-NMMA, to abolish NO production, or neutralizing anti-TNFα antibodies. Attempts to inhibit parasite killing by the addition of catalase to macrophage cultures were ineffective. The results of this study show thatB. malayiandO. lienalismicrofilariae have different susceptibility to H2O2, but are equally affected by exposure to NO. Moreover both species are killed by IFNγ-activated macrophages and in the case ofB. malayi, killing is dependent on the generation of NO via TNFα.
Eosinophils are the major effector cells of immunity to microfilariae in a mouse model of onchocerciasis
Authors: Folkard S. G. , Hogarth P. J. , Taylor M. J. , Bianco A. E.
Published: June 2009

Mice inoculated with microfilariae of the filarial nematodeOnchocerca lienalisclear their parasites over a period of 3–4 months and are highly resistant to re-infection. We have investigated the comparative roles of the eosinophil, macrophage and neutrophil in effecting this parasite clearance, employing agents specifically to perturb cell functionin vivo. Using the anti-IL-5 monoclonal antibody TRFK-5, we show that eosinophils are of primary importance in effecting resistance to re-infection. Ablation of macrophages (with carbon) and neutrophils (with the monoclonal antibody NIMP-R14) had no effect on parasite clearance following re-infection. Neutralization of these 3 cell types during a primary infection showed that while the removal of both eosinophils and macrophages caused a small but significant delay in parasite clearance, the depletion of neutrophils had no effect. This report describes the first direct evidence for eosinophil-mediated killing of microfilariaein vivo, and is consistent with Th-2 cell responses previously described in this model.
Establishment, survival and site selection of the cestode Eubothrium crassum in brown trout, Salmo trutta
Authors: Kennedy C. R.
Published: June 2009

Population dynamics, site selection, growth and maturation of the cestode Eubothrium crassum in a natural population of Salmo trutta in a small lake were studied over a period of 1 year, the life-span of a cohort in fish. Infection of fish commenced in spring but peaked in July. Small, plerocerciform parasites initially located in the intestine, but then some moved into the pyloric caecae whilst others, the majority in heavy infections, were lost from the fish causing a fall in abundance from 460 to 10 over 2 months. This mortality was density dependent. Initially, parasites were distributed more evenly throughout the caecae but as time increased larger parasites were found preferentially in the anterior caecae before moving back into the intestine when gravid, preparatory to being lost in the following summer. Only a small proportion of the infrapopulation became gravid. Although the proportion of caecae occupied was initially density dependent, by the time of maturation several preferred anterior caecae remained unoccupied and mean intensity always exceeded unity. Neither growth nor maturation was affected by intraspecific competition. It was concluded that caecal availability did not set a limit or threshold of infrapopulation density, and in this respect E. crassum–S. trutta differed from some acanthocephalan-fish systems but was similar to others. Heavy infection followed by heavy mortality appeared to be typical of this parasite-host system in other localities, and of several other cestode-fish systems. The implications of this for population regulation are discussed.
Identification and characterization of threeEncephalitozoon cuniculistrains
Authors: Didier E. S. , Vossbrinck C. R. , Baker M. D. , Rogers L. B. , Bertucci D. C. , Shadduck J. A.
Published: June 2009

Microsporidia are increasingly recognized as causing opportunistic infections in immunocompromised individuals.Encephalitozoon cuniculiis probably the most studied mammalian microsporidian that infects insects and mammals, including man. In this study, 8E. cuniculiisolates were compared and were found to fall into 3 strains. Strain type I includes the rabbit type isolate, as well as isolates from an additional rabbit, a dwarf rabbit, and a mouse. Strain type II includes 2 murine isolates and strain type III includes 2 isolates obtained from domestic dogs. By SDS-PAGE, the 3 strains differ primarily in the molecular weight range of 54–59 kDa where strain type I displays an apparent broad singlet at 57 kDa, strain type II displays an apparent doublet at 54 and 58 kDa, and strain type III displays an apparent broad band at 59 kDa. Antigenic differences were detected in the molecular weight regions of 54–58 kDa as well as 28–40 kDa by Western blot immunodetection using murine antisera raised againstE. cuniculi, Encephalitozoon hellem,and theEncephalitozoon-like Septata intestinalis.Polymerase chain reaction (PCR) products containing only small subunit rDNA sequences from the differentE. cuniculiisolates formed homoduplexes whereas PCR products containing intergenic rRNA gene sequences formed heteroduplexes in mobility shift analyses.FokI digestion of the PCR products containing the intergenic rRNA gene region resulted in unique restriction fragment length polymorphism patterns, and DNA sequencing demonstrated that in the intergenic spacer region, the sequence 5'-GTTT-3' was repeated 3 times in strain type I, twice in strain type II, and 4 times in strain type III. This study indicates that there exist at least 3E. cuniculistrains which may become important in the epidemiology of humanE. cuniculiinfections. Furthermore, as additionalE. cuniculiisolates are characterized, these strains will be named or reclassified once the criteria for taxonomy and phylogenetic tree construction for microsporidia become better defined.
Gene flow and cross-mating in Plasmodium falciparum in households in a Tanzanian village
Authors: Babiker H. A. , Charlwood J. D. , Smith T. , Walliker D.
Published: June 2009

The diversity of the genes encoding 2 merozoite surface proteins (MSP-1 and MSP-2) of Plasmodium falciparum has been examined in parasites infecting members of 4 households in a village in Tanzania. The polymerase chain reaction (PCR) was used to characterize allelic variants of these genes by the sizes and sequences of regions of tandemly repeated bases in each gene. In each household extensive polymorphism was detected among parasites in the inhabitants and in infected mosquitoes caught in their houses. Similar frequencies of the alleles of these genes were observed in all households. Capture-recapture data indicated that both Anopheles gambiae and A.funestus freely dispersed among households in the hamlet. The results confirm that cross-mating and gene flow occur extensively among the parasites, and are discussed within the context of spatial clustering of natural populations of P. falciparum.
Effects of phenothiazine neuroleptic drugs on the microtubular–membrane complex in bloodstream forms ofTrypanosoma brucei
Authors: Page A. M. , Lagnado J. R.
Published: June 2009

African trypanosomes are parasitic protozoa causing sleeping sickness in humans and related diseases in domestic animals against which no entirely satisfactory forms of chemotherapy are yet available. It was previously shown that related species of trypanosomes, as well as procyclic (insect) forms ofTrypanosoma bruceiare extremely sensitive to the action of phenothiazine neuroleptic drugsin vitro. In this work, we have carried out a more detailed investigation of the effects of thioridazine, one of the most potent neuroleptic phenothiazine drugs known, on the morphology of the infective bloodstream forms ofT. brucei, with particular reference to the parasite's prominent pellicular membrane complex. Our data show that this drug induces rapid changes in cell shape that appear to involve some reorganization of the microtubular membrane skeleton, but does not affect the structural integrity of the microtubular complex. Another early consequence of drug action involved damage to nuclear and cytoplasmic membranes and the appearance of tubular arrays of coated membrane within the flagellar pocket. It was also revealed that the drug induces a rapid release of the variant-specific glycoprotein (VSG) which makes up the surface coat protecting bloodstream forms of the parasite against the host immune system. Our evidence suggests that this release of VSG involves cleavage of the protein's glycosyl-phosphatidylinositol (GPI) membrane anchor by endogenous GPI-specific phospholipase C, probably as a consequence of minor damage to the parasite plasma membrane induced by the drug.
Eimeria tenella: infection with a single sporocyst gives a clonal population
Authors: Shirley M. W. , Harvey D. A.
Published: June 2009

Two genetically defined parents of Eimeria tenella, each characterized by a selectable phenotype, were mated to provide ‘recombinant’ oocysts for an analysis of the inheritance of DNA markers into the sporocyst stage of the life-cycle. A total of 23 populations was established from infection with a putative single sporocyst and their inheritance of DNA markers provided compelling evidence that the 2 sporozoites within each sporocyst are genetically identical. Each of the 5 polymorphic DNA markers used segregated independently within the ‘recombinant’ parasites and only 1 of the parental forms was inherited in 22 of the populations aimed to have been established from a single sporocyst.
Induction of changes in human behaviour by the parasitic protozoanToxoplasma gondii
Authors: Flegr J. , Zitková Š. , Kodym P. , Frynta D.
Published: June 2009

Toxoplasma gondii, the coccidian parasite, is known to induce changes in the behaviour of its intermediate hosts. The high prevalence of this parasite in the human population (20–80%) offers the opportunity of studying the influence of the parasite on human behaviour by screening of a normal population. A total of 224 men and 170 women were tested for toxoplasmosis and their personality profiles were measured by Cattell's questionnaire. Highly significant differences betweenToxoplasma-infected and uninfected subjects were observed (P< 0·01). For men the factorsG(low superego strength),L(protension),O(guilt proneness), andQ2(group dependency) were positively influenced in infected subjects. For women the prevailing factors wereA(affectothymia,P< 0·01),L(alaxia),O(untroubled adequacy) andQ2(self-sufficiency). To reveal whether toxoplasmosis induces personality factor-shifts or whether certain combinations of personality factors influence the probability of acquiringToxoplasmainfection, we examined the personality profiles of 164 male patients diagnosed with acute toxoplasmosis during the past 13 years. The existence of a positive correlation between the duration of latent toxoplasmosis and the intensity of superego strength decrease (P< 0·02) suggested that the decrease of superego strength (the willingness to accept group moral standards) was induced byT. gondiiinfection.
Pharmacology and efficacy of liposome-entrapped albendazole in experimental secondary alveolar echinococcosis and effect of co-administratration with cimetidine
Authors: Wen H. , New R. R. C. , Muhmut M. , Wang J. H. , Wang Y. H. , Zhang J. H. , Shao Y. M. , Craig P. S.
Published: June 2009

Encapsulation of the benzimidazole albendazole in multilamellar liposomes results in a preparation in which this normally insoluble anti-hydatid drug is well solublilized in aqueous media. The high entrapment efficiency observed (75–87%) and the stability of the formulation make this a promising delivery vehicle for improved chemotherapy with albendazole. In particular, the high degree of association with phospholipid may give rise to increased oral bioavailability. Oral adminisration of albendazole in liposomes led to increased concentration and/or altered metabolism of albendazole sulphoxide (ABZSX) in liver and/or plasma in non-infected Wistar rats. Results from experiments using cotton rats (Sigmodon hispidus) infected with metacestodes of Echinococcus multilocularis show that entrapment within liposomes clearly increases the uptake of albendazole via the oral route. This was reflected by increased levels of albendazole and the two major metabolites in plasma, liver and cyst homogenate when a dose of liposomal albendazole (35 mg/kg) was given orally compared to free albendazole at 50 mg/kg. There was a 75–94% reduction in biomass of the metacestode and a significant increase in survival time for the animals treated with liposome entrapped albendazole. A clear difference in distribution of albendazole and its metabolites in the liver and the metacestode tissues in the presence of cimetidine indicated that the latter has a profound effect on the metabolism of albendazole. There appeared to be a synergistic interaction between albendazole and cimetidine, since the metabolism of albendazole was markedly altered in the combined cimetidine/liposome–albendazole group, and higher therapeutic effect was observed. These findings indicate potential both for improvement of treatment of larval E. multilocularis infection and for reduction of albendazole dose levels.
Competitive exclusion in human schistosomes: the restricted distribution ofSchistosoma intercalatum
Authors: Tchuenté L. A. Tchuem , Morand S. , Imbert-Establet D. , Delay B. , Jourdane J.
Published: June 2009

A study on the immune and mating interactions betweenSchistosoma intercalatumandS. mansonihas been carried out. The immunologically mediated interactions and mating patterns observed between the two species demonstrate thatS. mansoniis competitively dominant overS. intercalatum. WhenS. mansonifemales are absent,S. mansonimales are more competitive thanS. intercalatummales at pairing withS. intercalatumfemales. The use of a mathematical model shows how the abundance ofS. mansoniworms per host could dramatically affect the mating probability ofS. intercalatumfemales with their homologous males. It appears that the competitive exclusion between these two species of schistosomes may probably be an important factor restricting the distribution ofS. intercalatumin Africa.
Re-assessing the global prevalence and distribution of lymphatic filariasis
Authors: Michael E. , Bundy D. A. P. , Grenfell B. T.
Published: June 2009

This paper estimates the global burden of lymphatic filariasis based on a review of the published literature on infection and disease surveys. A method for aggregating and projecting prevalence data from individual studies to national, regional and global levels, which also facilitates the estimation of gender and age-specific burdens, is presented. The method weights in favour of the larger, and hence presumbably more reliable, studies and relies on estimated empirical relationships between gender, age, infection and disease in order to correct studies with incomplete data. The results presented here suggest that although the overall prevalence of filariasis cases is 2·0% globally (approximately totalling 119 million cases), the disease continues to be of considerable local importance, particularly in India and Sub-Saharan Africa. Estimates by age and gender clearly show that, unlike other helminth infections, filariasis is mainly a disease of the adult and older age-classes and appears to be more prevalent in males. This work suggests that the derivation of more accurate estimates of the burden of filariasis will require a better understanding of both the epidemiology and the spatial aspects of infection and disease. It also suggests that filariasis is preventable based on a geographically targeted strategy for control.
Antigen localization and the induction of resistance in mice vaccinated with irradiated cercariae ofSchistosoma mansoni
Authors: Mountford A. P. , Coulson P. S. , Wilson R. A.
Published: June 2009

The fate of75Se-labelled parasites and their released pre-synthesized macromolecules has been followed in three murine infection models. Parasite numbers in specific tissues were determined by autoradiography, and released material was estimated by gamma-counting of tissues, with adjustment for the presence of parasite-associated radiolabel. Marked differences were found between the three models. The pattern of migration of normal schistosomula was similar to that previously reported. In addition we have described the transit of parasites through the lymph nodes draining the infection site. Significant quantities of released material were detected in the skin, draining lymph nodes, bloodstream and liver. The circulating material was of parasite origin, macromolecular, and hence potentially antigenic. In comparison to the normal infection, radiation-attenuated parasites (inducing a high level of resistance to challenge) persisted in the skin, draining lymph nodes and lungs, releasing a proportionally greater amount of material in the nodes. In mice exposed to attenuated parasites and treated with the compound ROl1–3128 at 24 h (inducing a low level of resistance) there was an early death and rapid clearance of the parasites whilst still in the skin. This situation resulted in the highest levels of released material in the skin, bloodstream and liver, but negligible levels in the draining lymph nodes. We suggest that the persistence of radiation-attenuated parasites in the skin and draining lymph nodes, together with the prolonged release of antigen in the latter site, compared to the normal situation, are major factors in the induction of resistance.
Molecular cloning of Taenia solium genomic DNA and characterization of taeniid cestodes by DNA analysis
Authors: Rishi A. K. , McManus D. P.
Published: June 2009

Total DNAs, isolated from a range of taeniid cestodes (Taenia solium, T. saginata, T. pisiformis, T. crassiceps, T. hydatigena, T. ovis, T. multiceps and T. taeniaeformis), have been subjected to restriction enzyme digestion, Southern transfer and hybridization analysis using cloned fragments of the ribosomal RNA gene of Schistosoma mansoni. Substantial inter-specific genetic differences have been revealed on the basis of characteristic hybridization patterns for each of the taeniid cestode species. Furthermore, a random genomic DNA library has been constructed in the vector plasmid pAT153 using DNA extracted from a pig isolate (Indian origin) of T. solium. A panel of taeniid cestode DNAs including DNA from Echinococcus granulosus, has been used in conjunction with hybridization and restriction enzyme analysis to identify in the library a single recombinant plasmid with a T. solium-specific insert (coded pTS10) and two recombinant plasmids with T. solium inserts having selective specificities for T. solium and T. ovis (coded pTS17) and T. solium, T. saginata, T. ovis and T. multiceps (coded pTS28). These recombinant plasmids and the cloned fragments of the ribosomal RNA gene of S. mansoni have been used in restriction endonuclease, Southern transfer and hybridization analysis to detect intra-specific genetic variation in cysticerci of T. solium from India, Mexico and Zimbabwe. In addition, pTS10 and pTS17 have been used in a simple dot-blot assay to distinguish T. solium from T. saginata.
Population dynamics in echinococcosis and cysticercosis: economic assessment of control strategies for Echinococcus granulosus, Taenia ovis and T. hydatigena
Authors: Lawson J. R. , Roberts M. G. , Gemmell M. A. , Best S. J.
Published: June 2009

An official control programme against Echinococcus granulosus and Taenia hydatigena has been in operation in New Zealand for more than 28 years and against Taenia ovis for more than 18 years. This unique effort to control three metazoan parasites at the same time has led to a change from endemic to extinction status for E. granulosus but only a change from hyperendemic to endemic status for T. hydatigena and T. ovis. This has presented problems in determining the most cost-effective future control strategies. To facilitate this, a benefit/cost analysis of 20 options for the combined control of E. granulosus, T. hydatigena and T. ovis in New Zealand was undertaken. This showed that for E. granulosus a future change from the current non-targeted to a targeted approach is strongly indicated. For T. ovis 6 options were cost-effective using a discount rate of 10%. These were (1) a targeted control package using a vaccine in the non-targeted attack phase; (2) a targeted control package using a larvicide in the attack phase; (3) the transfer of all losses due to and responsibility for the control of T. ovis to the producer who administers a larvicide to sheep to be killed for dog food; (4) the transfer of all losses due to and responsibility for the control of T. ovis to the producer who administers praziquantel every 6 weeks to dogs; (5) and (6) two options involving the discontinuation of control. Control of T. hydatigena was assumed to be an incidental outcome of the policies for the other two parasites.
A general model for the African trypanosomiases
Authors: Rogers D. J.
Published: June 2009

A general mathematical model of a vector-borne disease involving two vertebrate host species and one insect vector species is described. The model is easily extended to other situations involving more than two hosts and one vector species. The model, which was developed from the single-host model for malaria described by Aron & May (1982), is applied to the African trypanosomiases and allows for incubation and immune periods in the two host species and for variable efficiency of transmission of different trypanosome species from the vertebrates to the vectors and vice versa. Equations are derived for equilibrium disease prevalence in each of the species involved. Model predictions are examined by 3-dimensional phase-plane analysis, which is presented as a simple extension of the 2-dimensional phase-plane analysis of the malaria model. Parameter values appropriate for the African trypanosomiases are derived from the literature, and a typical West African village situation is considered, with 300 humans, 50 domestic animals and an average population of 5000 tsetse flies. The model predicts equilibrium prevalences of Trypanosoma vivax, T. congolense and T. brucei of 47·0, 45·8 and 28·7% respectively in the animal hosts, 24·2, 3·4 and 0·15% in the tsetse vectors, and a 7·0% infection of humans with human-infective T. brucei. The contribution to the basic rate of reproduction of the human-infective T. brucei is only 0·11 from the human hosts and 2·54 from the animal hosts, indicating that in the situation modelled human sleeping sickness cannot be maintained in the human hosts alone. The animal reservoir is therefore crucial in determining not only the continued occurrence of the disease in humans, but its prevalence in these hosts as well. The effect of changing average fly density on equilibrium disease prevalences is examined, together with the effect of seasonal changes in fly numbers on disease incidence. In a seasonal situation changes in fly mortality rates affect both future population size and infection rate. Peak disease incidence lags behind peak fly numbers, and that in the less favoured host lags behind that in the more favoured host. Near the threshold fly density for disease transmission disease incidence is more changeable than at higher fly densities and may even exceed equilibrium prevalence at the same average fly density (because most hosts are susceptible at the time that fly numbers begin their annual increase). The implications of the model for disease control are discussed. Identifying the precise role of the animal reservoir may suggest that treating such animals will achieve a greater reduction of human sleeping sickness than direct treatment of the humans alone. Statistically significant results of control campaigns may also be more easily shown by monitoring the non-human reservoirs. The model provides a means by which a correct perspective view can be obtained of the complex epidemiology and epizootiology of the African trypanosomiases.
Effects on inhibition of development of the transfer of Ostertagia ostertagi between geographical regions of Australia
Authors: Smeal M. G. , Donald A. B.
Published: June 2009

Pasture plots in a warm coastal region were separately contaminated in the autumn, winter and spring with eggs of a coastal strain of Ostertagia ostertagi derived from dairy calves. At the same times, a parallel set of plots was contaminated by a strain transferred from within a beef cattle management system in a cooler tablelands region. A reciprocal transfer of the coastal strain was also made to the tablelands, where pasture plots were contaminated with eggs of both strains of O. ostertagi in winter. Successive groups of parasite-free calves were grazed on the plots for 10–14 days at 4-week intervals and then killed for worm counts 14 days after their removal from pasture. In both environments, irrespective of the season of pasture contamination, inhibition of development reached a maximum in spring and the two strains differed only in the proportion of the population inhibited, which was significantly greater for the table- lands strain. There was no strain difference for either numbers of infective larvae on pasture or total O. ostertagi numbers. This suggested that the difference between coastal and tablelands populations in the extent of inhibition is genetically determined. If an environmental stimulus was implicated in the spring occurrence of inhibition, the stimulus was provided equally in coastal and tablelands environments and it cannot be exposure to low temperatures.
The effect of dehydration and rehydration on salt loss in the second-stage larvae of Anguina tritici
Authors: Womersley C.
Published: June 2009

The effect of repeated dehydration and hydration on the salt content of 2nd-stage larvae of Anguina tritici was studied. The sodium, potassium, magnesium and calcium contents of the larvae after subjection to varying periods of desiccation and rehydration were determined with atomic absorption spectrophotometry and flame photometry. External cation concentrations on the cuticle of the head, middle body and tail regions were determined semi-quantitatively with scanning electron microscopy in conjunction with X-ray analysis (EDAX). Salt concentrations decreased with each dehydration/rehydration cycle. The greatest loss occurred on revival from the first desiccation period. The results indicated that A. tritici was incapable of regulating it's internal sodium content during revival, but suggested a limited ability to control potassium, magnesium and calcium loss. Salt loss through the nematode cuticle was restricted to potassium and calcium during desiccation. The salt losses encountered are discussed in relation to nematode osmoregulation and to the survival of the nematode in the anhydrobiotic state.
Observations on relationships between infective juveniles of bovine lungworm, Dictyocaulus viviparus (Nematoda: Strongylida) and the fungi, Pilobolus kleinii and P. crystallinus (Zygomycotina: Zygomycetes)
Authors: Doncaster C. C.
Published: June 2009

Infective 3rd-stage larvae of Dictyocaulus viviparus were filmed whilst climbing sporangiophores of the coprophilous fungus, Pilobolus and invading sporangia in numbers up to about 50, shortly before the sporangia were explosively discharged. Like the sporangiophores of Pilobolus the nematodes reacted positively towards light. Robinson (1962) demonstrated the spectacular way in which D. viviparus can be dispersed by Pilobolus, although he saw the nematodes accumulating only on top of the sporangia. Hazards including desiccation would offset the advantage of dispersal unless protection is somehow provided. Free D. viviparus larvae are susceptible to desiccation and discharged sporangia appear to dry quickly, so what protection, if any, operates? Several other nematodes that are susceptible to desiccation survive because structures surrounding them dry quickly (for example, an ensheathing cuticle, egg-shell, gelatinous ‘egg-sac’ matrix) and in doing so form barriers which limit the rate of water loss from the nematode within. Such dried sporangia of Pilobolus could aid survival of the ensheathed D. viviparus larvae inside them by retarding desiccation of the nematodes, in much the same way that within cysts of Globodera and Heterodera spp. the cyst wall, egg matrix and outer eggs protect the inner eggs by reducing the rate, if not the extent, of water loss. The sporangium wall may also protect the nematodes from harmful ultraviolet irradiation and from being washed by rain into less advantageous situations.
Characterization of proteinases in extracts of adultHaemonchus contortus, the ovine abomasal nematode
Authors: Knox D. P. , Redmond D. L. , Jones D. G.
Published: June 2009

The degradation of several protein substrates, including the blood proteins haemoglobin, albumin and fibrinogen, by proteinases present in extracts of adultHaemonchus contortuswas examined over a broad pH range. These proteinases were further characterized on the basis of substrate specificity, inhibitor sensitivity and molecular size by spectrophotometric and substrate gel analysis. The majority of the proteinases capable of degrading the blood proteins tested were active at acidic pH and could be ascribed to the cysteine proteinase class. In addition, evidence is presented that these proteinases are differentially recognized and inhibited by immune sera and that parasites capable of withstanding protective host immune responses exhibit modified expression of proteinases.
The attachment of the ancyrocephalid monogenean Haliotrema balisticus to the gills of the trigger fish, Balistes capriscus (= carolinensis)
Authors: Kearn G. C.
Published: June 2009

Haliotrema balisticus attaches itself between the secondary gill lamellae of its host, Balistes caprisctis (= carolinensis), by means of a pair of ventral hamuli, which point ventrolaterally, and a pair of dorsal hamuli which point in a dorsal direction. The ventral hamuli, each of which pivots at the end of a ventral connecting bar, are operated by a pair of extrinsic muscles. The tendinous regions of these muscles pass through fibrous loops attached to the ventral hamuli and then join each other in the mid-line. Such an arrangement has a high mechanical advantage which may reduce the expenditure of energy required to maintain the hamuli in position in the gill tissue in the face of a strong gillventilating current and may also preserve the mobility of the free region of the body.

The dorsal hamuli are not operated by the muscles and tendons associated with the ventral hamuli.

Marginal hooklets and glands play subsidiary roles in attachment.

I wish to express my thanks to Commander J. Parreira, Director of the Aquario Vasco da Gama in Lisbon, and to the Staff of the Aquario, in particular to Mr A. Ferreira, for their kind assistance and hospitality. I am also grateful to Dr Maria Monteiro and to Dr Maria Baptista. I am indebted to the Calouste Gulbenkian Foundation for a grant which made my visit to Portugal possible.
Schistosoma mansonielastase: an immune target regulated during the parasite life-cycle
Authors: Pierrot C. , Godin C. , Liu J. L. , Capron A. , Khalife J.
Published: June 2009

RecombinantSchistosoma mansonielastase was expressed inEscherichia coliand an antiserum raised against the re-combinant protein was used to investigate stage-specific control of elastase in the parasite, and to determine whether the enzyme could form the basis of a strategy to prevent larval invasion of the host. Results showed that the expression of elastase is developmentally regulated, even if the basal promoter activity does not seem to be stage specific. The analysis of mRNA expression showed the presence of elastase transcript in adult worms although we could not detect the protein at this stage, suggesting thatS. mansoniemploys a form of translational control. The measurement of elastase levels in supernatants of culture schistosomula combined with the localization of elastase in cercariae invading mouse skin showed that the enzyme is heavily released during penetration. Finally, we studied the cytotoxic activity of rat anti-elastase sera, and the analysis of the isotypic profile suggested that IgG2a anti-elastase may be responsible for the cytotoxic effect.
The monoxenic culture of beet eelworm (Heterodera schachtii Schm.) on excised roots of sugar beet (Beta vulgaris L.)
Authors: Moriarty F.
Published: June 2009

A method is described for obtaining sterile second-instar larvae of beet eelworm, Heterodera schachtii Schm., and culturing them to the adult stage on sterile excised roots of sugar beet, Beta vulgaris L. It was shown that beet eelworm is a primary pathogen, for sound uninjured radicles were invaded by larvae, and normal development of adult males and females followed. No females were fertilized, and no eggs were produced, which suggested that parthenogenesis cannot occur. Eelworm development stimulated the production of lateral roots. More adult females developed on radicles inoculated 24 hr. after excision than on radicles inoculated 72 hr. after excision, which may be related to the occurrence of maximum root extension during the first few days after excision. It is suggested that there are two parts in root tissue reactions: a thickening of cell walls as a wound reaction to mechanical injury, and formation of a syncytium in response to a chemical stimulus from the eelworm.

I thank my wife for assistance with this work, which was financed by the Sugar Beet Research and Education Committee.
A new species of Notodelphyoid copepod, Notopterophorus ionthas from Kastela Bay, Yugoslavia
Authors: Gray Peter , Snyder R. Eileen
Published: June 2009

A description is given of a new species of notodelphyoid copepod which has been designated as Notopterophorus ionthus. It is parasitic or commensal in the branchial cavity of the tunicate Phallusia mamillata Cuvier.
Comparisons between microvascular changes in cerebral and non-cerebral malaria in mice, using the retinal whole-mount technique
Authors: Neill A. L. , Chan-Ling T. , Hunt N. H.
Published: June 2009

CBA/T6 mice inoculated withPlasmodium bergheiANKA strain (PbA) exhibited cerebral symptoms and died from cerebral malaria 6–8 days p.i. whereas DBA/2J mice developed (around days 6–9) a non-fatal cerebral malaria, with milder cerebral symptoms, and died between days 15 and 22 from other malaria-related complications. When inoculated withP. bergheiK173 (Pb) these mouse strains did not develop cerebral malaria. These mouse/parasite strain combinations were used, in conjunction with the retinal whole-mount technique, to elucidate factors critical in the pathology of murine cerebral malaria. CBA/T6 mice infected with PbA (PbA-CBA mice) demonstrated mild changes in vascular permeability as early as days 2–3, prior to the appearance on day 5 of cerebral symptoms, whereas mice with non-cerebral malaria did not show any vascular permeability changes until the very late stage of the disease (days 14–22). In the PbA infections, progressive deterioration of endothelial barrier properties, demonstrated by Evans' Blue leakage both generally and from specific focal areas, as well as a developing monocytosis and adherence of mononuclear cells to the endothelium of the retinal vessels continued until death (in CBA/T6 mice) or resolution (in DBA/2J mice). Adherent monocytes, particularly in PbA-CBA mice, were associated with reduced Hoechst staining of individual endothelial cells and a banking up proximally of both parasitized and non-parasitized blood cells in the small blood vessels, often with accompanying focal leakage of Evans' Blue from the retinal vessels. The occurrence and severity of these early changes in the microcirculation correlated with the subsequent development of cerebral symptoms. Monocyte margination appeared to be the most significant factor associated with the development of cerebral symptoms.
Dynamics of gastropod infection by first-stage larvae of protostrongylid nematodes — a model
Authors: Řezáč P. , Kindlmann P. , Dostálková I. , Holasová E.
Published: June 2009

For the description of the dynamics of snail infection by the 1st-stage larvae of protostrongylid nematodes, Skorping (1988) used the miracidia-snail model (Anderson, 1978). Here it is shown that, in contrast to miracidia, in protostrongylids the instantaneous rate of infection, α, is strongly dependent on the experimental design (factors like host size and size of the experimental arena). With respect to this, Anderson's model is modified by incorporation of the experimental design. The parameter α in its new sense as the rate of penetration (probability that the infective larva will penetrate into the host during a time unit) is shown to remain dependent, although much less so, on the experimental design. Only the inclusion of the assumed effect of mucus, which decreases the rate of penetration, yields a parameter α0 (the initial rate of penetration), which is completely independent of the design of the experiment, is species-specific, and also gives the best fit to the empirical data. As the above-mentioned factors can strongly influence the value of the instantaneous rate of infection in the laboratory experiments, α0 is more suitable as a measure of either the larval infectivity for the snail or snail susceptibility to infection by the protostrongylid larvae.
Phylogeny and evolution of the piroplasms
Authors: Allsopp M. T. E. P. , Cavalier-Smith T. , Waal D. T. De , Allsopp B. A.
Published: June 2009

Small subunit ribosomal RNA (srRNA) genes of three Theileria species, one Cytauxzoon and four Babesia species were amplified using the polymerase chain reaction (PCR), cloned and sequenced. Our sequences were aligned with srRNA sequences previously published for eight species of Apicomplexa, one ciliate and one dinoflagellate, the last two being included as free-living outgroup species. Phylogenetic relationships between the organisms were inferred by four in-dependent methods of phylogenetic tree construction using the ciliate Oxytricha nova to root the trees. Our trees fail to show a consensus branching order. They do, however, clearly indicate that the theilerias form a monophyletic taxon derived from a paraphyletic group which includes the species B. equi, C. felis and B. rodhaini. The distance trees indicate that the babesias sensu stricto (B. canis, B. caballi, B. bigemina and B. bovis) form another monophyletic taxon which diverged before the theilerias separated from the above-mentioned paraphyletic group. The parsimony and maximum likelihood trees suggest that the babesias and theilerias are sister taxa, both of which were derived from the paraphyletic group.
A nematode FMRFamide-like peptide, SDPNFLRFamide (PF1), relaxes the dorsal muscle strip preparation ofAscaris suum
Authors: Franks C. J. , Holden-Dye L. , Williams R. G. , Pang F. Y. , Walker R. J.
Published: June 2009

PF1 (SDPNFLRFamide) is a FMRFamide-like peptide extracted from the free-living nematodePanagrellus redivivus. Here we show that this peptide causes a hyperpolarization of somatic muscle cells of the parasitic nematodeAscaris suumand a relaxation of the somatic muscle strip preparation. We have assessed whether or not the relaxation ofAscarisdorsal muscle strip by PF1 is due to (i) inhibition of the release of the excitatory neuromuscular junction transmitter acetylcholine (ACh), (ii) potentiation of the release of the inhibitory neuromuscular junction transmitter γ-aminobutyric acid (GABA) or (iii) a direct inhibitory action of the peptide on the muscle cells. Under the experimental conditions described here, tonic ACh release does not seem to be involved in determining the resting membrane potential or resting tone of theAscarisdorsal muscle strip and thus inhibition of tonic ACh release is unlikely to explain the relaxation elicited by the peptide. Furthermore, PF1 (100 nM–1 μM) inhibited the contraction of the muscle strip elicited by bath application of ACh, suggesting either a direct inhibitory action of the peptide on the muscle cells or a potentiation of GABA release. In electrophysiological experiments, the reversal potential for the PF1 hyperpolarization was not the same as that for GABA. Thus, PF1 hyperpolarizesAscarismuscle by a mechanism that does not involve stimulation of GABA release from inhibitory pre-synaptic terminals.
On Cercaria chungathi Peter & Srivastava, 1955 and its relationship to Gastrothylax crumenifer (Creplin)
Authors: Peter C. T. , Srivastava H. D.
Published: June 2009

The post-cercarial development of G. crumenifer (Creplin) has been experimentally elucidated.

Gyraulus convexiusculus (Hutton) serves as the intermediate host under natural conditions.

The adult stage of the fluke was raised experimentally in ruminants, the time taken by the parasite to attain maturity being 118 days in the kid and 114 in the buffalo calf.

Cercaria chungathi Peter & Srivastava, 1955, has been established to be the larva of Gastrothylax crumenifer. The cercaria, the redial parthenita and the metacercaria have been described.

The authors are grateful to the Director, Indian Veterinary Research Institute, for his keen interest in these studies.
Synergism between coccidia parasites (Eimeria mitis and E. acervulina)and malarial parasites (Plasmodium gallinaceum and P. juxtanucleare) in the chick
Authors: Al-Dabagh M. A.
Published: June 2009

1. The coccidial parasites (Eimeria acervulina and E. mitis) cause a recrudescence in chicks harbouring chronic infection with Plasmodium juxtanucleare.

2. E. acervulina causes higher levels of parasitaemia in P. juxtanucleare infections in chicks if the coccidial infection is produced during the prepatent period of malaria, but it does not affect the length of patent and prepatent periods or raise the mortality rate among infected chicks.

3. E. acervulina induces a severe fatal relapse in chicks harbouring latent P. gallinaceum infections.

I wish to express my sincere thanks to Professor P.C.C. Garnham who supervised this work, and Dr R. Lainson who helped in identification, isolation of the coccidial parasites and the establishment of infection in clean laboratory-bred chicks.