bluuebunny/crossref_metadata_2025_split huggingface dataset:
Host strain, H-2 genotype and immunocompetence do not affect the survival or development of Onchocerca lienalis infective larvae implanted within micropore chambers into mice or rats
Authors: Taylor M. J. , Van Es R. P. , Townson S. , Bianco A. E. 
Published: June 2009

SUMMARYThe survival, growth and development of Onchocerca lienalis 3rd-stage (L3) larvae implanted into mice within micropore chambers has been studied with a view to developing a vaccination model for studies of protective immunity in onchocerciasis. The influence of host genetics on worm recoveries and development (growth and moulting rate) was analysed in a panel of inbred mice (CBA, BALB/c, DBA/2, SJL, 129J, C57BL/10 (B10), C3H/He and NIH), together with mice of BALB and B10 backgrounds with different major histocompatibility complex (H-2) genes (BALB/c, BALB.K, BALB.B and B10, B10.D2/n, B10.BR, B10.S). Parasite recoveries and development were similar in all mouse genotypes tested. They were unaffected by procedures designed to block or modulate phagocytic cell function with carbon or carrageenan, or to suppress inflammation by treatment with hydrocortisone acetate. A comparison of chambers sealed with membranes designed to admit (5·0 μm pore size) or exclude (0·2 μm pore size) host cells demonstrated no effect on the percentage recovery of living larvae, although dead larvae were more frequently retrieved when cells were excluded. Recoveries and rates of development of larvae implanted into immunodeficient scid mice and athymic Hooded rats were similar to those recorded in immunocompetent controls. We conclude that host genetic factors and immunocompetence are not significant determinants of survival, growth or development of O. lienalis larvae implanted within micropore chambers into naive mice. Despite its limitations, the use of this system merits further investigation as an approach to the study of protective immunity against developing larvae in onchocerciasis.
Comparative studies ofTrypanosoma (Duttonella) vivaxisolates from Colombia
Authors: Dirie M. F. , Otte M. J. , Thatthi R. , Gardiner P. R 
Published: June 2009

SUMMARYThe characterization of fourTrypanosoma vivaxisolates from Colombia in South America showed that although minor phenotypic differences existed between them, these parasites are antigenically related and belong to a single serodeme. Characterization by isoenzyme assay, karyotyping and DNA probe analysis, showed the Colombian isolates to be more similar to the West African than to KenyanT. vivax. There was, however, little serological cross-reactivity between South American and African groups ofT. vivax. Although theT. vivaxisolates from Colombia were pathogenic for dairy calves which showed the typical sign of progressive emaciation, these parasites failed to infect mice or tsetseand could not be cultivated as bloodstream formsin vitro.This study represents initial attempts to establish the phenotypic and serological diversity amongstT. vivaxisolates from South America.
Temporal changes in glucose and carbohydrate metabolism in the oncospheres of the cyclophyllidean tapeworm, Hymenolepis diminuta
Authors: Pappas P. W. , Durka G. M. 
Published: June 2009

SUMMARYWhen incubated in vitro for 24 h, oncospheres of Hymenolepis diminuta absorb and metabolize radioactive glucose. Between 0 and 12 h post-activation, oncospheres absorb glucose, but glucose is neither metabolized into other carbohydrates nor incorporated into the ethanol-precipitable fraction (which would contain glycogen). Between 12 and 24 h post-activation glucose is incorporated into a number of higher molecular weight carbohydrates that are demonstrable in ethanol extracts of the larvae, as well as the incubation media. Furthermore, measurable amounts of radioactivity are incorporated into the ethanol-precipitable carbohydrate fraction of oncospheres. To determine if these temporal changes in carbohydrate metabolism occurred spontaneously following activation, oncospheres were pre-incubated for 12 h (0–12 h post-activation) in the absence or presence of glucose, and then transferred to media containing radioactive glucose for an additional 12 h (12–24 h post-activation). In these latter experiments, glucose absorption and metabolism between 12 and 24 h post-activation were virtually identical to glucose metabolism in oncospheres that were incubated in radioactive glucose for 0–12 h immediately following activation. Thus, these data do not support the hypothesis that the temporal shift in carbohydrate metabolism occurs spontaneously.
Population genetics and dynamics ofPlasmodium falciparum: an ecological view
Authors: Day K. P. , Koella J. C. , Nee S. , Gupta S. , Read A. F. 
Published: June 2009

SUMMARYMolecular characterization of thePlasmodium falciparumgenome has led to identification of polymorphic loci and the mechanisms generating genetic diversity in this parasite. This information has resulted in the development of molecular methods to type parasite diversity in the field. Consequently, we are now in a position to describe the population genetics and dynamics ofP. falciparum. The limited number of field studies that have been conducted to date have revealed an extraordinary degree of genetic diversity in natural parasite populations. Heterozygous recombination which occurs during meiosis appears to be one mechanism for generating genetic diversity. The rate at which such recombination occurs in natural parasite populations defines the genetic structure of the parasite population and can influence the ability of the parasite to respond to selection pressure. The high frequency of single genotype infections and the female-biased gametocyte sex ratios found in hyperendemic malaria areas suggest that self-fertilization occurs frequently. Population- wide surveys of allele frequencies in endemic areas have, however, shown no evidence of linkage disequilibrium and are consistent with a panmictic population structure. We argue that these studies have only sampled symptomatic infections, within which rare or recombinant genotypes may be disproportionately represented. They also take no account of the spatial structure ofP. falciparumpopulations. Systematic investigations of the amount of heterozygosity in small areas as part of population-wide surveys are required to define the genetic structure ofP. falciparumpopulations. Population dynamic studies which consider genetic heterogeneity ofP. falciparumhave shown fluctuations of different serotypes in space and time. The host immune response appears to play an important role in generating these dynamics. Integrated field and laboratory studies, which consider the interaction between population genetics and dynamics, will be necessary to describe the population biology ofP. falciparum.
Ascariasis and childhood malnutrition
Authors: Hlaing Thein 
Published: June 2009

SUMMARYThe present review will examine epidemiological perspectives and be confined mainly to the results of those field studies published since 1975 in order to provide concrete scientific evidence of the effect of ascariasis on childhood malnutrition, particularly on growth. The field studies were done in many developing countries from Africa, Asia and Latin America, using cross-sectional and intervention studies in which anthelmintics were employed, with different dosing frequency and follow-up periods ranging from 33 days to 2 years. In general, a better nutritional status in terms of growth, lactose tolerance, vitamins A and C, and albumin levels were observed amongAscaris–free or treated than amongAscaris–infected or untreated children even in cross-sectional or non-randomized studies. More importantly, the improvement in weight or height after chemotherapeutic treatment was found to be significant particularly in those randomized controlled studies with an initially high prevalence of ascariasis and malnutrition, a low prevalence of other intestinal parasites, repetitive and regular treatments of children with tetramisole, levamisole or pyrantel, within a period of 12 or 24 months. Reasons for failures to detect improved growth in some studies are provided. This review strongly indicates thatA. lumbricoidesinfection definitely retards childhood growth.
Persistence and transmission of tick-borne viruses:Ixodes ricinusand louping-ill virus in red grouse populations
Authors: Hudson P. J. , Norman R. , Laurenson M. K. , Newborn D. , Gaunt M. , Jones L. , Reid H. , Gould E. , Bowers R. , Dobson A. 
Published: June 2009

SUMMARYThe population dynamics of tick-borne disease agents and in particular the mechanisms which influence their persistence are examined with reference to the flavivirus that causes louping-ill in red grouse and sheep. Pockets of infection cause heavy mortality and the infection probably persists as a consequence of immigration of susceptible hosts. Seroprevalence is positively associated with temporal variations in vectors per host, although variation between areas is associated with the abundance of mountain hares. The presence of alternative tick hosts, particularly large mammals, provides additional hosts for increasing tick abundance. Grouse alone can not support the vectors and the pathogen but both can persist when a non-viraemic mammalian host supports the tick population and a sufficiently high number of nymphs bite grouse. These alternative hosts may also amplify virus through non-viraemic transmission by the process of co-feeding, although the relative significance of this has yet to be determined. Another possible route of infection is through the ingestion of vectors when feeding or preening. Trans-ovarial transmission is a potentially important mechanism for virus persistence but has not been recorded with louping-ill andIxodes ricinus. The influence of non-viraemic hosts, both in the multiplication of vectors and the amplification of virus through non-viraemic transmission are considered significant for virus persistence.
Rate and course of sporulation of oocysts ofEimeria acervulinaunder different environmental conditions
Authors: Graat E. A. M. , Henken A. M. , Ploeger H. W. , Noordhuizen J. P. T. M. , Vertommen M. H. 
Published: June 2009

SummaryAn experiment was conducted to determine the rate and maximum percentage of sporulation ofEimeria acervulinaoocysts at various environmental conditions relating to temperature (21 versus 33 °C) and relative humidity (RH) (40 versus 80%). Measurements were made during 44 h after excretion of oocysts in 3 substrates: dry litter, clammy litter and pure faeces respectively. Maximum sporulation percentage in both dry (22·6%) and clammy litter (19·5%) was higher (P< 0·005) than in pure faeces (11·6%). Neither temperature nor RH had a significant influence on percentage of oocysts that sporulated. Under these simulated practical conditions approximately 25% of all oocysts sporulated, whereas sporulation under optimal conditions (29 °C, aeration, 2% K2Cr2O7) showed a higher (68%) sporulation ability of oocysts. At 33 °C sporulation proceeded at a faster pace than at 21 °C (P< 0·005). With respect to RH and substrate, once sporulation started, the rate of increase to maximum percentage was not different. Time of onset of sporulation was influenced by temperature (P< 0·0001) and RH (P< 0·001). Time of onset occurred 15 h later at 21 °C compared with 33 °C and 5 h later at 40% RH compared with 80%. Also, an interaction effect (P< 0·01) was found with effect of RH being stronger at 21 °C compared with 33 °C. It was concluded that the most important aspect in the epidemiology ofE. acervulinaduring a flock cycle is the time of onset of sporulation with temperature being the most important factor.
Burnellus gen.nov. (Digenea: Fellodistomatidae), the life history of the type-species, B. trichofurcatus (Johnston & Angel, 1940), and a note on a related species, Tandanicola bancrofti Johnston, 1927, both from the Australian freshwater catfish, Tandanus tandanus
Authors: Angel L. Madeline 
Published: June 2009

A new trematode, Burnellus trichofurcatus, is described from South Australia from the freshwater catfish, Tandanus tandanus. It appears to have affinities with Monodhelmis Dollfus, 1937 and Mehratrema Srivastava, 1939, but is probably most closely related to Tandanicola Johnston, 1927 (Fellodistomatidae: Tandanicolinae). It is assigned to the Fellodistomatidae Nicoll, 1909, as emended by Cable (1953). Cercaria trichofurcata Johnston & Angel, 1940 is shown to be the larval stage. The cyst stage is omitted from the life cycle, with infection of the catfish occurring directly, probably by mouth. Further comments on developmental stages are given. The sporocyst is not branched, as described by Johnston & Angel (1940). The miracidium of Tandanicola bancrofti is reported, and the life history of this species is discussed. The genus is named for Dr R. H. Burnell in recognition of his help, over a number of years, in collecting animals used in these life history studies.I would also like to acknowledge information and help given me by Dr J. C. Pearson, of the University of Queensland, and information on fish given me by Mr C. J. M. Glover, of the South Australian Museum.
Microspines on Schistosoma japonicum and S. haematobium egg shells
Authors: Schnitzer Bertram , Sodeman Thomas , Sodeman William A. , Durkee Thomas 
Published: June 2009

Microspines 0·05 μm long and 0·002 μm in diameter at the base have been demonstrated on the egg shells of S. japonicum. They are protrusions of the shell but are structured into inner and outer layers of differing electron density.Spines observed on the shell of S. haematobium can be flexed by contact with host cell membranes. Firm, perhaps binding, contact is suggested. The spine length serves to define a space between the shell wall and the host cell membrane which could represent the primary interface of host parasitic contact.
Effect of Toxoplasma gondii upon neophobic behaviour in wild brown rats, Rattus norvegicus
Authors: Webster J. P. , Brunton C. F. A. , Macdonald D. W. 
Published: June 2009

SUMMARYThe effect of Toxoplasma gondii on neophobic behaviour (the avoidance of novel stimuli) was assessed in four groups of wild rats with naturally occurring Toxoplasma infection. Two groups were placed in individual cages and tested in a series of experiments which examined the effect of Toxoplasma on the rat's reaction to 3 food-related novel stimuli (odour, food- container, food). A trappability study was performed on the other two groups to test whether Toxoplasma had an effect on probability of capture. The results show that low neophobia was significantly associated with positive Toxoplasma titres in 3 out of 4 groups. We suggest that differences between infected and uninfected wild rats arise from pathological changes caused by Toxoplasma cysts in the brains of infected rats. Such behavioural changes may be selectively advantageous for the parasite as they may render Toxoplasma-infected rats more susceptible to predation by domestic cats (the definitive host of Toxoplasma) and, as a side-effect, more susceptible to trapping and poisoning during pest control programmes.
The use of sheep fistulated at the oesophagus for the recovery of strongyloid larvae from pasture
Authors: Heath D. D. , Southcott W. H. , May P. F. 
Published: June 2009

SUMMARYEstimates were made of the intake of strongyloid infective larvae by sheep at pasture by the recovery of larvae from samples of herbage collected through oesophageal fistulae.All herbage eaten was not recovered through the fistula but few larvae were lost in the process of mastication and swallowing. More larvae could be recovered from macerated than from undamaged herbage.Samples were obtained from different sheep on different days and at different times during the day and the variance components associated with these factors were estimated from seven sets of observations. The contribution to variance differed widely for each factor with the major contribution coming from time changes in the differences between sheep.The authors wish to thank Mr G. W. Major for valuable technical assistance throughout these studies.
Transmission of Leucocytozoon sakharoffi in England by Simulium angustitarse
Authors: Baker J. R. 
Published: June 2009

SUMMARYLeucocytozoon sakharoffi of English rooks (Corvus f. frugilegus) underwent sporogony in female Simulium (Eusimulium) angustitarse, the cycle taking 3–4 days. Sporozoites from the salivary glands of S. angustitarse, both naturally and experimentally infected, gave rise to L. sakharoffi infections when injected to aparasitaemic rooks, with a minimum pre-patent period of 8 days.I am very grateful to the following persons, for invaluable help in many ways: Mr C. Swan and Mr A. Ponchaud (Ministry of Agriculture, Fisheries and Food); Dr J. Ash, Mr N. A. Wood and Mr M. Holland (Game Research Association); Mr N. A. Hancock (Smith, Kline and French); Mr N. Biddlecombe (Breamore Estate); Dr L. Davies (Durham University); Professor D. S. Bertram, Mr E. J. Blackie, Miss L. Selden, Miss J. Freeman and Mr P. Mellor (London School of Hygiene and Tropical Medicine).This work was generously supported by a grant from the Natural Environment Research Council.
Cold tolerance of an endoparasitic nematode within a freezing-tolerant orthopteran host
Authors: Tyrrell C. , Wharton D. A. , Ramløv H. , Moller H. 
Published: June 2009

SummaryWetanemasp. is a nematode parasite of the hind gut of the freezing-tolerant orthopteranHemideina maori(a New Zealand alpine weta). The prevalence and intensity of infection remains high throughout the winter, suggesting that the parasite can survive despite the regular freezing of the host. In the laboratory,Wetanemahas survived freezing within its host to temperatures as low as −61 °C, much lower than the supercooling point or lower lethal temperature of the weta. The freezing tolerance of the parasite is therefore much greater than that of its host. Female worms survived lower temperatures better than males and juveniles. Parasites might assist the freezing tolerance of their host if they acted as endogenous ice nucleators. However, there was no relationship between the size of the worm burden and the supercooling point of the host and no significant difference between the supercooling points of infected and uninfected hosts. The freezing and subsequent survival of isolatedWetanemawas observed directly on a microscope cold stage. This parasite of a freezing- tolerant host is thus also freezing tolerant. There are few other reports of a parasite surviving freezing within a living host.
The use of biotin-labelled, synthetic DNA oligomers for the detection and identification of Plasmodium falciparum
Authors: Hughes M. A. , Hommel M. , Crampton J. M. 
Published: June 2009

SUMMARYAn oligonucleotide mixture based on the 21 base pair repeat sequence of Plasmodium falciparum was covalently coupled to biotin and used as a probe to detect P. falciparum DNA. The limit of detection was 10 ng. This method was further developed as a fingerprint assay for parasite strain typing. After restrictian enzyme digestion, blotting and hybridization, distinct banding patterns were obtained for the strains tested and these were reproducible. In addition, discrete differences were found between PLF-3 S + /S-strains which may implicate genetic reorganization in the switching mechanism which occurs when parasites are passed from an intact to a splenectomized animal.
Hymenolepis diminuta: an investigation of juvenile hormone titre, degradation and supplementation in the intermediate host, Tenebrio molitor
Authors: Hurd H. , Strambi C. , Beckage N. E. 
Published: June 2009

SUMMARYMetacestodes of Hymenolepis diminuta cause a perturbance of vitellogenesis in the intermediate host Tenebrio molitor. The reduction in host reproductive output associated with infection may be due to this pathophysiology. Many of these events are regulated by host juvenile hormone (JH). A comparison of the titre of JH and its rate of degradation in female control and parasitized 15-day-old insects has been made. Haemolymph from female beetles contained 1·27 pMol JH equivalents/100 µl. No significant difference was associated with infection. However, topical application of a JH analogue, methoprene, at the time of infecion or 8 days post-infection reduced the significant accumulation of vitellogenin usually found in the haemolymph of females 12 days or more post-infection. These findings indicate that parasite-induced alteration of host vitellogenesis is not mediated via alteration in JH titres, although observations made after hormone supplementation suggest some form of interaction between the parasite and the host endocrine system.
Vaccination againstTrichinella spiralisin mice using antigens from different isolates
Authors: Goyal P. K. , Wakelin D. 
Published: June 2009

SummaryAntigen preparations from three isolates ofTrichinella spiralis (sensu-stricto)have been tested for their ability to immunize mice against homologous and heterologous challenge infections. Immunization was measured by accelerated expulsion of adult worms, reduction in female worm fecundity, stunting of growth, and level of antibody responses before and after challenge. Antigens of two isolates, from London (L) and Poland (P), immunized effectively against homologous challenge, adult worm recoveries being reduced by 64% and 51% respectively within 6 days. Antigen from a Spanish(S) isolate gave no homologous protection in terms of worm recovery at day 6 and only 43% reduction at day 8. L- and P-isolate antigens immunized well against heterologous challenge (day 6 worm recoveries reduced by 66% and 59%) but similar protection against S-isolate challenge was not seen until day 8. Immunization with S antigen gave better protection at day 6 against L-isolate challenge (77%) than against challenge with P-isolate (37%). These results imply considerable, but not complete, antigen cross-reactivity between the isolates and this was reflected in antibody responses. These variations in immunogenicity and immunization potential are discussed in terms of constraints on the use of vaccines against parasites that are widely distributed geographically.
Labelling larvae of the cattle-tick Boophilus microplus, with 32P to follow their movements on the host
Authors: Kemp D. H. , Koudstall D. , Kerr J. D. 
Published: June 2009

SUMMARYAfter 24 h desiccation at 28–29 °C and approximately 50 % relative humidity about 70 % of B. microplus larvae drank sufficient solution containing 1·5 mCi of 32P per ml for their movements on the host to be followed with a portable G-M counter. Reduced viability of the labelled ticks could not be detected when they were kept for 24 h on the host and either allowed to feed or prevented from doing so. When feeding was continued for 72 h or when larvae were incubated for 3–4 weeks, adverse effects were found, the severity of which could not be directly related to the amount of 32P label. Desiccation, handling of larvae and exposure to radiation in the drinking solution may have contributed to their reduced viability.Since resistance to the tick is manifest within the first 24 h after infestation labelled larvae could be used to compare development on different hosts during this time. Even after feeding for 72 h, larvae were more adversely affected by host resistance than by labelling damage.We would like to thank Mr C. A. Schuntner for helpful advice and Mrs J.Galligan for technical assistance. The financial support of the Australian Meat Research Committee is gratefully acknowledged. Messrs D. Hancox and S. R.Henderson assisted with some of the experiments.