bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of the in vitro feeding of Rhipicephalus appendiculatus nymphae for the transmission of Theileria parva
Authors: Waladde S. M. , Young A. S. , Mwaura S. N. , Njihia G. N. , Mwakima F. N. 
Published: June 2009

SUMMARYAn apparatus for artificial feeding of Rhipicephalus appendiculatus nymphae was modified to improve feeding performance. Heparinized blood was supplied above a treated artificial membrane while the ticks attached below on its undersurface. The feeding apparatus was incubated at 37 °C in an atmosphere of 3% CO2 concentration and a relative humidity of 75–80%. Under these conditions, 91% of the engorged nymphae attained a mean weight of 6–11 mg, and an average of 93% of those nymphae moulted into adults. When this system was used to feed nymphal ticks on blood infected with Theileria parva piroplasms, the mean prevalence of infection in the resultant female and male ticks was 86% and 54%, respectively. The feeding performance and T. parva infection levels were comparable to those of nymphal ticks fed on the blood donor cattle. The apparatus used in this study has potential for modification to suit the artificial feeding needs of other species of ixodid ticks and for use in investigations to examine other tick/pathogen relationships.
Observations on worm population dynamics in calves naturally infected withSchistosoma mattheei
Authors: De Bont J. , Vercruysse J. , Sabbe F. , Ysebaert M. T. 
Published: June 2009

SUMMARYThe evolution of faecal egg output, worm burdens and tissue egg counts in young calves was monitored during the first year of natural exposure toSchistosoma mattheeiinfection on a Zambian farm. According to the duration of their stay on the farm, these calves were classified into 2 groups of 14 temporary tracers (TT calves) which were introduced on a 2-monthly basis for residential periods of 2 months, and 12 permanent tracers (PT calves) introduced either at the beginning of the experiment (Group A) or 2 months later (Group B) and gradually removed after residential periods of 2, 4, 6, 8, 10 and 12 months on the farm. Worm counts in the TT calves showed that infection occurred throughout the year on the farm and that levels of infection acquired during each period of 8 weeks correlated well with the respective infected snail densities observed at the main transmission site. Marked differences in worm population dynamics were recorded between the 2 groups of PT calves. In Group B animals which apparently were initially exposed to heavy transmission, according to the results from TT calves, much higher worm counts and greater susceptibility to reinfection were observed than in Group A animals initially exposed to lighter exposure. These results suggest that the development of resistance to natural infection withS. mattheeimay depend on the initial exposure to the parasite. Low initial exposures may lead to resistance whereas high initial exposures may result in decreased immune responses resulting in susceptibility to infection.
Reversal of hypoglycaemia in murine malaria by drugs that inhibit insulin secretion
Authors: Elased K. M. , Playfair J. H. L. 
Published: June 2009

SUMMARYWe have investigated the metabolic disturbances in 2 murine models of blood-stage malaria,Plasmodium chabaudiandPlasmodium yoelii. Blood glucose, plasma insulin and parasitaemia were measured in normal and infected mice before and after treatment with diazoxide, adrenaline, Sandostatin and quinine. Severe hypoglycaemia and marked hypersinsulinaemia developed during both infections. A single injection of diazoxide (25 mg/kg i.p.) or adrenaline (0·03 mg s.c.) lowered insulin concentrations in normal mice, reversed the hypoglycaemia in both infections and significantly reduced the hyperinsulinaemia inP. chabaudi-infected mice (P< 0·0001). Higher doses of Sandostatin (500 μg/kg s.c.) were required to reverse hypoglycaemia. Quinine (25 mg/kg i.p.) significantly increased blood glucose in normal and infected mice (P< 0·001) and no hypoglycaemia was observed in mice with normal blood glucose for more than 3 h. This study shows that the major cause of hypoglycaemia in murine malaria is hyperinsulinaemia rather than high consumption of glucose by host and parasites or chemotherapy with quinine, and that hypoglycaemia can be reversed by correcting the hyperinsulinaemia.
The capacity of the fungusDuddingtonia flagransto prevent strongyle infections in foals on pasture
Authors: Larsen M. , Nansen P. , Grøndahl C. , Thamsborg S. M. , Grønvold J. , Wolstrup J. , Henriksen S. A. , Monrad J. 
Published: June 2009

SUMMARYA field trial was conducted to evaluate the potential of the nematode-destroying fungusDuddingtonia flagransto control free-living stages of horse strongyles. In late Spring 2 groups of horses (yearlings) with mixed infections of strongyles were allowed to contaminate 2 equal-sized pastures. One of the groups (F) received a daily dose ofD. flagransmixed in a feed supplement, while the other (C) received a similar amount of supplement without fungus. During a 3-month contamination period strongyle egg counts in faeces and number of infective strongyle larvae harvested from faecal cultures were determined. Grass samples were collected fortnightly. After the contamination period the yearlings were removed and 2 groups of young tracer foals (TF and TC) grazed the fungus and control pastures respectively for 4 weeks, housed for another 15 weeks and then killed to determine their worm burdens. The number of larvae in cultures from group TF was significantly lower than that in TC and herbage infectivity was reduced to a very low level on the pasture grazed by horses fed fungi. The number ofStrongylus vulgarisandStrongylus edentatuslarvae was also significantly lowered in group TF. Cyathostome larvae recovered from the mucosa of the ventral and dorsal colon and from the caecum were significantly lowered in group TF foals. Also, the number of strongyles found in the gut contents of group TF foals were significantly reduced in the dorsal colon, but numbers of worms in the ventral colon and in the caecum were similar to those of the controls.
The ultrastructure of the anterior end of maleOnchocerca volvulus: papillae, amphids, nerve ring and first indication of an excretory system in the adult filarial worm
Authors: Strote G. , Bonow I. , Attah S. 
Published: June 2009

SUMMARYA detailed morphological investigation of the anterior sensory organs, the nerve ring and a glomerulus-like structure in maleOnchocerca volvuluswas performed by means of electron microscopy. The 8 head papillae are arranged in the common 4 + 4 pattern of most filarial worms in circles around the mouth opening. The amphidial openings are found between the circles of inner and outer papillae on both sides of the mouth. Inside, several additional nerve axons are seen in the tissue of the anterior tip not related to one of the identified papillar structures. The inner and outer papillae exhibit a remarkably different fine structure, and are part of a complex system of at least 2 different receptor cell types at the anterior tip of the worm. The amphidial channel contains 8 modified cilia; accessory axons are associated with the cytoplasm of the sheath cell. The anterior nerve ring of male worms is located about 150 µm posterior from the outermost tip of the head region. It consists of several fibres coiled around the oesophagus. The comparison of the fine structure of the central nervous system did not show the expected morphological differences associated with the heterogeneous age distribution in the natural worm population. This was in contrast to previous findings with respect to tissues in different parts of the worm. The study also provides the first evidence that suggests the existence of an excretory organ in a filarial worm in the region of the anterior nerve ring. Paired glomerulus-like structures in the lateral chords and a canal formed by a projection of the basal zone of the cuticle were identified.
The effect of infection with Lyme disease spirochetes (Borrelia burgdorferi) on the phototaxis, activity, and questing height of the tick vector Ixodes scapularis
Authors: Lefcort H. , Durden L. A. 
Published: June 2009

SUMMARYLittle is known about the effects of infection with Borrelia burgdorferi, the bacterium that causes Lyme disease, on its tick vectors. The purpose of this study was to determine the behavioural and ecological effects of infection by the bacterium in nymphal and adult black-legged (Ixodes scapularis) ticks. We found that the effects of infection were more pronounced in adults than in nymphs. Compared to uninfected adults, infected adults were less able to overcome physical obstacles, avoided vertical surfaces, were less active and quested at lower heights. Infected nymphs showed increased phototaxis and attraction to vertical surfaces. Infected nymphs also showed trends toward increased questing height and a greater tendency to overcome physical obstacles although these trends were not statistically significant. These altered behaviours in an infected tick may affect survival or pathogen transmission and may reflect kin selection in the bacterial pathogen.
Infestation with larvae of the sea anemone Edwardsia lineata affects nutrition and growth of the ctenophore Mnemiopsis leidyi
Authors: Bumann D. , Puls G. 
Published: June 2009

SUMMARYThe lobate ctenophore Mnemiopsis leidyi is a periodically abundant and voracious plankton predator in coastal waters along the east coast of the United States. In the 1980s it was accidentally introduced to the Black Sea where it caused a dramatic reduction in fisheries. We investigated how M. leidyi is affected by infestation with parasitic larvae of the sea anemone Edwardsia lineata. Infested M. leidyi contained 1–30 (median 7) E. lineata larvae. Within M. leidyi most larvae had their mouth in the gastrovascular system near the aboral end of the pharynx. Parasitic E. lineata ingested all food previously ingested and pre-digested by M. leidyi. Non-infested M. leidyi had higher growth rates than infested individuals, which had zero or negative growth rates. Egg production was similar for infested and non-infested M. leidyi of similar size. Simulation based on the empirical data suggests that growing, non-infested, M. leidyi are expected to have a larger life-time egg production than infested shrinking individuals. E. lineata could be at least partially responsible for the sharp decline of M. leidyi populations in fall in US coastal waters. Advantages and disadvantages of E. lineata as a potential candidate for the control of the artificially introduced M. leidyi population in the Black Sea are discussed.
Nippostrongylus brasiliensisinfection evokes neuronal abnormalities and alterations in neurally regulated electrolyte transport in rat jejunum
Authors: Masson S. D. , McKay D. M. , Stead R. H. , Agro A. , Stanisz A. , Perdue M. H. 
Published: June 2009

SUMMARYNeuronal abnormalities have been described in the intestine of helminth-infected rats. However, the physiological ramifications of these changes have not been determined. Here, we examined epithelial ion secretion, indicated by increases in short-circuit current (Isc), evoked by electrical transmural stimulation (TS) of enteric nerves in Ussing-chambered jejunal tissues fromNippostrongylus brasiliensis-infected rats. Rats were examined at 10 and 35 days post-infection (p.i.); non-infected rats served as controls. TS resulted in significantly reduced ion secretion in jejunum from 10 day p.i. rats compared to controls or jejunum from 35 day p.i. rats. The TS response in tissue from infected rats had, unlike controls, no cholinergic component. Tissues from both non-infected and infected rats were equally responsive to the muscarinic agonist bethanechol, suggesting that the cholinergic defect was neuronal and not an inability of the epithelium to respond to cholinergic stimulation. However, increases in Isc evoked by exogenous substance P (SP) in tissue from rats 10 day p.i. were reduced in magnitude to approximately 25% of control values. Concomitant with these physiological changes, tissue from infected rats contained increased amounts of substance P immunoreactivity and intestinal sections displayed increased numbers of substance P-immunoreactive nerve fibre profiles at both 10 and 35 days p.i. Thus, followingN. brasiliensisinfection there is a shift in the enteric nervous system away from cholinergic to non-cholinergic regulation, associated with increased amounts of the pro-inflammatory neuropeptide, substance P. We speculate that changes in neuronal structure and function are intimately involved in the co-ordinated multicellular response to intestinal parasitic infection and subsequent gut recovery.
Setaria digitatamicrofilaraemia inMastomys coucha: an animal model for chemotherapeutic and immunobiological studies
Authors: Mukhopadhyay S. , Dash A. P. , Ravindran B. 
Published: June 2009

SUMMARYIntraperitoneal implantation of adult gravid females of the bovine filarial parasite,Setaria digitatainMastomys couchawas found to induce microfilaraemia lasting for about 125 days. The microfilariae (mf) could be detected as early as 4 days postimplantation (p.i.) and peak levels of about 30 mf in 20 µl of blood were observed by 21 days. A significant positive correlation was found between mf density and the body weight of recipients pre-implantation. The implanted adult worms were generally viable only for less than 1 week. Implantation resulted in a significant decrease in total leucocytes and erythrocytes, induction of eosinophilia, splenomegaly and anti-erythrocyte autoantibodies. The microfilariae in circulation developed into 3rd-stage infective larvae (L3) when fed ontoAedes aegypti(refm, Liverpool strain). The mf in circulation were found to be eliminated by oral administration of diethylcarbamazine citrate, indicating the usefulness of this model for screening potential anti-microfilarial drugs. During the microfilaraemic phase, priming with tetanus toxoid (TT) resulted in significantly decreased production of anti-toxin levels indicating a state of generalized immunosuppression. Induction of antibodies to various fractionated antigenic components of adult parasites could be demonstrated by enzyme immunoassay (EIA) inM. couchaimplanted with live or cold-stunned adult worms. TheS. digitata–M. couchamodel thus is found amenable to perform chemotherapeutic and immunobiological investigations in experimental filariasis.
Codon usage inCryptosporidium parvumdiffers from that in other Eimeriorina
Authors: Char S. , Kelly P. , Naeem A. , Farthing M. J. G. 
Published: June 2009

SUMMARYCodon usage ofCrytosporidium parvumwas compared with those of other EimeriorinaToxoplasma gondiiandEimeria tenellaand revealed a biased use of synonymous codons with a preference for NNU (40·0%) and NNA (33·4%). There was no close resemblance of the codon usage ofC. parvumtoT. gondii(correlation coefficient, r = 0·14) orE. tenella(r = 0·14) but it was similar toEntamoeba histolytica(r = 0·75) andPlasmodium falciparum(r = 0·5). Analysis of the codon usage in homologous gene sequences (actin, β-tubulin) also failed to reveal a close relationship betweenC. parvumandT. gondiiorE. tenella. The low usage codons inC. parvumwere most frequently used codons inT. gondiiandE. tenella. These observations are consistent with 18S rRNA sequence analysis which shows no close relationship ofCryptosporidiumwith other Eimeriorina (Sarcocystis, ToxoplasmaandEimeria) and questions the validity of the current classification ofC. parvum.
Extravascular foci ofTrypanosoma vivaxin goats: the central nervous system and aqueous humor of the eye as potential sources of relapse infections after chemotherapy
Authors: Whitelaw D. D. , Gardiner P. R. , Murray M. 
Published: June 2009

SUMMARYRelapse of parasitaemia after drug treatment of trypanosome infections is normally attributed to drug-resistance on the part of the parasite, under-dosage of the drug or reinfection of the host. In addition, inaccessibility of parasites to drug through sequestration in privileged extravascular sites has been shown in the past to occur withTrypanosoma brucei, and we have obtained evidence that extravascular foci ofT. vivaxcan also serve as a source of relapsing infections. Infection of goats with a West African stock ofT. vivaxresulted in severe illness, which was fatal if untreated. During the terminal stage of an acute infection, clinical signs of central nervous system involvement were apparent. Histologically, the choroid plexus was swollen and oedematous, and in some cases meningitis or meningoencephalitis was seen. Trypanosomes could be detected in the cerebrospinal fluid, and also extravascularly in the choroid plexus and meninges. In three cases they were present in the aqueous humor, associated with corneal cloudiness or opacity. Treatment of 2 goats with the trypanocidal drug diminazene aceturate eliminated parasitaemia, but infections in both relapsed about 6 weeks later, despite trypanosomes being undetectable in the bloodstream during the intervening period. We conclude that the relapse infections were caused by re-emergence of trypanosomes from the CNS and/or the eye, where sequestered parasites may have been inaccessible to the trypanocide.
Hymenolepis nana: the fine structure of the ‘penetration gland’ and nerve cells within the oncosphere
Authors: Fairweather I. , Threadgold L. T. 
Published: June 2009

SUMMARYThe fine structure of the oncosphere of Hymenolepis nana has been investigated by transmission and scanning electron microscopy, together with light microscope observations of JB–4 embedded material. The outer surface of the oncosphere is covered by an epithelial layer, termed the embryonic epithelium. Cell types present within the oncosphere include the penetration gland cell, oncoblast, or hook-forming cells, nerve cells, muscle cells (both somatic and hook), and undifferentiated ‘stem’ cells. The penetration gland is a large, U-shaped structure, situated in the anterior region of the oncosphere, and filled with secretory granules of 2 distinct morphological types. Histochemically, the secretory material yields reactions characteristic of an acid mucopolysaccharide. A proteinaceous-substance and small amounts of glycogen are also present. Up to 4 pairs of ducts from the penetration gland have been observed. They pass through the basal lamina and the epithelial layer to open against the polar filament layer at the anterior end of the oncosphere. Nerve cells are described in a cestode oncosphere for the first time. The cells are paraldehyde-fuchsin-positive and show a high level of secretory activity, as evidenced by the large numbers of dense-cored vesicles produced by the Golgi apparatus in the perikarya; consequently, they are tentatively regarded as possible neurosecretory cells. The vesicles are transported down the axon to be stored in specialized swollen axon terminals, which form definite junctions with the muscle cells.
Pheromone of Ornithodoros spp. (Argasidae) in the coxal fluid of female ticks
Authors: Schlein Y. , Gunders A. E. 
Published: June 2009

SUMMARYCoxal secretion of adult female Ornithodoros erraticus was found to contain a sex pheromone that induces in males of this species a mating response towards nymphs smeared with this secretion. Heterospecific coxal fluid from O. tholozani and O. moubata also elicited a mating response from O. erraticus males. Adult O. erraticus females did not evoke courting behaviour when immobilized or killed, but normal mating behaviour was regained when the immobilized females were freed – proving that both pheromone and recognition of a behavioural pattern are essential components of mating behaviour. Secretion of the sex pheromone appears by the 4th day after a blood meal and accumulates with time, thus increasing the number of attempted matings.
Reinfection with hookworm after chemotherapy in Papua New Guinea
Authors: Quinnell R. J. , Slater A. F. G. , Tighe P. , Walsh E. A. , Keymer A. E. , Pritchard D. I. 
Published: June 2009

SUMMARYReinfection with hookworm (Necator americanus) following chemotherapy was studied over 2 years in a rural village in Madang Province, Papua New Guinea. The prevalence of hookworm infection had returned to pre-treatment levels after 2 years, and the geometric mean hookworm burden had returned to 58 % of the pre-treatment value. The rate of acquisition of adult worms was independent of host age, and was estimated as a geometric mean of 2·9–3·3 worms/host/year (arithmetic mean 7·9–8·9 worms/host/year). There was significant predisposition to hookworm infection; the strength of this predisposition did not vary significantly between age or sex classes.
Epidemiology of Toxocara canis in red foxes (Vulpes vulpes) from urban areas of Bristol
Authors: Richards D. T. , Harris S. , Lewis J. W. 
Published: June 2009

SUMMARYA descriptive epidemiological survey was undertaken of the ascarid nematode Toxocara canis in 521 red foxes (vulpes, vulpes) during the period January 1986 to July 1990. Age–prevalence and age–intensity profiles show that worm are significantly higher in cubs than in subadult or adult foxes and higher in subadult than in adult foxes. variations in worm burdens occur, with the highest prevalences and intensities being found during the spring, when are born, and in the summer months. Prevalences and intensities then decrease during the autumn and winter months both subadult and adult foxes, but, during this period, prevalences are significantly higher in male than in female Variations in worm burdens in the fox population are likely to be related to the reproductive cycle of the fox, with proportion of cubs becoming infected in utero. The role of the fox in the transmission of T. canis in the urban environment is discussed.
Viability of Onchocerca volvulus in vitro
Authors: Strotel G. , Bokhof A. , Comley J. C. W. 
Published: June 2009

SUMMARYThe use of a selective schedule of tests to identify a viable population of isolated adult Onchocerca volvulus (Nematoda: Filarioidea) has been investigated in a large worm population. The study was initiated to develop methodology appropriate to test new candidate macrofilaricides for their in vitro activity against O. volvulus. After removal from the host the viability of isolated intact parasites was estimated by assessing the motility indices of male worms, and the colorimetric quantification of the reduction of the bioreducible tetrazolium reagent XTT and lactate output by female worms. Additionally the motility of whole females and the movement of inner organs of female worms were scored quantitatively. These response parameters were used to sort the adult worms into viability groups at the start of the in vitro culture. The adult worms were then observed for 6 days and viability was assessed regularly during the culture period. At the end of the culture period, the reduction of the water-insoluble tetrazolium reagent MTT was used to determine the formazan formed by the entire male and female worms. The response parameters used at the start of the culture proved to be highly predictive for detecting viable and non-viable adult worms. In the group of worms selected as ‘viable’ around 70% kept their motility and metabolic activity at a high level until the end of the culture compared to the initial level. In contrast, none of the female worms and only 13% of the male worms categorized as ‘poorly viable’ demonstrated a motility index or metabolic level at the end of the culture period that was comparable to that of the worms in the ‘viable’ groups. For female worms the lactate output correlated significantly with weight whereas no correlation was seen between MTT reduction and weight.