bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental induction of Theileria parva lawrencei carrier state in an African buffalo (Syncerus caffer)
Authors: Grootenhuis J. G. , Leitch B. L. , Stagg D. A. , Dolan T. T. , Young A. S.
Published: June 2009

An African buffalo (Syncerus caffer), born in captivity and demonstrated to be Theileria-free, and 2 susceptible cattle were inoculated with a Theileria parva lawrencei sporozoite stabilate. The buffalo had a very mild disease reaction, while the 2 cattle died of acute theileriosis. It was possible to isolate T. p. lawrencei from the buffalo up to 888 days after infection by the application of non-infected Rhipicephalus appendiculatus nymphs and up to 657 days after infection by the establishment of lymphoblastoid cell lines infected with T. p. lawrencei schizonts from peripheral mononuclear blood cells. The infection rate and levels of Theileria in the resultant adult ticks varied from 11 to 70% with 0·3–11 acini infected/tick. Stabilates prepared from these tick batches caused fatal T. p. lawrencei infections in cattle.
Factors affecting the acquisition of resistance against Schistosoma mansoni in the mouse. The effect of varying the route and the number of primary infections, and the correlation between the size of the primary infection and the degree of resistance that is acquired
Authors: Long E. , Harrison R. , Bickle Q. , Bain J. , Nelson G. , Doenhoff M.
Published: June 2009

Mice given primary infections of Schistosoma mansoni by percutaneous or subcutaneous routes were found to acquire a higher degree of resistance against homologous challenge after 7–8 weeks than mice infected intraperitoneally. Mice infected by the intraperitoneal route tended to have smaller worm burdens than those infected with the same number of cercariae by the other two routes and this may, in part, have contributed to the relative lack of efficacy of intraperitoneal infections in inducing resistance to re-infection. The same degree of resistance was acquired after primary percutaneous infection irrespective of whether it was administered in 3 equivalent weekly doses, or the same total number of cercariae was administered as a single infection. The same degree of resistance was also observed when a percutaneous challenge was administered on the same or a different skin site to that which received the percutaneous primary infection. The degree of resistance to re-infection acquired after a percutaneous primary infection correlated well with the size of the primary worm burden and the number of eggs in the intestine and liver, but did not correlate with the number of eggs in the lungs.
Morphology of the reproductive system of femaleMoniliformis dubius(Acanthocephala)
Authors: Asaolu S. O.
Published: June 2009

By means of light and electron microscopical techniques, the organization of the reproductive tract of femaleMoniliformis dubiusis described. The tract consists of an efferent duct system associated with 2 ligament sacs present in the body cavity. The efferent duct system consists of uterine bell, uterus and vagina. The uterine bell contains a complex system of routes and is associated with the ligament sacs in a way that facilitates egg sorting. The dorsal and ventral ligament sacs exist with separate cavities at the posterior end, where they are attached to the efferent duct, but merge into a single sac at the anterior of the trunk.
Pregnancy-induced recrudescences strengthen malarial immunity in mice infected withPlasmodium berghei
Authors: Van Zon A. A. J. C. , Eling W. M. C. , Hermsen C. C.
Published: June 2009

A considerable proportion of mice lose acquired immunity toPlasmodium bergheiduring the first pregnancy. Immune parous mice, however, have a better immune status than virgin mice, the risk of loss of immunity during a subsequent pregnancy is greatly reduced, the capacity to clear parasites is enhanced, and the maintenance of immunity is less dependent on certain splenic functions. The establishment of improved immunity is dependent on the presence of proliferating parasites during the second half of pregnancy when immunosup pression results in recrudescence. Immune reactivity is also improved after a (chemothera peutically controlled) recrudescent infection provoked by immunosuppressive treatment of immune mice with corticoids or anti-T cell serum. This mimics the situation encountered during pregnancy. Hence, improved immunity after pregnancy is a consequence of a reconfrontation of a suppressed and/or convalescent immune system with proliferating parasites.
Corynetoxins and nematodes
Authors: Bird A. F. , Jago M. V. , Cockrum P. A.
Published: June 2009

Corynetoxins, the toxic glycolipids produced by Corynebacterium rathayi colonizing bacterial galls induced by the seed gall nematode Anguina agrostis in annual ryegrass (Loliurn rigidum), did not affect embryogenesis or larval development of A. agrostis although they did inhibit the rate of egg hatching. Corynetoxins were not toxic to several species of nematode which are parasites of roots nor to various stages of the free-living nematode Caenorhabditis elegana and they did not appear to influence the numbers of C. rathayi that became attached to the surface of the cuticle of infective larvae of A. agrostis.
Elleipsisoma thomsoni Franca, 1912: an Apicomplexan parasite in the red blood cells of the mole (Talpa europaea)
Authors: Mohamed Hassan A. , Molyneux D. H.
Published: June 2009

The rediscovery of Elleipsisoma thomsoni Franca 1912 from Talpa europaea is reported. This organism, whose identity as a parasite was initially doubted, is shown to be an intra-erythrocytic protozoan parasite. Light microscope observation confirmed the original description and 22/53 (42·5%) moles examined from a locality near Blackpool were positive. Organ impression smears demonstrated that E. thomsoni was concentrated in the heart and lungs, occasionally in the kidneys, liver and spleen. Electron microscope studies conclusively showed that the parasite was a member of the phylum Apicomplexa. A typical apical complex was present with rhoptries, micronemes, polar ring and microtubules but, in contrast to the genera Plasmodium, Babesia and Theileria, a conoid was also present. The parasitized red cells were larger than normal mature erythrocytes and the remaining cytoplasm of the erythrocyte was less dense than that of non-infected red cells. The problem of studying this enigmatic parasite and its life-cycle are described.
Thymidine uptake by chicken kidney cells parasitized by Eimeria tenella: evidence for a diffusable mediating substance
Authors: Urquhart Catriona
Published: June 2009

The pattern of DNA synthesis in chicken kidney (CK) cells parasitized by Eimeria tenella was altered; a 2-fold increase in the uptake of [3H]-thymidine occurred in these cells compared with that shown by the controls. This difference was significantly different at 16 h post-inoculation (p.i.) and reached a peak at 20 h p.i. Non-parasitized cells in co-culture with parasitized cells showed a level of incorporation intermediate between that of the parasitized and non-parasitized mono- cultures. It was shown that this stimulation was due to a factor released into the medium by the parasite or the parasitized cell. A possible course of events leading to induced and prolonged DNA synthesis by the host cell and the significance of this change in the life-cycle of the parasite is discussed.
Babesia divergens infections in the Mongolian gerbil: characteristics of a human strain
Authors: Liddell K. G. , Lucas S. B. , Williams H.
Published: June 2009

A strain of the cattle piroplasm Babesia divergens isolated from a fatal human infection was propagated in the Mongolian gerbil through 150 semi-continuous intraperitoneal passages. The infection was normally fatal; death, accompanied by profuse haemoglobinuria and debilitation, occurred as early as 44 h after intraperitoneal inoculation of heavily parasitized blood with precipitous drops in red blood cell and platelet counts. The average maximum parasitaemia achieved increased on continuous passage reaching 80% by the 150th stage. Twenty-four hours after infection erythrophagocytosis and splenic congestion were apparent by light and electron-microscopical examination and by 48 h hepatic necrosis, renal tubular damage with haemoglobin cast accumulation and ischaemic necrosis of ileal mucosa had developed. Gerbils were highly susceptible to small numbers of parasites when the inoculum was either fresh parasitized blood in high dilution or erythrocytes concentrated from animals showing minimal parasitaemia. Animals inoculated with parasites preserved in dimethyl sulphoxide at low temperatures usually developed fatal infections. However, occasionally animals suffered at most a low grade parasitaemia subsequent to recovery with parasite elimination. These animals were immune to further challenge, and no chronic infections developed. A. field strain of B. divergens isolated locally from a case of bovine redwater behaved similarly to the human strain on continuous passage in gerbils.
Morphology of the reproductive system of maleMoniliformis dubius(Acanthocephala)
Authors: Asaolu S. O.
Published: June 2009

The histology of the reproductive system of maleMoniliformis dubiushas been studied by a variety of microscopical techniques. The system includes 2 testes from each of which arises a vas efferens. Products from the testis enter the vas efferens through openings present in the wall of the vas efferens. The testes are contained in a ligament sac and each testis is enveloped separately by an outgrowth of the ligament sac wall. There are 8 unicellular cement glands. The cement substance contains spherical electron-dense droplets presumed to be lipids. Saefftigen's pouch appears to be a hydraulic mechanism to regulate the turgidity of the wall of the bursal cap to effect successful copulation with female worms. The muscles attaching the genital sheath and bursa to the body wall are likely to be concerned with bursal eversion and inversion. Stimuli receptors connected to the genital nervous system are located in the penis and bursa.
Schistosoma mansoni: temporal distribution of radioselenium-labelled schistosomula in lungs of mice during the first two weeks of infection
Authors: Georgi Jay R. , Dean D. A. , Mangold Beverly L.
Published: June 2009

The number of schistosomula in lungs was determined by compressed organ autoradiography at intervals up to 14 days after exposure of mice to 75Se-labelled cercariae by tail immersion. Probit analysis of compressed lung autoradiogram focus counts, expressed as percentages of initial infection level, yielded estimates of the average time of arrival, peak accumulation in the lungs and average time of departure of schistosomula: 4·5±0·87, 6·3 ± 0·45 and 11±0·58 days, respectively. At peak accumulation 92±3·5 % of the initial number of schistosomula were found in the lungs. It thus appears that little or no significant attrition of schistosomula occurred in the skin and, instead, that most of the 50–70% of penetrant cercariae that fail to reach adulthood are lost somewhere between the pulmonary and hepatic phases of development. Loss of 75Se label from schistosomula during the first 14 days was exponential, with an average half-life of 4·5±0·81 days. However, the high sensitivity of autoradiography tended to compensate for this rather rapid rate of label loss. It was pointed out that autoradiographic detection of schistosomula as discrete loci of radioactivity can also be expected to overcome the problem posed by the accumulation in such tissues as liver and kidney of 75Se label that has become separated from larvae.
Pathology ofSchistosoma curassoniinfection in sheep
Authors: Vercruysse J. , Fransen J. , Southgate V. R. , Rollinson D.
Published: June 2009

The gross- and histopathology of natural and experimentalSchistosoma curassoniinfections in sheep were studied. The data obtained showed thatS. curassoniinfection in sheep causes only slight clinico-pathological manifestations with preferential involvement of the liver, the lower intestine and the urinary bladder. A variable spectrum of host reaction to the eggs within an individual animal was observed, reflecting the duration of presence of eggs in the organs. In the liver, egg granulomas were most numerous in the perilobular regions, while in the intestine, lesions were most pronounced in the mucosa of the rectum. The presence of eggs in 10% of the urinary bladders examined indicated some bladder involvement.
Evidence against the hypothesis that metacestodes of Hymenolepis diminuta inhibit corpora allata functioning in the intermediate host, Tenebrio molitor
Authors: Hurd Hilary , Weaver R. J.
Published: June 2009

Several of the pathophysiological responses made by the beetle Tenebrio molitor, when infected with metacestodes of Hymenolepis diminuta, may be attributed to a parasite-induced reduction in host juvenile hormone titre. It has been suggested that production of this hormone by the corpora allata may be inhibited in parasitized insects. This hypothesis was tested using an in vitro radiochemical assay to compare the biosynthesis of juvenile hormone by single pairs of corpora allata taken from mated 12- and 15-day-old infected and control female insects. The results demonstrate, however, that there was no difference in hormone production associated with metacestode infection. Other possible mechanisms for parasite interference in this host endocrine system are discussed.
Parasitological observations ofSchistosoma bovisin normal and T-cell deprived mice
Authors: Murare H. M. , Doenhoff M. J.
Published: June 2009

A laboratory life-cycle ofSchistosoma boviswas established in order to study the host-parasite relationship in immunologically intact and T-cell deprived mice. Normal mice were found to have ‘self-cured’ theirS. bovisinfections almost completely by 10 weeks after cercarial administration, and there was no evidence of self-cure by day 79 in T-cell deprived animals, Thus, groups of deprived mice autopsied between 9 and 11 weeks after infection were invariably found to have greater worm burdens and a greater total number of eggs in the liver than comparably-infected normal mice. However, liver egg counts/worm pair were similar in the two types of host, and differences between normal and deprived mice with respect to totalS. bovisegg counts in the intestine were also not consistently in the same direction in all experiments. Faecal egg counts were always less in deprived mice than in normal mice, even in an experiment in which the deprived mice had a significantly higher intestinal tissue egg count than the normal control group. The results are discussed in relation to the better knownS. mansoni/mouse host-parasite relationship.
Trypanosoma musculi:influence of uric acid onin vitroformation of metacyclic trypomastigotes
Authors: Roger M. , Viens P.
Published: June 2009

Uric acid is the most important constituent in the urine of insects. Infective metacyclic forms of the stercorarian trypanosomes are produced in the rectum of their insect vector and are thus in contact with uric acid. Using a culture system which permitted the growth of the insect stages ofTrypanosoma musculi, we studied the influence of uric acid on the metacyclogenesis of this parasite. When added to the culture, uric acid enhanced the production of metacyclic forms. Furthermore, it rendered these trypanosomes highly infective by the oral route. It is suggested that uric acid may play an important role on the metacyclogenesis ofT. musculi.
Microfilaria density distribution in the human population and its infectivity index for the mosquito population
Authors: Park Chai Bin
Published: June 2009

A new method of computing the infectivity index of microfilariae (mf) for the mosquito population is proposed using the estimated mf density distribution in the human population. The observed density distribution is considered a compound of the Poisson and the gamma distributions. The former distribution describes the probability of a specimen containing a specified number of mf and the latter describes the density distribution of mf in the host population. The mf infectivity index is the probability that a blood meal will include at least 1 mf, conditional on the population-density distribution of mf as specified by the gamma distribution. Actual data indicate that this population-density-based infectivity index can be considerably different from the conventional index based on the survey-density distribution. The level of the carrier rate of mf in a survey is greatly influenced, apart from the sample variation, by the average volume of blood taken from each person. The rate computed on the estimated population-density distribution of mf is convertible to any base amount of blood.
Observations on crystals found in the intestine of Nematodirus battus during the development of immunity to this nematode in lambs
Authors: Martin J. , Lee D. L.
Published: June 2009

Lambs which were given 60000 infective larvae ofNematodirus battus progressively threw off adult nematodes from day 20 onwards. Large, hexagonal crystals appeared in the intestine of the adult nematode at about this time and caused blockage of the intestinal-rectal or -cloacal junction. Lambs which were given 1000–2000 infective larvae did not throw off the infection, and adult nematodes from lambs which had been infected for up to 74 days did not contain these crystals. Chemical, histo-chemical and X-ray microanalysis tests on the crystals indicated that they are lipoprotein in composition. The crystals arise within the lumen of the nematode and appear to be associated with the development of immunity to this nematode in lambs.
Use of two-colour flow cytometry to assess killing ofGiardia muristrophozoites by antibody and complement
Authors: Heyworth M. F. , Pappo J.
Published: June 2009

A two-colour flow cytometry technique was used to assess killing ofGiardia muristrophozoites by rabbit anti-trophozoite antibodies and complement. Binding of rabbit antibody to trophozoites and killing of trophozoites were documented by flow cytometry, after incubating the organisms with fluorescein-conjugated anti-rabbit IgG and propidium iodide (PI). Percentages of PI+(dead) trophozoites ranged from >80%, after incubation with rabbit antiserum and complement, to <30%, after incubation with complement alone. The assay technique may be applicable to studies aimed at determining whether intestinal antibodies fromGiardia-infected mammals can killGiardiatrophozoites.
Effect of age and initial infection intensity on the rate of reinfection with Trichuris trichiura after treatment
Authors: Bundy D. A. P. , Cooper E. S. , Thompson D. E. , Didier J. M. , Simmons I.
Published: June 2009

The study examines the rate of re-acquisition of Trichuris trichiura infection after treatment in two populations, one of mixed age and the other of children with known preintervention infection intensity. A population living in a Caribbean village was treated with mebendazole and the rate of reacquisition of infection of four age classes (2–4, 5–10, 11–30, 30+ years) monitored over a 20-month period. The reinfection rate was higher in the child age-classes indicating either that children are more exposed to infection or that adults slowly develop a partially effective acquired immunity. A cohort of children (mean age 4·5 years) was separated into 3 intensity categories on the basis of expelled worm burdens and their rate of reacquisition of infection monitored over a 12-month period. The rate of reinfection was directly and positively associated with initial infection status. This may indicate that children with low intensity infections are consistently less exposed to infection or that they have effective immune responses. The latter conclusion, however, would imply that they had acquired this immunity early in life, and so appears to contradict the suggestion that resistance is only slowly acquired by adults. Reconciling these two conclusions may require more sophisticated immunological models than have been suggested previously for geohelminthiases.
An analysis of staining methods for the detection ofCryptosporidiumspp. oocysts in water-related samples
Authors: Smith H. V. , McDiarmid A. , Smith A. L. , Hinson A. R. , Gilmour R. A.
Published: June 2009

The ability of five staining techniques, originally developed for the rapid identification ofCryptosporidiumspp. oocysts in faecal samples, to detect oocysts in water and water-related samples was assessed. All the stains used (modified Ziehl Neelsen, auramine-phenol (Lempert), Wright-Giemsa, safranin-methylene blue and FITC-labelled monoclonal antibody) stained oocysts after storage in water for 2 months at 4 °C (71–89 % of control values). Storage of oocysts below 0 °C greatly reduced the staining ability of auramine-phenol. With the exception of oocysts stored in raw and final waters, the histochemical stains proved less useful in detecting oocysts than the monoclonal antibody. Organisms of similar size and shape took up these stains, causing confusion in interpretation. Cold Ziehl Neelsen and the FITC-labelled monoclonal antibody were best at identifying oocysts from a waterborne outbreak. Screening with a fluorescent antibody, followed by confirmation with cold Ziehl Neelsen, where possible, are the currently recommended procedures for the detection of oocysts in water-related samples.
Schistosoma mansoni: evidence that vascular abnormalities correlate with the ‘non- permissive’ trait in 129/Ola mice
Authors: Elsaghier A. A. F. , Mclaren D. J.
Published: June 2009

The pulmonary and portal vasculature of naïve mice of the 129/Ola and CBA/Ca strains has been studied by means of the vasculature casting technique. This involves injection of pigmented vinylite resin into the arterial and venous systems, followed by digestion of the tissues with KOH. The peripheral vessels of the arterial and portal systems of CBA/Ca mice were numerous and highly branched. In contrast, casts prepared from 70–80% of naïve 129/Ola mice showed dramatic reductions in the number and extent of the peripheral vessels. In addition, such vessels appeared severely truncated. The remaining 20–30% of naïve 129/Ola mice yielded lung and liver casts that were indistinguishable from the CBA/Ca casts. Casts prepared from 129/Ola mice infected 6 weeks previously withSchistosoma mansonicercariae showed the same segregation; faecal smears, together with observations of presence or absence of gross pathology in such mice confirmed that the vascular changes correlated with the ‘non-permissive trait’. We propose that such alterations facilitate the reportedly abnormal migration of schistosomes from the liver to the lungs in ‘non-permissive’ 129/Ola mice.
Culture characteristics of Trypanosoma catostomi and Trypanosoma phaleri from North American freshwater fishes
Authors: Jones S. R. M. , Woo P. T. K.
Published: June 2009

Culture characteristics of two species of piscine trypanosomes were compared. Trypanosoma catostomi from Catostomus commersoni was isolated in hypo-osmotic blood agar media but not in hyper-osmotic media. However, T. phaleri from Amia calva was isolated in both media. Only T. catostomi was stimulated to divide by diluting infected blood with water. The maximum number of T. phaleri and percentage of trypomastigotes were not affected by NaCl concentration. The maximum number of T. catostomi was inversely related to osmotic pressure and the percentage of trypomastigotes was directly related to osmotic pressure. This was confirmed by using equi-osmotic concentrations of NaCl, NaBr, Na acetate, KCl, choline-Cl or sucrose. Supplementation with urea had no effect on the number or morphology of trypanosomes. The survival of T. catostomi following cryopreservation was enhanced by prior incubation in hyper-osmotic media. Differential culture characteristics of these species may reflect adaptation to different host–vector systems.
Evidence for the presence of quinone methide isomerase in the metacercarial cyst of Microphallus sp. (Trematoda: Microphallidae)
Authors: Nellaiappan K. , Ramakrishnan R. , Jameela Banu M.
Published: June 2009

The white colour of the cyst wall of the metacercaria of Microphallus sp., even in the presence of dihydroxy phenol and phenoloxidase, is due to proteins generated through a possible quinone methide interaction. The quinone methide isomerase converts the phenoloxidase mediated quinone into β-hydroxy catechol. Formation of catechol from quinone by cyst extracts was observed spectrophotometrically and chromatographically. This enzyme is involved in detoxification of excess quinone and β-sclerotization of the cyst wall.
Heterogeneities in water contact patterns and the epidemiology of schistosoma haematobium
Authors: Chandiwana S. K. , Woolhouse M. E. J.
Published: June 2009

Variations in the amount of water contact made by individuals and in the amount of water contact made at different sites may have significant impacts on patterns of human schistosome infection. Previous studies have reported variations in the rate of water contact and differences in the sites used between age/sex classes, but there is limited information on variations in individual water contact behaviour. In this paper we report and analyse observations of essentially all water contacts made over a two week period by all individuals in a rural community in eastern Zimbabwe. The mean rate of water contact was 0.43 contacts/person/day. These data were over-dispersed, ranging from zero to 3.3 contacts/person/day; 90% of contacts were made by only 37% of the population. Contact rates were related to age (highest in 8 to 10-year-olds) but not sex, with substantial variation unaccounted for by these variables. Age and sex classes differed in types of water-related activities and the time of day of contact. A greater diversity of sites was used by children than by adults and by males than by females. Individual contact rates were correlated with intensities of infection, although the risk of infection per contact was estimated to be highest in 2 to 4-year-old children and higher for males than females. Five contact sites were used during the study period, with more than 50% of contacts occurring at just 2 sites. Different age and sex classes used different sites and there were additional site-related differences in types of activity and the time of day of use. The implications of these water contact patterns for schistosome epidemiology are discussed. In particular the results provide strong quantitative support for control programmes aimed at heavily used sites (e.g. focal mollusciciding) or at the minority of individuals making most water contacts (e.g. targeted chemotherapy).
Effects ofPlagiorhynchus cylindraceus(Acanthocephala) on the energy metabolism of adult starlings,sturnus vulgaris
Authors: Connors V. A. , Nickol B. B.
Published: June 2009

Although the relationship between intestinal parasitism, the ingestion and use of energy, and host survival is expected, little work has been done to outline the effect of such organisms upon their host's nutritional requirements in an ecological context. This study is the first to demonstrate that an intestinal helminth previously reported to be of little or no histopathological consequence,Plagiorhynchus cylindraceus, has a significant detrimental impact upon the flow of food energy through a definitive host, the European starling,Sturnus vulgaris. Within both male and female adult European starlings reductions in standard metabolic rates occurred as the result of initial infection, indicating that the host's basal metabolism/thermal regulatory abilities were altered. Moreover, initially infected male starlings, but not females, had an increased consumption and excretion of energy and maintained lower average daily body weights versus controls when temperature stressed. These results appear to be due to either a parasite-mediated alteration in host activity and/or to the disruption of host-digestive abilities. Additionally, these data indicate that, overall, male and femaleS. vulgarisrespond differently to infection and that intestinal helminths normally thought to be of little or no pathological consequence to the host are factors that should be addressed in future studies regarding animal energetics, ecology, and behaviour.
Plasmodium vivax: gametocyte infectivity of naturally infected Thai adults
Authors: Sattabongkot Jetsumon , Maneechai Nongnuj , Rosenberg Ronald
Published: June 2009

Up to 200 laboratory rearedAnopheles dirusmosquitoes were fed on each of 496 symptomatic Thai men who had patent, naturally acquiredPlasmodium vivaxgametocytaemia. Mean gametocyte densities were 455/mm3(range: 0–3281), geometric mean oocyst number was 9 (0–142), mean frequency of infection was 43% (0–100%), and mean sporozoite number in salivary glands was 9525 (0–285 000). There was little relation between gametocyte density and either oocyst number or frequency of mosquito infection. There were, however, statistically strong positive correlations between oocyst numbers and frequency of infection, and between number of oocysts and number of salivary gland sporozoites. The data suggest that each oocyst contributed about 850 sporozoites to a gland infection.
Penetration stimuli of fish skin for Acanthostomum brauni cercariae
Authors: Ostrowski De Nuñez M. , Haas W.
Published: June 2009

The cercaria of Acanthostomum brauni penetrates the skin of its fish host in response to a combination of two chemical signals from the fish skin surface: free fatty acids and a macro-molecular mucus component. The latter seems to be a protein, as the penetration-stimulating activity of fish skin surface mucus is eliminated by digestion with proteinase, but not by digestion with glycosidases, nor by a removal of glycosaminoglycans. These penetration-stimulating host signals differ from the glycoproteins that stimulate the attachment of A. brauni cercariae to the host and also from the macro-molecular fish host signals which have been found to stimulate the attachment and penetration by Opisthorchis viverrini cercariae.
Differential regulation of murineMesocestoides cortiinfection by bacterial lipopolysaccharide and interferon-γ
Authors: Jenkins P. , Dixon J. B. , Haywood S. , Rakha N. K. , Carter S. D.
Published: June 2009

Many liver-invasive parasites cause extensive liver damage which may result in an impaired ability to catabolize endotoxin. The influence of endogenous endotoxin on the progress of liver-invasive parasitic diseases has been investigated in murineMesocestoides cortiinfection. Invasion of liver tissue by tetrathyridia resulted in extensive parenchymal destruction with fibrosis. In association with this, undetoxified endotoxin, in potentially biologically active concentration, was found on peritoneal macrophages, 5 months post-M. cortiinfection. Host susceptibility was influenced by theLpsgene for responsiveness to lipopolysaccharide (LPS). The parasite burden of LPS-responsive (C3H/HeN) mice was significantly increased in the livers of these mice when compared to LPS-resistant (C3H/HeJ) mice. LPS reduced the ability of normal peritoneal macrophages to kill tetrathyridia, when co-culturedin vitro. LPS also abrogated the ability of recombinant interferon-γ (r.IFN-γ) to enhance macrophage larvicidal activity. Thesein vitrofindings were confirmedin vivo. Daily intraperitoneal administration of LPS, at low concentration, caused a 4-fold increase in parasite burden in the liver, while r.IFN-γ at optimal concentration reduced parasite burden by 57%. Post-infection macrophages have previously been shown to be refractory to cytokine-activation for larval killing. In this report, we conclude that (1) this refractoriness may be due to the presence of undetoxified endotoxin on post-infection macrophages and (2) endotoxin may reduce host resistance by abrogating effector macrophage response to IFN-γ.
Fate of attenuated schistosomula administered to mice by different routes, relative to the immunity induced againstSchistosoma mansoni
Authors: Coulson Patricia S. , Mountford A. P.
Published: June 2009

Newly transformed schistosomula and day 8 lung parasites, derived from optimally irradiated cercariae, were used to immunize groups of C57B1/6 mice via 4 different injection routes. Schistosomula administered intradermally induced high levels of protection, comparable with that achieved by percutaneous vaccination. Intermediate levels were elicited by delivery of parasites via intraperitoneal or intratracheal routes. In contrast, intravenous injection of schistosomula to the lungs resulted in little or no resistance. Attenuated day 8 schistosomula administered intradermally were at least as immunogenic as irradiated cercariae. The fate of radio-isotope labelled attenuated lung schistosomula, injected via the various routes, was examined by compressed organ autoradiography. After intradermal vaccination, a proportion of parasites migrated from the site of injection to the draining lymph node and lungs. Conversely, schistosomula administered via the other 3 routes persisted to varying degrees at the injection site, but little onward migration was observed. We suggest that successful vaccination requires that some attenuated parasites migrate to, and sequester in, lymph nodes draining the vaccination site; persistence at the site of administration alone is not an adequate stimulus.
The possible role of Rickettsia-like organisms in trypanosomiasis epidemiology
Authors: Baker R. D. , Maudlin I. , Milligan P. J. M. , Molyneux D. H. , Welburn S. C.
Published: June 2009

A simple model of human and animal trypanosomiasis is proposed in which the Ross equation for disease transmission is supplemented by a differential equation describing the inheritance of susceptibility in the vector. The model predicts an equilibrium state of balanced polymorphism for the fraction, θ, of susceptible tsetse and the occurrence of periodic epidemics at roughly the observed intervals. A loss of infectivity to tsetse of mechanically transmitted strains of trypano some would seem to be a good evolutionary strategy for the trypanosome. The main implication for disease control is that measures initially reducing trypanosomiasis incidence could trigger off subsequent epidemics. Since θ leads incidence, monitoring θ could give several years advance warning of major epidemics.
Host—parasite relationships and cysts of Leptomonas lygaei (Trypanosomatidae) in Lygaeus pandurus (Hemiptera: Lygaeidae)
Authors: Tieszen K. L. , Molyneux D. H. , Abdel-Hafez S. K.
Published: June 2009

A study of Leptomonas lygaei in Lygaeus pandurus is described. Flagellates with promastigote configuration were found in the midgut, ileum and rectum. Cysts and encysting stages (straphangers) were found in the rectum either attached to the flagella of promastigotes or free in the lumen. In the posterior midgut, the crypts were frequently filled with flagellates, but no attachment to host epithelium was observed. A close association between the flagellates and extracellular membrane layers was observed. In the rectum the flagellates frequently attached by hemidesmosomes to the cuticle of the gland cells and less frequently to the rest of the rectal wall. Interflagellar desmosomes between the expanded sheaths of flagella of adjacent parasites were also observed. Straphanger cysts attached to parental flagella by the formation of zonular desmosomes. Differences were apparent between the organelles of the encysting stages and the parental flagellates. In mature cysts, the cellular organelles were unrecognizable. A comparison between the cysts and flagellates of L. lygaei and Blastocrithidia familiaris is made.
Behavioural adaptation of the tapewormHymenolepis diminutato its environment
Authors: Sukhdeo M. V. K. , Kerr M. S.
Published: June 2009

Hymenolepis diminutamigrates up the small intestine in response to feeding the host 1 g of glucose. Locomotion during migration may result from fixed patterns of retrograde peristaltic-like waves in the strobila of the tapeworm which propel the organism against the normal expulsive forces in the small intestine. The peristaltic-like locomotory waves occur in a gradient along the strobila with a frequency of 24·9±0·9 cycles/min in the anterior segments of the worm, decreasing linearly to 6·6±1·4 cycles/min in the posterior segments of the worm. Chemical signals, isolated from the small intestine of fed hosts, which stimulate migration behaviourin vivodo not alter the behaviour of the scolex or strobilain vitro. Removal of the scolex containing the cerebral ganglia does not alter the frequency or pattern of locomotory activity in the strobila. After the worm is cut into pieces, each region generates the pattern of locomotory activity that is appropriate for that region. These data suggest that the peripheral nervous system, and not the central nervous system, is responsible for the coordination of the fixed patterns of locomotory activity in these tapeworms.
Demonstrating parasitic water mite-induced mortality in natural host populations
Authors: Lanciani Carmine A. , Boyett J. M.
Published: June 2009

The truncated negative binomial distribution is used to demonstrate water mite-induced mortality in a field population of the mosquito host Anopheles crucians. Consistent changes in the parameters of this distribution and in the number of hosts expected in higher mite load classes as truncation is applied to successively lower mite load classes suggest that many heavily parasitized individuals were missing from field samples. These changes are not observed in distributions derived from an association between parasitic larvae of another water mite, Hydrachna conjecta, and the insect Sigara ornata, which is apparently immune to this parasite. Although the method discloses parasite-induced mortality that is non-linearly related to parasite load, it fails to reveal linear parasite-induced mortality in a hypothetical example.
Schistosoma mansoni: a scanning electron microscope study of the developing schistosomulum
Authors: Crabtree Jean E. , Wilson R. A.
Published: June 2009

The surface morphology of schistosomula extracted from the skin, lungs and hepatic portal system (hps) of mice was investigated from Days 0 to 18 post-infection. Skin schistosomula and newly arrived schistosomula from the hps were of similar dimensions but were morphologically distinct. Lung schistosomula were considerably elongated with an estimated 53% increase in surface area compared to skin schistosomula. The pitted tegument of lung schistosomula was formed into ridges and troughs. These were compressed together in contracted individuals recovered from the hps on Day 10. The annular ridges were cross-linked by longitudinal septae which possibly prevent further elongation of the body. A regression of the spines between the mouth and the ventral sucker was observed in Day 2 skin schistosomula. In lung schistosomula only the spines at the anterior and posterior of the body remained. New spines were formed after the schistosomula reached the hps. It is suggested that the spines in the mid-region of the body are selectively disassembled and that their loss facilitates migration along the lumina of capillaries with the residual spines acting as anterior and posterior anchors. The mouth opening was enlarged in schistosomula from the hps recovered from Day 10 onwards. Skin schistosomula lost the cercarial apical tegumentary ridges between 24 and 48 h after penetration but a spineless protrusible area remained. After arrival in the hps this area became integrated into the anterior surface as the oral sucker developed around the sub-terminal mouth. The cercarial ciliated papillae were lost on penetration. The migrating schistosomulum had few visible sensory papillae but following arrival in the hps new papillae were observed.
Changes in the adenylate energy charge ofNematospiroides dubiusandTrichostrongylus colubriformisparalysed by levamisolein vivo
Authors: Sharpe M. J.
Published: June 2009

The adenine nucleotide content and adenylate energy charge ofNematospiroides dubiusfrom laboratory mice and ofTrichostrongylus colubriformisfrom lambs has been measured. Administration of the anthelmintic, levamisole, to infected hosts resulted in only a slight fall in the adenylate energy charge ofN. dubiusover a 3-h period but there was a greater fall in the adenylate energy charge ofT. colubriformisduring this period. In neither case did the energy charge fall quickly, nor did it fall to the low levels which would be expected if the levamisole were inhibiting synthesis of ATP. The changes in energy charge of the nematodes which occurred following administration of levamisole to their hosts was of the order which can be satisfactorily explained by changes in the environment of the nematodes, such as reduced oxygen tension. It is concluded that the maintenance of levamisole-induced paralysis of these two species of trichostrongylein vivodoes not rely on the inhibition of fumarate reductase.
Interactions between population growth and sexual reproduction in the viviparous monogenean Gyrodactylus turnbulli Harris, 1986 from the guppy, Poecilia reticulata Peters
Authors: Harris P.D.
Published: June 2009

Mating was observed in populations of Gyrodactylus turnbulli from guppies. Copulation took place between older (post-1st birth) flukes and resulted in the insemination of spermatozoa into the seminal receptacle. New-born flukes, and flukes which had only recently given birth for the first time (in which the penis was absent or developing), were never inseminated. Flukes were promiscuous, copulating with several partners in succession. The occurrence of mating was related to the size, age and crowding of the G. turnbulli population, taking place most frequently when the parasites were most densely crowded upon the peduncle of the fish on days 5 and 6 of the infection. Maximum population size was positively correlated with the number of flukes initiating an infection. As a result, mating began earlier, and continued for longer in populations founded by several parasites rather than those begun by single flukes. These observations are discussed with respect to the population biology of G. turnbulli: it is likely that sexual and asexual reproduction alternate, with sex being important only during phases of epidemic population growth. The significance of sex in gyrodactylids is discussed, and the potential importance of continuous sexual reproduction in G. turnbulli infections on cultivated guppies is noted.
The diet and gastrodermal ultrastructure of polystomatid monogeneans infecting chelonians
Authors: Allen K. M. , Tinsley R. C.
Published: June 2009

All polyopisthocotylean monogeneans previously studied, including representatives of the Polystomatidae infecting anuran amphibians, feed on host blood. However, the present analysis of species of Polystomoides, Polystomoidella and Neopolystoma, polystomatids which infect chelonian reptiles, has shown that this group has diverged nutritionally from related parasites. Histochemical tests failed to demonstrate haemoglobin in the gut caeca, and X-ray microanalysis confirmed the absence of haematin (or high concentrations of bound iron) in the gastrodermis. The chelonian poly-stomatids (and also the single monogenean which infects a mammal, Oculotrema hippopotami) feed on epithelial cells and mucus, the diet typical of monopisthocotyleans. Transmission electron microscopy revealed the same gastrodermal architecture in representatives of Polystomoides from Africa, N. America and S.E. Asia. The organization of the caecal epithelium conforms with that of blood-feeding polyopisthocotyleans, with two components: lamellated cells responsible for intracellular digestion interspersed with elements of a non-lamellated connecting syncytium. In other polyopistho-cotyleans, the syncytium probably has a skeletal, supportive role, related to the problems of intracellular accumulation of haematin, but in polystomatids infecting chelonians the syncytium is extremely reduced and its presence probably reflects an ancestry amongst blood-feeding relatives. The utilization of the presumably more primitive monogenean diet of epithelial cells and mucus by chelonian polystomatids may be related to the scarcity of superficial blood vessels in their oral and urinary bladder habitats.
Vaccination of lambs against infection with Taenia ovis using antigens collected during short-term in vitro incubation of activated T. ovis oncospheres
Authors: Rickard M. D. , Adolph A. J.
Published: June 2009

Activated oncospheres of Taenia ovis were incubated for 24 h or 48 h at 37.5°C in Medium 858 alone or in Medium 858 enriched with 20% lamb serum or foetal calf serum. Antigens contained in the supernatant medium from these incubations were concentrated, emulsified in Freund's incomplete adjuvant and injected intramuscularly into lambs. These lambs developed a very high level of immunity to subsequent challenge infection with T. ovis eggs.
A cloned kinetoplast DNA mini-circle fragment from a Leishmania spp. specific for post-kala-azar dermal leishmaniasis strains
Authors: Das Gupta S. , Ghosh D. K. , Majumder H. K.
Published: June 2009

DNA–DNA hybridization techniques have been found to be very useful in the classification and identification of Leishmania parasites. We report here the cloning of a mini-circle from Leishmania strain UR6 in a plasmid and subcloning of the mini-circle fragments in M13 mp9. Clone MLURk32, containing a 560 bp fragment of mini-circle, has been found to have unique specificity. Application of this specific probe in identifying different Leishmania isolates reveals that the probe reacted only with strains of post-kala-azar dermal leishmaniasis but not with strains or isolates of visceral leishmaniasis.
Parasite–induced reduction in host survival and fecundity: the effect of the nematode Elaphostrongylus rangiferi on the snail intermediate host
Authors: Skorping Arne
Published: June 2009

The effect of the protostrongylid nematode, Elaphostrongylus rangiferi, on the fecundity and survival of an intermediate snail host, Arianta arbustorum, was studied. Over an experimental period of 12 weeks, infected snails had a significantly lower egg production than uninfected control snails. No significant difference in survival was found between infected and uninfected adult snails. Infected juvenile snails showed a consistent decrease in survival with increasing mean density of parasites. A linear relationship was found between snail instantaneous death rate over a 28–day interval and the mean number of parasites/snail. When calculated for 4–day intervals, the instantaneous death rate was highest between 8 and 12 days post–infection. It is concluded that the most pathogenic phase of this parasite is during the first moult.
Experimental infections with Trichostrongylus colubriformis (Giles, 1892) Loos, 1905 in lambs: worm burden, growth rate and host resistance resulting from prolonged escalating infections
Authors: Chiejina S. N. , Sewell M. M. H.
Published: June 2009

Lambs were infected at daily intervals from 3 weeks of age with increasing doses of infective larvae of Trichostrongylus colubriformis, according to an exponential infection schedule designed to simulate the pattern of infection experienced by grazing lambs during the spring and early summer in Britain. The faecal egg counts and the worm burdens in the lambs followed a similar exponential trend for 12 weeks after initial infection.

The T. colubriformis burdens in these lambs appeared to be cumulative during the first 12 weeks, after which the animals developed a resistance to further reinfection, which was very strong by 16 weeks after initial infection. However, even lambs which were refractory to new infection continued to harbour large numbers of adult worms, which caused clinical disease in most of the lambs.

There was no evidence to suggest that either a turnover of the worm burden, inhibition of larval development or the sudden loss of established parasites played any major role in the regulation of the burdens of T. colubriformis in these young lambs.

The removal of the established burden 16 weeks after initial infection in one lamb appeared to result in a partial loss of resistance to a challenge infection given 10 days later.