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PubMed1984

Life cycle of the endoparasitic nematophagous fungus Meria coniospora: a light and electron microscopic study.

The obligate endoparasitic fungus Meria coniospora lives its entire vegetative life within infected nematodes. Conidia of M. coniospora infect the nematode Panagrellus redivivus mainly in the mouth region. The infection, starting with adhesion of conidia to the nematode surface, growth of trophic hyphae, production of conidiophores and conidia, was followed using light, scanning and transmission electron microscopy.

Animals↗
PubMedDate not supplied

Immunoepidemiology of intestinal helminthic infections. 1. The global burden of intestinal nematode disease.

Estimates of the world-wide prevalence of intestinal nematode infections indicate that there are more than 1000 million people infected, and several million cases of clinical helminthiases. Recent studies suggest that the morbidity has been underestimated and that moderate intensities of infection may have important developmental consequences, particularly for children of school age.

Ascariasis↗
PubMed2003

Evaluation of anthelmintic properties of extracts from some plants used as livestock dewormers by pastoralist and smallholder farmers in Kenya against Heligmosomoides polygyrus infections in mice.

Parasitic nematodes are among the most common and economically important infectious diseases of grazing livestock, especially in small ruminants in the tropics and subtropics in Kenya the control of gastrointestinal nematode infections in sheep and goats is usually made with synthetic anthelmintics but substantial levels of anthelmintic resistance have been recorded. A number of medicinal plants, that may provide possible alternatives, and are used by pastoralists and smallholder farmers in Kenya as deworming agents for their livestock and equines, namely Aframomum sanguineum, Dodonea angustifolia, Hildebrandtia sepalosa, Myrsine africana, Rapanea melanophloeos from Kenya, and Azadirachta indica from Kenya and Malaysia, together with the chemicals embelin and santonin that occur in some of these plants, were evaluated against Heligmosomoides polygyrus in mice. Commercial anthelmintics, namely ivermectin, pyrantel and piperazine, were also investigated, both to validate the mouse model system and to assess efficacy of these drugs against H. polygyrus. Pyrantel and ivermectin were highly effective in reducing the numbers of H. polygyrus worms as well as eggs in faeces of the mice, but piperazine had a lower activity. Application of santonin and M. africana significantly reduced the number of total worm counts (TWC) but not faecal egg counts (FEC). The use of embelin, R. melanophloeos and A. indica reduced FEC but not TWC. In all cases, however, reductions were well below the a priori level of 70% required for biological significance. A. sanguineum, D. angustifolia and H. sepalosa had no effect on either TWC or FEC. In conclusion, none of the plant preparations had any biologically significant anthelmintic effect in this monogastric host-parasite model system.

Animals↗
PubMed2000

The intensity and duration of primary Heligmosomoides polygyrusinfection in TO mice modify acquired immunity to secondary challenge.

The effect of dose and duration of immunizing infections of Heligmosomoides polygyrus on protection against homologous challenge was studied in female TO mice. Primary infections were terminated at various levels with pyrantel embonate (adult infections) or ivermectin (larval infections) and mice were then challenged with 500 infective larvae (L3). The level of protection to secondary challenge positively correlated with the intensity of the primary immunizing infection but truncation of larval infection produced significantly better protection than termination of the adult nematode infection. The duration of the primary larval infection (1-6 days) positively correlated with the level of protection to secondary challenge, antibody responses and the proportion of circulating eosinophils. Histological changes in the gastrointestinal tract, peripheral leucocytic changes and antibody responses of the mice to H. polygyrus adult somatic antigens indicate both a cellular and humoral basis of host immunity to secondary challenge. Although the TO mice are slow responders in that they harbour chronic infections, immunization by intramucosal killing of the larval stage produced strong protection against secondary challenge infection. The presence of dead immunogenic larval stages within the intestinal wall may well be an important factor, since it exposes the host to stage specific antigens at an appropriate location. The implications of the findings for the control of gastrointestinal nematode infections are also discussed.

Analysis of Variance↗
PubMed2007

Delayed goblet cell hyperplasia, acetylcholine receptor expression, and worm expulsion in SMC-specific IL-4Ralpha-deficient mice.

Interleukin 4 receptor alpha (IL-4Ralpha) is essential for effective clearance of gastrointestinal nematode infections. Smooth muscle cells are considered to play a role in the type 2 immune response-driven expulsion of gastrointestinal nematodes. Previous studies have shown in vitro that signal transducer and activator of transcription 6 signaling in response to parasitic nematode infection significantly increases smooth muscle cell contractility. Inhibition of the IL-4Ralpha pathway inhibits this response. How this response manifests itself in vivo is unknown. In this study, smooth muscle cell IL-4Ralpha-deficient mice (SM-MHC(Cre)IL-4Ralpha(-/lox)) were generated and characterized to uncover any role for IL-4/IL-13 in this non-immune cell type in response to Nippostrongylus brasiliensis infection. IL-4Ralpha was absent from alpha-actin-positive smooth muscle cells, while other cell types showed normal IL-4Ralpha expression, thus demonstrating efficient cell-type-specific deletion of the IL-4Ralpha gene. N. brasiliensis-infected SM-MHC(Cre)IL-4Ralpha(-/lox) mice showed delayed ability to resolve infection with significantly prolonged fecal egg recovery and delayed worm expulsion. The delayed expulsion was related to a delayed intestinal goblet cell hyperplasia, reduced T helper 2 cytokine production in the mesenteric lymph node, and reduced M3 muscarinic receptor expression during infection. Together, these results demonstrate that in vivo IL-4Ralpha-responsive smooth muscle cells are beneficial for N. brasiliensis expulsion by coordinating T helper 2 cytokine responses, goblet hyperplasia, and acetylcholine responsiveness, which drive smooth muscle cell contractions.

Animals↗
PubMed1989

Genetic resistance of hosts and its influence on epidemiology.

Evidence for the genetic control of resistance of sheep to gastrointestinal nematode infections was reviewed and compared with that of cattle to infestation with the cattle tick. Variation within sheep breeds in resistance to nematode infection is as great as that between breeds, is moderately heritable, and selection of lines of resistant sheep should result in animals carrying worm burdens around 10%-20% of those of unselected animals. The consequences of genetically resistant sheep for the epidemiology of Trichostrongylus colubriformis infection were examined with the aid of a simulation model. Predicted results were similar to those observed in cattle herds resistant to Boophilus microplus; seasonal peaks in parasite burdens were greatly reduced, and larval numbers on pasture were reduced even further. The use of genetically resistant hosts should permit a reduced frequency of anthelmintic treatment, and hence reduce the rate of development of anthelmintic resistance in the parasite.

Animals↗
PubMed1997

An immunoreactive protein to wheat-germ agglutinin antibody is induced in oat roots following invasion of the cereal cyst nematode Heterodera avenae, and by jasmonate.

A protein that cross-reacts to a wheat-germ agglutinin antibody was induced in oat roots following the invasion of second-stage juveniles (J2) of the cereal cyst nematode Heterodera avenae. This protein, designated ASP45, was acid soluble, and its molecular mass was about 45 kDa on a sodium dodecyl sulfate-polyacrylamide gel. ASP45 was induced in both compatible and incompatible interactions between the nematode and the plant, and also in roots by exposure to jasmonic acid (JA) or methyl jasmonate. However, ASP45 was not induced by elicitors of pathogenesis-related proteins, abscisic acid, or wounding. Lipoxygenase activity, which is involved in JA synthesis, was higher in nematode-infected and JA-treated roots than in their noninfected, untreated counterparts. Inhibition of lipoxygenase activity in roots abolished ASP45 induction in the nematode-infected roots. Amino acid sequences similar to that of ASP45 were found in chitinases of poplar tree and Arabidopsis, even though ASP45 showed no chitinase activity. Although the biological role of ASP45 in infected roots is not clear, JA is suggested to be involved in signal transduction after pathogen invasion of the plant.

Acetates↗
PubMed1984

Intestinal mast cell changes in guinea pigs infected with the nematode Trichostrongylus colubriformis.

Infection of guinea pigs with the parasitic nematode Trichostrongylus colubriformis was followed by a three- to fourfold increase in the number of mast cells in the small intestine mucosa. Mitotic figures were observed in many mast cells during the period numbers were increasing. Many mast cells developed cytoplasmic granules which, unlike pre-infection mast cell granules, contained crystalline structures.

Animals↗
PubMed1976

Effect of nematode parasite infection on the performance of stocker cattle at high stocking rates on coastal bermudagrass pastures.

Studies were conducted during the summer of 2 successive years (1971 and 1972) to determine the effects of gastrointestinal nematode parasitism on performance failure of stocker beef steers grazed at high stocking rates on Coastal bermudagrass pastures. During each of the 2 years, 3 groups of steers were rotated at 7- to 10-day intervals on sets of three 1.63-ha pastures from mid-May to late October. (Each group was maintained on a given set of pastures.) In the 1971 program, from mid-May to early August (phase 1) each group consisted of 48 steers for a stocking rate of 29.6 steers/ha. From early August to late October (phase 2) the number of steers per group was reduced to 36 (stocking rate of 22.2 steers/ha) to improve the plane of nutrition. In the 1972 program, 2 groups were stocked at 48 steers per group (29.6 steers/ha) and a 3rd group was temporarily stocked with 58 steers (10 additional steers) to provide 2 animals each month for necropsy evaluation of worm burdens. With exception of the monthly removal of 2 steers from the 3rd group, the stocking rate in 1972 remained intact for the entire grazing season. In 1971, the 3 groups (groups 1, 2, and 3) were treated with thiabendazole (2 doses, 16 days between doses) before grazing. Parasite burdens and levels of pasture contamination were low initially and body weight gains were good during the 1st 3 months of grazing (phase 1). In the 2nd half (phase 2) of the grazing program, 1 group of steers given free-choice supplemental feed (1% of body weight/steer each day) and treated with anthelmintic (thiabendazole; 2 doses, 18 days between doses, during August) and another group, given supplemental feed only, had significantly better weight gains than did the 3rd group, not given supplemental feed nor treated with anthelmintic. There was no weight gain advantage derived from the reduced stocking rate in phase 2. Tracer calves, which were allowed to graze on pastures, developed an increased level of infection after August. Fecal egg counts in the principal steers and recovery of infective larvae from pasture paralleled the infection level in tracer calves. Necropsy evaluation of steers from groups 1, 2, and 3 at the end of the 1971 program indicated a similarity in total worm counts, but in the group not given supplemental feed nor treated with anthelmintic there was more generalized inflammation and a greater number of lesions in the abomasum (Ostertagia) and the caudal portion of the intestine (Oesophagostomum). Steers in the 3rd group also were in poorer condition. Initial worm burdens in the 3 steer groups (groups 4, 5, and 6) were low at the start of the 1972 program. One group was given freechoice supplemental feed (0.5% of body weight/steer each day) and treated with anthelmintics (thiabendazole in the 1st dose, levamisole in the 2nd dose, 12 days between doses, in May and August) and another group was given supplemental feed throughout the summer; the 3rd group was treated with anthelmintics (in May and August)...

Animal Feed↗
PubMed1981

Characterization of surface antigens of Trichinella spiralis infective larvae.

Infective larvae of trichinella spiralis were surface-labelled with radioactive iodine, and the products were characterized biochemically and immunochemically. The labelled material was restricted to two basic subunits: a lentil lectin-adherent glycoprotein (GP), mol. wt 47K, and a lentil lectin-nonadherent protein fraction (P), mol. wt 55K. Both of these form homologous dimers through as yet unspecified covalent bonds to yield GP90 and P105. GP is further polymerized into higher molecular weight forms by disulphide bond-dependent associations. suggesting a highly cross-linked arrangement in the cuticle. To what extent this structure contributes to the overall organization of the cuticle remains to be established. The two labelled surface molecules are immunogenic in the infected host, and do not react with a panel of sera taken from animals chronically infected with other nematode species. The approach therefore offers immediate possibilities for immunodiagnosis in nematode infections, and for a comparative immunochemical study of the surface cuticle of different stages of the same and different nematode species and for studies of the function of the nematode cuticle.

Animals↗
PubMed1989

Nematode parasite infections of domestic pigs in a sub-tropical and high-rainfall area of India.

Fourteen hundred and ninety-six domestic pigs, Sus scrofa domestica L., from a sub-tropical and high-rainfall area of India were examined over a period of 18 months to ascertain their nematode parasite spectrum. The eleven species recovered, arranged in descending order of prevalence, are as follows: Ascaris suum, Oesophagostomum dentatum, Bourgelatia diducta, Stephanurus dentatus, Globocephalus connorfilii, Physocephalus sexalutus, Ascarops dentata, A. strongylina, Pseudocruzia orientalis, Setaria bernardi and Gnathostoma hispidum. This is also the first report of the occurrence of Setaria bernardi in pigs in India. A. Suum, the most prevalent species (51.67%) found in the pigs of the region, is presumably of zoonotic importance. Another species of public health significance that was encountered in the survey was Gnathostoma hispidum. The overall infection rate was considerably higher (76.42%) in the low-altitude region than in the high-altitude one (62.50%). The highest level of infection (73.2%) was observed during autumn and the lowest (63.0%) in winter.

Altitude↗
PubMed1996

Induction of cdc2a and cyc1At expression in Arabidopsis thaliana during early phases of nematode-induced feeding cell formation.

Root-knot and cyst nematodes are plant parasites that induce large multinucleated feeding cells in the roots of their hosts. Cytological observations have shown that root-knot nematodes induce giant cells by cycles of mitosis without cytokinesis whereas cyst nematodes provoke cell wall degradation leading to the formation of a large syncytium. This study was intended to characterize and compare the ability of both types of nematodes to induce progression through the cell cycle. For this purpose, the expression, upon nematode infection, of two cell cycle markers was followed: a marker for division competence, the cyclin-dependent kinase cdc2a and a marker for the G2 phase, the mitotic cyclin cyc1At. For both types of nematodes, transcriptional activation of these markers was correlated with early phases of feeding cell development. Using molecular markers, it was thus possible to confirm and extend the observations of repeated mitosis in root-knot nematode-induced giant cells. Surprisingly, promoter activation of both cdc2a and cyc1At markers was also found upon cyst nematode infection, in feeding cells in which mitosis has not been clearly reported. Incorporation of tritiated thymidine in these syncytia confirms that they progress through the S phase of the cell cycle. One possibility is that cyst nematodes induce cycles of DNA endoreduplication shunting the M phase. Despite obvious differences in ontogeny, common molecular mechanisms, involving cycles of DNA endoreduplication and cdc2a and cyc1At expression, might thus be involved in the formation of a giant cell or a syncytium.

Animals↗
PubMed1999

Interaction of catenaria anguillulae with romanomermis culicivorax

The development of Catenaria anguillulae, at 27 degrees C, in live and heat-immobilized Romanomermis culicivorax was studied at the ultrastructural level. C. anguillulae zoospores infected eggs, preparasites, and postparasites. The zoospores attached predominately to the head of preparasites but in postparasites attachment was primarily on the attenuated tail region. Zoospore attachment usually occurred within 4 h but at high zoospore densities attachment occurred within 30 min. Infection hyphae penetrated the cuticle and developed sporangial swellings within the nematode tissues and pseudocoelom. Sporangia produced exit tubes within 48 h. Those regions of the J3 and J4 nematodes infected by C. anguillulae became immobile whereas uninfected regions remained mobile. The J2 infected nematodes usually died within 1-2 days. Tissues adjacent to C. anguillulae hyphae or developing sporangia appeared to be relatively unaffected and ultrastructurally normal. The lack of an apparent host response in the nematode suggested either a lack of hypersensitivity or a long evolutionary host-parasite relationship. Copyright 1999 Academic Press.

Journal Article↗
PubMed2005

Identification of novel genes in intestinal tissue that are regulated after infection with an intestinal nematode parasite.

Infection of resistant or susceptible mice with Trichuris muris provokes mesenteric lymph node responses which are polarized towards Th2 or Th1, respectively. These responses are well documented in the literature. In contrast, little is known about the local responses occurring within the infected intestine. Through microarray analyses, we demonstrate that the gene expression profile of infected gut tissue differs according to whether the parasite is expelled or not. Genes differentially regulated postinfection in resistant BALB/c mice include several antimicrobial genes, in particular, intelectin (Itln). In contrast, analyses in AKR mice which ultimately progress to chronic infection provide evidence for a Th1-dominated mucosa with up-regulated expression of genes regulated by gamma interferon. Increases in the expression of genes associated with tryptophan metabolism were also apparent with the coinduction of tryptophanyl tRNA synthetase (Wars) and indoleamine-2,3-dioxygenase (Indo). With the emerging literature on the role of these gene products in the suppression of T-cell responses in vitro and in vivo, their up-regulated expression here may suggest a role for tryptophan metabolism in the parasite survival strategy.

Animals↗
PubMed1996

Mucosal mast cells and the allergic response against nematode parasites.

IgE-mediated Type-I allergic reactions at nematode-infected mucosal surfaces are considered to have a direct protective function. The contribution of mucosal mast cells (MMC) to these mucosal allergic responses is reviewed. In addition to the T helper 2 cell-mediated regulation of MMC hyperplasia during nematode infection the kit ligand, stem cell factor (SCF), plays a key role in the early development of the MMC response. Studies in the mouse suggest that MMC protect against certain nematodes which enter the mucosa but not against lumen dwelling nematodes. The protective roles of MMC in other species, including sheep, are less certain and there is some evidence that MMC might enhance parasite fecundity. The measurement of MMC-specific granule chymases released systemically, and into the gut lumen, permits precise monitoring of mast cell activation and suggests that the secreted chymases may target epithelial junctional complex proteins, thereby causing increased mucosal permeability. The abundant intraepithelial MMC found in parasitised mucosa may, therefore, serve as epithelial gatekeepers permitting the translocation of plasma proteins onto the mucosal surface.

Animals↗
PubMed1996

Serum IgE levels in dairy calves: evaluation of parasite and pasture exposure as possible determinants of IgE response.

Immunoglobulin E (IgE) has been regarded as an antibody isotype important in the host response to helminth infection and allergic conditions. Level of parasitic infection has been associated with serum total IgE level and the highest levels have been observed during the spring when environmental allergen levels are also high. Two groups of five parasite-native calves were maintained in a barn and one of the groups received an experimental gastrointestinal nematode infection. One group of five parasite-native calves was placed on clean pasture and another group of five was placed on a nematode-contaminated pasture. The contaminated pasture group acquired an acute gastrointestinal nematode infection, compared with a relatively low infection in the experimentally infected group. The only difference between the groups was a significant change (increase) in IgE level in calves on contaminated pasture, compared with the other three groups. This suggested that the infection acquired on pasture and not the experimental infection or environmental allergens encountered while grazing or in the barn stimulated an IgE response.

Allergens↗
PubMed1984

[Current aspects of the ELISA technic applied to the serological diagnosis of helminthiasis].

The authors reviewed the data acquired in ELISA technique for serological diagnosis of parasitosis. They reviewed the literature on Schistosomisis, Fasciolasis, Cestode infections (hydatidoses and cysticercoses) and nematode infections. They described their adaptation of the technique for detection of antimicrofilaria Loa loa antibodies and concluded that ELISA technique is reliable in the diagnosis of parasitic diseases even in areas where they are endemic.

Cestode Infections↗