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PubMed2003

Approaches for monitoring the release of Pochonia chlamydosporia var. catenulata, a biocontrol agent of root-knot nematodes.

Pochonia chlamydosporia var. catenulata is a potential biocontrol agent against root-knot nematodes. Diagnosis of isolates has relied on morphological identification, and is both time-consuming and difficult. beta-tubulin primers have been developed for the identification of this fungus that were specific enough to distinguish between varieties of the fungus within the same species. Separate primers have been developed for the specific detection of P. chlamydosporia var. catenulata based on ITS sequences, which were able to detect the fungus in soil from various sites in Cuba where the biocontrol agent had been added. When the PCR diagnosis was combined with serial dilution of soil samples on selective medium, colonies were rapidly identified. The fungus was still present, albeit at low densities, in soils inoculated five years previously. The development of a baiting method allowed quick in situ screening of the isolates' ability to infect nematode eggs, and when combined with PCR diagnosis both varieties of the fungus could be detected in infected eggs. RFLP analysis of ITS sequences from P. chlamydosporia provided an extra level of discrimination between isolates.

Animals↗
PubMed2005

The role of phosphoinositide-3-kinase in mast cell homing to the gastrointestinal tract.

Phosphoinositide-3-kinases (PI3Ks) are a family of lipid kinases essential in a variety of physiological reactions. A series of gene-targeted mice lacking different PI3Ks and related molecules has enabled us to understand their in vivo roles, particularly those of class IA members. Studies on knockout mice lacking class IA PI3Ks and knock-in mice expressing mutant forms of enzymes have revealed the importance of this class of PI3Ks in mast cell development in the gastrointestinal tract. Here we studied the role of the p85a regulatory subunit, the most abundantly expressed regulatory subunit of class IA PI3Ks, using p85a knockout mice. Development of mast cells in the gastrointestinal tract but not in the skin was severely impaired in mice lacking the p85a regulatory subunit. Stem cell factor (SCF)-mediated signalling functions including proliferative response and chemotactic activities were both impaired in p85a knockout mast cells, likely due to the mast cell deficiency. Mastocytosis upon Strongyloides veneZuelensis infection was also impaired in p85alpha knockout mice. Reconstitution with Th2-conditioned but not untreated bone marrow-derived mast cells (BMMCs) restored anti-bacterial immunity, indicating the importance of Th2 response in addition to the recruitment of mast cells in the control of nematode infection.

Animals↗
PubMed1983

White spots of the liver in pigs experimentally infected with Ascaris suum.

To make clear the relationship between Ascaris suum infection and the appearance of white spot lesions on the surface of the liver in pigs, three groups of pigs were inoculated orally with embryonated A. suum eggs and observed clinicopathologically. Group A of three pigs were inoculated 21 times with 100 eggs each of the nematode, group B of three pigs 4 times with 50,000 eggs each for 10 weeks, and group C of two pigs 2 times with 50,000 eggs each at a one-week interval. All the pigs were sacrificed at the same time 1 week after the final inoculation. Such signs of the nematode infection as dyspnea, coughing and fever appeared in all the pigs of groups B and C seven days after inoculation to continue for several days. In addition, peripheral blood eosinophilia was recorded in these animals 7 or 14 days after inoculation. At autopsy, mesh-worked white spots, some compact and others lymphonodular, were observed on the surface of the liver in all the pigs of the three groups. Main white spots were mesh-worked and lymphonodular in the pigs of group A. They were severe and compact in group B. Therefore, they were rough to the touch. In group C mesh-worked white spots fused with one another and covered the surface of the liver. These white spot lesions observed were morphologically very similar to those found in the field conditions. Complement-fixating antibodies reacting to adult A. suum antigen were detected only in sera from the pigs of group B. Moreover, antibodies involved in the intradermal reaction of immediate type were found in the pigs of groups A and B.

Animals↗
PubMed2004

Getting to the roots of parasitism by nematodes.

Most phytoparasitic nematodes infect plant roots and some species have evolved sophisticated interactive relationships with host cells to sustain a sedentary parasitic habit. The recent isolation of multiple 'parasitism genes' expressed specifically within the esophageal gland cells of sedentary phytonematodes suggests that an arsenal of different secreted parasitism proteins from the nematode might have direct effects on recipient host cells. These include cell wall modifications and potential interactions with signal transduction receptors in the extracellular space, as well as direct introduction of proteins into host cells that might influence cellular metabolism, the cell cycle, selective protein degradation, a localized defense response and regulatory activity within the host cell nucleus.

Animals↗
PubMed2003

Nematodes and water pollution in eastern part of Nile Delta.

Examination of some represented water sites revealed presence larvae and eggs of the nematodes infecting man and animals. Eggs in a descending order of abundance were Trichostrongylus, Toxocara canis, T. vitolorum, and Ascaris sp., then Trichocephalus and Ancylostoma sp. Larvae in a descending order were Strongyloides, Trichostrongylus and Ancylostoma sp. No doubt contaminated or polluted water plays an important role as nematode-borne source.

Animals↗
PubMed1999

[An attempt to extract an intraretinal nematode located in the papillomacular bundle].

BACKGROUND: The nematode infection of the retina is a rare disease with sight threatening prognosis. Untreated eyes usually become blind. There are different types of clinical progression: granuloma causing tractional detachment chronic inflammation called diffuse unilateral subacute neuroretinitis (DUSN) and rapid loss of vision named "ocular wipe-out syndrome". Efficient drugs are not available. The progression of the disease can be stopped by killing the nematode by means of photocoagulation. For parasites in the periphery of the fundus this is the therapy of choice. Photocoagulation of the nematode close to the posterior pole can cause severe damage to the visual functions. There is a need for a less detrimental treatment. PATIENT AND METHODS: We report on a 48-year-old woman with an intraretinal nematode inside the papillomacular bundle. At an early stage of the disease with normal visual acuity the eye was vitrectomized and a posterior vitreous detachment performed. It was intended to extract the worm out of the retina in toto. The retina over the parasite was incised parallel to the nerve fibers, a tiny hook inserted and the worm pulled out. RESULTS: Only one half of the parasite could be removed since the adhesion of the parasite to the retina was stronger than its own cohesion. Nevertheless the inflammation rapidly regressed. Finally a small area of pigment mottling persisted around the former location of the parasite corresponding to a relative scotoma in the visual field. Visual acuity remained unchanged at full vision. CONCLUSION: We demonstrated that nematode larvae can be removed successfully from the central retina using vitrectomy techniques. By that means the damage to the visual functions can be limited. Near the posterior pole surgical extraction of the worm may be favorable compared to photocoagulation.

Animals↗
PubMed1977

Controlled trials of the anthelmintic oxfendazole in ewes and lambs naturally infected with gastrointestinal nematodes.

Oxfendazole doses at a rate of 5 mg per kg, before or after lambing, reduced nematode egg output to insignificant levels in ewes, most of which were not exposed to re-infection. Ewes treated with oxfendazole had a significantly lower egg output than those treated with levamisole, although the latter anthelmintic was also highly effective. In lambs, oxfendazole at a dose rate of 5 mg per kg, showed 100 per cent efficacy for Ostertagia circumcincta, O trifurcata, Teledorsagia davtiani, Trichostrongylus axei, T vitrinus, T colubriformis, Nematodirus battus, N filicollis, immature Nematodirus, Chabertia ovina, and 93 per cent efficacy for Trichuris spp. Levamisole showed similar efficacies but did not remove Trichuris.

Animals↗
PubMed2006

Effect of nutritional status and fat reserves on the periparturient immune response to Haemonchus contortus infection in sheep.

A study was made of the effect of body fat stored by ewes in early pregnancy on the subsequent immune response to gastrointestinal parasites around parturition. Pregnant ewes were given access to a lucerne pelleted diet either ad libitum (H) or at approximately 0.70 of their maintenance requirements (L) from the 42nd day of pregnancy in order to achieve a clearly differentiated level of body reserves by the 90th day of pregnancy. Then, all animals were put on the same plane of nutrition till 3 weeks after parturition. All ewes in both groups received 7,000 infective larvae of Haemonchus contortus per week for 7 weeks prior to lambing. The dietary treatments led to large differences between both groups of ewes in back-fat thickness that had a high correlation with mean plasma concentrations of leptin. In spite of the fact that animals were on the same plane of nutrition at infection time, host resistance, as measured by faecal egg counts, was significantly affected by the nutritional treatment established during early pregnancy. This effect produced noticeable differences in worm size and in worm burden at lambing. The response was accompanied by a marked increase in circulating eosinophils in better-fed ewes than in those maintained on a restricted diet in early pregnancy. Serum pepsinogen concentration, however, was inversely affected by the nutritional treatment till lambing, showing a maximum difference as early as 2 weeks after infection. The results support the view that higher levels of nutrition during early pregnancy enhance the expression of immunity against gastrointestinal parasites around parturition. Furthermore, the differences in the immune response appeared associated with serum leptin levels suggesting that leptin may be a key link between nutritional status and the protective immune reactivity against GI nematode infection.

Adipose Tissue↗
PubMed2005

Field evaluation of the efficacy and safety of emodepside/praziquantel spot-on solution against naturally acquired nematode and cestode infections in domestic cats.

Two controlled, blinded and randomized multi-site clinical field studies evaluated the efficacy and safety of emodepside/praziquantel spot-on in the treatment of gastrointestinal nematode and cestode infections in cats. In a study conducted in Europe, faecal egg count reductions of >98% for all nematode eggs and eggs of Toxocara cati, respectively, were observed in cats treated with emodepside/praziquantel spot-on (Profender, Bayer AG, Leverkusen, Germany). For a positive-control product containing selamectin (Stronghold) reductions of >95% were observed. A 100% reduction of faecal eggs and proglottids was observed in cats treated with emodepside/praziquantel spot-on that were infected with cestodes. In a study conducted in North America, cats were treated with either emodepside/praziquantel spot-on plus a placebo tablet or a combination of two control products containing, respectively, selamectin (Revolution) and epsiprantel (Cestex). Faecal egg count reduction for eggs of T. cati was >99% for both treatments. For faecal eggs and proglottids of Dipylidium caninum reductions of >99 and >97% were recorded for cats treated with emodepside/praziquantel spot-on and the control group, respectively. No adverse reactions were observed in the European study, and only mild ones of short duration in a few cats from both treatment groups of the North American study. The two studies demonstrated that emodepside/praziquantel spot-on is highly efficacious and safe under field conditions.

Administration, Topical↗
PubMed1996

Long-term subclinical infection with Trichostrongylus colubriformis: effects on food intake, diet selection and performance of growing lambs.

Growing lambs (mean liveweight 22.4 kg) were used to test for the effects of long-term subclinical infection with Trichostrongylus colubriformis (2500 larvae per day) on the voluntary food intake (VFI), diet selection and performance of sheep given a choice between two foods of different protein content (low versus high). Sheep were either uninfected controls or parasitised for 27 weeks (Group 27P). Additional sheep were infected for either 9 or 18 weeks (before and after the development of complete resistance to parasites, as assessed by faecal egg counts) and then treated with anthelmintic to remove the parasites (Groups 9P and 18P). Group 18P remained uninfected after anthelmintic treatment whereas Group 9P was infected again for the last 9 weeks after a 9 week worm-free period. The VFI declined or remained static from Week 5 up to Week 11/12 of continuous infection, for the 27P and 18P groups. For 9P sheep, VFI recovered within a few days after the anthelmintic administration and was unaffected during re-infection over the last 9 weeks of the experiment. Diet selection changed in such a pattern that the proportion of the high protein food (prop H) in the selected diet started to increase from Week 6 of the infection. The prop H selected remained higher over the interval 10-18 weeks of the continuous infection for 27P and 18P groups than the uninfected controls. There were no significant differences in diet selection among any of the groups beyond Week 18 of the experiment. The infection caused a growth check from Week 7 to approximately Week 12/14 of dosing; these was no evidence of compensatory growth following the development of resistance or recovery. The results are consistent with the view that sheep given a choice between two appropriate foods will modify their diet selection in order to moderate the adverse effects of subclinical nematode infection. The performance and diet selection of all sheep beyond Week 18 of infection suggest that no obvious nutritional penalties are incurred with the continuation of the infection once the animals have become resistant to parasites.

Animals↗
PubMed1996

Mammomonogamus laryngeus (Railliet, 1899) infections in cattle in Mindanao, Philippines.

During one year, 597 cattle were examined for Mammomonogamus laryngeus infections in the abattoir of Cagayan de Oro, Philippines. The overall prevalence was 23% with no obvious seasonal variations. The infection rate was 19% in animals up to 4 years old and 24% in animals 4-12 years old. In infected animals up to 8 years old an average of eight parasite pairs was found; infected animals of 8-12 years old had 5.2 parasite pairs on average. All worms were located on the posterior side of the epiglottis. Field observations on cattle in Mindanao revealed that adult M. laryngeus had developed on the epiglottis of a tracer calf that had been on pasture for 30 days and then kept away from possible nematode infection for 28 days.

Abattoirs↗
PubMed2004

[Evaluation of the resistance to two nematodes: Radopholus similis and Meloidogyne spp. in four banana genotypes in Morocco].

Radopholus similis and Meloidogyne spp. are the main nematode parasites of banana plants grown under plastic shelters in Morocco. A test was made in pots to evaluate the resistance of four genotypes of banana to these nematodes. Infection by Meloidogyne spp. brought about an increase in root weight in all banana plants tested because of gall formation. The inoculation of R. similis produced a reduction in length and diameter of the pseudo-trunk as well as in root and aerial mass in all genotypes. Pisang jari buaya showed the significantly lowest number of Meloidogyne nematodes per 10 g of roots, whereas for R. similis, the significantly smallest numbers were obtained in Pisang berlin and Pisang jari buaya. Therefore, Pisang jari buaya was the only banana genotype studied to show some degree of resistance to both nematodes.

Animals↗
PubMed2003

Dose confirmation of moxidectin 0.5% pour-on against adults and fourth-stage larvae of various Cooperia spp. and Trichostrongylus colubriformis in Louisiana.

Thirty-five castrate or intact Holstein male calves, ranging in weight from 122 to 210kg, were used in the study. On study Days -15 and -14, all study calves were treated with fenbendazole 10% paste at 10mg/kg to remove existing nematode infections. All cattle had zero egg counts on Day -1. Experimental infections of a mixed species inoculum were administered to all calves on Day 0. The inoculum consisted of Cooperia spp. (primarily C. punctata, but also C. pectinata, C. spatulata, C. oncophora and C. surnabada-total 40,961); Ostertagia ostertagi-1550; Trichostrongylus colubriformis-4996; and Oesophagostomum radiatum-38. Necropsy results from two of three monitor calves slaughtered on Day 6 after infection indicated that Day 6 was an appropriate time to evaluate efficacy of moxidectin against fourth larval stages (L(4)). The remaining 32 calves were randomly allotted to four groups of eight based on body weights. Eight calves (Group 1) were treated with moxidectin 0.5% pour-on at 0.5mg/kg on Day 6 to evaluate efficacy against nematode larval stages; eight control calves (Group 2) were matched with these principals. Eight calves (Group 3) were also treated with moxidectin pour-on at the same dosage on Day 23 in order to determine efficacy against adult nematodes; eight control calves (Group 4) were matched with these principals. In both cases, principals and controls of the Days 6 and 23 treatments were necropsied at 14-15 days after treatment. C. punctata was the only species found in a sufficient number of controls to evaluate moxidectin efficacy against the L(4). Moxidectin pour-on was not effective (P<0.05) against C. punctata L(4) by arithmetic means, but was highly effective based on geometric means. Regardless of whether arithmetic or geometric means were used for percent efficacy calculations, moxidectin pour-on was demonstrated to be highly effective (>99%) against the adult stages of C. oncophora, C. punctata, C. spatulata, C. surnabada, Cooperia spp. adult females and T. colubriformis adults.

Administration, Topical↗
PubMed1993

Globule leukocytes in the lumen of the small intestine and the resistance status of sheep infected with parasitic nematodes.

The presence of globule leukocytes in the lumen (LuGLs) of the small intestine was studied in Romney sheep reared parasite free and then experimentally infected or immunized with Trichostrongylus colubriformis infective larvae, or naturally infected when gazed on pasture. It was discovered that high numbers of LuGLs were associated with both parasitic infection and the sheep protective immune response. A high positive correlation was observed between LuGLs and tissue globule leukocytes. The highest correlation (r = 0.92) observed was between larval migration inhibition (LMI) and numbers of LuGLs. This was the only correlation between LMI and other parameters studied. Significant positive correlations were also observed between LuGLs and IgG1 and eosinophils. There was a negative correlation between LuGLs and the number of parasites in the intestine and parasite egg production. Progeny of genetically resistant and susceptible sires had significantly different abilities to produce LuGLs.

Animals↗
PubMed2005

Characterization of susceptibility and resistance responses to potato cyst nematode (Globodera spp.) infection of tomato lines in the absence and presence of the broad-spectrum nematode resistance Hero gene.

The tomato Hero A gene is the only member of a multigene family that confers a high level (>80%) of resistance to all the economically important pathotypes of potato cyst nematode (PCN) species Globodera rostochiensis and G. pallida. Although the resistance levels of transgenic tomato lines were similar to those of the tomato line LA1792 containing the introgressed Hero multigene family, transgenic potato plants expressing the tomato Hero A gene are not resistant to PCNs. Comparative microscopy studies of in vitro infected roots of PCN-susceptible tomato cv. Money Maker, the resistant breeding line LA1792, and transgenic line L10 with Ro1 pathotype have revealed no statistically significant difference in the number of juveniles invading roots. However, syncytia (specialized feeding cells) induced in LA1792 and L10 roots mostly were found to have degenerated a few days after their induction, and a few surviving syncytia were able to support only the development of males rather than females. Thus, the ratio between males and females was biased towards males on LA1792 and L10 roots. A series of changes occur in resistant plants leading to formation of a layer of necrotic cells separating the syncytium from stellar conductive tissues and this is followed by degradation of the syncytium. Although the Hero A gene is expressed in all tissues, including roots, stems, leaves, and flower buds, its expression is upregulated in roots in response to PCN infection. Moreover, the expression profiles of the Hero A correlates with the timing of death of the syncytium.

Animals↗
PubMed2000

Nematode parasites of sheep: a survey of epidemiological parameters and their application in a simple model.

We review the literature on parameter values relevant to the epidemiology of strongyle nematode infections of domestic sheep. Information is subdivided by parasite genus, country of origin and climate type. While field observations have been made in a large number of countries, the bulk of studies under controlled conditions have been conducted in Australia, New Zealand and the UK. For these countries, experiments and parameters are interpreted in terms of a previously published model of nematode dynamics, and are used to calculate the basic reproduction number. Average values range from less than 6 for Haemonchus contortus in New Zealand and a winter rainfall region of Australia, to more than 16 for Ostertagia circumcincta in New Zealand and the UK. Additional considerations of the effects of climate and the annual replacement of host stock show that for conditions favourable for parasite transmission this is a robust indicator of parasite epidemiology. When climate variation and annual replacement are added to the model, it is shown to reasonably describe the qualitative behaviour of an experimental data set, indicating it to be a useful tool for further investigation of some of the underlying assumptions of sheep-nematode dynamics.

Animals↗
PubMed2005

Searching new targets for anthelminthic strategies: Interference with glycosphingolipid biosynthesis and phosphorylcholine metabolism affects development of Caenorhabditis elegans.

Nematode infections are amongst the most abundant diseases of man and animals. They are characterised by a low mortality but high morbidity, thus reflecting the adaptation of these parasites to their hosts. Resistance as well as severe side-effects and efficacies restricted to distinct larval stages or parasites of the anthelmithics used at present require the urgent development of new and more nematode-specific drugs, targeting enzymes of parasite restricted biosynthetic routes. Caenorhabditis elegans has been found to be a good model system for parasitic nematodes, drug screening and developmental studies. Structural analyses have revealed nematode-specific glycosphingolipid structures of the arthro-series, carrying in part, phosphorylcholine substituents. These biomolecules appear to play important roles in nematode development, fertility and survival within the host and are, therefore, good target-candidates for the development of new anthelminthic strategies. Here we show that RNAi experiments targeting enzymes of glycosphingolipid biosynthesis or choline metabolism result, in part, in a drastic reduction of fertility. We further tested various chemical inhibitors of these pathways and found significant effects on the development of the worms, resulting in developmental arrest, sterility and, in part, lethality. Such inhibitors can, therefore, help to define new classes of anthelminthics.

Animals↗