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PubMed1982

The infectivity of some nematode parasites of reindeer (Rangifer tarandus L.) and elk (Alces alces L.) for cattle and sheep.

Cross infections were carried out by dosing parasite-free calves and lambs with third stage nematode larvae cultured from the faeces of reindeer and elk. Two lambs each received 20,000 larvae from reindeer, and one lamb 20,000 larvae from elk. One calf received 50,000 larvae from reindeer and one 50,000 from elk. The animals were killed 28 days after infection. Egg output did not differ significantly between the lambs nor between the calves, but in the lambs the output was much higher than in the calves (highest cound 4300 versus 275). Worm counts varied among the animals independent of the origin of the larvae. The highest take was found in the lamb infected with larvae from elk (81.5%) and the lowest in the calf infected with larvae from elk (15.1%). Ostertagia leptospicularis was the dominant species (80% or more) and the only other species present were Skrjabinagia kolchida and Spiculopteragia boehmi. The latter was found in a higher percentage (14.0 and 10.4) in the animals that received larvae cultured from elk faeces. Under natural conditions O. leptospicularis is possibly the only pathogenic species that can play a role in cross contamination to cattle and sheep.

Animals↗
PubMed2005

Impacts of fluctuating temperature on the development and infectivity of entomopathogenic nematode Steinernema carpocapsae A10.

Three different laboratory conditions were used to examine the impacts of fluctuating temperature on the development and infectivity of entomopathogenic nematode (EPN) Steinernema carpocaposae A10. Set I experiments focused on the impact of cold stress early in the development cycle. In these studies Galleria mellonella hosts were infected and incubated for 2 days at the control temperature of 23 degrees C and then subjected to lower temperatures of -10, 4, 10 or 14 degrees C, respectively, from days 3 to 36 post-infection (PI). Dissections of infected cadavers indicated arrested development at the adult stage at all lower temperatures tested. Set II experiments examined the impacts of cold stress early in the development followed by a return to 23 degrees C. Hosts were infected and incubated as in Set I and subjected to the same temperatures as above for 7 days, followed by incubation at 23 degrees C until 23 days PI. A limited number of EPN populations were able to complete development at 10 and 14 degrees C though emergent population numbers were significantly lower than those of control infections incubated continuously at 23 degrees C. In Set III experiments, infected hosts were subjected to cold stress later during development starting at day 4 post-infection followed by incubation at the control temperature. Population survival past first and second stage juveniles was reduced by at least 95% or more at the lower temperatures compared with controls. Emergent populations from the Set III cold-stressed hosts were not infectious. These studies may provide insights as to how EPN survive seasonal temperature fluctuations under natural environmental conditions.

Animals↗
PubMed1986

Albendazole, a broad-spectrum anthelmintic, in the treatment of intestinal nematode and cestode infection: a multicenter study in 480 patients.

The anthelmintic activity of and patient tolerance to albendazole, a broad-spectrum anthelmintic, were studied in a multicenter trial involving 480 patients ranging in age from 2 to 60 years. The patients had single or mixed infections caused by pinworms, roundworms, hookworms, whipworms, threadworms, or tapeworms. The stools were examined by the direct method, and ova were counted by means of the Kato-Katz technique. A Graham-Scotch test was also done in patients infected with Enterobius vermicularis. Most patients received a single 400-mg dose of albendazole; adults were given two tablets, and children were given a 2% suspension. All patients with Hymenolepis nana and about half of those with Taenia infections were treated for three successive days. Patients were carefully evaluated before and after treatment to assess the efficacy and safety of the drug. After a single dose of albendazole, the cure rate was 95.3% in ascariasis, 92.2% in ancylostomiasis, 90.5% in trichuriasis, 64.9% in taeniasis, and 100% in enterobiasis. Among patients receiving 400 mg of albendazole for three days, the cure rate was 63.4% in hymenolepiasis and 86.1% in taeniasis. The drug was well tolerated, and no significant side effects were reported.

Adolescent↗
PubMed2006

Functionality of resistance gene Hero, which controls plant root-infecting potato cyst nematodes, in leaves of tomato.

The expression of host genomes is modified locally by root endoparasitic nematode secretions to induce the development of complex cellular structures referred as feeding sites. In compatible interactions, the feeding sites provide the environment and nutrients for the completion of the nematode's life cycle, whereas in an incompatible (resistant) interaction, the host immune system triggers a plant cell death programme, often in the form of a hypersensitive reaction, which restricts nematode reproduction. These processes have been studied in great detail in organ tissues normally infected by these nematodes: the roots. Here we show that host leaves can support a similar set of programmed developmental events in the potato cyst nematode Globodera rostochiensis life cycle that are typical of the root-invading nematodes. We also show that a gene-for-gene type specific disease resistance that is effective against potato cyst nematodes (PCN) in roots also operates in leaves: the expression of the resistance (R) gene Hero and members of its gene family in leaves correlates with the elicitation of a hypersensitive response only during the incompatible interaction. These findings, and the ability to isolate RNA from relevant parasitic stages of the nematode, may have significant implications for the identification of nematode factors involved in incompatible interactions.

Amino Acid Sequence↗
PubMed2003

Impact of the host cadaver on survival and infectivity of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) under desiccating conditions.

Entomopathogenic nematode species of Steinernema carpocapsae, Steinernema riobrave, or Heterorhabditis bacteriophora were used to compare survival and infectivity among infective juveniles (IJs) emerging in water from hosts in White traps (treatment a), emerging in sand from hosts placed in sand (treatment c), and emerging from hosts placed on a mesh suspended over sand (treatment m). Nematode survival and infectivity was recorded in sand at three-day intervals during 21 days of storage in desiccators at 75% relative humidity and 25 degrees C. Infectivity was measured by exposing 5 Galleria mellonella for 16 h to IJs. Treatment did not affect percent survival of H. bacteriophora IJs. Percent survival of S. riobrave and S. carpocapsae IJs was lowest in treatment a. Across all treatments, by 10 days after the beginning of the experiments, IJ survival declined to 93, 43, and 28% of levels on day 1 for H. bacteriophora, S. riobrave, and S. carpocapsae, respectively. For the three treatments, infection rate over time was described by a negative exponential function for S. riobrave and S. carpocapsae and by a sigmoid function for H. bacteriophora.

Animals↗
PubMed1998

Spatial and discrimination learning in rodents infected with the nematode Strongyloides ratti.

Recent work has shown that mice with subclinical parasitic infections suffer impaired spatial learning and memory, as assayed in an open-field water maze. Although the mechanism underlying this effect is not clear, the phenomenon has been reported following infection with both a protozoan parasite (Eimeria vermiformis) and a gastrointestinal nematode (Heligmosomoides polygyrus). In a variety of experiments, we examined the effects of a different gastrointestinal nematode, Strongyloides ratti, on the ability of rats and mice to learn a spatial or a discrimination task. Animals were tested at various stages post-infection, with different levels of infection, using different lines of S. ratti and with varying experimental protocols. All animals learned the tasks, but we found no evidence of an effect of S. ratti infection on learning or memory. Even rats infected with approximately 5000 S. ratti larvae, a dose which has an impact on rat body size, showed no deficit in learning ability. Various reasons for the conflict between our results and those previously reported for E. vermiformis and H. polygyrus are discussed. Our results show that impaired learning and memory following parasitic infection is not a ubiquitous or at least easily replicated phenomenon.

Analysis of Variance↗
PubMed1988

Efficacy of a levamisole bolus in field infections of bovine nematodes.

Forty four parasite free calves were divided into eight groups, four of six and four of five calves. Two of the groups of six were given a bolus containing 22 g of levamisole in a formulation designed to release the anthelmintic for ninety days. One group of treated calves was put out to graze at the beginning of May with one of the untreated larger groups on a field contaminated with O ostertagi and C oncophora, and the other treated group grazed with controls on a field known to have the same species plus D viviparus. On mid August these resident calves were removed, slaughtered and worm counts estimated. At the same time, the other groups of untreated calves were put onto the same fields to act as tracers of the level of infection. After grazing for one month they were housed, slaughtered and worm counts carried out. The faecal egg counts of treated calves were much less than those of the controls until the end of July. Control calves on the paddock infected with lungworm were severely affected by parasitic bronchitis whereas treated calves although infected did not display clinical symptoms. In the resident calves, O ostertagi burdens were reduced by 65 and 67% and C oncophora by 97% compared to untreated controls. In the tracer calves, there was no difference in burdens of O ostertagi and D viviparus but large differences in the number of C oncophora established.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1979

Oxfendazole--anthelmintic activity in Egyptian goats artificially infected with gastrointestinal nematodes.

The recently developed benzimidazole anthelmintic, oxfendazole, was tested against artificial nematode infestations in Egyptian goats using oral dosing at 4.5 and 2.8 mg/kg. A 100% clearance of mature and immature Haemonchus contortus, Trichostrongylus axei, Ostertagia circumcincta, Coopera curticei, Bunostomum trigonocephalum and Chabertia ovina was obtained at the 4.5 mg/kg level. Very high levels of clearance against the mature worms were obtained at 2.8 mg/kg but the drug was less effective against immature worms at the lower dose rate. PCV, hemoglobin concentration and total erythrocyte counts declined after infection but became significantly (P less than 0.001) raised in treated animal.

Animals↗
PubMed1999

Enhancement of apoptosis with loss of cellular adherence in the villus epithelium of the small intestine after infection with the nematode Nippostrongylus brasiliensis in rats.

It has been reported that infection with Nippostrongylus brasiliensis induces villus atrophy with various histological alterations. In N. brasiliensis-infected rats, villus length in the jejunum was reduced significantly at day 10 p.i., when serum levels of rat mast cell protease (RMCP) II had increased significantly. To determine whether the villus atrophy is associated with enhancement of apoptosis, apoptotic nuclei were labelled using the nick end-labelling method. Numbers of labelled cells were markedly increased in the villus epithelium at 7-10 days p.i., while the numbers returned to normal 14 days p.i. when worms were rejected from the intestine and villus length became normal. Examination of the expression of the adhesion molecule E-cadherin showed granular immunoreactivity in the cytoplasm of atrophic villus epithelium with loss of normal localization to epithelial cell borders. In mast cell-deficient Ws/Ws rats, villus length was reduced as significantly as in +/+ counterparts at day 10 p.i. with marked increases in the numbers of apoptotic cells. These results suggested that villus atrophy was closely associated with enhanced apoptosis and loss of adhesion in epithelial cells. Mast cell activation appears not to be involved in these alterations.

Animals↗
PubMed2002

The effect of an experimental infection of the nematode Heterakis gallinarum on hand-reared grey partridges Perdix perdix.

We compared 26 hand-reared grey partridges given an experimental infection of the caecal nematode Heterakis gallinarum with 26 uninfected ones. Under laboratory conditions after 91 days, there were no measurable clinical effects of the infection. We found no effect of treatment on the amount of food eaten or on caecal dropping production. However, treated birds, in particular females, developed slightly lower body mass (around 2%) compared to the controls. At post-mortem examination, we found a positive relationship between breast muscle mass and the number of worms collected from the caeca of treated birds. Treated birds with no worms when examined had smaller breast muscle mass (4.6%) compared to the uninfected control birds. These results are largely different to those found in a similar study that documented significant negative impacts on most of these factors in 8 infected birds compared to 6 controls. Its findings were used in a published model to support a hypothesis that H. gallinarum maintained in the environment by common pheasants, the primary host for this worm, could negatively affect wild grey partridge productivity and survival. In the same model our data would not support this hypothesis. Possible explanations for the different results from the 2 experiments are discussed. Together they suggest that only in certain, as yet unidentified circumstances, could experimental H. gallinarum infections have deleterious effects on hand-reared grey partridges.

Animals↗
PubMed1992

Morphology of the liver of the brook lamprey, Lampetra lamottenii before and during infection with the nematode, Truttaedacnitis stelmioides, hepatocytes, sinusoids, and perisinusoidal cells.

Routine light microscopy and transmission and scanning electron microscopy were used to describe and compare the livers of larval lampreys, Lampetra lamottenii before and during infection of the bile ducts by the nematode, Truttaedacnitis stelmioides. The hepatocytes of uninfected animals differ from other lamprey species in that they contain abundant glycogen, smooth endoplasmic reticulum (SER), and lipoprotein indicating that the liver may be involved in glucose metabolism. Infestation of the biliary tree by T. stelmioides coincides with alterations to the hepatocytes. These changes include dilation of the bile canaliculi, smooth endoplasmic reticulum (SER), rough endoplasmic reticulum (RER), and Golgi apparatus, swollen mitochondria in cells showing a high degree of hypertrophy, and an abundance of dense bodies. Following infection, the sinusoidal lumina became dilated and contain a moderate electron-dense precipitate, an abundance of melanomacrophages, lipocytes, and mononuclear cells. There is also a widening of the fenestrae of the sinusoidal endothelium following infection. Many of the changes in hepatocytes and sinusoids following parasite infections closely resemble those observed in hepatocytes in various pathologies and following experimental bile duct ligation and, therefore, are likely a consequence of increased biliary pressure due to bile duct obstruction.

Animals↗
PubMed2000

The epidemiology of nematode and fluke infections in cattle in the Red River Delta in Vietnam.

Over a period of 13 months, faecal samples were collected monthly from approximately 45 cattle over 3 months of age. Additionally, 74 calves of 1-2 months were sampled to determine the presence of Toxocara vitulorum eggs. Individual egg counts and infective strongyle larvae from pooled faecal samples were examined. Post-mortem worm counts were carried out on six groups of tracer calves (n=12) that had been kept for 4 weeks on pasture in and around the village studied. The following helminths were identified: T. vitulorum, Cooperia punctata, C. pectinata, C. oncophora, Oesophagostomum radiatum, Trichostrongylus axei, T. colubriformis, Haemonchus spp., Fasciola spp. and Paramphistomum spp. In 8% of the samples collected from young calves, individual egg counts for T. vitulorum were found indicative for pathogenic worm burdens. Strongyle egg counts and worm counts indicated that transmission is low without a distinct seasonality. In animals of 3-9 months old, a strongyle egg count peak can be demonstrated which at a higher age steadily and significantly decreased. In faecal cultures Cooperia spp. were most prominent in all age groups throughout the year with the exception of the period September-November when Haemonchus spp. and Oesophagostomum spp. were most prevalent. Fasciola spp. eggs were found in 22% of the collected faecal samples and the egg counts were low indicating that the intensity of Fasciola spp. infection is mild. Based on the present data, regular anthelmintic treatments seem not to be justified, except for a single treatment at the age of 2 weeks against toxocariosis.

Animals↗
PubMed2000

Re-assessing the infection strategies of the entomopathogenic nematode Steinernema feltiae (Rhabditidae; Steinernematidae).

Previous studies have indicated that between 60 and 80% of a population of entomopathogenic nematodes do not infect their insect hosts at any one period in time. Two hypotheses explain this behaviour: the first that there is a subpopulation of non-infectious nematodes and the second that the non-infectious group is created by inhibitory cues derived from infected insects. Through an experimental approach with the Galleria mellonella-Steinernema feltiae system we show that both mechanisms operate together. When conditions for infection were optimized, the sum of individual infection behaviours was similar to the number infecting as a population, implying observed infection rates are driven by intrinsic mechanisms. In addition, there was evidence that an infected host released a chemical cue into the environment which inhibited subsequent levels of infection. This degree of inhibition was independent of the number of infecting nematodes. Both these mechanisms are dynamic, so the observed proportion of infectious nematodes depended heavily on the time of exposure. The implications of these findings for both the design of laboratory trials and the use of entomopathogenic nematodes in biological control are discussed.

Animals↗
PubMed1986

The Ig class distribution of anti-phosphoryl choline responses in mice infected with parasitic nematodes.

The anti-phosphoryl choline antibody responses of resistant and susceptible strains of mice infected with microfilariae of Dipetalonema viteae or the gastrointestinal nematode parasite Trichinella spiralis were determined. The responses were characterized both in terms of their kinetics and the constituent role played by each immunoglobulin heavy-chain class. Infection with either parasite elicited detectable responses in all strains investigated. However, the kinetics of the response of each heavy-chain class within each strain could vary independently. Furthermore, differences were observed between the responses of inbred mouse strains that differ in their ability to control infection. It was not possible, however, to correlate these differences in the serological response with the ability of these animals to control infection. The results are discussed in relation to attempts to improve serological diagnostic assays.

Animals↗
PubMed1987

Suppression of mucosal mastocytosis by infection with the intestinal nematode Nematospiroides dubius.

Mice exposed to primary infections with the parasite intestinal nematode Nematospiroides dubius failed to show the mucosal mast cell (MMC) response which is characteristic of infections with other species of intestinal nematode and which was readily induced in these mice by infections with Nippostrongylus brasiliensis or Trichinella spiralis. The failure to generate a mucosal mastocytosis was independent of host strain or sex. When infections with N. dubius were established before, or concurrently with, T. spiralis or N. brasiliensis, the MMC response elicited by these species was delayed and/or depressed as was expulsion of the worms themselves. Infection with N. dubius given when a MMC response was already established, by exposure to T. spiralis, had no effect on MMC numbers. The possibility that the effects of N. dubius upon MMC responses reflect a lack of mastocytopoietic potential, rather than an active interference, was excluded by showing that SJL mice, which expel primary infections with N. dubius and express strong immunity to reinfection, developed marked mastocytosis during secondary infections. The depression of MMC responses by N. dubius is discussed in relation to the known immunosuppressive properties of this parasite and in relation to the T cell mediated control of MMC development.

Animals↗
PubMed1986

Activity of ivermectin against natural infections by abomasal nematodes in lambs in controlled tests: evaluation of equine and bovine injectable formulations administered intraorally.

The efficacy of 2 injectable formulations of ivermectin, administered intraorally at the dosage of 200 micrograms/kg of body weight, was evaluated against naturally occurring infections by abomasal nematodes in lambs in 2 controlled tests. One test (A) included 17 lambs treated with the equine formulation and 16 nontreated lambs. For the other test (B), 14 lambs were treated with the bovine formulation, and 12 were nontreated. In controlled test A, only mature nematodes were recovered, and removals were 98% to 100% for Haemonchus contortus, Ostertagia circumcincta male, O trifurcata male, Ostertagia spp female, and Trichostrongylus axei. For controlled test B, removals were 99% to 100% for Haemonchus spp (immature), H contortus (mature), Ostertagia spp (immature), O circumcincta male (mature), O trifurcata male (mature), Ostertagia spp female (mature), Trichostrongylus spp (immature), and T axei (mature). Toxicosis was not evident in treated lambs.

Abomasum↗
PubMed1995

Efficacy of doramectin against experimental infections by some nematode parasites in cattle in New Zealand.

A study was undertaken to determine the efficacy of the novel avermectin, doramectin, against experimental larval and adult infections of three species of nematode parasite important to cattle production in New Zealand. Eighteen worm-free dairy bull beef calves were randomly allocated on live weight to three similar treatment groups. Each calf was given 30,000 Ostertagia ostertagi, 20,000 Cooperia spp. and 10,000 Trichostrongylus axei infective larvae as a single dose. One group was treated with doramectin 6 days after infection while the remaining groups received saline or doramectin 27 days after infection. Given as a single subcutaneous injection behind the ear, doramectin at 200 microg/kg removed 99.9-100% of adult and larval stages of O. ostertagi, Cooperia spp. and T. axei when compared to infections established in untreated controls (p<0.001). No adverse reactions were observed following treatment in the doramectin-treated animals. No injection site lesions were found by palpation following treatment or by injection site examination at necropsy.

Journal Article↗