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At least 865 records · Page 48Linked to original sources
PubMed2004

Effects of host desiccation on development, survival, and infectivity of entomopathogenic nematode Steinernema carpocapsae.

This study investigates the effect of host desiccation on entomopathogenic nematode (EPN) development, emergence, infectivity, and cross-protection against secondary environmental stress. Galleria mellonella hosts infected with the EPN Steinernema carpocapsae A10 were allowed to dehydrate in an environmental chamber for up to 56 days at 23 degrees C achieving a weight loss of approximately 86% by day 44 post-infection. Host carcasses were rehydrated on water-saturated filter paper in White traps to collect emergent infective juveniles (IJ) at specific time intervals. Populations were counted with an apparent peak coinciding with desiccated hosts rehydrated at 24-day post-infection. Desiccation-stressed IJ populations from each time interval were tested for infectivity, and cross-resistance to secondary temperature and pH stresses and were found to have significant increases in both infectivity and protection from extremes of temperature and pH compared with controls. Total aqueous soluble protein profiles from control and desiccation-stressed IJs were analyzed using 10% SDS Laemmli gels. Several novel proteins were over-expressed in EPN from hosts subjected to desiccation suggesting the induction and expression of stress response genes.

Animals↗
PubMed2004

Visceral hyperalgesia and intestinal dysmotility in a mouse model of postinfective gut dysfunction.

BACKGROUND & AIMS: We established the concept that transient enteric infection may lead to persistent gut dysfunction, evident in vitro, in nematode-infected mice. The present study determined whether gut dysfunction in this model involves motor and sensory changes reminiscent of changes found in patients with postinfective irritable bowel syndrome (PI-IBS) and investigated underlying mechanisms. METHODS: Mice infected up to 70 days previously with Trichinella spiralis (Tsp) underwent videofluoroscopy with image analysis to assess upper gastrointestinal motility. Pseudoaffective responses to colorectal distention (CRD) were assessed using a barostat and validated by single fiber recordings from spinal nerves during CRD. Tissues were examined at different time points for histology, immunohistochemistry, and cytokine analysis. Some mice received dexamethasone intraperitoneally on days 23-25 PI or Tsp antigen orally on days 29, 43, and 57 PI. RESULTS: From day 28 PI, no discernible inflammation was present in the gut. Frequency and propagation velocity of intestinal contractions decreased, and retroperistalsis increased at days 28 to 42 PI. CRD induced an allodynic and hyperalgesic response in PI mice, which was accompanied by increased single unit discharge. Gavage of Tsp antigen induced T-cell responses and sustained gut dysfunction for 70 days PI. Administration of dexamethasone postinfection normalized dysmotility and visceral hyperalgesia. CONCLUSIONS: Long-lasting gut dysmotility and hyperalgesia develop in mice after transient intestinal inflammation. These changes are maintained by luminal exposure to antigen and reversed by corticosteroid treatment. The findings prompt consideration of this as a model of PI-IBS.

Animals↗
PubMed1986

Distribution and prevalence of Octomyomermis troglodytis (Nematoda: Mermithidae), a parasite of the western tree hole mosquito, Aedes sierrensis.

Octomyomermis troglodytis was found infecting Aedes sierrensis larvae in 14.5% of 165 tree holes sampled between 1982 and 1986. Mermithid infections were detected in tree hole waters that ranged in pH from 6.5 to 9.3 and electrical conductivities between 0.10 and 5.11 mmhos/cm. Third and fourth instar larvae were most frequently infected, and most immatures that succumbed to infections died while in the fourth instar. Most hosts contained only one nematode. Infected adults were obtained from emergence traps over tree holes, from field-collected immatures reared in the laboratory, and from mosquito collections from sentinel humans. Octomyomermis troglodytis escaped from adults into water vials in the laboratory, suggesting that infected adult mosquitoes serve as dispersal agents for this parasite.

Aedes↗
PubMed2002

The effect of feeding sulla (Hedysarum coronarium) or lucerne (Medicago sativa) on lamb parasite burdens and development of immunity to gastrointestinal nematodes.

Two experiments investigated the efficacy of the legume Hedysarum coronarium (sulla), which contains condensed tannins (CTs), for reducing gastrointestinal nematode infections relative to lucerne. Experiment 1 was aimed to show whether the lower faecal egg count (FEC) and larval establishment previously reported in lambs grazing sulla were due to direct effects of the forage on Ostertagia circumcincta and Trichostrongylus colubriformis or were mediated through an enhanced immune response. Experiment 2 evaluated the impact of feeding sulla relative to feeding lucerne (Medicago sativa), before, at, or after larval challenge on subsequent FECs and nematode burdens. In experiment 1, 64 Romney lambs were fed either freshly cut lucerne or sulla (32 lambs per herbage) for the duration of the trial. Within each herbage there were four treatment groups (n=8 per group). Initial levels of immunity were assessed in uninfected (UN) lambs which were maintained parasite-free until challenged with 15,000 O. circumcincta and 15,000 T. colubriformis larvae on day 63, and slaughtered on day 81. The other three treatment groups were trickle-infected with each of 5000 O. circumcincta and 5000 T. colubriformis larvae three times per week from day 1 to 35. Non-steroid infected (CONTROL) and steroid-treated (STER) groups were treated with anthelmintic on day 49 and challenged with 15,000 O. circumcincta and 15,000 T. colubriformis on day 63 and slaughtered on day 81. The STER lambs were given dexamethasone trimethylacetate from day 49 to 81 to determine effects of immunity on parasite infection. From day 35 an establishment group (EST) on each herbage was fed a common pelleted lucerne diet and slaughtered on day 56 to determine nematode establishment during trickle-infection. Diet did not affect FECs but feeding lucerne increased (P<0.05) numbers of T. colubriformis in CONTROL lambs compared to those fed sulla. O. circumcincta numbers were lower (P<0.05) in UN lambs fed sulla than lucerne. The sulla diet was associated with higher (P<0.05) antibody titres against secretory-excretory antigens to adult O. circumcincta and to adult and larval T. colubriformis, so there appeared to be some immunogenic response to the sulla diet but effects upon T. colubriformis numbers were not significant. The second experiment involved 48 Romney lambs grazing conventional pasture which were infected with 10,000 each of O. circumcincta and T. colubriformis larvae either 7 days before, 7 days after, or at the time they commenced grazing either sulla or lucerne. Lambs which grazed sulla had lower (P<0.05) FEC and lower (P<0.05) O. circumcincta burdens than lambs which grazed lucerne but timing of infection had no effect on FEC or worm burdens. T. colubriformis numbers were not affected by treatment or herbage. In conclusion, the sulla diet resulted in lower O. circumcincta numbers compared to lucerne outdoors and some evidence of an immunogenic response was obtained indoors. However, neither the herbage nor the immunogenic response reduced T. colubriformis numbers in either experiment.

Animals↗
PubMed2006

Resistance to a triple combination of broad-spectrum anthelmintics in naturally-acquired Ostertagia circumcincta infections in sheep.

AIM: To measure the efficacy of two macrocyclic lactone-levamisole-benzimidazole combination drenches against naturally-acquired abomasal nematode infections on a sheep farm in the North Island, New Zealand. METHODS: Eighteen lambs carrying naturally-acquired worm burdens were removed from pasture and randomly allocated to one of three equal-sized groups, consisting of an untreated control group and two treatment groups. One treatment group was given a single oral dose of a triple-combination anthelmintic administered at the manufacturer's recommended dose rate of 0.2 mg/kg ivermectin, 7.5 mg/kg levamisole and 5.0 mg/kg albendazole. The other treatment group received a similar dose of another triple-combination drench consisting of 0.2 mg/kg abamectin, 8.0 mg/kg levamisole and 4.5 mg/kg oxfendazole. Worm counts were carried out post mortem on the abomasa of all animals in all groups, 10 days after treatment. RESULTS: While the abamectin-levamisole-oxfendazole combination was highly effective against all three abomasal nematode species present, the ivermectin-levamisole-albendazole combination was not. In the latter instance, a reduction of only 78% was achieved against infections of Ostertagia (=Teladorsagia) circumcincta. CONCLUSIONS: These results provide evidence of resistance to an ivermectin-levamisole-albendazole combination drench by O. circumcincta. CLINICAL RELEVANCE: Besides representing the first confirmed report of resistance to a combination drench consisting of three broad-spectrum anthelmintics, the present results provide further evidence of the continuing escalation of multiple anthelmintic resistance in sheep nematodes in New Zealand.

Albendazole↗
PubMed2006

Up-regulated expression of the alpha7 nicotinic acetylcholine receptor subunit on inflammatory infiltrates during Dictyocaulus viviparus infection.

Cholinergic signalling is known to affect immune cell function, but few studies have addressed its relevance during nematode infection. We therefore analysed the anatomical distribution and expression pattern of the nicotinic acetylcholine receptor (nAChR) alpha7 subunit in lungs obtained from Dictyocaulus viviparus-infected and uninfected control cattle. The analysis was performed on trachea and lung parenchyma from uninfected animals and animals necropsied at 15, 22 and 43 days post-infection (DPI). Localization of the alpha7 nAChR was evaluated by immunohistology and mRNA expression analysed by gene-specific reverse transcription-polymerase chain reaction (RT-PCR). In uninfected animals, tracheal, bronchial and bronchiolar epithelium and smooth muscle cells constitutively expressed the alpha7 nAChR, as did type I and II alveolar epithelial cells and alveolar macrophages and a few infiltrating leucocytes. By 15 DPI, immunohistology revealed a massive influx of alpha7 nAChR+ inflammatory cells into the lung parenchyma and tracheal wall. This was reflected in the RT-PCR results. At later time points, both parenchyma and tracheal wall contained large numbers of alpha7 nAChR+ leucocytes, but detection of transcript was restricted to the trachea. Recruitment of nAChR-containing leucocytes to the lungs of D. viviparus-infected cattle suggests that these cells may represent possible downstream targets for parasite-secreted acetylcholinesterases.

Acetylcholinesterase↗
PubMed1980

Altered lysophospholipase B responsiveness in lactating mice infected with intestinal nematode parasites.

Lactating and nulliparous outbred Swiss (CF-1 strain) mice were infected at 12-16 weeks of age with Nippostrongylus brasiliensis or Trichinella spiralis. Lysophospholipase B levels in the intestinal tissue and faecal pellets were greatly in infected lactating mice in contrast to infected nulliparous mice. Correlated with these depressions in lysophospholipase levels were markedly reduced numbers of bone-marrow eosinophils in infected lactating mice. Although the peak levels of lysophospholipase in the intestinal tissues occurred in both nulliparous and lactating mice by days 9 and 14 after infection with N. brasiliensis and T. spiralis, respectively, lactating mice had significantly lower lysophospholipase peak levels than nulliparous mice. The peak of luminal levels of the enzyme coincided with peak levels of the enzyme in the intestinal tissues and with the expulsion of the majority of the worms from the small intestines of nulliparous mice. However, lactation delayed the temporal relation between the peak of lysophospholipase levels in the intestinal lumen and worm expulsion. These results suggest that lactation depressed the levels of the enzyme and interfered with its release into the intestinal lumen.

Animals↗
PubMed1979

Evaluation of oxfendazole against natural infections of gastrointestinal nematodes in Nigerian calves.

The efficacy of oxfendazole was tested in naturally infected Sokoto-Gudali calves at a dosage of 2.8 mg per kg. At this dosage level, oxfendazole showed 100 per cent efficacy against adult and immature forms of Haemonchus spp, Trichostrongylus spp, Bunostomum phlebotomum and Oesophagostomum radiatum. Although efficacy of 100 per cent was recorded for the adult form of Cooperia spp, only 48 per cent reduction was recorded for its immature stages. Similarly, a percentage reduction of 75 was recorded for adult Trichuris spp. No larvae hatched out of a seven-day vermiculite culture of faeces collected from the treated calves 24 h after treatment.

Animals↗
PubMed1993

The effect of age on the response of Romney sheep to gastrointestinal nematodes during grazing.

Three groups of Romney sheep, reared worm-free in pens from birth until 4, 16 or 28 months of age, were permitted to graze nematode-infected pasture for 4 weeks after which they were returned to pens and slaughtered 4 weeks later. Three groups of three Romney sheep reared and maintained worm-free for similar periods served as uninfected control groups. Faecal egg counts (FECs) 8 weeks after grazing commenced were significantly greater in 4-month-old sheep than the 28-month-old animals. At slaughter, no difference in nematode burdens among these three age groups was found. Histological examination of the abomasal and small intestine mucosa, taken from sheep at slaughter, revealed significantly greater numbers of globule leukocytes/mucosal mast cells (GL/MMC) bur fewer connective tissue type mast cells (CTMC) in sheep aged 16 and 28 months than in those aged 4 months. The numbers of eosinophils in the gastrointestinal mucosal tissues of the three groups of infected sheep were not significantly different. In uninfected sheep the numbers of eosinophils, GL/MMC and CTMC in the mucosal tissues did not differ between the three age groups and the numbers of GL/MMC and CTMC were similar to those in 4-month-old infected sheep. Eosinophil numbers in the mucosal tissue of the infected groups were significantly higher than in the uninfected groups. In the infected groups, FECs but not worm burdens were significantly negatively correlated with GL/MMC numbers.(ABSTRACT TRUNCATED AT 250 WORDS)

Abomasum↗
PubMed2000

Halicephalobus gingivalis (Nematoda) infection in a Grevy's zebra (Equus grevyi).

A 6-yr-old female Grevy's zebra (Equus grevyi) with a disseminated rhabditiform nematode infection is described. Antemortem clinical signs were limited to blindness and abnormal behavior believed to be caused by a recurrent nematode-induced uveitis. Histologic examination of the kidneys, heart, eyes, uterus, and lymph nodes revealed granulomas containing multiple sections of rhabditiform nematodes. Most of the recovered nematodes were larval stages with only a few adult females noted. The adults measured 243-297 microm x 11-16 microm (x = 269 x 14 microm). The distinctive rhabditiform esophagi had corpus:isthmus:bulb proportions of 19:11:5. On the basis of adult morphology, the nematode was identified as Halicephalobus gingivalis. This is the first report of this parasite in a zebra and indicates that this parasitic granulomatous disease should be considered in zebras with neurologic disease.

Animals↗
PubMed2002

Strategic use of moxidectin or closantel in combination with levamisole in the control of nematodes of sheep in the highlands of central Kenya.

The strategic use of moxidectin or closantel in combination with levamisole (LEV) to control gastrointestinal nematodes of sheep in the highlands of central Kenya was examined. Thirty Corriedale female lambs aged between 6 and 8 months were assigned to three treatment groups of ten lambs each. The three groups of lambs were set stocked on separate paddocks for the entire study period of 12 months. Lambs in Group 1 were dewormed strategically with moxidectin at 0.2 mg/kg body weight and those in Group 2 with closantel at 10 mg/kg body weight together with LEV at 7.5 mg/kg body weight. These strategic treatments were given 3 weeks after the onset of both the short and long rains and at the end of the long rainy season. The third group of lambs remained untreated (control group). Nematode infections in the treated groups of lambs and larval infectivity for the pastures on which the lambs were grazing were well controlled compared with the untreated control group. This resulted in higher weight gains and packed cell volume (PCV) in the treated lambs compared with the untreated lambs. These parameters were comparable between the lambs treated with moxidectin and those treated with closantel plus LEV. The estimated monitory benefit per animal from the control of gastrointestinal nematodes using moxidectin or closantel in combination with LEV when compared with animals in the control group were US dollars 26 and 25, respectively. It was concluded that worm control strategies for sheep in the study area, which are based on anthelmintic treatments during the rainy seasons, are effective. Due to the extended period during which pastures remain infective in the high rainfall central highlands of Kenya, anthelmintics with sustained action such as moxidectin or closantel may be most effective. On farms where resistance to the commonly used benzimidazoles or LEV groups of anthelmintics has developed, moxidectin or closantel may be used in helminth control programs for sheep.

Animals↗
PubMed1998

Hymenolepsis diminuta: mucosal mastocytosis and intestinal smooth muscle hypertrophy occur in tapeworm-infected rats.

The mechanisms mediating motility changes during noninvasive tapeworm infection have not been characterized. In contrast, host intestinal motility changes during invasive nematode infection are mediated by mucosal mast cells (MMC). The purpose of this study was to examine and the correlate onset of myoelectric alterations 8 days after initial tapeworm infection with changes in intestinal morphology, MMC numbers, and MMC secretory activity. Segments of the small intestine, the tapeworms normal habitat, along with stomach, colon, and bladder were taken from tapeworm-infected and control rats. Tissues were fixed and stained to identify MMC and for morphologic measurement. Tapeworm-infected and uninfected rats with chronically implanted intestinal electrodes were treated with ketotifen, a mast cell stabilizer, and in vivo myoelectric activity monitored. In tapeworm-infected rats, the muscularis externa, on day 20 postinfection, and crypts of Lieberkuhn, on day 26 postinfection, from the entire small intestine appeared thickened or deeper, respectively. Increased muscularis thickness was due to smooth muscle hypertrophy in both the circular and the longitudinal muscle layers. Mucosal mastocytosis was first observed on day 26 postinfection and occurred only in the ileum of tapeworm-infected rats. Pharmacologic stabilization of mast cells with ketotifen did not prevent onset of enteric myoelectric alterations during tapeworm infection. Stomach, colon, and bladder MMC numbers and tissue dimensions were not different between Hymenolepis diminuta-infected rats and uninfected controls. Initiation of myoelectric alterations 8 days after infection precedes and may be a contributing factor to the onset of both smooth muscle hypertrophy and mucosal mastocytosis. Taken together, our data indicate that mast cells are not an initiating factor nor chronic stimulus maintaining intestinal myoelectric alterations during H. diminuta infection.

Animals↗
PubMed1990

Helminthosis in goats in southern Tanzania: investigations on epidemiology and control.

Investigations were conducted in naturally infected goats to determine the main epidemiological factors related to gastro-intestinal nematode infections in southern Tanzania with a view to making appropriate recommendations for control. Faecal worm egg counts rose during the single rainy season and then fell to remain low during the dry season. The beneficial effect of an anthelmintic treatment after the rains was demonstrated in weaner goats under traditional management and this should form the basis of rational control.

Animals↗
PubMed2004

Survey of intestinal parasites in pigs from intensive farms in Guangdong Province, People's Republic of China.

The prevalence of intestinal parasites was investigated in intensive pig farms in Guangdong Province, China between July 2000 and July 2002. Faecal samples from 3636 pigs (both sexes and five age groups) from 38 representative intensive pig farms employing different parasite control strategies were examined for the presence of helminth ova and protozoan oocysts, cysts and/or trophozoites using standard techniques. Of the 3636 pigs sampled, 209 (5.7%) were infected with Trichuris suis, 189 (5.2%) with Ascaris, 91 (2.5%) with Oesophagostomum spp., 905 (24.9%) with coccidia (Eimeria spp. and/or Isospora suis) and 1716 (47.2%) with Balantidium coli. These infected pigs were mainly from farms without a strategic anti-parasite treatment regime. Concurrent infection of multiple parasites was common, and T. suis was the most common nematode infecting breeding, young and mature pigs. The results of the present investigation provide relevant 'base-line' data for assessing the effectiveness of control strategies against intestinal parasitism in intensively raised pigs in Guangdong Province, China.

Animals↗
PubMed2000

Efficacy of mebendazole in treatment of selected parasitoses--a retrospective study.

The efficacy of mebendazole was evaluated as a result of six-year experience in the treatment of patients of Outpatients Clinic and Clinic of Infectious, Parasitic and Tropical Diseases in Lódź. The treatment covered 6132 subjects infected with: Ascaris lumbricoides, Ancylostoma duodenale, Trichiuris trichiura, Enterobius vermicularis and Echinococcus granulosus. Nematode infections were diagnosed by coproscopic methods whereas echinococcosis with serologic tests and ultrasonographic examination of abdominal cavity. Mebendazole was administered in the dose of 200 mg per day: for 3 days in ascariasis, for 5 days in A. duodenale, T. trichiura and mixed infections. In enterobiosis was applied a pulsation therapy: 200 mg a day for 3 days, a week of break (three subsequent cycles). In echinococcosis the drug was administered in the daily dose of 600 mg for 30 days. Follow-up examinations were carried out 30, 60, 120 and 160 days after the treatment. In the case of ineffectiveness of the first course, the treatment was repeated. The efficacy of the therapy was as follows: ascariasis 97.1%, A. duodenale infection 100%, trichuriasis 92.1%, enterobiosis 93.3 %, mixed infections 95.3%, echinococcosis 77.2%. No side effects were observed.

Animals↗
PubMed1987

[Therapeutic possibilities in diseases caused by intestinal parasites].

Compatible and efficient drugs for the therapy, caused by protozoal- or helminthic-infections, are available today. Many of them are not registered in Austria. Metronidazole, Mebendazole and Praziquantel are particularly effective. Most protozoal-infections can be treated with metronidazole. Mebendazole can be used against numerous nematode-infections (Ascariasis, Trichuriasis, Oxyuriasis, Ancylostomiasis), Niclosamide against cestode-infections (Taeniasis, Hymenolepiasis, Diphyllobothriasis), whereas, Praziquantel is applied against trematode-infections.

Anthelmintics↗
PubMed1984

Seasonal changes in the abomasal nematodes of naturally infected ewes in Moulay-Bouazza (Morocco).

The nematode populations of 93 abomasa of ewes from Middle-Atlas (Morocco) were studied over a period of 3 years. The main species present were Ostertagia circumcincta, Marshallagia marshalli, Trichostrongylus axei and T. vitrinus; less frequent species were O. ostertagi and O. trifurcata. Two peaks of infection were recorded, 1 at the end of winter or the beginning of spring (February--March), and another in autumn (September). The first population peak consisted mostly of O. circumcincta and T. axei, and the second population peak, in autumn, had a high prevalence of M. marshalli and T. vitrinus.

Abomasum↗
PubMed2001

Phytoalexins from Pinus strobus bark infected with pinewood nematode, bursaphelenchus xylophilus.

From the bark of Pinus strobus infected with pinewood nematode, Bursaphelenchus xylophilus, a stilbenoid 3-O-methyldihydropinosylvin and a flavanone (2S)-pinocembrin were isolated as active principles of inducibly produced antifungal compounds. The structures of the compounds were determined on the basis of spectroscopic analyses. Close investigations of spectroscopic analyses led to the complete assignment of 13C NMR and 1H NMR chemical shifts for the former compound and to the determination of the stereochemistry of the latter compound from P. strobus to be 2S. Furthermore, the distribution and time course accumulation of the identified compounds were investigated. The former compound was demonstrated to be nematocidal and the concentrations of the compound in the inoculated branches were sufficient enough to inactivate the pinewood nematode within one week after inoculation.

Animals↗