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PubMed2002

The effects of chemoprophylaxis on acquired immunity against gastrointestinal nematodes in cattle.

The level and duration of exposure to gastrointestinal nematode infections are of crucial importance for the development of acquired immunity in first season grazing calves. An excessive reduction of host-parasite contact by chemoprophylaxis, pasture management, or both, causes a diminished level of acquired immunity. Moreover, the level of acquired resistance is negatively related to the degree of suppression of host-parasite contact. Whether or not a reduced resistance against establishment and development of gastrointestinal nematode infections has a negative effect on weight gain in the second grazing season, depends both on the intensity of the prophylaxis used and on the level of the challenge infection. Cross-sectional serological surveys and questionnaire surveys in The Netherlands, Germany and Belgium indicated that parasitic nematode control in first season grazing calves tends to be overprotective. Possible consequences of over-treatment, besides higher treatment costs and a reduced level of acquired immunity, are more drug residues in animal products and in the environment and increased selection for anthelmintic resistance.

Animals↗
PubMed1992

Dictyocaulus viviparus in calves: effect of rotational grazing on the development of infections.

A study was made of the possibility of reducing lungworm infections in young grazing calves by rotational grazing for weekly periods on six paddocks. For this purpose three groups of four calves each were grazed on separate pastures in 1989, whereas a fourth group served as a permanently housed control group. Two groups of calves were infected experimentally with six doses of 10 larvae of Dictyocaulus viviparus during the first 3 weeks on pasture. In the third group, low natural infections with overwintered larvae occurred. One of the experimentally infected groups was rotationally grazed for weekly periods on six small plots while both other groups were set-stocked. Faecal larval counts and worm counts in tracer calves demonstrated lower lungworm infections in the rotationally grazed group than in both set-stocked groups. However, the numbers of worms found after challenge infection and subsequent necropsy were relatively high in the rotationally grazed group, indicating that development of immunity was less than in both other groups. Owing to the dry weather conditions in the summer of 1989, no serious clinical signs of husk developed in any of the three groups. These dry conditions, however, did not prevent the build-up of heavy pasture infectivity with gastrointestinal nematodes resulting in heavy worm burdens and serious clinical signs in tracer calves grazing for 4 days in August and September-October, respectively. This implies that rotational grazing did not have a clear effect on build-up of gastrointestinal nematode infections.

Animal Feed↗
PubMed1998

The effect of previous cold storage on the subsequent recovery of infective third stage nematode larvae from sheep faeces.

An investigation undertaken to determine the effect of previous cold storage on the recovery of third stage larvae of gastrointestinal nematodes of sheep, showed that increasing periods of exposure of faeces to 4 degrees C resulted in decreasing numbers of larvae subsequently recovered from them. Differences in the abilities of the eggs of the various genera, to survive such treatment, were found to lead to significant changes in the percentage generic compositions of their third stage larvae--in some cases following the prior refrigeration of faecal samples for as little as 24 h. These results suggest that where larval cultures are intended to provide estimates of the proportions of the various worm eggs in the faeces of sheep harboring mixed gastrointestinal nematode burdens, they should be performed only on freshly collected samples.

Animals↗
PubMed1982

Relationship between tissue sensitization and IgE antibody production in rats infected with the nematode, Nippostrongylus brasiliensis.

In Nippostrongylus brasiliensis rats, tracheal sensitivity to worm allergens developed prior to intestinal sensitivity and correlated with the early local synthesis of reaginic antibody in the mediastinal (bronchial) lymph nodes. Skin and intestinal sensitivity to worm allergens more nearly correlated with serum reaginic antibody and its synthesis by mesenteric lymph nodes and other tissues. Prostaglandins appeared to modulate intestinal responsiveness to worm allergens. Thus, local reagin synthesis and other microenvironmental factors influence local tissue sensitization and responsiveness to allergens.

Allergens↗
PubMed1975

Anthelmintic effect of oxantel pamoate and pyrantel pamoate suspension against intestinal nematode infestations.

A total of 56 subjects with multiple nematode infections with T. trichiura, Ascaris, hookworms and Enterobius were treated with oxantel and pyrantel pamoate mixture in a paratable suspension(50 mg of each per ml). A single dose of 10 mg per kg body weight in each cured 100 per cent of 54 subjects with Ascaris, 97.1 per cent of 35 subjects with hookworms, 77.8 per cent of 36 with Enterobius and 73.2 per cent of 56 subjects with T. trichiura infestation. The mean egg per gram stool reduction rate in T. trichiura infection was 91.9%. Of the 31 subjects infected with Ancylostoma doudenale 96.8% were cured with a single dose and 4 infected with Necator americanus showed a 100% cure rate with a similar daily dose on 3 consecutive days. Side effects were few and mild. There was no clinical or laboratory evidence of drug toxicity. These findings show a single dose of oxantel and pyrantel pamoate mixture to be a highly effective and acceptable treatment for multiple infections with these nematodes.

Journal Article↗
PubMed2000

Effects of anthelmintic treatment and feed supplementation on grazing Tuli weaner steers naturally infected with gastrointestinal nematodes.

A study was carried out to determine the epidemiology of gastrointestinal nematodes in indigenous Tuli cattle and the effect of dietary protein supplementation and anthelmintic treatment on productivity in young growing cattle. Forty steers with an average age of 18 months were divided into 4 groups; 1) fenbendazole (slow release bolus) and cottonseed meal (FCSM group), 2) fenbendazole (FBZ group), 3) cottonseed meal (CSM group) and 4) control (no cottonseed meal and no fenbendazole) (control group). Performance parameters measured included worm eggs per gram of faeces (EPG), packed cell volume (PCV), albumin and live-weight gain. Results showed that faecal worm egg counts were lower and PCV was higher in the FCSM and FBZ groups than in the CSM and control groups (P < 0.01). Weight gains were higher in the CSM and FCSM groups than in the FBZ and control groups (P < 0.05). The cost benefits of anthelmintic treatment and dietary supplementation were apparent in this study. The improved growth performance of the FCSM, FBZ and CSM groups reflected a financial gain over the controls on termination of the study. The dominant genera of gastrointestinal nematodes on faecal culture, pasture larval counts and necropsy were Cooperia and Haemonchus. The incidences of Trichostrongylus, Oesophagostomum and Bunostomum were low.

Animals↗
PubMed2004

Effect of urea-molasses block supplementation on grazing weaner goats naturally infected with gastrointestinal nematodes.

The influence of feeding urea-molasses blocks (UMB) on growth and gastrointestinal (GI) nematode parasitism of weaner goats grazing the same pasture was investigated on a farm in Nyandarua District, Kenya. Thirty female Small East African goat kids at an average age of 5 months were initially treated with albendazole orally (5 mg kg(-1) body mass) and randomly assigned into one of two groups: group I were fed UMB prepared using a cold process and group II kids (controls) received no block supplementation (NBS). The UMB were given in the evening when the animals returned from grazing and were consumed during the night at a rate of 95.0 g head(-1) day(-1). Supplementation was undertaken for 3 consecutive months from July to September 2001 and January to March 2002. Body mass of the kids and faecal egg counts were measured monthly and larval cultures were performed on positive faecal samples of kids of each group. Five goats from each group were randomly selected for slaughter and total counts and identification of worms at the end of June 2002. Significant differences (P < 0.05) were found in cumulative mass gains of kids in group I from September compared with those in group II. On termination of the study kids in group I had gained an average of (+/- SD) 20.4 +/- 1.4 kg while those in group II had gained 11.8 +/- 1.1 kg. From January 2002, faecal egg counts of the kids in the UMB group differed significantly (P < 0.05) from those of the NBS group and at slaughter, the mean (+/- SD) worm counts for the UMB group was 482 +/- 299 while that of the NBS group was 1 302 +/- 410. In all the goats, Haemonchus contortus was the predominant nematode recovered. These results indicate that UMB had significant effects in the control of GI nematode parasitism and enhanced growth of the young goats.

Animal Feed↗
PubMed1991

IL-4 requirements for the generation of secondary in vivo IgE responses.

IL-4 has been shown to induce B lymphocytes to switch from the expression of membrane IgM to the expression of membrane IgE and to be required for the generation of primary polyclonal and secondary Ag-specific IgE responses in mice. To further define the role of IL-4 in the generation of memory IgE responses, we investigated the ability of a combination of anti-IL-4 and anti-IL-4R mAb to block the generation of secondary IgE responses induced by: 1) a second infection with the nematode parasites Nippostrongylus brasiliensis or Heligmosomoides polygyrus; or 2) injection of anti-IgD antibody-primed mice with anti-IgE antibody. The latter stimulus was designed to induce intrinsic membrane IgE-expressing B cells to differentiate into IgE-secreting cells. Although the IgE responses induced by a second nematode infection were completely inhibited by the combination of anti-IL-4 and anti-IL-4R mAb, anti-IgE antibody-induced IgE responses in anti-IgD primed mice were not inhibited by these antibodies to a large degree. Additional experiments demonstrated that the anti-IgE antibody-induced memory IgE response was dependent on CD4+ T cells but did not involve the low affinity B cell Fc epsilon RII. Taken together, these observations provide evidence that IL-4 is required for virgin B lymphocytes to develop into IgE-expressing cells, but is not required for B cells that express intrinsic membrane IgE to differentiate into IgE-secreting cells in a T-dependent response. Furthermore, these data suggest that secondary IgE responses in the parasite models that we have studied develop from B cells that had not previously switched to the expression of IgE.

Animals↗
PubMed1987

Use of an oxfendazole pulse release bolus in calves exposed to natural subclinical infection with gastrointestinal nematodes.

During the first grazing season a group of calves treated with an oxfendazole pulse release bolus achieved a mean (+/- sem) weight gain of 140.7 (+/- 6.7) kg compared with 106.5 (+/- 5.7) kg by a group treated once with ivermectin mid-season, and 116.9 (+/- 6.9) kg by a group which received no treatment. This economic advantage was maintained during the period of winter housing. By the end of the second grazing season, during which the animals received no anthelmintic medication, they weighed on average 20 kg more than the wholly untreated group, a difference which was not statistically significant. No signs of clinical disease were observed in either the animals dosed with a pulse release bolus or the undosed control animals during the two year trial period. The treatment with the oxfendazole pulse release bolus greatly reduced the degree of pasture contamination in the first year but in the second year those animals that had been treated in the first year developed higher worm egg counts (P less than 0.001) and thus augmented the levels of pasture contamination compared with the untreated control animals. Nematodirus battus and N filicollis both produced low grade but fertile infestations in the calves.

Animals↗