Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “HELMINTH INFECTIONS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed2000

A study on the time of ovicidal effect of some anthelmintics in Djallonke sheep and its implication for the control of parasitic helminth infections.

The time lag between the administration of five different anthelmintics and the exertion of their ovicidal effect on worm eggs was monitored in five groups of Djallonke sheep. In this experiment, all the animals in all treated groups and an untreated control group were grazed together. Worm egg output and the number of infective strongylate nematode larvae (L3s) recovered from fecal cultures from each group were observed every four hours for 72 h. The earliest time observed for the occurrence of ovicidal effect resulting in the absence of L3s in fecal cultures was 8 h after the administration of the anthelmintics. However, this time was not the same for all the anthelmintics. The implication of the results are discussed in relation to its application for worm control.

Albendazole↗
PubMed1987

Effects of helminth infection on the pre-weaning production of ewes and lambs: evaluation of pre- and post-lambing drenching and provision of safe lambing pasture.

The pre-weaning production of ewes and lambs in spring on pastures grazed during the previous autumn and early winter by either weaner sheep, adult sheep, or cattle was investigated together with estimating the benefits of pre- and post-lambing drenches to ewes. These treatments were compared with one in which parasitism was uncontrolled in ewes lambing on pastures grazed previously by untreated weaner sheep, and another where parasitism was suppressed by 2-weekly drenching of the weaner sheep and also of the ewes and their lambs. Prior grazing by cattle effectively eliminated infection of pastures with intestinal Trichostrongylus and Nematodirus spp, but less so for Ostertagia spp. Worthwhile reductions in contamination were also achieved by grazing by adult sheep compared with grazing by undrenched weaners. Despite differences in the parasitological status of the pastures, there were no indications that pre-weaning growth rates of lambs were affected. However, wool growth in ewes was reduced by 10 to 20% by parasite infection. Wool growth of ewes on pastures grazed by cattle during the pre-experimental period exceeded that on any other treatment, and was significantly greater than that of ewes on pastures grazed by undrenched weaners. There was no production benefit in giving a pre-lambing drench to ewes on plots contaminated by weaners, or in giving the additional post-lambing drench to ewes grazing on plots contaminated by weaners, adult sheep or cattle.

Animals↗
PubMed1976

Suppressive effect of a chronic helminth infection, schistosomiasis mansoni, on the in vitro responses of spleen and lymph node cells to the T cell mitogens phytohemagglutinin and concanavalin A.

Chronic murine schistosomiasis mansoni is associated with depressed cell-mediated immune responses to Schistosoma mansoni egg antigens. The present study has examined the possibility that factors develop during infection that are capable of altering the response of lymphocytes to stimuli other than specific schistosomal antigens. Egg production begins at 5 weeks, and 1 to 3 weeks later there is a moderate degree of unresponsiveness of lymph node and spleen cells to the mitogens concanavalin A and phytohemagglutinin. This was associated with an altered dose response curve to the mitogens similar to that observed in antigenic systems. Seven weeks after the initiation of antigenic stimulation (egg prodiction lymph node and spleen cells from chronically infected animals were profoundly unresponsive to all concentrations of concanavalin A and phytohemagglutinin tested. These investigations suggest that, in addition to possible blockade by serum antibody, other suppressive factors may be involved in the spontaneous modulation of immunopathology in chronic schistosomiasis. These are detectable 1 to 3 weeks after the onset of egg production and are prominent at 12 weeks. Such findings are consistent with, but do not prove, the existence of suppressor T cells in chronic schistosomiasis.

Animals↗
PubMed2002

Increased activation and oligoclonality of peripheral CD8(+) T cells in the chronic human helminth infection alveolar echinococcosis.

Alveolar echinococcosis (AE) in humans is a chronic disease characterized by slowly expanding liver lesions. Cellular immunity restricts the spreading of the extracellular pathogen, but functional contributions of CD4(+) and CD8(+) T cells are not defined. Here we studied ex vivo the phenotype and function of circulating T-cell subsets in AE patients by means of flow cytometry, T-cell receptor spectratyping, and lymphocyte proliferation. AE patients with parasitic lesions displayed a significant increase of activation of predominantly CD8(+) T cells compared to healthy controls and AE patients without lesions. In vitro, proliferative T-cell responses to polyclonal stimulation with recall antigens and Echinococcus multilocularis vesicular fluid antigen were sustained during chronic persisting infection in all AE patients. Only in AE patients with parasitic lesions did T-cell receptor spectratyping reveal increased oligoclonality of CD8(+) but not CD4(+) T cells, suggesting a persistent antigenic drive for CD8(+) T cells with subsequent proliferation of selected clonotypes. Thus, our data provide strong evidence for an active role of CD8(+) T cells in AE.

Adult↗
PubMed1978

The incidence, pathogenesis and treatment of helminth infections in rhesus monkeys (Macaca mulatta).

In a survey of 259 newly-imported rhesus monkeys, 5 species of nematode parasites were commonly found. Of these 5 species, Oesophagostomum spp. and Strongyloides fulleborni were implicated in the deaths of 3 monkeys. 5 other nematode species, 2 cestode species and 1 trematode species were also found; their pathogenicity is discussed. The results of treatment of parasitic infections with 6 different drugs is reported. Thiabendazole at an initial dose of 100 or 133 mg/kg and repeated at 50 mg/kg was found to be the most effective treatment against Oesophagostomum spp.

Animals↗
PubMed1997

The debate over the effector function of eosinophils in helminth infection: new evidence from studies on the regulation of vaccine immunity by IL-12.

The production of Th1-type cytokines is associated with strong cell-mediated immunity while Th2-type cytokines are typically involved in the generation of humoral immune responses. In mice vaccinated a single time (1X) with attenuated cercariae of Schistosoma mansoni, the immunity induced is highly dependent on CD4+ T cells and IFN-gamma. In contrast, mice vaccinated multiple times (3X) have decreased IFN-gamma expression, develop a more dominant Th2-type cytokine response as well as protective antibodies which can passively transfer immunity to naive recipients. Previously, we demonstrated the ability of IL-12, a potent IFN-gamma-inducing cytokine to enhance (1X) schistosome cell-mediated saline-treated mice demonstrated a 70 immunity when administered during the period of immunization. More recently, we asked what effects IL-12 would have on the development humoral-based immunity. While multiply-immunized/ saline-treated mice demonstrated a 70-80% reduction in parasite burden, 3X/IL-12-vaccinated animals displayed an even more striking > 90% reduction in challenge infection, with many mice in the later group demonstrating complete protection. Analysis of pulmonary cytokine mRNA responses demonstrated that control challenged mice elicited a dominant Th2-type response, 3X/saline-vaccinated produced a mixed Th1/Th2-type cytokine response, while 3X/IL-12-immunized animals displayed a dominant Th1-type response. The IL-12-treated group also showed a marked reduction in total serum IgE and tissue eosinophilia while SWAP-specific IgG2a and IgG2b Abs were elevated. Interestingly, animals vaccinated with IL-12 also showed a highly significant increase in total Ig titers specific for IrV, a known protective antigen. More importantly, 3X/IL-12 serum transferred significantly less protection. Nevertheless, animals vaccinated in the presence of IL-12 also develop macrophages with enhanced nitric oxide dependent killing activity against the parasites. Together, these observation suggest that IL-12, initially described as an adjuvant for cell-mediated immunity, may also be used as an adjuvant for promoting both humoral and cell-mediated protective responses.

Animals↗