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Results for “HELMINTH INFECTIONS”

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At least 397 records · Page 22Linked to original sources
PubMed1990

Response to helminth infection of sheep selected for resistance to Haemonchus contortus.

Lines of Merino sheep selected for increased (IRH) and decreased (DRH) resistance to Haemonchus contortus were compared with an unselected (CH) line, after approximately four generations of selection. Measurements were recorded on 69 IRH, 47 DRH and 84 CH animals. Following artificial challenge with H. contortus, the IRH line had significantly (P less than 0.001) lower faecal egg counts than the CH and DRH lines (2730, 12,720 and 17,400 epg, respectively). Significant differences (P less than 0.05) were found between all lines in the minimum packed cell volumes during artificial infection (25.7, 22.0 and 20.3%) and in faecal egg counts after natural infection (140, 3590 and 8750 epg). Differences were also recorded (P less than 0.05) following artificial challenge with Trichostrongylus colubriformis (490, 840 and 1340 epg). On a percentage basis, faecal egg counts in the IRH line deviated less from the CH line following artificial infection with T. colubriformis (42%) than with H. contortus (79%). The reverse was true for the DRH line (60 and 37%, respectively). Differences in egg output of this magnitude should have a marked effect on requirements for anthelmintic treatment, rate of development of drug resistance and level of pasture contamination when the lines are grazed separately.

Animals↗
PubMedDate not supplied

Immunoepidemiology of intestinal helminthic infections. 1. The global burden of intestinal nematode disease.

Estimates of the world-wide prevalence of intestinal nematode infections indicate that there are more than 1000 million people infected, and several million cases of clinical helminthiases. Recent studies suggest that the morbidity has been underestimated and that moderate intensities of infection may have important developmental consequences, particularly for children of school age.

Ascariasis↗
PubMedDate not supplied

Immunoepidemiology of intestinal helminthic infections. 3. Mucosal macrophages and cytokine production in the colon of children with Trichuris trichiura dysentery.

Mucosal macrophages and accessory cells have been studied by immunohistochemistry in the lamina propria of the colon of children with Trichuris trichiura dysentery syndrome (TDS). No difference was found in the numbers of cells recognized by the monoclonal antibodies CD11c, CD68, or RFD7 between TDS children and local controls. However, large numbers of cells were recognized by an antibody against calprotectin (an anti-bacterial glycoprotein found in tissue infiltrating-monocytes) in TDS colonic mucosa, but few in control colon. Large numbers of cells containing tumour necrosis factor alpha (TNF alpha) were also seen in TDS mucosa; cells isolated from TDS mucosa secreted more TNF alpha than cells from control mucosa; and children with TDS had high levels of circulating TNF alpha. Non-specific macrophage-mediated inflammation and local cytokine production may therefore play a role in the pathogenesis of TDS.

Child↗
PubMedDate not supplied

Immunoepidemiology of intestinal helminth infections. 4. Immunopathology in trichuriasis: lessons from the mouse model.

The severity and consequences of human Trichuris infection vary widely. This may reflect differences in immune response. T. muris is a natural parasite of mice which provides a close, well defined, easily manipulated model for otherwise uninvestigatable aspects of this response. Normal mice reject the parasite in 3 weeks, but mice subjected to transient immunosuppression around the time of infection develop a persistent caecal infection. Sequential histopathological studies have shown that infected, normal mice develop a marked intraepithelial, mucosal, 'globule leucocyte' response, accompanied by low-level lymphocytic and histiocytic responses in the lamina propria. The reaction is maximal at 3 weeks and declines towards normal after rejection. Infected, immunosuppressed mice show a slower response with, by weeks 4 and 5, fewer 'globule leucocytes', but a chronic colitis comprising heavy, mixed, mucosal and submucosal inflammation and crypt damage accompanied by persistent parasite infection. The 'globule leucocyte' has been characterized by cytochemistry and electron microscopy as having a mast cell origin. This study, with other evidence, suggests that the replacement of a Th2 (allergic) T helper cell response by a Th1 (cell-mediated) response may result in increased severity and persistence of colitis in response to Trichuris infection.

Animals↗
PubMed1995

Dry areas: an example of seasonal evolution of helminth infection of sheep and goats in southern Mauritania.

A total of 647 faecal egg counts and 53 necropsies were performed on sheep and goats originating from three sites of a Sahelian region of Mauritania (Gorgol) over a period of 2 years (1990-1992). Haemonchus contortus, Oesophagostomum columbianum and Stilesia globipunctata were the most prevalent species. The seasonal pattern was characterized by long survival of adults and high percentages of arrested fourth-stage larvae in the dry season, suggesting that two different strategies were used to survive from one rainy season to the next. Sheep and goats were equally infected, except for Stilesia globipunctata, which was found more often in sheep. The influence of age was limited, although kids and lambs born in the beginning of the dry season did not become infected until their first grazing in the rainy season.

Analysis of Variance↗
PubMed2002

A novel and sensitive method to monitor helminth infections by faecal sampling.

The Kato-Katz technique is the method routinely used for diagnosing human schistosomiasis mansoni by estimating faecal egg burdens. To improve the sensitivity of faecal diagnosis, we established and validated a novel separation technique based upon the greater density of viable schistosome eggs relative to faecal material. Subsequently, it was used for faecal examination of 27 schistosomiasis patients in El-Sharkia, Egypt, with Kato-Katz smears as criterion standard. Low intensity infections (<100 eggs/g) were only detected by our technique. Moreover, triple Kato-Katz analysis on consecutive samples still missed 7.4% of all human patients, whereas the new method diagnosed 100% of samples correctly on second analysis. We conclude that in endemic areas many patients are being systematically missed by routine diagnosis. Moreover, the sensitivity of our method allows its use in proposed pre-clinical and clinical vaccine trials in non-human primates and humans, where reliable estimates of faecal egg counts are essential.

Animals↗