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PubMed2004

Impact of drainage and sewerage on intestinal nematode infections in poor urban areas in Salvador, Brazil.

This cross-sectional study was conducted in 1989 among children aged between 5 and 14 years old living in nine poor urban areas of the city of Salvador (pop. 2.44 million), capital of Bahia State, in Northeast Brazil. Three of these areas had benefited from both drainage and sewerage, 3 from improved drainage only, and 3 from neither. The children studied thus belonged to 3 exposure groups regarding their level of sanitation infrastructure. An extensive questionnaire was applied to collect information on each child and on the conditions of the household, and stool examinations of the children 5-14 years old were performed to measure nematode infection. Comparison of the sewerage group with the drainage-only group and the latter with the control (no sewerage or drainage) group showed that, when the level of community sanitation was better, the prevalence of infection among children was less, but risk factors identified for infection were more numerous and more significant. Intensity of infection with Trichuris, but not with Ascaris or hookworm, was also less. The results suggest that sewerage and drainage can have a significant effect on intestinal nematode infections, by reducing transmission occurring in the public domain.

Adolescent↗

PubMed1997

Field evaluation of a fenbendazole slow release bolus in the control of nematode infections in first-season cattle.

The efficacy of a fenbendazole slow release bolus in controlling nematode infections of first-season cattle was evaluated in a field study in northern Germany. Two groups, each of 11 male calves, were set-stocked on separate pastures from May until October 1989 (157 days). The animals of one group were given the bolus at turnout and the animals of the control group were treated with fenbendazole (7.5 mg/kg bodyweight) eight weeks after turnout. Clinical inspections and measurements of faecal egg and larval counts, herbage trichostrongyle larval counts, plasma pepsinogen concentrations and bodyweight were made throughout the study. All the animals were slaughtered for worm counts and the evaluation of carcase quality two weeks after housing. The pasture grazed by the control group showed a marked increase in trichostrongyle larvae from late August onwards and, as a result, the control calves had increasing faecal egg counts and increased plasma pepsinogen concentrations in the latter part of the grazing season, although no clinical signs of parasitic gastroenteritis were apparent. The fenbendazole slow release bolus suppressed the trichostrongyle infections during the grazing season, and larval counts on the pasture grazed by the bolus-treated group remained low throughout the study. Postmortem examination showed that the bolus-treated calves harboured significantly (P < 0.01) fewer trichostrongyle worms, including inhibited stages, than the controls. Because of an inadequate lungworm challenge during the grazing season it was not possible to evaluate the efficacy of the fenbendazole slow release bolus in preventing parasitic bronchitis. At slaughter, the bolus-treated animals weighed more than the controls and tended to have a better carcase quality.

Animals↗

PubMed2004

Expression of integrin-alphaE by mucosal mast cells in the intestinal epithelium and its absence in nematode-infected mice lacking the transforming growth factor-beta1-activating integrin alphavbeta6.

Peak intestinal mucosal mast cell (MMC) recruitment coincides with expulsion of Trichinella spiralis, at a time when the majority of the MMCs are located within the epithelium in BALB/c mice. Although expression of integrin-alpha(E)beta(7) by MMCs has not been formally demonstrated, it has been proposed as a potential mechanism to account for the predominantly intraepithelial location of MMCs during nematode infection. Co-expression of integrin-alpha(E)beta(7) and the MMC chymase mouse mast cell protease-1, by mouse bone marrow-derived mast cells, is strictly regulated by transforming growth factor (TGF)-beta(1). However, TGF-beta(1) is secreted as part of a latent complex in vivo and subsequent extracellular modification is required to render it biologically active. We now show, for the first time, that intraepithelial MMCs express integrin-alpha(E)beta(7) in Trichinella-infected BALB/c and S129 mice. In S129 mice that lack the gene for the integrin-beta(6) subunit and, as consequence, do not express the epithelial integrin-alpha(v)beta(6), integrin-alpha(E) expression is virtually abolished and recruitment of MMCs into the intestinal epithelium is dramatically reduced despite significant overall augmentation of the MMC population. Because a major function of integrin-alpha(v)beta(6) is to activate latent TGF-beta(1,) these findings strongly support a role for TGF-beta(1) in both the recruitment and differentiation of murine MMCs during nematode infection.

Animals↗

PubMed2002

Benefit of the control of gastrointestinal nematode infection in goats in the dry zone of Sri Lanka.

The benefit of gastrointestinal nematode control in cross-bred goats in the dry area of Sri Lanka was studied throughout 1 year by comparing the performances of three groups: group 1 animals (n = 11) were left untreated against gastrointestinal nematodes; group 2 animals (n = 11) were given monthly anthelmintic treatment. doramectin, at the dose rate of 300 microg/kg bodyweight during the entire study period; group 3 animals (n = 11) were also given monthly doramectin treatment at the dose rate of 300 microg/kg bodyweight but only during the rainy months, October to January and again once in April. All three groups were turned out together on to communal pasture. Tracers were used for the monthly estimation of gastrointestinal nematode burdens. Four untreated animals and a group 3 animal suffered from parasitic gastroenteritis during the study period. When compared with the controls, the treated groups had significantly lower gastrointestinal nematode infection as indicated by faecal egg counts (P<0.01). Faecal egg counts in group 3 were significantly higher than those in group 2 (P < 0.01). When compared with the controls, the treated groups had significantly greater weight gains (P< 0.05). Haemonchus contortus and Trichostrongylus colubriformis were the predominant gastrointestinal nematodes identified from tracers. The worm burden varied according to the rainfall pattern, with very minimal transmission during the dry period which extends from May to August. Under the conditions of this study, the monthly anthelmintic treatments increased weight gains and prevented parasitic gastroenteritis of goats in the dry zone of Sri Lanka.

Animals↗

PubMed1995

Faecal egg output, contamination of pastures and serum pepsinogen concentrations in heifers with natural gastrointestinal nematode infections in north-west Spain.

In 1988, 1989 and 1990 second year grazing heifers, naturally infected with gastrointestinal nematodes, were separated into two groups, one of which was treated orally with albendazole. In 1988 and 1989 treatment was administered immediately after parturition (February), and in 1990 during the last term of pregnancy (December). Both treated and control animals were grazed on separate plots in a rotational system. Maximum faecal egg counts were observed around parturition, except in 1990, when treatment was given at the end of gestation. The main genera identified were Cooperia, Trichostrongylus, Ostertagia and Oesophagostomum. The number of Ostertagia larvae in the treated groups increased from 1989 to 1990, while the others decreased. Pasture contamination with third stage larvae (L3) was lower on the plots grazed by treated heifers. Maximum numbers of L3 were found in autumn, at the end of winter, and at the beginning of spring. Mean serum pepsinogen concentrations were significantly higher in the untreated groups. This concurs with the pattern for L3 on pasture. The trial shows that if a single treatment against gastrointestinal nematodes is carried out, and the animals remain on contaminated pastures, the parasitic load tends to level out after 4-5 months under favourable climatic conditions. However, the percentages of nematode genera occurring in the new populations may differ from those in the original infection.

Albendazole↗

PubMed2000

[Some aspects of the immune response of Polish Wrzosówka sheep against gastrointestinal nematodes infection].

The paper presents different aspects of natural gastrointestinal nematode infection in this primitive, prolific Polish Wrzosówka breed of sheep. The study was carried out on the flock located at the farm run by Warsaw Agricultural University at Zelazna (central Poland) in 1995-1998. Egg counts per gram of faeces, larval differentiation, total white blood cell counts, blood eosinophil counts, interleukin-5 concentration, lymphocyte blastogenic activity and IgG immune response were discussed. The egg counts were overdispersed and followed a different pattern each grazing season. The larvae obtained from faecal culture belonged to 6 categories: Trichostrongylus spp., Haemonchus contortus, Teladorsagia spp., Cooperia spp., Chabertia ovina/Oesophagostomum spp. and Nematodirus spp. However there were no discernible patterns in the composition of nematode population over time. Data analyses have shown that egg counts, eosinophil counts, IL-5 concentration and IgG level in different months each year were repeatable. The results obtained in two divergent groups of sheep, chosen for consistently low or high faecal egg counts have been presented also. Polish Wrzosówka breed of sheep is under conservation breeding program based mainly on the markers of breed standard. The results obtained in this study revealed that some parasitological, haematological and immunological parameters should be added to this program.

Animal Husbandry↗

PubMed1994

The evaluation of potential global morbidity attributable to intestinal nematode infections.

This paper presents a method of estimating the potential global morbidity due to human intestinal nematode infections (Ascaris lumbricoides, Trichuris trichiura and hookworms), based on the observed prevalence of infection. The method relies on the observed relationships between prevalence and intensity of infection, and between worm burden and potential morbidity. This approach is shown to be sensitive to the precision of the original prevalence estimates and, in particular, to the degree of spatial heterogeneity in levels of infection. The estimates presented here indicate that several tens of millions of children are likely to suffer developmental consequences from infection, and suggest that the global disease burden of geohelminthiasis may be significantly greater than was supposed.

Adolescent↗

PubMed2004

WSX-1: a key role in induction of chronic intestinal nematode infection.

Chronic infection by the gastrointestinal nematode Trichuris muris in susceptible AKR mice, which mount a Th1 response, is associated with IL-27p28 expression in the cecum. In contrast to wild-type mice, mice that lack the WSX-1/IL-27R gene fail to harbor a chronic infection, having significantly lower Th1 responses. The lower level of Ag-specific IFN-gamma-positive cells in WSX-1 knockout (KO) mice was found to be CD4(+) T cell specific, and the KO mice also had increased levels of IL-4-positive CD4(+) T cells. Polyclonal activation of mesenteric lymph node cells from naive WSX-1 KO or wild-type mice demonstrated that there was no inherent defect in the production of IFN-gamma by CD4(+) T cells, suggesting the decrease in these cells seen in infected WSX-1 KO mice is an in vivo Ag-driven effect. IL-12 treatment of WSX-1 KO mice failed to rescue the type 1 response, resulting in unaltered type-2-driven resistance. Infection of WSX-1 KO mice was also associated with a reduction of IL-27/WSX-1 downstream signaling gene expression within the cecum. These studies demonstrate an important role for WSX-1 signaling in the promotion of type 1 responses and chronic gastrointestinal nematode infection.

Animals↗

PubMed1986

The population dynamics and epidemiology of intestinal nematode infections.

The paper reviews recent studies on the population biology, transmission dynamics and epidemiology of intestinal nematode infections. Particular attention is given to patterns of change in average intensity of infection with age, the possible role of acquired immunity assessed via reinfection studies after chemotherapy, evidence of predisposition to heavy (or light) infection by single and multiple species of parasites and control by mass, selective and targetted chemotherapy.

Adolescent↗

PubMed1989

Efficacy of three broad-spectrum anthelmintics against gastrointestinal nematode infections of goats.

Groups of 10 goats, harbouring both naturally acquired and experimental infections of gastrointestinal nematodes, were drenched with either levamisole (5 mg kg-1), albendazole (3.8 mg kg-1) or parbendazole (15 mg kg-1), or remained untreated. Haemonchus contortus was the numerically dominant infection, with Strongyloides papillosus, Trichostrongylus colubriformis and Oesophagostomum columbianum also present. At 5-6 days post-treatment, goats were killed and necropsied. Post-mortem worm counts showed that the reduction in mean total worm burdens was 57.4% in levamisole-treated animals, 71.1% in the albendazole group and 85.1% in the parbendazole group. Reductions for H. contortus were 80.2, 87.9 and 83.9% in the levamisole-, albendazole- and parbendazole-treated groups, respectively. These data indicate that the anthelmintics in question are not being applied at an adequate dose rate for goats, and/or resistance to anthelmintics is occurring in the field in Pernambuco State, northeast Brazil.

Albendazole↗

PubMed2003

[Clinical observation on the efficacy of ivermectin in the treatment of intestinal nematode infections].

OBJECTIVE: To observe the efficacy and side effects of ivermectin in the treatment of intestinal nematode infections. METHODS: A single dose of ivermectin 0.1, 0.2, 0.2 and 0.2 mg/kg was orally administered to cases with infection of Ascaris, hookworm, Trichuris and Enterobius respectively. A single dose of albendazole 400 mg was used as control. RESULTS: The egg negative conversion rates of ivermectin and albendazole were both 100% (34/34) for Ascaris infection, 17.6% (6/34) and 76.5% (26/34) respectively for hookworm infection, 67.6% (23/34) and 47.1% (16/34) respectively for Trichuris infection, 58.8% (20/34) and 100% (34/34) respectively for Enterobius infection. The worm discharge reached a peak in 1-2 days after treatment. The side effect of ivermectin was mild and transient showing no adverse effect on blood picture, liver function, renal function or ECG. CONCLUSION: Ivermectin shows similar effect on Ascaris with albendazole, better effect on Trichuris and poorer effect on hookworm and Enterobius than albendazole.

Adolescent↗

PubMed1995

A comparison of the mast cell and eosinophil responses of sheep and goats to gastrointestinal nematode infections.

The mucosal mast cell and eosinophil responses of goats and sheep to a mixed gastrointestinal nematode infection were compared. Groups of eight does and nine ewes, previously maintained on pasture and treated with anthelmintic when they were housed and five worm-free lambs were challenged with 10,000 Trichostrongylus vitrinus third stage larvae (L3) and 10,000 Teladorsagia circumcincta L3. Eleven days after challenge, the ewes had significantly (P < 0.001) lower burdens of abomasal and intestinal worms than the does or naive lambs, but significantly higher (P < 0.001) tissue concentrations of mast cell proteinase. Toluidine blue-stained sections indicated a paucity of mast cells in the does compared with the ewes, whereas the immunolocalisation of sheep mast cell proteinase revealed similar numbers of stained cells in the two species. This discrepancy was due to the relatively high proportion of globule leucocytes (77 and 91 per cent in the jejunum and abomasum, respectively) in the does compared with the ewes (7 and 24 per cent in the jejunum and abomasum, respectively). No differences were detected between the numbers of circulating or tissue eosinophils in the ewes and does.

Animals↗

PubMed1985

Cellular repository for blood histamine in normal and nematode-infected rats.

Infections with the nematode N. brasiliensis is associated with a recruitment of intestinal mucosal mast cells (MMC) which increase greatly in numbers. We have studied histamine levels in the gut, whole blood and plasma in relation to MMC of the gut and blood cell morphology during the course of the infection in an attempt to clarify possible relations between circulating blood basophils and MMC. The results show a parallel increase in MMC numbers and histamine content of the gut, remaining high to day 20 after infection. Blood histamine increased from a control level of 30-40 ng/ml to a maximum of 200 ng/ml on day 12 to 14, but returned towards the control level already on day 16 after infection. There was a corresponding increase in plasma histamine to a maximum of 80 ng/ml. The total number of blood neutrophils increased during the early phase of the infection and there was a pronounced eosinophilia from day 10 to 16. No cells containing metachromatic granules were found in a screening comprised of 10,000 cells per specimen. During day 10 to 16 we found a number of coarsely granuled and vacuolated cells. The granules stained darkly by the Giemsa stain but not metachromatically with Toluidine Blue or with Alcian Blue at a low pH. We interpret this as an equivalent to the so-called toxic granulation occurring in human neutrophils. These cells may have been mistaken for basophils by previous investigators. The cellular repository for the high concentration of histamine in the blood is unknown. We suggest, as a working hypothesis, that it is contained in a circulating progenitor for MMC which has the ability to synthesize and, in a loosely bound state store, histamine, but which has not yet acquired the ability to assemble the specific metachromatic granules.

Animals↗

PubMed1994

The effect of the availability of latrines on soil-transmitted nematode infections in the plantation sector in Sri Lanka.

The relationship of soil-transmitted nematode infections to the availability of latrines was studied among 1,614 children 3-12 years of age living on plantations in Sri Lanka. The majority (89.7%) of the children had at least one type of soil-transmitted nematode. There was a significantly lower mean count of hookworm eggs for children coming from plantations with good sanitary facilities. For Ascaris and Trichuris, a similar association was observed between the mean egg count and the availability of latrines for children from the low-country plantations, where people live in more scattered settlements, but not in the up-country area, where worker settlements are larger and more crowded. Congested living conditions in themselves consequently seem to be a major determinant for ascariasis and trichuriasis, and the provision of latrines and safe water does not substantially change that situation. However, improvements of sanitary facilities will probably have a more immediate effect on the prevalence of hookworm infection.

Ascariasis↗

PubMed1995

Vaccine research and development for the prevention of filarial nematode infections.

The development of vaccines for the prevention of filarial nematode infections is in a state of relative infancy in comparison to vaccines for other parasitic diseases, such as schistosomiasis and malaria. There are many reasons for this slow start. Some of the principal problems are: (1) the lengthy and complex life cycle of these organisms with attendant complex immune responses, (2) the unique characteristics associated with a relatively large number of different pathogens, (3) the lack of suitable model systems for study of medically important infections, (4) the paucity of parasite material for antigen discovery and recombinant library construction, (5) the lack of substantial evidence suggesting the natural occurrence of protective immune responses, and (6) the limited data on mechanisms responsible for protective immunity. As technical hurdles are considered, it is also critical to focus on the characteristics of a vaccine necessary for its eventual utility. In the case of a vaccine for D. immitis a completely successful product will need to approach a 99+% efficacy. This is because of the 99+% efficacy of competitive chemotherapeutic products and the fact that microfilaremia observed on blood examination, resulting from as few as two worms, would present as a vaccine failure. Although very low worm burdens in large dogs could be perceived as success in the context of protection from clinical disease, because of the option of virtually complete chemoprophylactic protection, the typical veterinary practitioner would probably fail to appreciate less than complete vaccine protection. In contrast, a vaccine that produced a reduction in adult worm burdens without complete protection in either lymphatic filariasis or onchocerciasis would be very important. Highly effective chemoprophylactic agents are not widely available for prevention of the human filariases, and dramatically reduced clinical disease provided by less than a completely effective vaccine could occur as the result of fewer adult worms. The importance of developing these vaccines has outweighed the obstacles to this research. There has been a great deal of epidemiological and experimental evidence to suggest a vaccine is feasible and antigen discovery has progressed relatively rapidly within just the past few years. Efforts to generate appropriate larval cDNA libraries are beginning to yield dividends and a variety of fascinating vaccine candidates have been cloned. Additional antigen discovery, research on appropriate modalities for overexpression of genes from these parasites, and the complex tasks associated with vaccinology remain as significant research and development obstacles.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2006

Nematode infection and reproduction in transgenic and mutant Arabidopsis and tobacco with an altered phenylpropanoid metabolism.

Transgenic and mutant Arabidopsis and tobacco plants with altered phenylpropanoid metabolism were infected with the plant parasitic root knot nematode Meloidogyne incognita to assess the effect of the transgene or mutation on nematode infection and reproduction. Modifications in the lignin biosynthetic pathway which alter lignin composition in roots affected reproduction. In Arabidopsis with increased levels of syringyl lignin, reproduction was lower than in wild-type plants, while in tobacco with reduced levels of syringyl lignin, life cycle progression was stimulated. Overexpression of a MYB transcription factor of phenylpropanoid metabolism in tobacco significantly stimulated reproduction of M. incognita, while overexpression of L-phenylalanine ammonia-lyase had no effect. Arabidopsis transparent testa mutants with deficiencies in flavonoid pathway enzymes did not affect reproduction of M. incognita in the present infection tests.

Animals↗

PubMedDate not supplied

The histopathology of Scomber japonicus infection by Nematobothrium scombri (Trematoda:Didymozoidae) and of larval anisakid nematode infections in the liver of Pagrus pagrus.

The histopathology induced by Nematobothrium scombri (Trematoda) in Scomber japonicus and of larval anisakid nematodes in Pagrus pagrus is described. Nematodes larvae occurred within the liver capsule and N. scombri occurred within nodules in the opercula. The fishes were collected off the coast of Rio de Janeiro State.

Animals↗

PubMed2003

Efficacy of mebendazole and levamisole alone or in combination against intestinal nematode infections after repeated targeted mebendazole treatment in Zanzibar.

OBJECTIVE: To evaluate the efficacy of and resistance to mebendazole (500 mg) and levamisole (40 or 80 mg), alone or in combination, for the treatment of Ascaris lumbricoides, Trichuris trichiura and hookworm infections on Pemba Island - an area exposed to periodic school-based mebendazole treatment since 1994. METHODS: A randomized, placebo-controlled trial was carried out in 914 children enrolled from the first and fifth grades of primary schools. Stool samples collected at baseline and 21 days after treatment were examined by the Kato-Katz technique to assess the prevalence and intensity of helminth infection. FINDINGS: Efficacies of mebendazole and levamisole as single treatments against intestinal nematode infections were comparable with those in previous trials, but mebendazole treatment of hookworm infections gave significantly lower cure (7.6%) and egg reduction (52.1%) rates than reported in a study undertaken before the beginning of periodic chemotherapy (cure rate, 22.4%; egg reduction rate, 82.4%). Combined treatment with mebendazole and levamisole had a significantly higher efficacy against hookworm infections (cure rate, 26.1%; egg reduction rate, 88.7%) than either drug given alone. No difference in mebendazole efficacy was found in children who had been treated repeatedly compared with those who had not been treated previously. CONCLUSION: The overall efficacy of mebendazole against hookworm infections after periodic chemotherapy is reduced. The efficacy of benzimidazoles in chemotherapy-based control programmes should be monitored closely. Combined treatment with mebendazole and levamisole may be useful as a tool to delay the development of benzimidazole resistance.

Antinematodal Agents↗