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Parasitology Mar 2017Parasitic nematodes are important and abundant parasites adapted to live a parasitic lifestyle, with these adaptations all aimed at facilitating their survival and... (Review)
Review
Parasitic nematodes are important and abundant parasites adapted to live a parasitic lifestyle, with these adaptations all aimed at facilitating their survival and reproduction in their hosts. The recently sequenced genomes of four Strongyloides species, gastrointestinal parasites of humans and other animals, alongside transcriptomic and proteomic analysis of free-living and parasitic stages of their life cycles have revealed a number of protein families with a putative role in their parasitism. Many of these protein families have also been associated with parasitism in other parasitic nematode species, suggesting that these proteins may play a fundamental role in nematode parasitism more generally. Here, we review key protein families that have a putative role in Strongyloides' parasitism - acetylcholinesterases, astacins, aspartic proteases, prolyl oligopeptidases, proteinase inhibitors (trypsin inhibitors and cystatins), SCP/TAPS and transthyretin-like proteins - and the evidence for their key, yet diverse, roles in the parasitic lifestyle.
Topics: Animals; Helminth Proteins; Host-Parasite Interactions; Humans; Strongyloides; Strongyloidiasis; Virulence Factors
PubMed: 27618747
DOI: 10.1017/S0031182016001554 -
Clinical Microbiology and Infection :... Oct 2006Severe strongyloidiasis, caused by Strongyloides stercoralis, is a preventable life-threatening disease that can occur in any corticosteroid-treated patient who has...
Severe strongyloidiasis, caused by Strongyloides stercoralis, is a preventable life-threatening disease that can occur in any corticosteroid-treated patient who has travelled to a country with infested soil, even if the contact occurred up to 30 years previously. This diagnosis should be considered in corticosteroid-treated patients who experience either unusual gastrointestinal or pulmonary symptoms, or who suffer from unexplained sepsis caused by Gram-negative bacilli. Peripheral eosinophilia is not observed systematically and, even if present, is moderate in most cases. Ivermectine is the best prophylactic and therapeutic option, and thiabendazole should no longer be used. However, guidelines for the prevention and management of S. stercoralis infection in such patients have not yet been established.
Topics: Adrenal Cortex Hormones; Animals; Anthelmintics; Humans; Ivermectin; Strongyloides stercoralis; Strongyloidiasis
PubMed: 16961629
DOI: 10.1111/j.1469-0691.2006.01443.x -
Clinical Microbiology and Infection :... Nov 2021The clinical and laboratory characterization of Strongyloides stercoralis infection at diagnosis and after treatment is still poorly defined. (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
The clinical and laboratory characterization of Strongyloides stercoralis infection at diagnosis and after treatment is still poorly defined.
OBJECTIVES
The primary objective was to describe the pattern and frequency of clinical and laboratory characteristics associated with S. stercoralis infection. The secondary objectives were (a) comparison of characteristics reported in endemic versus non-endemic areas; and (b) the evaluation of the resolution of identified characteristics after treatment.
METHODS
We searched PubMed, EMBASE, LILACS and CENTRAL up to May 2021. Eligible studies were randomized controlled trials (RCTs) for the treatment of S. stercoralis infection and prospective observational studies reporting data on symptoms caused by strongyloidiasis in individuals diagnosed with a highly specific test. Quality assessment was performed to assess the risk of bias. Demographic and clinical data were summarized using descriptive statistics. Meta-analysis was done by pooling the proportion of participants with symptoms with random effects model.
RESULTS
Twenty studies were included: nine RCTs and 13 observational studies. Overall, symptoms were reported in 50.4% cases (95% CI 47.6-53.1), and were more often reported in non-endemic (58.6%, 95% CI 55.0-62.2) than in endemic (35.7%, 95% CI 31.4-39.9) areas. The removal of an article of lower quality did not impact on figures. Frequency of symptoms tended to reduce after treatment. Three studies reported the proportion of participants with eosinophilia before and after treatment: 76.9% of participants (95% CI 73.4-80.4) had eosinophilia at diagnosis, reducing to 27.4% (95% CI 24.0-30.7) after treatment.
CONCLUSIONS
About half of infected people complain at least of one symptom and almost 70% have eosinophilia. The frequency of symptoms and eosinophilia decreased after treatment, though the association with cure is not clearly defined. Providing relief from symptoms and eosinophilia is another reason, in addition to prevention of disseminated disease, for promoting screening and treatment of individuals with strongyloidiasis.
Topics: Animals; Eosinophilia; Humans; Observational Studies as Topic; Randomized Controlled Trials as Topic; Strongyloides stercoralis; Strongyloidiasis
PubMed: 34325063
DOI: 10.1016/j.cmi.2021.07.016 -
Parasitology Mar 2017Strongyloides spp. are common parasites of vertebrates and two species, S. ratti and S. venezuelensis, parasitize rats; there are no known species that naturally infect... (Review)
Review
Strongyloides spp. are common parasites of vertebrates and two species, S. ratti and S. venezuelensis, parasitize rats; there are no known species that naturally infect mice. Strongyloides ratti and S. venezuelensis overlap in their geographical range and in these regions co-infections appear to be common. These species have been widely used as tractable laboratory systems in rats as well as mice. The core biology of these two species is similar, but there are clear differences in aspects of their within-host biology as well as in their free-living generation. Phylogenetic evidence suggests that S. ratti and S. venezuelensis are the result of two independent evolutionary transitions to parasitism of rats, which therefore presents an ideal opportunity to begin to investigate the basis of host specificity in Strongyloides spp.
Topics: Animals; Disease Models, Animal; Host Specificity; Mice; Rats; Rodent Diseases; Strongyloides; Strongyloidiasis; Virulence Factors
PubMed: 26935155
DOI: 10.1017/S0031182016000020 -
Archives of Razi Institute Dec 2022Parasitic infections are one of the main problems in sheep breeding farms. For this reason, in order to control the damage caused by parasitic infections, a wide range...
Parasitic infections are one of the main problems in sheep breeding farms. For this reason, in order to control the damage caused by parasitic infections, a wide range of antiparasitic drugs with different forms are used. A particular area is important due to contamination with radioactive substances and its effect on the immune system of livestock in the area. Therefore, the aim of the present study was the effectiveness of antiparasitic drugs in sheep farms in Kazakhstan. In the current study, 3 groups of lambs were evaluated; each one included 30 infected lambs of 5 to 6 months with and and treated with antiparasitic compounds in two forms of tablets (Albendazole, Pyrantel, Ivermectin, Phenasal) and mineral-salt cube (Albenvet, Trimeratinvet). The result of the study showed that began 10, 20, and 30 days after experimentation, the mineral-salt cube significantly reduced the number of helminths and in sheep (92.18%) (≤0.05). Ant antiparasitic drugs in livestock diet are essential in reducing contamination and its effects on the herd.
Topics: Animals; Sheep; Eimeria; Coccidiosis; Strongyloides; Sheep Diseases; Feces; Antiparasitic Agents; Minerals
PubMed: 37274915
DOI: 10.22092/ARI.2022.360104.2552 -
PLoS Neglected Tropical Diseases 2013The soil-transmitted threadworm, Strongyloides stercoralis, is one of the most neglected among the so-called neglected tropical diseases (NTDs). We reviewed studies of... (Review)
Review
BACKGROUND
The soil-transmitted threadworm, Strongyloides stercoralis, is one of the most neglected among the so-called neglected tropical diseases (NTDs). We reviewed studies of the last 20 years on S. stercoralis's global prevalence in general populations and risk groups.
METHODS/PRINCIPAL FINDINGS
A literature search was performed in PubMed for articles published between January 1989 and October 2011. Articles presenting information on infection prevalence were included. A Bayesian meta-analysis was carried out to obtain country-specific prevalence estimates and to compare disease odds ratios in different risk groups taking into account the sensitivities of the diagnostic methods applied. A total of 354 studies from 78 countries were included for the prevalence calculations, 194 (62.4%) were community-based studies, 121 (34.2%) were hospital-based studies and 39 (11.0%) were studies on refugees and immigrants. World maps with country data are provided. In numerous African, Asian and South-American resource-poor countries, information on S. stercoralis is lacking. The meta-analysis showed an association between HIV-infection/alcoholism and S. stercoralis infection (OR: 2.17 BCI: 1.18-4.01; OR: 6.69; BCI: 1.47-33.8), respectively.
CONCLUSIONS
Our findings show high infection prevalence rates in the general population in selected countries and geographical regions. S. stercoralis infection is prominent in several risk groups. Adequate information on the prevalence is still lacking from many countries. However, current information underscore that S. stercoralis must not be neglected. Further assessments in socio-economic and ecological settings are needed and integration into global helminth control is warranted.
Topics: Animals; Global Health; Humans; Neglected Diseases; Prevalence; Risk Factors; Strongyloides stercoralis; Strongyloidiasis; Topography, Medical
PubMed: 23875033
DOI: 10.1371/journal.pntd.0002288 -
Philosophical Transactions of the Royal... Jan 2024The genus of parasitic nematodes have a fascinating life cycle and biology, but are also important pathogens of people and a World Health Organization-defined neglected... (Review)
Review
The genus of parasitic nematodes have a fascinating life cycle and biology, but are also important pathogens of people and a World Health Organization-defined neglected tropical disease. Here, a community of researchers have posed thirteen major questions about biology and infection that sets a research agenda for the future. This article is part of the Theo Murphy meeting issue ': omics to worm-free populations'.
Topics: Animals; Humans; Strongyloides; Life Cycle Stages
PubMed: 38008122
DOI: 10.1098/rstb.2023.0004 -
WormBook : the Online Review of C.... Feb 2007Because of their free-living life cycle alternatives, Strongyloides and related nematode parasites may represent the best models for translating C. elegans science to... (Review)
Review
Because of their free-living life cycle alternatives, Strongyloides and related nematode parasites may represent the best models for translating C. elegans science to the study of nematode parasitism. S. stercoralis, a significant pathogen of humans, can be maintained in laboratory dogs and gerbils. Biosafety precautions necessary for work with S. stercoralis, though unfamiliar to many C. elegans researchers, are straightforward and easily accomplished. Although specialized methods are necessary for large-scale culture of the free-living stages of S. stercoralis, small-scale cultures for experimental purposes may be undertaken using minor modifications of standard C. elegans methods. Similarly, the morphological similarities between C. elegans and the free-living stages of S. stercoralis allow investigational methods such as laser cell ablation and DNA transformation by gonadal microinjection to be easily adapted from C. elegans to S. stercoralis. Comparative studies employing these methods have yielded new insights into the neuronal control of the infective process in parasites and its similarity to regulation of dauer development in C. elegans. Furthermore, we have developed a practical method for transient transformation of S. stercoralis with vector constructs having various tissue- and cell-specific expression patterns and have assembled these into a modular vector kit for distribution to the community.
Topics: Animals; Denervation; Dogs; Forecasting; Gene Transfer Techniques; Gerbillinae; Humans; Models, Animal; Research; Strongyloides stercoralis; Strongyloidiasis
PubMed: 18050500
DOI: 10.1895/wormbook.1.134.1 -
Journal of Visualized Experiments : JoVE Oct 2021The genus Strongyloides consists of multiple species of skin-penetrating nematodes with different host ranges, including Strongyloides stercoralis and Strongyloides...
The genus Strongyloides consists of multiple species of skin-penetrating nematodes with different host ranges, including Strongyloides stercoralis and Strongyloides ratti. S. stercoralis is a human-parasitic, skin-penetrating nematode that infects approximately 610 million people, while the rat parasite S. ratti is closely related to S. stercoralis and is often used as a laboratory model for S. stercoralis. Both S. stercoralis and S. ratti are easily amenable to the generation of transgenics and knockouts through the exogenous nucleic acid delivery technique of intragonadal microinjection, and as such, have emerged as model systems for other parasitic helminths that are not yet amenable to this technique. Parasitic Strongyloides adults inhabit the small intestine of their host and release progeny into the environment via the feces. Once in the environment, the larvae develop into free-living adults, which live in feces and produce progeny that must find and invade a new host. This environmental generation is unique to the Strongyloides species and similar enough in morphology to the model free-living nematode Caenorhabditis elegans that techniques developed for C. elegans can be adapted for use with these parasitic nematodes, including intragonadal microinjection. Using intragonadal microinjection, a wide variety of transgenes can be introduced into Strongyloides. CRISPR/Cas9 components can also be microinjected to create mutant Strongyloides larvae. Here, the technique of intragonadal microinjection into Strongyloides, including the preparation of free-living adults, the injection procedure, and the selection of transgenic progeny, is described. Images of transgenic Strongyloides larvae created using CRISPR/Cas9 mutagenesis are included. The aim of this paper is to enable other researchers to use microinjection to create transgenic and mutant Strongyloides.
Topics: Animals; Animals, Genetically Modified; Caenorhabditis elegans; Humans; Microinjections; Rats; Strongyloides ratti; Strongyloides stercoralis
PubMed: 34694289
DOI: 10.3791/63023 -
PLoS Neglected Tropical Diseases 2013Strongyloidiasis is frequently under diagnosed since many infections remain asymptomatic and conventional diagnostic tests based on parasitological examination are not... (Review)
Review
BACKGROUND
Strongyloidiasis is frequently under diagnosed since many infections remain asymptomatic and conventional diagnostic tests based on parasitological examination are not sufficiently sensitive. Serology is useful but is still only available in reference laboratories. The need for improved diagnostic tests in terms of sensitivity and specificity is clear, particularly in immunocompromised patients or candidates to immunosuppressive treatments. This review aims to evaluate both conventional and novel techniques for the diagnosis of strongyloidiasis as well as available cure markers for this parasitic infection.
METHODOLOGY/PRINCIPAL FINDINGS
The search strategy was based on the data-base sources MEDLINE, Cochrane Library Register for systematic review, EmBase, Global Health and LILACS and was limited in the search string to articles published from 1960 to August 2012 and to English, Spanish, French, Portuguese and German languages. Case reports, case series and animal studies were excluded. 2003 potentially relevant citations were selected for retrieval, of which 1649 were selected for review of the abstract. 143 were eligible for final inclusion.
CONCLUSIONS
Sensitivity of microscopic-based techniques is not good enough, particularly in chronic infections. Furthermore, techniques such as Baermann or agar plate culture are cumbersome and time-consuming and several specimens should be collected on different days to improve the detection rate. Serology is a useful tool but it might overestimate the prevalence of disease due to cross-reactivity with other nematode infections and its difficulty distinguishing recent from past (and cured) infections. To evaluate treatment efficacy is still a major concern because direct parasitological methods might overestimate it and the serology has not yet been well evaluated; even if there is a decline in antibody titres after treatment, it is slow and it needs to be done at 6 to 12 months after treatment which can cause a substantial loss to follow-up in a clinical trial.
Topics: Animals; Clinical Laboratory Techniques; Drug Monitoring; Humans; Parasitology; Sensitivity and Specificity; Strongyloides; Strongyloidiasis
PubMed: 23350004
DOI: 10.1371/journal.pntd.0002002