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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 -
The Cochrane Database of Systematic... Jan 2016Strongyloidiasis is a gut infection with Strongyloides stercoralis which is common world wide. Chronic infection usually causes a skin rash, vomiting, diarrhoea or... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Strongyloidiasis is a gut infection with Strongyloides stercoralis which is common world wide. Chronic infection usually causes a skin rash, vomiting, diarrhoea or constipation, and respiratory problems, and it can be fatal in people with immune deficiency. It may be treated with ivermectin or albendazole or thiabendazole.
OBJECTIVES
To assess the effects of ivermectin versus benzimidazoles (albendazole and thiabendazole) for treating chronic strongyloides infection.
SEARCH METHODS
We searched the Cochrane Infectious Diseases Group Specialized Register (24 August 2015); the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (January 1966 to August 2015); EMBASE (January 1980 to August 2015); LILACS (August 2015); and reference lists of articles. We also searched the metaRegister of Controlled Trials (mRCT) using 'strongyloid*' as a search term, reference lists, and conference abstracts.
SELECTION CRITERIA
Randomized controlled trials of ivermectin versus albendazole or thiabendazole for treating chronic strongyloides infection.
DATA COLLECTION AND ANALYSIS
Two review authors independently extracted data and assessed risk of bias in the included trials. We used risk ratios (RRs) with 95% confidence intervals (CIs) and fixed- or random-effects models. We pooled adverse event data if the trials were sufficiently similar in their adverse event definitions.
MAIN RESULTS
We included seven trials, enrolling 1147 participants, conducted between 1994 and 2011 in different locations (Africa, Southeast Asia, America and Europe).In trials comparing ivermectin with albendazole, parasitological cure was higher with ivermectin (RR 1.79, 95% CI 1.55 to 2.08; 478 participants, four trials, moderate quality evidence). There were no statistically significant differences in adverse events (RR 0.80, 95% CI 0.59 to 1.09; 518 participants, four trials, low quality evidence).In trials comparing ivermectin with thiabendazole, there was little or no difference in parasitological cure (RR 1.07, 95% CI 0.96 to 1.20; 467 participants, three trials, low quality evidence). However, adverse events were less common with ivermectin (RR 0.31, 95% CI 0.20 to 0.50; 507 participants; three trials, moderate quality evidence).In trials comparing different dosages of ivermectin, taking a second dose of 200 μg/kg of ivermectin was not associated with higher cure in a small subgroup of participants (RR 1.02, 95% CI 0.94 to 1.11; 94 participants, two trials).Dizziness, nausea, and disorientation were commonly reported in all drug groups. There were no reports of serious adverse events or death.
AUTHORS' CONCLUSIONS
Ivermectin results in more people cured than albendazole, and is at least as well tolerated. In trials of ivermectin with thiabendazole, parasitological cure is similar but there are more adverse events with thiabendazole.
Topics: Albendazole; Animals; Anthelmintics; Humans; Ivermectin; Randomized Controlled Trials as Topic; Strongyloides stercoralis; Strongyloidiasis; Thiabendazole
PubMed: 26778150
DOI: 10.1002/14651858.CD007745.pub3 -
The American Journal of Tropical... Aug 2020We reported 865 cases of soil-transmitted nematodiasis occurring in Japan during 2000-2017. The predominant nematode was ( = 279, 32.3% of all cases), and other species...
We reported 865 cases of soil-transmitted nematodiasis occurring in Japan during 2000-2017. The predominant nematode was ( = 279, 32.3% of all cases), and other species included (30.7%), (23.1%), and spp. (13.9%). was detected primarily in patients in Okinawa and Kagoshima prefectures, which are in the south of Japan and are endemic areas for this parasitic infection, and also in about half of the prefectures of all Japan. At least 15.5 cases of strongyloidiasis occurred on average each year. The period incidence rate of strongyloidiasis cases relative to the total population of Japan was 0.012 cases per 10 person-years. The male-to-female ratio was 2.1. The average age was 75.1 ± 16.9 years, and 96.1% of patients were older than 50 years. Several reasons may explain why this previously non-endemic outside of Okinawa region, serious nematode disease is now found in much of Japan, including the increased number of transmigration and sightseeing trips in Japan, use of immunosuppressive drugs, and lack of awareness of the risks. Thus, information of strongyloidiasis and its risks must be disseminated to travelers, residents, and physicians to prevent this life-threatening parasite infection.
Topics: Adult; Aged; Aged, 80 and over; Ancylostomiasis; Animals; Ascariasis; Ascaris lumbricoides; Female; Humans; Japan; Male; Middle Aged; Strongyloides stercoralis; Strongyloidiasis; Trichuriasis; Trichuris; Young Adult
PubMed: 32588800
DOI: 10.4269/ajtmh.19-0969 -
International Journal For Parasitology.... Dec 2018Infection with gastrointestinal parasitic nematodes is a major cause of chronic morbidity and economic burden around the world, particularly in low-resource settings.... (Review)
Review
Infection with gastrointestinal parasitic nematodes is a major cause of chronic morbidity and economic burden around the world, particularly in low-resource settings. Some parasitic nematode species, including the human-parasitic threadworm Strongyloides stercoralis and human-parasitic hookworms in the genera Ancylostoma and Necator, feature a soil-dwelling infective larval stage that seeks out hosts for infection using a variety of host-emitted sensory cues. Here, we review our current understanding of the behavioral responses of soil-dwelling infective larvae to host-emitted sensory cues, and the molecular and cellular mechanisms that mediate these responses. We also discuss the development of methods for transgenesis and CRISPR/Cas9-mediated targeted mutagenesis in Strongyloides stercoralis and the closely related rat parasite Strongyloides ratti. These methods have established S. stercoralis and S. ratti as genetic model systems for gastrointestinal parasitic nematodes and are enabling more detailed investigations into the neural mechanisms that underlie the sensory-driven behaviors of this medically and economically important class of parasites.
Topics: Ancylostoma; Ancylostomiasis; Animals; Gastrointestinal Diseases; Host-Parasite Interactions; Humans; Larva; Necator; Nematoda; Nematode Infections; Rats; Sensation; Soil; Strongyloides ratti; Strongyloides stercoralis
PubMed: 30396862
DOI: 10.1016/j.ijpddr.2018.10.008 -
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 -
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 -
BMC Biology Oct 2021Skin-penetrating nematodes of the genus Strongyloides infect over 600 million people, posing a major global health burden. Their life cycle includes both a parasitic and...
BACKGROUND
Skin-penetrating nematodes of the genus Strongyloides infect over 600 million people, posing a major global health burden. Their life cycle includes both a parasitic and free-living generation. During the parasitic generation, infective third-stage larvae (iL3s) actively engage in host seeking. During the free-living generation, the nematodes develop and reproduce on host feces. At different points during their life cycle, Strongyloides species encounter a wide variety of host-associated and environmental bacteria. However, the microbiome associated with Strongyloides species, and the behavioral and physiological interactions between Strongyloides species and bacteria, remain unclear.
RESULTS
We first investigated the microbiome of the human parasite Strongyloides stercoralis using 16S-based amplicon sequencing. We found that S. stercoralis free-living adults have an associated microbiome consisting of specific fecal bacteria. We then investigated the behavioral responses of S. stercoralis and the closely related rat parasite Strongyloides ratti to an ecologically diverse panel of bacteria. We found that S. stercoralis and S. ratti showed similar responses to bacteria. The responses of both nematodes to bacteria varied dramatically across life stages: free-living adults were strongly attracted to most of the bacteria tested, while iL3s were attracted specifically to a narrow range of environmental bacteria. The behavioral responses to bacteria were dynamic, consisting of distinct short- and long-term behaviors. Finally, a comparison of the growth and reproduction of S. stercoralis free-living adults on different bacteria revealed that the bacterium Proteus mirabilis inhibits S. stercoralis egg hatching, and thereby greatly decreases parasite viability.
CONCLUSIONS
Skin-penetrating nematodes encounter bacteria from various ecological niches throughout their life cycle. Our results demonstrate that bacteria function as key chemosensory cues for directing parasite movement in a life-stage-specific manner. Some bacterial genera may form essential associations with the nematodes, while others are detrimental and serve as a potential source of novel nematicides.
Topics: Animals; Bacteria; Larva; Life Cycle Stages; Nematoda; Rats; Skin; Strongyloides ratti; Strongyloides stercoralis
PubMed: 34620172
DOI: 10.1186/s12915-021-01153-7 -
PLoS Neglected Tropical Diseases Sep 2014Strongyloides stercoralis infects human hosts mainly through skin contact with contaminated soil. The result is strongyloidiasis, a parasitic disease, with a unique... (Review)
Review
BACKGROUND
Strongyloides stercoralis infects human hosts mainly through skin contact with contaminated soil. The result is strongyloidiasis, a parasitic disease, with a unique cycle of auto-infection causing a variety of symptoms and signs, with possible fatality from hyper-infection. Australian Indigenous community members, often living in rural and remote settings, are exposed to and infected with S. stercoralis. The aim of this review is to determine barriers to control of strongyloidiasis. The purpose is to contribute to the development of initiatives for prevention, early detection and effective treatment of strongyloidiasis.
METHODOLOGY/PRINCIPLE FINDINGS
Systematic search reviewing research published 2012 and earlier was conducted. Research articles discussing aspects of strongyloidiasis, context of infection and overall health in Indigenous Australians were reviewed. Based on the PRISMA statement, the systematic search of health databases, Academic Search Premier, Informit, Medline, PubMed, AMED, CINAHL, Health Source Nursing and Academic was conducted. Key search terms included strongyloidiasis, Indigenous, Australia, health, and community. 340 articles were retrieved with 16 original research articles published between 1969 and 2006 meeting criteria. Review found barriers to control defined across three key themes, (1) health status, (2) socioeconomic status, and (3) health care literacy and procedures.
CONCLUSIONS/SIGNIFICANCE
This study identifies five points of intervention: (1) develop reporting protocols between health care system and communities; (2) test all Indigenous Australian patients, immunocompromised patients and those exposed to areas with S. stercoralis; (3) health professionals require detailed information on strongyloidiasis and potential for exposure to Indigenous Australian people; (4) to establish testing and treatment initiatives within communities; and (5) to measure and report prevalence rates specific to communities and to act with initiatives based on these results. By defining barriers to control of strongyloidiasis in Australian Indigenous people, improved outcomes of prevention, treatment of strongyloidiasis and increased health overall are attainable.
Topics: Adolescent; Adult; Animals; Australia; Child; Child, Preschool; Female; Humans; Infant; Infant, Newborn; Male; Middle Aged; Native Hawaiian or Other Pacific Islander; Rural Population; Strongyloides stercoralis; Strongyloidiasis
PubMed: 25254655
DOI: 10.1371/journal.pntd.0003141 -
Revista Espanola de Enfermedades... Feb 2023We herein report a case of ulcerative colitis (UC) exacerbated by strongyloidiasis. Parasites including Strongyloides stercoralis and Entamoeba histolytica can cause...
We herein report a case of ulcerative colitis (UC) exacerbated by strongyloidiasis. Parasites including Strongyloides stercoralis and Entamoeba histolytica can cause chronic gastrointestinal inflammation and long-lasting symptoms resembling UC. On the other hand, it is not well-known that such organisms can trigger the exacerbation of pre-existing UC. We would like to highlight the importance of recognition of strongyloidiasis in the management of UC patients who have lived in or migrated from endemic regions, such as Asia, Africa, and South America.
Topics: Animals; Humans; Strongyloidiasis; Colitis, Ulcerative; Strongyloides stercoralis; Inflammation
PubMed: 35815784
DOI: 10.17235/reed.2022.9044/2022 -
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