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Epidemiology and Infection Feb 2015Strongyloides stercoralis is rarely recognized as a major public health issue, probably because its burden is largely underestimated. We reviewed the literature (both... (Review)
Review
Strongyloides stercoralis is rarely recognized as a major public health issue, probably because its burden is largely underestimated. We reviewed the literature (both PubMed and 'grey' literature) about the prevalence of strongyloidiasis in Latin America, an area of presumable high endemicity. There were finally 88 papers involved in the analysis, covering the period between 1981 and 2011. Studies were heterogeneous in several aspects, such as the populations screened and the diagnostic methods used. Most of the studies relied on direct coproparasitological examination, which has low sensitivity for the detection of S. stercoralis larvae. The following countries presented areas of high prevalence (>20%): Argentina, Ecuador, Venezuela, Peru and Brazil. Globally, for most of the included countries it was not possible to define reliable data because of paucity and/or inadequacy of studies. S. stercoralis requires specific diagnostic methods for its detection; therefore, surveys should be specifically designed in order to avoid underestimation of the infection.
Topics: Animals; Feces; Humans; Latin America; Prevalence; Strongyloides stercoralis; Strongyloidiasis
PubMed: 24990510
DOI: 10.1017/S0950268814001563 -
Parasites & Vectors Apr 2023Strongyloides stercoralis is a soil-transmitted helminth that is mainly found in the tropical and subtropical regions and affects approximately 600 million people... (Review)
Review
Strongyloides stercoralis is a soil-transmitted helminth that is mainly found in the tropical and subtropical regions and affects approximately 600 million people globally. The medical importance of strongyloidiasis lies in its capacity to remain asymptomatic and chronically unnoticed until the host is immunocompromised. Additionally, in severe strongyloidiasis, hyperinfection syndrome and larva dissemination to various organs can occur. Parasitological techniques such as Baermann-Moraes and agar plate culture to detect larvae in stool samples are the current gold standard. However, the sensitivity might be inadequate, especially with reduced worm burden. Complementing parasitological techniques, immunological techniques including immunoblot and immunosorbent assays are employed, with higher sensitivity. However, cross-reactivity to other parasites may occur, hampering the assay's specificity. Recently, advances in molecular techniques such as polymerase chain reaction and next-generation sequencing technology have provided the opportunity to detect parasite DNA in stool, blood, and environmental samples. Molecular techniques, known for their high sensitivity and specificity, have the potential to circumvent some of the challenges associated with chronicity and intermittent larval output for increased detection. Here, as S. stercoralis was recently included by the World Health Organization as another soil-transmitted helminth targeted for control from 2021 to 2030, we aimed to present a review of the current molecular techniques for detecting and diagnosing S. stercoralis in a bid to consolidate the molecular studies that have been performed. Upcoming molecular trends, especially next-generation sequencing technologies, are also discussed to increase the awareness of its potential for diagnosis and detection. Improved and novel detection methods can aid in making accurate and informed choices, especially in this era where infectious and non-infectious diseases are increasingly commonplace.
Topics: Animals; Strongyloides stercoralis; Strongyloidiasis; Polymerase Chain Reaction; Feces; Immunocompromised Host; Larva
PubMed: 37041645
DOI: 10.1186/s13071-023-05763-8 -
PLoS Neglected Tropical Diseases Sep 2022Strongyloides stercoralis infection typically causes severe symptoms in immunocompromised patients. This infection can also alter the gut microbiota and is often found...
BACKGROUND
Strongyloides stercoralis infection typically causes severe symptoms in immunocompromised patients. This infection can also alter the gut microbiota and is often found in areas where chronic kidney disease (CKD) is common. However, the relationship between S. stercoralis and the gut microbiome in chronic kidney disease (CKD) is not understood fully. Recent studies have shown that gut dysbiosis plays an important role in the progression of CKD. Hence, this study aims to investigate the association of S. stercoralis infection and gut microbiome in CKD patients.
METHODOLOGY/PRINCIPAL FINDINGS
Among 838 volunteers from Khon Kaen Province, northeastern Thailand, 40 subjects with CKD were enrolled and divided into two groups (S. stercoralis-infected and -uninfected) matched for age, sex and biochemical parameters. Next-generation technology was used to amplify and sequence the V3-V4 region of the 16S rRNA gene to provide a profile of the gut microbiota. Results revealed that members of the S. stercoralis-infected group had lower gut microbial diversity than was seen in the uninfected group. Interestingly, there was significantly greater representation of some pathogenic bacteria in the S. stercoralis-infected CKD group, including Escherichia-Shigella (P = 0.013), Rothia (P = 0.013) and Aggregatibacter (P = 0.03). There was also a trend towards increased Actinomyces, Streptococcus and Haemophilus (P > 0.05) in this group. On the other hand, the S. stercoralis-infected CKD group had significantly lower representation of SCFA-producing bacteria such as Anaerostipes (P = 0.01), Coprococcus_1 (0.043) and a non-significant decrease of Akkermansia, Eubacterium rectale and Eubacterium hallii (P > 0.05) relative to the uninfected group. Interesting, the genera Escherichia-Shigella and Anaerostipes exhibited opposing trends, which were significantly related to sex, age, infection status and CKD stages. The genus Escherichia-Shigella was significantly more abundant in CKD patients over the age of 65 years and infected with S. stercoralis. A correlation analysis showed inverse moderate correlation between the abundance of the genus of Escherichia-Shigella and the level of estimated glomerular filtration rate (eGFR).
CONCLUSIONS/SIGNIFICANCE
Conclusion, the results suggest that S. stercoralis infection induced gut dysbiosis in the CKD patients, which might be involved in CKD progression.
Topics: Aged; Animals; Bacteria; Dysbiosis; Feces; Humans; RNA, Ribosomal, 16S; Renal Insufficiency, Chronic; Strongyloides stercoralis; Strongyloidiasis; Thailand
PubMed: 36067216
DOI: 10.1371/journal.pntd.0010302 -
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 -
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 -
Parasites & Vectors Jan 2018Strongyloides stercoralis and hookworm are two soil-transmitted helminths (STH) that are highly prevalent in Cambodia. Strongyloides stercoralis causes long-lasting...
BACKGROUND
Strongyloides stercoralis and hookworm are two soil-transmitted helminths (STH) that are highly prevalent in Cambodia. Strongyloides stercoralis causes long-lasting infections and significant morbidity but is largely neglected, while hookworm causes the highest public health burden among STH. The two parasites have the same infection route, i.e. skin penetration. The extent of co-distribution, which could result in potential high co-morbidities, is unknown in highly endemic settings like Cambodia. The aim of this study was to predict the spatial distribution of S. stercoralis-hookworm co-infection risk and to investigate determinants of co-infection in Preah Vihear Province, North Cambodia.
METHODS
A cross-sectional survey was conducted in 2010 in 60 villages of Preah Vihear Province. Diagnosis was performed on two stool samples, using combined Baermann technique and Koga agar culture plate for S. stercoralis and Kato-Katz technique for hookworm. Bayesian multinomial geostatistical models were used to assess demographic, socioeconomic, and behavioural determinants of S. stercoralis-hookworm co-infection and to predict co-infection risk at non-surveyed locations.
RESULTS
Of the 2576 participants included in the study, 48.6% and 49.0% were infected with S. stercoralis and hookworm, respectively; 43.8% of the cases were co-infections. Females, preschool aged children, adults aged 19-49 years, and participants who reported regularly defecating in toilets, systematically boiling drinking water and having been treated with anthelmintic drugs had lower odds of co-infection. While S. stercoralis infection risk did not appear to be spatially structured, hookworm mono-infection and co-infection exhibited spatial correlation at about 20 km. Co-infection risk was positively associated with longer walking distances to a health centre and exhibited a small clustering tendency. The association was only partly explained by climatic variables, suggesting a role for underlying factors, such as living conditions and remoteness.
CONCLUSIONS
Both parasites were ubiquitous in the province, with co-infections accounting for almost half of all cases. The high prevalence of S. stercoralis calls for control measures. Despite several years of school-based de-worming programmes, hookworm infection levels remain high. Mebendazole efficacy, as well as coverage of and compliance to STH control programmes should be investigated.
Topics: Adolescent; Adult; Ancylostomatoidea; Animals; Anthelmintics; Bayes Theorem; Cambodia; Child; Child, Preschool; Coinfection; Cross-Sectional Studies; Feces; Female; Hookworm Infections; Humans; Male; Middle Aged; Models, Statistical; Prevalence; Risk Factors; Rural Population; Soil; Strongyloides stercoralis; Strongyloidiasis; Surveys and Questionnaires; Young Adult
PubMed: 29329561
DOI: 10.1186/s13071-017-2604-8 -
Revista Chilena de Infectologia :... Oct 2016Strongyloidiasis is an infection caused by the parasite Strongyloides stercoralis, which can be asymptomatic and means a high morbidity and mortality in...
Strongyloidiasis is an infection caused by the parasite Strongyloides stercoralis, which can be asymptomatic and means a high morbidity and mortality in immunocompromised hosts, severe malnutrition and coinfection with HTLV-1 virus. The parasite has the potential to produce and multiply internal autoinfection in humans, thus an hyperinfection can be developed. A case of pulmonary infection by this parasite is presented in this study, infection which advanced into a respiratory failure and required mechanical ventilation and hemodynamic support in an intensive care unit. The standard treatment combined with ivermectin and albendazole was provided, achieving an appropriate response.
Topics: Albendazole; Animals; Antiparasitic Agents; Female; Humans; Ivermectin; Lung Diseases, Parasitic; Middle Aged; Strongyloides stercoralis; Strongyloidiasis
PubMed: 28112345
DOI: 10.4067/S0716-10182016000500016 -
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 -
International Journal of Environmental... May 2016Strongyloidiasis is a disease caused by soil transmitted helminths of the Strongyloides genus. Currently, it is predominately described as a neglected tropical disease.... (Review)
Review
Strongyloidiasis is a disease caused by soil transmitted helminths of the Strongyloides genus. Currently, it is predominately described as a neglected tropical disease. However, this description is misleading as it focuses on the geographical location of the disease and not the primary consideration, which is the socioeconomic conditions and poor infrastructure found within endemic regions. This classification may result in misdiagnosis and mistreatment by physicians, but more importantly, it influences how the disease is fundamentally viewed. Strongyloidiasis must be first and foremost considered as a disease of disadvantage, to ensure the correct strategies and control measures are used to prevent infection. Changing how strongyloidiasis is perceived from a geographic and clinical issue to an environmental health issue represents the first step in identifying appropriate long term control measures. This includes emphasis on environmental health controls, such as better infrastructure, sanitation and living conditions. This review explores the global prevalence of strongyloidiasis in relation to its presence in subtropical, tropical and temperate climate zones with mild and cold winters, but also explores the corresponding socioeconomic conditions of these regions. The evidence shows that strongyloidiasis is primarily determined by the socioeconomic status of the communities rather than geographic or climatic conditions. It demonstrates that strongyloidiasis should no longer be referred to as a "tropical" disease but rather a disease of disadvantage. This philosophical shift will promote the development of correct control strategies for preventing this disease of disadvantage.
Topics: Animals; Humans; Prevalence; Social Class; Strongyloides stercoralis; Strongyloidiasis
PubMed: 27213420
DOI: 10.3390/ijerph13050517 -
PLoS Neglected Tropical Diseases Jul 2021Viral and parasitic coinfections are known to lead to both enhanced disease progression and altered disease states. HTLV-1 and Strongyloides stercoralis are co-endemic...
Viral and parasitic coinfections are known to lead to both enhanced disease progression and altered disease states. HTLV-1 and Strongyloides stercoralis are co-endemic throughout much of their worldwide ranges resulting in a significant incidence of coinfection. Independently, HTLV-1 induces a Th1 response and S. stercoralis infection induces a Th2 response. However, coinfection with the two pathogens has been associated with the development of S. stercoralis hyperinfection and an alteration of the Th1/Th2 balance. In this study, a model of HTLV-1 and S. stercoralis coinfection in CD34+ umbilical cord blood hematopoietic stem cell engrafted humanized mice was established. An increased level of mortality was observed in the HTLV-1 and coinfected animals when compared to the S. stercoralis infected group. The mortality was not correlated with proviral loads or total viral RNA. Analysis of cytokine profiles showed a distinct shift towards Th1 responses in HTLV-1 infected animals, a shift towards Th2 cytokines in S. stercoralis infected animals and elevated TNF-α responses in coinfected animals. HTLV-1 infected and coinfection groups showed a significant, yet non-clonal expansion of the CD4+CD25+ T-cell population. Numbers of worms in the coinfection group did not differ from those of the S. stercoralis infected group and no autoinfective larvae were found. However, infective larvae recovered from the coinfection group showed an enhancement in growth, as was seen in mice with S. stercoralis hyperinfection caused by treatment with steroids. Humanized mice coinfected with S. stercoralis and HTLV-1 demonstrate features associated with human infection with these pathogens and provide a unique opportunity to study the interaction between these two infections in vivo in the context of human immune cells.
Topics: Animals; Antigens, CD34; Cell Line; Coinfection; Cytokines; Fetal Blood; HTLV-I Infections; Hematopoietic Stem Cells; Human T-lymphotropic virus 1; Larva; Mice; Mice, Inbred C57BL; Mice, Transgenic; Strongyloides stercoralis; Strongyloidiasis
PubMed: 34314415
DOI: 10.1371/journal.pntd.0009559