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The American Journal of Tropical... Jun 2019, a worldwide-distributed soil-transmitted helminth, causes chronic infection which may be life threatening. Limitations of diagnostic tests and nonspecificity of... (Meta-Analysis)
Meta-Analysis
, a worldwide-distributed soil-transmitted helminth, causes chronic infection which may be life threatening. Limitations of diagnostic tests and nonspecificity of symptoms have hampered the estimation of the global morbidity due to strongyloidiasis. This work aimed at assessing -associated morbidity through a systematic review and meta-analysis of the available literature. MEDLINE, Embase, CENTRAL, LILACS, and trial registries (WHO portal) were searched. The study quality was assessed using the Newcastle-Ottawa scale. Odds ratios (ORs) of the association between symptoms and infection status and frequency of infection-associated symptoms were calculated. Six articles from five countries, including 6,014 individuals, were included in the meta-analysis-three were of low quality, one of high quality, and two of very high quality. Abdominal pain (OR 1.74 [CI 1.07-2.94]), diarrhea (OR 1.66 [CI 1.09-2.55]), and urticaria (OR 1.73 [CI 1.22-2.44]) were associated with infection. In 17 eligible studies, these symptoms were reported by a large proportion of the individuals with strongyloidiasis-abdominal pain by 53.1% individuals, diarrhea by 41.6%, and urticaria by 27.8%. After removing the low-quality studies, urticaria remained the only symptom significantly associated with infection (OR 1.42 [CI 1.24-1.61]). Limitations of evidence included the low number and quality of studies. Our findings especially highlight the appalling knowledge gap about clinical manifestations of this common yet neglected soil-transmitted helminthiasis. Further studies focusing on morbidity and risk factors for dissemination and mortality due to strongyloidiasis are absolutely needed to quantify the burden of infection and inform public health policies.
Topics: Abdominal Pain; Africa; Animals; Asia; Australia; Diarrhea; Female; Humans; Japan; Male; Odds Ratio; Risk Factors; Soil; Strongyloides stercoralis; Strongyloidiasis; Urticaria
PubMed: 30963990
DOI: 10.4269/ajtmh.18-0895 -
PloS One 2021Hyperinfection and disseminated infection by the parasitic nematode Strongyloides stercoralis can be induced by iatrogenic administration of steroids and...
Hyperinfection and disseminated infection by the parasitic nematode Strongyloides stercoralis can be induced by iatrogenic administration of steroids and immunosuppression and lead to an elevated risk of mortality. Responses of free-living stages of S. stercoralis to the therapeutic corticosteroid dexamethasone (DXM) were investigated using RNA-seq transcriptomes of DXM-treated female and male worms. A total of 17,950 genes representing the transcriptome of these free-living adult stages were obtained, among which 199 and 263 were differentially expressed between DXM-treated females and DXM-treated males, respectively, compared with controls. According to Gene Ontology analysis, differentially expressed genes from DXM-treated females participate in developmental process, multicellular organismal process, cell differentiation, carbohydrate metabolic process and embryonic morphogenesis. Others are involved in signaling and signal transduction, including cAMP, cGMP-dependent protein kinase pathway, endocrine system, and thyroid hormone pathway, as based on Kyoto Encyclopedia of Genes and Genomes analysis. The novel findings warrant deeper investigation of the influence of DXM on growth and other pathways in this neglected tropical disease pathogen, particularly in a setting of autoimmune and/or allergic disease, which may require the clinical use of steroid-like hormones during latent or covert strongyloidiasis.
Topics: Animals; Dexamethasone; Female; Life Cycle Stages; Male; Second Messenger Systems; Strongyloides stercoralis; Transcriptome
PubMed: 34181669
DOI: 10.1371/journal.pone.0253701 -
PLoS Neglected Tropical Diseases Mar 2021There are no national prevalence studies of Strongyloides stercoralis infection in Australia, although it is known to be endemic in northern Australia and is reported in...
BACKGROUND
There are no national prevalence studies of Strongyloides stercoralis infection in Australia, although it is known to be endemic in northern Australia and is reported in high risk groups such as immigrants and returned travellers. We aimed to determine the seropositivity (number positive per 100,000 of population and percent positive of those tested) and geographical distribution of S. stercoralis by using data from pathology laboratories.
METHODOLOGY
We contacted all seven Australian laboratories that undertake Strongyloides serological (ELISA antibody) testing to request de-identified data from 2012-2016 inclusive. Six responded. One provided positive data only. The number of people positive, number negative and number tested per 100,000 of population (Australian Bureau of Statistics data) were calculated including for each state/territory, each Australian Bureau of Statistics Statistical Area Level 3 (region), and each suburb/town/community/locality. The data was summarized and expressed as maps of Australia and Greater Capital Cities.
PRINCIPAL FINDINGS
We obtained data for 81,777 people who underwent serological testing for Strongyloides infection, 631 of whom were from a laboratory that provided positive data only. Overall, 32 (95% CI: 31, 33) people per 100,000 of population were seropositive, ranging between 23/100,000 (95% CI: 19, 29) (Tasmania) and 489/100,000 population (95%CI: 462, 517) (Northern Territory). Positive cases were detected across all states and territories, with the highest (260-996/100,000 and 17-40% of those tested) in regions across northern Australia, north-east New South Wales and north-west South Australia. Some regions in Greater Capital Cities also had a high seropositivity (112-188/100,000 and 17-20% of those tested). Relatively more males than females tested positive. Relatively more adults than children tested positive. Children were under-represented in the data.
CONCLUSIONS/SIGNIFICANCE
The study confirms that substantial numbers of S. stercoralis infections occur in Australia and provides data to inform public health planning.
Topics: Adolescent; Adult; Aged; Animals; Antibodies, Helminth; Australia; Child; Child, Preschool; Enzyme-Linked Immunosorbent Assay; Female; Humans; Infant; Male; Middle Aged; Prevalence; Seroepidemiologic Studies; Strongyloides stercoralis; Strongyloidiasis
PubMed: 33690623
DOI: 10.1371/journal.pntd.0009160 -
Experimental Parasitology Feb 2008Transgenesis is a valuable methodology for studying gene expression patterns and gene function. It has recently become available for research on some parasitic...
Transgenesis is a valuable methodology for studying gene expression patterns and gene function. It has recently become available for research on some parasitic nematodes, including Strongyloides stercoralis. Previously, we described a vector construct, comprising the promoter and 3' UTR of the S. stercoralis gene Ss era-1 that gives expression of GFP in intestinal cells of developing F1 progeny. In the present study, we identified three new S. stercoralis promoters, which, in combination with the Ss era-1 3' UTR, can drive expression of GFP or the red fluorescent protein, mRFPmars, in tissue-specific fashion. These include Ss act-2, which drives expression in body wall muscle cells, Ss gpa-3, which drives expression in amphidial and phasmidial neurons and Ss rps-21, which drives ubiquitous expression in F1 transformants and in the gonads of microinjected P0 female worms. Concomitant microinjection of vectors containing GFP and mRFPmars gave dually transformed F1 progeny, suggesting that these constructs could be used as co-injection markers for other transgenes of interest. We have developed a vector "toolkit" for S. stercoralis including constructs with the Ss era-1 3' UTR and each of the promoters described above.
Topics: 3' Untranslated Regions; Animals; Caenorhabditis elegans; DNA, Helminth; Dogs; Female; Gene Expression Regulation; Genes, Reporter; Genetic Vectors; Gerbillinae; Green Fluorescent Proteins; Microinjections; Molecular Sequence Data; Promoter Regions, Genetic; Serial Passage; Strongyloides stercoralis; Transformation, Genetic; Transgenes
PubMed: 17945217
DOI: 10.1016/j.exppara.2007.08.018 -
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 -
Parasitology Jan 2022This study analysed Strongyloides stercoralis genetic variability based on a 404 bp region of the cox1 gene from Latin-American samples in a clinical context including... (Observational Study)
Observational Study
This study analysed Strongyloides stercoralis genetic variability based on a 404 bp region of the cox1 gene from Latin-American samples in a clinical context including epidemiological, diagnosis and follow-up variables. A prospective, descriptive, observational study was conducted to evaluate clinical and parasitological evolution after ivermectin treatment of 41 patients infected with S. stercoralis. Reactivation of the disease was defined both by clinical symptoms appearance and/or direct larvae detection 30 days after treatment or later. We described 10 haplotypes organized in two clusters. Most frequent variants were also described in the Asian continent in human (HP24 and HP93) and canine (HP24) samples. Clinical presentation (intestinal, severe, cutaneous and asymptomatic), immunological status and eosinophil count were not associated with specific haplotypes or clusters. Nevertheless, presence of cluster 1 haplotypes during diagnosis increased the risk of reactivation with an odds ratio (OR) of 7.51 [confidence interval (CI) 95% 1.38–44.29, P = 0.026]. In contrast, reactivation probability was 83 times lower if cluster 2 (I152V mutation) was detected (OR = 0.17, CI 95% 0.02–0.80, P = 0.02). This is the first analysis of S. stercoralis cox1 diversity in the clinical context. Determination of clusters during the diagnosis could facilitate and improve the design of follow-up strategies to prevent severe reactivations of this chronic disease.
Topics: Animals; Dogs; Feces; Humans; Latin America; Molecular Typing; Prospective Studies; Strongyloides stercoralis; Strongyloidiasis
PubMed: 35184784
DOI: 10.1017/S0031182021001517 -
World Journal of Gastroenterology Sep 2017Animal models and clinical studies have shown that helminth infections exert immunomodulatory activity, altering intestinal permeability and providing a potential...
Animal models and clinical studies have shown that helminth infections exert immunomodulatory activity, altering intestinal permeability and providing a potential beneficial action on autoimmune and inflammatory disorders in human beings, such as inflammatory bowel disease (IBD) and celiac disease. This is consistent with the theory that intestinal microbiota is responsible for shaping human immunological responses. With the arrival of the immunobiologic era and the use of antibodies, we propose a distinctive pathway for treating patients with IBD and celiac disease. We have some evidence about the safety and tolerability of helminth use, but evidence about their impact on disease activity is lacking. Using worms to treat diseases could be a possible way to lower treatment costs, since the era of immunobiologic agents is responsible for a significant rise in expenses. Some questions remain to be investigated regarding the use of helminths in intestinal disease, such as the importance of the specific species of helminths used, appropriate dosing regimens, optimal timing of treatment, the role of host genetics, diet, environment, and the elucidation of the exact mechanisms of action. One promising approach is the use of helminth-derived anti-inflammatory molecules as drugs. Yet there are still many challenges with this method, especially with regard to safety. Studies on intestinal permeability point to as a useful nematode for these purposes.
Topics: Animals; Biological Products; Biological Therapy; Celiac Disease; Clinical Trials as Topic; Complementary Therapies; Humans; Hygiene Hypothesis; Immunotherapy; Inflammatory Bowel Diseases; Intestinal Mucosa; Permeability; Strongyloides stercoralis; Treatment Outcome
PubMed: 28970717
DOI: 10.3748/wjg.v23.i33.6009 -
Parasite Immunology 2004Strongyloides stercoralis is the most common human parasitic nematode that is able to complete a life cycle and proliferate within its host. The majority of patients... (Review)
Review
Strongyloides stercoralis is the most common human parasitic nematode that is able to complete a life cycle and proliferate within its host. The majority of patients with strongyloidiasis have an asymptomatic infection or mild disease. However, when autoinfection occurs, a high number of infecting larvae can gain access to the bloodstream by penetrating the colonic mucosa leading to a severe hyperinfection and the development of disseminated strongyloidiasis. The human T cell lymphotropic virus type 1 (HTLV-1) predominantly infects T cells and induces spontaneous lymphocyte proliferation and secretion of high levels of type 1 cytokines. Strongyloides stercoralis patients with HTLV-1 co-infection have a modified immunological responses against parasite antigens and co-infection has clinical implications for strongyloidiasis. The high production of IFN-gamma observed in patients co-infected with HTLV-1 and Strongyloides stercoralis decreases the production of IL-4, IL-5, IL-13 and IgE, molecules that participate in the host defence mechanism against helminths. Moreover, there is a decrease in the efficacy of treatment of Strongyloides stercoralis in patients co-infected with HTLV-1. Alterations in the immune response against Strongyloides stercoralis and the decrease in the efficacy of anti-parasitic drugs are responsible for the increased prevalence of Strongyloides stercoralis among HTLV-1 infected subjects and make HTLV-1 infection the most important risk factor for disseminated strongyloidiasis.
Topics: Animals; HTLV-I Infections; Human T-lymphotropic virus 1; Humans; Strongyloides stercoralis; Strongyloidiasis
PubMed: 15771684
DOI: 10.1111/j.0141-9838.2004.00726.x -
Revista Chilena de Infectologia :... Oct 2013
Topics: Animals; Humans; Strongyloides stercoralis; Strongyloidiasis
PubMed: 24248166
DOI: 10.4067/S0716-10182013000500008 -
PLoS Neglected Tropical Diseases 2013
Review
Topics: Animals; Anthelmintics; Global Health; Humans; Neglected Diseases; Strongyloides stercoralis; Strongyloidiasis
PubMed: 23675546
DOI: 10.1371/journal.pntd.0002214