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Handbook of Clinical Neurology 2013Strongyloides stercoralis is a nematode endemic in humid tropical regions. The life cycle of this parasite is complex and unique due to its capacity to cause... (Review)
Review
Strongyloides stercoralis is a nematode endemic in humid tropical regions. The life cycle of this parasite is complex and unique due to its capacity to cause autoinfection, resulting in chronic infections. Innate and adaptive immune responses are responsible for clearing the parasite. Many risk factors have been described, but the most important is living in or having visited an endemic area. The clinical presentation of strongyloidiasis is varied and ranges from asymptomatic chronic infection to hyperinfection syndrome. Hyperinfection syndrome is more common in patients with immunosuppresion due to therapy with corticosteroids, coinfection with human T-lymphotropic virus type I (HTLV-1), transplant patients, or patients receiving chemotherapy. Multiplication and migration of large parasite numbers cause worsening of the initial symptoms and leads to a high mortality rate. CNS involvement in strongyloidiasis has only been seen in patients with hyperinfection syndrome. Meningitis is the most common form of CNS involvement and gram-negative bacteria are the more frequent etiology. Repeated stool samples with concentration methods have a good sensitivity and specificity. In patients that are not from endemic areas serum antibody tests may be useful in the diagnosis. Treatment with a single dose of ivermectin is recommended for most patients. In severe or hyperinfection cases repeated doses may be needed.
Topics: Animals; Central Nervous System Diseases; Humans; Strongyloides stercoralis; Strongyloidiasis
PubMed: 23829913
DOI: 10.1016/B978-0-444-53490-3.00017-0 -
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 -
Parasites & Vectors May 2020Strongyloidiasis is a soil borne helminthiasis, which in most cases is caused by Strongyloides stercoralis. Human infections with S. fuelleborni fuelleborni and S....
BACKGROUND
Strongyloidiasis is a soil borne helminthiasis, which in most cases is caused by Strongyloides stercoralis. Human infections with S. fuelleborni fuelleborni and S. fuelleborni kellyi also occur. Although up to 370 million people are currently estimated to be infected with S. stercoralis, this parasite is frequently overlooked. Strongyloides stercoralis is prevalent among humans in Thailand; however, S. fuelleborni fuelleborni has also been reported. Three recent genomic studies of individual S. stercoralis worms found genetically diverse populations of S. stercoralis, with comparably low heterozygosity in Cambodia and Myanmar, and less diverse populations with high heterozygosity in Japan and southern China that presumably reproduce asexually.
METHODS
We isolated individual Strongyloides spp. from different localities in northern and western Thailand and determined their nuclear small ribosomal subunit rDNA (18S rDNA, SSU), in particular the hypervariable regions I and IV (HVR-I and HVR-IV), mitochondrial cytochrome c oxidase subunit 1 (cox1) and for a subset whole genome sequences. These sequences were then compared with each other and with published sequences from different geographical locations.
RESULTS
All 237 worms isolated from 16 different human hosts were S. stercoralis, no S. fuelleborni was found. All worms had the common S. stercoralis SSU HVR IV haplotype A. Two different SSU HVR I haplotypes (I and II), both previously described in S. stercoralis, were found. No animal heterozygous for the two haplotypes was identified. Among the twelve cox1 haplotypes found, five had not been previously described. Based upon the mitochondrial cox1 and the nuclear whole genome sequences, S. stercoralis in Thailand was phylogenetically intermixed with the samples from other Southeast Asian countries and did not form its own branch. The genomic heterozygosity was even slightly lower than in the samples from the neighboring countries.
CONCLUSIONS
In our sample from humans, all Strongyloides spp. were S. stercoralis. The S. stercoralis from northern and western Thailand appear to be part of a diverse, intermixing continental Southeast Asian population. No obvious indication for genetic sub-structuring of S. stercoralis within Thailand or within the Southeast Asian peninsula was detected.
Topics: Animals; DNA, Helminth; Feces; Female; Genetic Variation; Genome, Helminth; Genomics; Genotype; Humans; Male; Neglected Diseases; Phylogeny; RNA, Ribosomal, 18S; Strongyloides stercoralis; Strongyloidiasis; Thailand; Whole Genome Sequencing
PubMed: 32404172
DOI: 10.1186/s13071-020-04115-0 -
Inflammatory Bowel Diseases Mar 2022
Topics: Animals; Colitis; Colitis, Ulcerative; Humans; Strongyloides stercoralis
PubMed: 34788803
DOI: 10.1093/ibd/izab261 -
PLoS Neglected Tropical Diseases Feb 2022Strongyloidiasis and Chagas disease are endemic in northern Argentina. In this study we evaluate the association between S. stercoralis and T. cruzi infections in...
BACKGROUND
Strongyloidiasis and Chagas disease are endemic in northern Argentina. In this study we evaluate the association between S. stercoralis and T. cruzi infections in villages with diverse prevalence levels for these parasites. Further understanding in the relationship between these Neglected Tropical Diseases of South America is relevant for the design of integrated control measures as well as exploring potential biologic interactions.
METHODOLOGY
Community based cross-sectional studies were carried in different villages of the Chaco and Yungas regions in Argentina. Individuals were diagnosed by serology for S. stercoralis and T. cruzi. The association between S. stercoralis and T. cruzi, and between anemia and the two parasites was evaluated using two approaches: marginal (Ma) and multilevel regression (Mu).
RESULTS
A total of 706 individuals from six villages of northern Argentina were included. A total of 37% were positive for S. stercoralis, 14% were positive for T. cruzi and 5% were positive for both. No association was found between infection with S. stercoralis and T. cruzi in any of the models, but we found a negative correlation between the prevalence of these species in the different villages (r = -0.91). Adults (> 15 years) presented association with S. stercoralis (Ma OR = 2.72; Mu OR = 2.84) and T. cruzi (Ma OR = 5.12; Mu OR = 5.48). Also, 12% and 2% of the variance of infection with S. stercoralis and T. cruzi, respectively, could be explained by differences among villages. On the other hand, anemia was associated with infection with S. stercoralis (Ma OR = 1.73; Mu OR = 1.78) and was more prevalent in adults (Ma OR = 2.59; Mu OR = 2.69).
CONCLUSION
We found that coinfection between S. stercoralis and T. cruzi is not more frequent than chance in endemic areas. However, the high prevalence for both parasites, raises the need for an integrated strategy for the control of STH and Chagas disease.
Topics: Adolescent; Adult; Animals; Argentina; Chagas Disease; Child; Child, Preschool; Coinfection; Cross-Sectional Studies; Emigrants and Immigrants; Endemic Diseases; Feces; Female; Humans; Male; Middle Aged; Prevalence; Strongyloides stercoralis; Strongyloidiasis; Trypanosoma cruzi; Young Adult
PubMed: 35120117
DOI: 10.1371/journal.pntd.0010179 -
The American Journal of Case Reports Apr 2017BACKGROUND Strongyloides stercoralis infection is endemic in subtropical and tropical regions but is reported rather sporadically in temperate countries. In the USA, the... (Review)
Review
BACKGROUND Strongyloides stercoralis infection is endemic in subtropical and tropical regions but is reported rather sporadically in temperate countries. In the USA, the highest rates of infection are from the southeastern states, predominantly among immigrants. There is paucity of case reports on S. stercoralis infection among HIV-infected patients who were born and raised in the USA. CASE REPORT A 61-year-old male with known HIV infection (CD4 count: 235 cells/uL, undetectable HIV RNA, on antiretroviral therapy) presented with a 3-month history of diarrhea. He was initially diagnosed to have diarrhea secondary to norovirus and later with Escherichia coli. He was treated with levofloxacin but the diarrhea persisted. Stool PCR, Clostridium difficile enzyme-linked immunoassay, cryptosporidium and giardia antigen, cyclospora and isospora smear, and fecal microscopy were all negative. Peripheral blood eosinophil count was 1,000 eosinophils/mcL. Colonic biopsies revealed fragments of S. stercoralis larvae within the crypts. The patient was treated with ivermectin with improvement of symptoms. Social history revealed that he was born and raised in the northeastern USA. He was a daily methamphetamine user and engaged in anal sex with men. He denied travel to endemic areas, except for a visit to Japan more than 30 years ago. CONCLUSIONS Our case highlights that S. stercoralis may be an underdiagnosed/under-reported cause of chronic diarrhea among HIV-infected patients. What makes this case peculiar is that the patient was born and raised in the continental USA, absence of recent travel to endemic areas, and relatively high CD4 counts. Parasitic infections, such as S. stercoralis, should be considered among HIV-infected patients with persistent diarrhea and eosinophilia regardless of ethnicity or recent travel history.
Topics: AIDS-Related Opportunistic Infections; Animals; Diarrhea; HIV Infections; Humans; Male; Middle Aged; Strongyloides stercoralis; Strongyloidiasis; United States
PubMed: 28366929
DOI: 10.12659/ajcr.902626 -
Microbial Pathogenesis Mar 2021Strongyloides stercoralis is a parasite widely distributed in the tropical and subtropical areas in the world. Its treatment and diagnosis have a limitation as many...
Strongyloides stercoralis is a parasite widely distributed in the tropical and subtropical areas in the world. Its treatment and diagnosis have a limitation as many other parasitic diseases. Nowadays, there is a great interest in designing an efficient epitope for vaccines or diagnostic. In this study, a bioinformatics-based screening approach has been incorporated in order to explore potential immunogens in the S. stercoralis proteome. Bioinformatic tools were used to predict diagnostic and vaccinology approaches. 12.851 cell immunology proteins from Uniprot were analyzed. Thirty-four immunogenic candidates were identified, they had higher antigenic activity, less than 2 α-helices, non-allergen activity and they do not have homology with host proteins, all of them have ortholog protein with Strongyloides ratti. Some of them presented a good binding with immunological cell (T and B cell). These proteins could be a good alternative as a candidate for the design of the novel vaccines or diagnostic tests of strongyloides stercoralis.
Topics: Animals; Epitopes; Proteome; Strongyloides ratti; Strongyloides stercoralis; Vaccinology
PubMed: 33091578
DOI: 10.1016/j.micpath.2020.104545 -
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 -
Clinical Infectious Diseases : An... Oct 2001Strongyloides stercoralis infects 30 million people in 70 countries. Infection usually results in asymptomatic chronic disease of the gut, which can remain undetected... (Review)
Review
Strongyloides stercoralis infects 30 million people in 70 countries. Infection usually results in asymptomatic chronic disease of the gut, which can remain undetected for decades. However, in patients receiving long-term corticosteroid therapy, hyperinfection can occur, resulting in high mortality rates (up to 87%). Strongyloidiasis is difficult to diagnose because the parasite load is low and the larval output is irregular. Results of a single stool examination by use of conventional techniques fail to detect larvae in up to 70% of cases. Several immunodiagnostic assays have been found ineffective in detecting disseminated infections and show extensive cross-reactivity with hookworms, filariae, and schistosomes. Although it is important to detect latent S. stercoralis infections before administering chemotherapy or before the onset of immunosuppression in patients at risk, a specific and sensitive diagnostic test is lacking. This review describes the clinical manifestations of strongyloidiasis, as well as various diagnostic tests and treatment strategies.
Topics: Animals; Antinematodal Agents; Feces; Humans; Serologic Tests; Strongyloides stercoralis; Strongyloidiasis
PubMed: 11528578
DOI: 10.1086/322707 -
Inflammatory Bowel Diseases Mar 2022
Topics: Animals; Colitis; Colitis, Ulcerative; Humans; Strongyloides stercoralis
PubMed: 34791284
DOI: 10.1093/ibd/izab262