Abstract
BackgroundStrongyloides stercoralis, the chief causative agent of human strongyloidiasis, is a nematode globally distributed but mainly endemic in tropical and subtropical regions. Chronic infection is often clinically asymptomatic but it can result in severe hyperinfection syndrome or disseminated strongyloidiasis in immunocompromised patients. There is a great diversity of techniques used in diagnosing the disease, but definitive diagnosis is accomplished by parasitological examination of stool samples for morphological identification of parasite. Until now, no molecular method has been tested in urine samples as an alternative to stool samples for diagnosing strongyloidiasis. This study aimed to evaluate the use of a new molecular LAMP assay in a well-established Wistar rat experimental infection model using both stool and, for the first time, urine samples. The LAMP assay was also clinically evaluated in patients´ stool samples.Methodology/Principal FindingsStool and urine samples were obtained daily during a 28-day period from rats infected subcutaneously with different infective third-stage larvae doses of S. venezuelensis. The dynamics of parasite infection was determined by daily counting the number of eggs per gram of feces from day 1 to 28 post-infection. A set of primers for LAMP assay based on a DNA partial sequence in the 18S rRNA gene from S. venezuelensis was designed. The set up LAMP assay (namely, Strong-LAMP) allowed the sensitive detection of S. venezuelensis DNA in both stool and urine samples obtained from each infection group of rats and was also effective in S. stercoralis DNA amplification in patients´ stool samples with previously confirmed strongyloidiasis by parasitological and real-time PCR tests.Conclusions/SignificanceOur Strong-LAMP assay is an useful molecular tool in research of a strongyloidiasis experimental infection model in both stool and urine samples. After further validation, the Strong-LAMP could also be potentially applied for effective diagnosis of strongyloidiasis in a clinical setting.
Highlights
Strongyloidiasis, a soil-transmitted helminth human infection, is considered by World Health Organization (WHO) as a neglected condition affecting an estimated 30–100 million people worldwide [1]
A soil-transmitted infection mainly caused by Strongyloides stercoralis, is one of the most neglected among the so-called neglected tropical diseases (NTDs)
In this study we have developed, for the first time, a molecular assay using loop-mediated isothermal amplification (LAMP) methodology as a simple, sensible and robust method for the detection of S. venezuelensis DNA in a well-established Wistar rats experimental infection in both stool and urine samples
Summary
Strongyloidiasis, a soil-transmitted helminth human infection, is considered by World Health Organization (WHO) as a neglected condition affecting an estimated 30–100 million people worldwide [1]. The accuracy of these estimates remains uncertain due to lack of efficient guidelines for screening the population in epidemiological surveys [2, 3]. Chronic infection is often clinically asymptomatic but it can result in severe hyperinfection syndrome or disseminated strongyloidiasis in immunocompromised patients. This study aimed to evaluate the use of a new molecular LAMP assay in a well-established Wistar rat experimental infection model using both stool and, for the first time, urine samples. The LAMP assay was clinically evaluated in patientsstool samples
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