The Recombinase Polymerase Amplification Test for Strongyloides stercoralis Is More Sensitive than Microscopy and Real-Time PCR in High-Risk Communities of Cusco, Peru.

Strongyloidiasis is a neglected, soil-transmitted helminth infection prevalent worldwide. The true burden of strongyloidiasis is unclear due to the lack of sensitive, field-friendly diagnostic tests. PCR tests to detect Strongyloides DNA in stool are sensitive and specific, but the need for expensive equipment limits their use in endemic regions. Isothermal PCR amplification tests are easier to deploy while maintaining sensitivity and specificity. We developed and evaluated a recombinase polymerase amplification lateral flow assay (RPA-LFA) to detect Strongyloides stercoralis in human stool samples. Three hundred stool samples were collected in three communities in the jungle of Cusco, Peru. Samples were tested for S. stercoralis larvae using microscopy (Baermann's, agar plate culture (APC), and rapid sedimentation), real-time PCR, and RPA-LF for Strongyloides DNA. The RPA-LFA showed an analytical limit of detection of 20 pg/µL. The prevalence of S. stercoralis was 27%, 38%, 46.3%, and 46% using microscopy, PCR, microscopy/PCR, and RPA-LFA, respectively. RPA-LFA had a sensitivity and specificity of 59.3% and 58.9%, 66.2% and 71.4%, and 77.2% and 73.1% when microscopy, microscopy/PCR, and real-time PCR were used as the gold standards, respectively. The Strongyloides RPA-LFA is a novel, fast, highly sensitive, and specific molecular method with the potential for deployment in endemic regions.

Spectrum of endoscopic findings in Strongyloides stercoralis infection with gastroduodenal involvement-A case series.

Strongyloides stercoralis infects the duodenum and jejunum with rare involvement of the stomach. However, the clinical presentation and endoscopic findings are non-specific. There are limited data on upper gastrointestinal endoscopy findings in S. stercoralis with gastroduodenal involvement. In this case series of seven patients, we summarize such findings after diagnosis with tissue biopsy.

Detection of human strongyloidiasis among patients with a high risk of complications attending selected tertiary care hospitals in Colombo, Sri Lanka using molecular and serological diagnostic tools.

BACKGROUND: Strongyloidiasis a neglected tropical disease is known to cause severe disease among immunosuppressed and has not been studied extensively in Sri Lanka. Parasitological diagnostic approaches based on faecal microscopy and culture often fail to detect low-intensity infections. This study investigates the presence of strongyloidiasis among selected immunocompromised individuals using parasitological, molecular and serological techniques. METHODS: Adult patients with immunocompromising conditions admitted to three tertiary care hospitals in Sri Lanka were recruited. A faecal sample and 2 ml of venous blood were collected. The faecal samples were subjected to direct faecal smear and cultures (agar plate, charcoal and Harada-Mori) and polymerase chain reaction (PCR) using species specific primers designed for Strongyloides stercoralis. The presence of Strongyloides IgG antibodies was tested in the collected serum samples using DRG Strongyloides IgG enzyme-linked immunosorbent assay (ELISA) kits. The PCR products of the positive samples were sequenced using Sanger sequencing method. RESULTS: A total of 260 patients were recruited to this study, out of which 160 provided faecal samples and 122 provided blood samples. Out of the 160 faecal samples, none were positive for strongyloidiasis by direct smear, charcoal and Harada-Mori cultures. Only one sample (0.6%) was positive by agar plate culture. Out of the 123 samples subjected to PCR, 14 (11.4%), including the culture positive patient, were positive for S. stercoralis. Sequencing results of the PCR products indicated 100% similarity to S. stercoralis. Out of the 122 serum samples subjected to ELISA, 20 (16.4%), including the culture positive patient, were positive for Strongyloides IgG antibodies. However, sociodemographic, exposure factors, clinical features were not significantly associated with the presence of strongyloidiasis infection. CONCLUSIONS: Strongyloidiasis is present among the immunocompromised population in Sri Lanka, even in the absence of a significant relationship with associated factors. It is advisable to screen such patients with highly sensitive tests such as PCR for early diagnosis and treatment.

Understanding Strongyloides Stercoralis infection and its relationship to chronic alcohol abuse: Understanding pathogenesis and therapeutic strategies.

Globally, Strongyloides stercoralis is a prevalent nematode parasite infecting over 600 million individuals, predominantly in tropical regions. Despite its widespread occurrence, it is frequently underdiagnosed and neglected, posing significant health risks, particularly to immunocompromised individuals. This parasite's life cycle includes a concerning capability for autoinfection, potentially leading to hyperinfection syndrome with high mortality rates. Alcoholism is recognized as a major risk factor for exacerbating S. stercoralis infections due to its harmful impact on the immune system. Chronic alcohol consumption impairs adaptive immunity by reducing T-cell and B-cell function, which facilitates parasitic infections. This review examines the complex relationship between alcohol abuse and strongyloidiasis, emphasizing the molecular mechanisms involved. Diagnostic challenges and treatment options, particularly the efficacy of antiparasitic drugs like ivermectin, are also discussed. Understanding these interactions is essential for developing improved diagnostic and therapeutic strategies to combat strongyloidiasis, especially among vulnerable populations, highlighting areas for future study.

Seroprevalence of Strongyloides stercoralis Infection in Patients with Hyperlipidemia: A Case-Control Study.

Background: Strongyloides stercoralis is one of the soil-transmitted helminths (STH) in tropical and subtropical regions. The role of lipid profile has been investigated in the survival of larval stages of helminths, but there is limited information about the role of lipid profiles and strongyloidiasis. Hence, we aimed to investigate the seroprevalence of S. stercoralis infection in patients with hyperlipidemia is compared with the nonhyperlipidemia. Methods: In 2023, participants were selected from the laboratory of Porsina Hospital in Guilan Province, northern Iran and their lipid profiles including TG, CHOL, LDL, HDL, and VLDL were measured. They were divided into two groups of case and control and matched based on sex and age. S. stercoralis Ab (IgG) was measured by ELISA methods, using the NovaTec kit. Finally, statistical analysis was performed. Results: Each case and control group consisted of 105 participants, from 13 to 80 years old. 56.66% were female and 43.33% were male. The seroprevalence of S. stercoralis was found 4.76% in the case group compared to 0.95% in the control group. We found an association between TG fall and VLDL with seroprevalence of S. stercoralis in hyperlipidemia group (P= 0.034), but other lipid profiles did not show a significant association. A significant relationship was found between contact with dogs and seroprevalence of S. stercoralis (P=0.001). Conclusion: The seroprevalence of S. stercoralis in the case group was 5 times higher than the control group. A significant association between TG and VLDL fall with S. stercoralis Ab (IgG) was observed, but future studies with more sample sizes are suggested to investigate the anti-atherogenic effect of S. stercoralis. Also, a genetic assessment of S. stercoralis and the host (humane and dogs) is recommended to research zoonotic potential in epidemic areas.

A Pilot Study for the Characterization of Bacillus spp. and Analysis of Possible B. thuringiensis/Strongyloides stercoralis Correlation.

Differentiating between Bacillus species is relevant in human medicine. Bacillus thuringiensis toxins might be effective against Strongyloides stercoralis, a nematode causing relevant human morbidity. Our first objective was to evaluate genomic and MALDI-TOF identification methods for B. thuringiensis. Our secondary objective was to evaluate a possible negative selection pressure of B. thuringiensis against S. stercoralis. PCR and Sanger were compared to MALDI-TOF on a collection of 44 B. cereus group strains. B. thuringiensis toxin genes were searched on 17 stool samples from S. stercoralis-infected and uninfected dogs. Metagenomic 16S rRNA was used for microbiome composition. The inter-rate agreement between PCR, Sanger, and MALDI-TOF was 0.631 k (p-value = 6.4 × 10-10). B. thuringiensis toxins were not found in dogs' stool. Bacteroidota and Bacillota were the major phyla in the dogs' microbiome (both represented >20% of the total bacterial community). Prevotella was underrepresented in all Strongyloides-positive dogs. However, the general composition of bacterial communities was not significantly linked with S. stercoralis infection. The genomic methods allowed accurate differentiation between B. thuringiensis and B. cereus. There was no association between B. thuringiensis and S. stercoralis infection, but further studies are needed to confirm this finding. We provide the first descriptive results about bacterial fecal composition in dogs with S. stercoralis infection.

Dermatological Presentation of Strongyloides stercoralis Infection in Two Elderly Italian Inpatients.

Persistent infections caused by Strongyloides stercoralis are probably underestimated in the elderly Italian population. This nematode is unique among helminths: it can last asymptomatically in the host for decades and may present with a broad range of clinical pictures upon reactivation. Misdiagnosis often occurs even when the clinical picture is suggestive. If undetected, this parasitosis can lead to serious consequences when hyperinfection occurs. Herein, we report two peculiar clinical cases of complicated strongyloidiasis with multiple skin lesions. The aim of our report is to lead clinicians to familiarize themselves with skin patterns and clinical features that can suggest a possible underlying strongyloidiasis.

An evaluation of a lateral flow rapid diagnostic test for Strongyloides stercoralis infection.

Strongyloides stercoralis in humans often presents as a chronic asymptomatic infection. Diagnosis can be challenging due to the limited sensitivity of faecal-based parasitological techniques. A prototype lateral flow rapid diagnostic test (RDT) for the detection of specific antibodies against Strongyloides stercoralis (SsRapid) was evaluated using 143 samples from the serum bank of the Swiss Tropical and Public Health Institute. Group 1 (n = 30) comprised serum samples from larvae-positive individuals; the RDT's diagnostic sensitivity was 97 % (29/30). Group II comprised serum samples from patients with other parasitic infections (n = 86) and Swiss blood donors (n = 27); the RDT's diagnostic specificity for this group was 90 % (102/113). The RDT showed good diagnostic performance and is a promising point-of-care test for detecting human Strongyloides stercoralis infection.

Comparison of parasitological methods for the identification of soil-transmitted helminths, including Strongyloides stercoralis, in a regional reference laboratory in northwestern Argentina: An observational study.

Soil-transmitted helminths (STH) are a significant public health problem in impoverished communities of tropical and subtropical areas. Improved diagnostic methods are crucial for Neglected Tropical Diseases programs, particularly for S. stercoralis, as traditional methods are inadequate. Thus, it is important to identify the most accurate and efficient methods for the diagnosis of STH. We performed a retrospective study analyzing laboratory data at the Instituto de Investigaciones de Enfermedades Tropicales from 2010 to 2019. The study included data from outpatients referred for stool analysis and public health interventions from urban and rural communities in northern Salta province, Argentina. Samples were included in this analysis if processed through sedimentation/concentration, Baermann, Harada-Mori and McMaster's, with a subgroup that also included Agar plate culture method (APC). Sensitivity was calculated against a composite reference standard. Of the 5625 samples collected, 944 qualified for this analysis, with a prevalence of 11.14% for A. lumbricoides, 8.16% for hookworm, 1.38% for T. trichiura, and 6.36% for S. stercoralis. The sedimentation/concentration method was the most sensitive for A. lumbricoides (96%), compared to the McMaster method, with a sensitivity of 62%. Similarly, for hookworms, sedimentation/concentration was more sensitive than McMaster's, Harada-Mori, and Baermann with sensitivities of 87%, 70%, 43%, and 13%, respectively. Most of these infections were of light intensity. For S. stercoralis, Baermann and sedimentation/concentration methods were the most sensitive, with 70% and 62% respectively, while Harada-Mori was the least sensitive. In a subset of 389 samples also analyzed by the APC, Baermann was more sensitive than APC for detecting S. stercoralis, and both methods were superior to Harada-Mori. Parasitological methods, mostly when used combined, offer adequate opportunities for the diagnosis of STH in clinical and public health laboratories. The incorporation of S. stercoralis into the control strategies of the World Health Organization requires rethinking the current diagnostic approach used for surveys. With sedimentation/concentration and Baermann appearing as the most sensitive methods for this species. Further studies, including implementation assessments, should help in identifying the most adequate and feasible all-STH diagnostic approach.

Human Strongyloides stercoralis infection.

Strongyloides stercoralis is an important soil-transmitted helminth occurring world-wide and affecting 30-100 million people. Because many cases are asymptomatic and sensitive diagnostic methods are lacking, S. stercoralis infection is frequently underdiagnosed. The increasing incidence of autoimmune and wasting diseases and increased use of immunosuppressive agents, as well as the increased use of immunosuppressants and cytotoxic drugs, have increased S. stercoralis infection and their mortality. This review provides information about S. stercoralis epidemiology, life cycle, aetiology, pathology, comorbidities, immunology, vaccines, diagnosis, treatment, prevention, control and makes some recommendations for future prevention and control of this important parasite.

Detection of Anti-Strongyloides Antibodies in the Serum of Liver Transplant Recipients: Need of Screening for This Neglected Helminthiasis.

Immunosuppressed patients, particularly transplant recipients, can develop severe strongyloidiasis. This study aimed to detect anti-Strongyloides IgG antibodies in a panel of sera from liver transplant patients. Two techniques were used: ELISA as the initial screening test and Western blotting as a confirmatory test. ELISA reactivity of 10.9% (32/294) was observed. The 40-30 kDa fraction was recognised in 93.7% (30/32) of the patients, resulting in a positivity rate of 10.2%. These data highlight the importance of serological screening for Strongyloides stercoralis infection in liver transplant recipients.

A silent threat behind bars: Serosurvey and associated risk factors for strongyloidiasis in female inmates and correctional officers.

Strongyloidiasis has been a neglected parasitic infection caused by Strongyloides genus parasites. Despite assessment of S. stercoralis exposure in different vulnerable populations, seroprevalence in inmates worldwide remains to be fully established. Due to poor sanitation and lack of personal hygienic practices, incarcerated individuals have been considered prone to spread infectious illnesses. Accordingly, the present study has assessed exposure and associated risk factors for strongyloidiasis in women inmates and correctional officers at the Women's State Penitentiary of Parana, part of the third largest incarceration complex in Brazil at the time. Blood samplings were performed in 2020 and 2021from a total of 503 women inmates and 92 correctional officers. Participants voluntarily responded to an epidemiological questionnaire to assess associated risk factors to strongyloidiasis. Serological analysis was performed by ELISA for anti-S. stercoralis IgG detection. Statistical analysis was performed using R software, adopting a 5% level of significance. The data were submitted to univariate analysis by chi-square or Fisher´s Exact test for assessing the association among seropositivity and the variables. The variables with p-value < 0.2 in the univariate analysis were considered fit to be included in the logistic regression. In overall, 356/503 (70.8%; 95% CI: 66.7-74.6) inmates were seropositive for anti-S. stercoralis antibodies, with no statistically associated risk factor to seropositivity. A total of 57/92 (62.0%; 95% CI: 51.8-71.2) correctional officers were seropositive, and logistic regression revealed that individuals older than 50 years were more likely seropositive. In conclusion, the high endemicity observed herein has indicated a history of previous exposure to S. stercoralis and warned for a systematic strongyloidiasis screening for inmates, to prevent long term morbidity and disseminated infection during incarceration.

Prevalence of Strongyloides stercoralis and other helminths in four districts of Madagascar.

BACKGROUND: Estimation of prevalence of Strongyloides stercoralis infection is required in endemic areas, in order to identify areas in need of control programmes. Data on prevalence of strongyloidiasis in Madagascar are scant. Aim of this work was to estimate prevalence of S. stercoralis in four districts of Madagascar. METHODS: Fecal and serum samples collected in the context of a previous study on schistosomiasis were tested with S. stercoralis real-time PCR and serology, respectively. A multiplex real-time PCR for Ascaris lumbricoides, Ancylostoma duodenalis, Necator americanus, and Trichuris trichiura was done on fecal samples collected in the areas demonstrating higher prevalence of strongyloidiasis. Comparisons between proportions were made using Fisher exact test, with false discovery rate correction used for post-hoc comparisons. A multivariable Firth logistic regression model was used to assess potential risk factors for S. stercoralis infection. RESULTS: Overall, 1775 serum samples were tested, of which 102 of 487 (20.9%) and 104 of 296 (35.2%) were serological-positive in Marovoay and in Vatomandry districts (both coastal areas), respectively, compared to 28 of 496 (5.6%) and 30 of 496 (6.1%) in Tsiroanomandidy and in Ambositra districts (both highlands), respectively (adj. p < 0.001). PCR for S. stercoralis was positive in 15 of 210 (7.1%) and in 11 of 296 (3.7%) samples from Marovoay from Vatomandry, respectively, while was negative for all samples tested in the other two districts. High prevalence of A. lumbricoides (45.9%), hookworm (44.6%) and T. trichiura (32.1%) was found in Vatomandry. In the multivariable analysis, strongyloidiasis was associated with hookworm infection. Hookworm infection was also associated with male sex and lower education level. CONCLUSIONS: S. stercoralis prevalence proved higher in coastal areas compared to highlands. Different climatic conditions may explain this distribution, along with previous rounds of anthelminthics distributed in the country, which may have reduced the parasite load in the population. The high prevalence of the other soil-transmitted helminths (STH) in Vatomandry was unexpected, given the good coverage with benzimidazole in control campaigns. Further studies are needed to explore the risk factors for STH and S. stercoralis infections in Madagascar, in order to align with the WHO recommendations.

A case of disseminated strongyloidiasis diagnosed by worms in the urinary sediment.

Strongyloidiasis is a chronic infection caused by the intestinal nematode parasite Strongyloides stercoralis and is characterized by a diverse spectrum of nonspecific clinical manifestations. This report describe a case of disseminated strongyloidiasis with urination difficulty, generalized weakness, and chronic alcoholism diagnosed through the presence of worms in the urinary sediment. A 53-year-old man was hospitalized for severe abdominal distension and urinary difficulties that started 7-10 days prior. The patient also presented with generalized weakness that had persisted for 3 years, passed loose stools without diarrhea, and complained of dyspnea. In the emergency room, approximately 7 L of urine was collected, in which several free-living female adult and rhabditiform larvae of S. stercoralis, identified through their morphological characteristics and size measurements, were detected via microscopic examination. Rhabditiform larvae of S. stercoralis were also found in the patient's stool. During hospitalization, the patient received treatment for strongyloidiasis, chronic alcoholism, peripheral neurosis, neurogenic bladder, and megaloblastic anemia, and was subsequently discharged with improved generalized conditions. Overall, this report presents a rare case of disseminated strongyloidiasis in which worms were detected in the urinary sediment of a patient with urination difficulties and generalized weakness combined with chronic alcoholism, neurogenic bladder, and megaloblastic anemia.

The generation of stable transgenic lines in the human-infective nematode Strongyloides stercoralis.

The skin-penetrating gastrointestinal parasitic nematode Strongyloides stercoralis causes strongyloidiasis, which is a neglected tropical disease that is associated with severe chronic illness and fatalities. Unlike other human-infective nematodes, S. stercoralis cycles through a single free-living generation and thus serves as a genetically tractable model organism for understanding the mechanisms that enable parasitism. Techniques such as CRISPR/Cas9-mediated mutagenesis and transgenesis are now routinely performed in S. stercoralis by introducing exogenous DNA into free-living adults and then screening their F1 progeny for transgenic or mutant larvae. However, transgenesis in S. stercoralis has been severely hindered by the inability to establish stable transgenic lines that can be propagated for multiple generations through a host; to date, studies of transgenic S. stercoralis have been limited to heterogeneous populations of transgenic F1 larvae. Here, we develop an efficient pipeline for the generation of stable transgenic lines in S. stercoralis. We also show that this approach can be used to efficiently generate stable transgenic lines in the rat-infective nematode Strongyloides ratti. The ability to generate stable transgenic lines circumvents the limitations of working with heterogeneous F1 populations, such as variable transgene expression and the inability to generate transgenics of all life stages. Our transgenesis approach will enable novel lines of inquiry into parasite biology, such as transgene-based comparisons between free-living and parasitic generations.

High prevalence of anti-Strongyloides antibody in SARS-CoV-2-infected human sera in a Thai hospital: Rapid serological screening.

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can stimulate a systemic inflammatory response with severe lung involvement, multisystem dysfunction, and death in some cases. Immunosuppressive treatments have been proposed for management of COVID-19 patients, but these bring the risk of flare-up of pre-existing infections. Strongyloidiasis can become severe or fatal in immunocompromised individuals. This cross-sectional study determined the prevalence of anti-Strongyloides IgG antibody in sera collected from SARS-CoV-2 infected persons in a tertiary-care Thai hospital from January 2021 to January 2022. The survey was conducted using a rapid immunochromatographic test (ICT) kit based on a recombinant antigen of Strongyloides stercoralis known to be IgG-immunoreactive. High prevalence of anti-Strongyloides IgG antibody was found. Out of 297 SARS-CoV-2-infected patients 117 (39.4 %, 95 % CI 33.8-45.2 %) were positive for S. stercoralis according to the ICT kit. In areas where strongyloidiasis is endemic, we suggest using this point-of-care ICT kit for routine rapid screening in seriously ill COVID-19 patients who will be subjected to immunosuppressive treatment. Prompt anthelminthic treatment should be administered to prevent serious systemic strongyloidiasis in at-risk patients.