Diagnosis of \u3cem\u3eStrongyloides stercoralis\u3c/em\u3e: Detection of Parasite-Derived DNA in Urine

Detecting infections of Strongyloides stercoralis is arduous and has low sensitivity. Clinically this is a major problem because chronic infections may disseminate in the host and lead to a life threatening condition. Epidemiologically, S. stercoralis is often missed in surveys as it is difficult to identify by standard stool examination procedures. We present, for the first time, evidence that the infection can be detected in filtered urine samples collected and processed in the field and subsequently assayed for the presence of parasite DNA. Urine specimens (∼40 mL) were collected from 125 test and control individuals living in rural and peri-urban regions of Northern Argentina. From the same individuals, fresh stool specimens were processed using three different copropological methods. Urine specimens were filtered in the field through a 12.5 cm Whatman No. 3 filter. The filters were dried and packed individually in sealable plastic bags with desiccant and shipped to a laboratory where DNA was recovered from the filter and PCR-amplified with primers specific to a dispersed repetitive sequence. Prevalence of S. stercoralis infection by stool culture and direct examination was 35/125 (28%), In contrast, PCR-based detection of parasite-specific trans-renal DNA in urine indicated that 56/125 (44.8%) carried the parasite. Of the patients that tested positive for urine-based parasite DNA, approximately half also tested positive in their stool specimens. There were 6.4% of cases where parasite larvae were seen in the stool but no DNA was amplified from the urine. As proof of principle, DNA amplification from urine residue reveals significantly more cases of S. stercoralis infection than the current standard stool examination techniques. Additional work is required to establish the relative utility, sensitivity and specificity of urine-based analysis compared to parasitological and nucleic acid detection from stool for clinical and epidemiological detection for S. stercoralis infection

The Strongyloides stercoralis-hookworms association as a path to the estimation of the global burden of strongyloidiasis: A systematic review

Soil-transmitted helminths (STH) represent a significant public health problem. However, Strongyloides stercoralis is not yet integrated into the control strategy against STH, given limi- tations to accurately assess its burden. Considering that S. stercoralis shares biological and epidemiological characteristics with hookworms, we describe a new approach for an improved estimation of the burden of infections by S. stercoralis based on the prevalence and burden of hookworms and the relationship between these species. A systematic review of publications reporting prevalence rates for S. stercoralis and hookworms was carried out. The data was classified into two categories: 1) “Community”, with surveys including all age groups, and 2) “SAC”, with surveys limited to school-aged children. The relationship between S. stercoralis and hookworms was characterized in order to estimate the global burden of S. stercoralis infections. The study is registered in PROSPERO (CRD42019131127). Spearman correlation coefficient between S. stercoralis and hookworms was estimated and the global burden of S. stercoralis infections was estimated using a regression model. A total of 119 articles were included, and a significant positive correlation between the burden of S. stercoralis and hook- worms was identified. Spearman’s coefficient for Community surveys was 0.94 and for SAC surveys it was 0.63. Based on the linear model, the global burden of S. stercoralis infections was estimated at 386 million (95%CI 324–449 million) people, including 22 million (95%CI 20–24 million) SAC. The significant relationship between S. stercoralis and hookworms allows an estimation of the global burden of S. stercoralis infections in most epidemiologic settings using hookworm burden and justifies the search of integrated control activities

Safety and pharmacokinetic profile of fixed-dose ivermectin with an innovative 18mg tablet in healthy adult volunteers

Ivermectin is a pivotal drug for the control of onchocerciasis and lymphatic filariasis, which is increasingly identified as a useful drug for the control of other Neglected Tropical Diseases. Its role in the treatment of soil transmitted helminthiasis through improved efficacy against Trichuris trichiura in combination with other anthelmintics might accelerate the progress towards breaking transmission. Ivermectin is a derivative of Avermectin B1, and consists of an 80:20 mixture of the equipotent homologous 22,23 dehydro B1a and B1b. Pharmacokinetic characteristics and safety profile of ivermectin allow to explore innovative uses to further expand its utilization through mass drug administration campaigns to improve coverage rates. We conducted a phase I clinical trial with 54 healthy adult volunteers who sequentially received 2 experimental treatments using a new 18 mg ivermectin tablet in a fixed-dose strategy of 18 and 36 mg single dose regimens, compared to the standard, weight based 150-200 μg/kg, regimen. Volunteers were recruited in 3 groups based on body weight. Plasma concentrations of ivermectin were measured through HPLC up to 168 hours post treatment. Safety data showed no significant differences between groups and no serious adverse events: headache was the most frequent adverse event in all treatment groups, none of them severe. Pharmacokinetic parameters showed a half-life between 81 and 91 h in the different treatment groups. When comparing the systemic bioavailability (AUC0t and Cmax) of the reference product (WA-ref) with the other two study groups using fixed doses, we observed an overall increase in AUC0t and Cmax for the two experimental treatments of 18 mg and 36 mg. Body mass index (BMI) and weight were associated with t1/2 and V/F, probably reflecting the high liposolubility of IVM with longer retention times proportional to the presence of more adipose tissue. Systemic exposure to ivermectin (AUC0t or Cmax) was not associated with BMI or weight in our study. These findings contribute to further understand the pharmacokinetic characteristics of ivermectin, highlighting its safety across different dosing regimens. They also correlate with known pharmacokinetic parameters showing stable levels of AUC and Cmax across a wide range of body weights, which justifies the strategy of fix dosing from a pharmacokinetic perspective

A Novel, Species-Specific, Real-Time PCR Assay for the Detection of the Emerging Zoonotic Parasite Ancylostoma Ceylanicum in Human Stool

Historically, Ancylostoma ceylanicum has been viewed as an uncommon cause of human hookworm infection, with minimal public health importance. However, recent reports have indicated that this zoonotic hookworm causes a much greater incidence of infection within certain human populations than was previously believed. Current methods for the species-level detection of A. ceylanicum rely on techniques that involve conventional PCR accompanied by restriction enzyme digestions. These PCR-based assays are not only labo- rious but they lack sensitivity as they target suboptimal regions on the DNA. As efforts aimed at the eradication of hookworm disease have grown substantially over the last decade, the need for sensitive and specific tools to monitor and evaluate programmatic successes has correspondingly escalated. Since a growing body of evidence suggests that patient responses to drug treatment can vary based upon the species of hookworm that is causing infection, accurate species-level diagnostics are advantageous. Accordingly, the novel real-time PCR-based assay described here provides a sensitive, species-specific diag- nostic tool that will facilitate the accurate mapping of disease endemicity and will aid in the evaluation of progress of programmatic deworming efforts

Lack of efficacy of standard doses of ivermectin in severe COVID-19 patients

Ivermectin has recently shown efficacy against SARS-CoV-2 in-vitro. We retrospectively reviewed severe COVID-19 patients receiving standard doses of ivermectin and we compared clinical and microbiological outcomes with a similar group of patients not receiving ivermectin. No differences were found between groups. We recommend the evaluation of high-doses of ivermectin in randomized trials against SARS-CoV-2

Role of DNA-detection–based tools for monitoring the soil-transmitted helminth treatment response in drug-efficacy trials

[EN] More than 1 billion people have been reported to be infected with at least one soil-transmitted helminth (STH) worldwide, according to the last published report of the World Health Organization (WHO) [1]. WHO guidelines for STH control mainly encompass periodic administration of benzimidazoles (albendazole or mebendazole) to at-risk people of the endemic areas [1]. However, extended use of benzimidazoles could entail a great selection pressure for parasitic-resistant strains. In veterinary medicine, anthelmintic resistance in gastrointestinal nematodes has been developed in response to their excessive use, and it is currently considered a serious threat to livestock health and welfare [2, 3]. In humans, the estimated efficacy of albendazole and mebendazole against Trichuris trichiura has been observed to significantly decrease over time [4]. This observed decrement in drug efficacy could be due to the development of anthelmintic resistance (among other reasons such as drug quality and administration, the increasing of drug-efficacy studies, improvements in sensitivity of diagnostic tools after treatment, etc) after years of mass drug-administration campaigns, which is one of the major oncerns in STH controlSIThe Stopping Transmission Of intestinal Parasites (STOP) project is part of the EDCTP2 programme supported by the European Union (grant number RIA2017NCT-1845 — STOP). JG is personally supported by Ramon Areces Foundation, Spain; MMV by the Spanish ‘Ramo´n y Cajal’ Programme, Ministry of Economy and Competitiveness (RYC-2015-18368); and SK is supported by DELTAS Africa Initiative grant # DEL- 15-011 to THRiVE-2. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip

Strongyloides stercoralis: a plea for action.

This paper argues that enough is now known on this neglected parasite to justify starting specific control measures

Diagnostic accuracy of five serologic tests for Strongyloides stercoralis infection.

Background: The diagnosis of Strongyloides stercoralis (S. stercoralis) infection is hampered by the suboptimal sensitivity of fecal-based tests. Serological methods are believed to be more sensitive, although assessing their accuracy is difficult because of the lack of sensitivity of a fecal-based reference ('gold') standard. Methods: The sensitivity and specificity of 5 serologic tests for S. stercoralis (in-house IFAT, NIE-ELISA and NIE-LIPS and the commercially available Bordier-ELISA and IVD-ELISA) were assessed on 399 cryopreserved serum samples. Accuracy was measured using fecal results as the primary reference standard, but also using a composite reference standard (based on a combination of tests). Results: According to the latter standard, the most sensitive test was IFAT, with 94.6% sensitivity (91.2-96.9), followed by IVD-ELISA (92.3%, 87.7-96.9). The most specific test was NIE-LIPS, with specificity 99.6% (98.9-100), followed by IVD-ELISA (97.4%, 95.5-99.3). NIE-LIPS did not cross-react with any of the specimens from subjects with other parasitic infections. NIE-LIPS and the two commercial ELISAs approach 100% specificity at a cut off level that maintains ≥70% sensitivity. Conclusions: NIE-LIPS is the most accurate serologic test for the diagnosis of S. stercoralis infection. IFAT and each of the ELISA tests are sufficiently accurate, above a given cut off, for diagnosis, prevalence studies and inclusion in clinical trials

Transrenal DNA-based diagnosis of Strongyloides stercoralis (Grassi, 1879) infection: Bayesian latent class modeling of test accuracy.

For epidemiological work with soil transmitted helminths the recommended diagnostic approaches are to examine fecal samples for microscopic evidence of the parasite. In addition to several logistical and processing issues, traditional diagnostic approaches have been shown to lack the sensitivity required to reliably identify patients harboring low-level infections such as those associated with effective mass drug intervention programs. In this context, there is a need to rethink the approaches used for helminth diagnostics. Serological methods are now in use, however these tests are indirect and depend on individual immune responses, exposure patterns and the nature of the antigen. However, it has been demonstrated that cell-free DNA from pathogens and cancers can be readily detected in patient's urine which can be collected in the field, filtered in situ and processed later for analysis. In the work presented here, we employ three diagnostic procedures-stool examination, serology (NIE-ELISA) and PCR-based amplification of parasite transrenal DNA from urine-to determine their relative utility in the diagnosis of S. stercoralis infections from 359 field samples from an endemic area of Argentina. Bayesian Latent Class analysis was used to assess the relative performance of the three diagnostic procedures. The results underscore the low sensitivity of stool examination and support the idea that the use of serology combined with parasite transrenal DNA detection may be a useful strategy for sensitive and specific detection of low-level strongyloidiasis

Strongyloides stercoralis: a plea for action

More than one century later, the key issues regarding this parasite (subsequently renamed Strongyloides stercoralis) are essentially the same, and although researchers have recently given more attention to this infection, systematic action plans still lag behind. There is widespread agreement in the scientific community that its prevalence is largely underestimated [2]. The current estimate of 30 to 100 million infected persons in the world dates back to review articles published between 1989 and 1996 [3], [4], and is cited by most subsequent papers. These figures were mostly based on surveys aimed at defining the prevalence of parasitic infections, without using adequate diagnostic techniques for S. stercoralis. For example, Kato-Katz, a technique that is commonly used in surveys aiming to assess intestinal helminth infections [5], is poorly sensitive for this parasite. Larvae of S. stercoralis in stool are often scanty, and therefore they are most often missed by this technique that examines a small amount of faeces (between 20 and 50 mg, depending on the template). Larvae can be detected by this technique only occasionally, when the larval output is particularly high [6]. More reliable prevalence estimates have been made by geographically confined surveys, using alternative faecal-based diagnostic methods that are much more sensitive such as Baermann or Koga agar plate culture [7], [8]. Serology (ELISA or IFAT) is even more sensitive, but its specificity is less well defined. Problems of cross-reactivity seem to arise especially in areas where other nematodes, particularly filariae, are also endemic. New and promising tools such as serologic methods based on recombinant antigens or PCR are also available in some referral centers. However, the optimal diagnostic strategy, both for epidemiological surveys and for individual diagnosis and screening, has yet to be defined and certainly deserves further researc