Dataset Information

Limitations of PCR detection of filarial DNA in human stools from subjects non-infected with soil-transmitted helminths.

ABSTRACT: The standard techniques for diagnosis of human filariasis are the microscopic examination of blood smears or skin biopsies, which are relatively invasive and poorly sensitive at low levels of infection. Recently, filarial DNA has been detected in fecal samples from non-human primates in Central Africa. The aim of this study was to demonstrate proof-of-concept of a non-invasive molecular diagnosis technique for human filariasis by targeting fragments of 12S rDNA, Cox1, ITS1 and LL20-15kDa ladder antigen-gene by conventional PCR in DNA extracted from stool samples of 52 people infected with Mansonella perstans and/or Loa loa. Of these, 10 patients were infected with soil-transmitted helminths (Trichuris trichiura and/or Ascaris lumbricoides), and none were positive for Necator americanus. Interestingly, no filarial gene fragments were detected in the stools of any of the 52 patients. Future studies should evaluate whether a co-infection with soil-transmitted helminths causing gastrointestinal bleeding and likely allowing (micro)filaria exit into the digestive tract, may facilitate the molecular detection of filarial DNA fragments in stool samples.

SUBMITTER: Doret MPM

PROVIDER: S-EPMC8162058 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Limitations of PCR detection of filarial DNA in human stools from subjects non-infected with soil-transmitted helminths.

Doret Maxime P M MPM Nana-Djeunga Hugues C HC Nzune-Toche Narcisse N Pion Sébastien D S SDS Chesnais Cédric B CB Boussinesq Michel M Kamgno Joseph J Varlet-Marie Emmanuelle E Locatelli Sabrina S

Parasite (Paris, France) 20210527

The standard techniques for diagnosis of human filariasis are the microscopic examination of blood smears or skin biopsies, which are relatively invasive and poorly sensitive at low levels of infection. Recently, filarial DNA has been detected in fecal samples from non-human primates in Central Africa. The aim of this study was to demonstrate proof-of-concept of a non-invasive molecular diagnosis technique for human filariasis by targeting fragments of 12S rDNA, Cox1, ITS1 and LL20-15kDa ladder ...[more]

PMID: 34047694

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Project description:BackgroundDue to the recent increased use of the McMaster (MM) fecal egg counting method for assessing benzimidazole drug efficacy for treating soil-transmitted helminth (STH) infections, the aim of the current study was to determine the operational value of including the MM method alongside the Kato-Katz (KK) fecal thick smear to increase the diagnostic sensitivity when STHs are co-endemic with trematode helminths (e.g., Schistosoma mansoni).MethodsA cross-sectional study was conducted in school-aged children aged 4-18 years in the northeastern region of the State of Minas Gerais (Brazil), where Necator americanus, Ascaris lumbricoides, Trichuris trichiura, and S. mansoni are co-endemic. One fecal sample from each participant was collected and transported to the field laboratory for analysis. Coprological diagnosis was performed on each fecal sample by three different methods: Formalin-Ether Sedimentation (FES), KK and the MM technique. The diagnostic sensitivity and negative predictive value (NPV) of each technique was calculated using the combination of all three techniques as the composite standard. In order to determine the agreement between the three techniques Fleiss´ kappa was used. Both the Cure Rate (CR) and the Fecal Egg Count Reduction (FECR) were calculated using the two quantification techniques (i.e., the MM and KK).ResultsFecal samples from 1260 children were analyzed. The KK had higher diagnostic sensitivity than the MM for the detection of both A. lumbricoides (KK 97.3%, MM 69.5%) and hookworm (KK 95.1%, MM 80.8%). The CR of a single dose of mebendazole varied significantly between the KK and MM for both A. lumbricoides (p = 0.016) and hookworm (p = 0.000), with lower rates obtained with the KK. On the other hand, the FECR was very similar between both techniques for both A. lumbricoides and hookworm.ConclusionThe MM did not add any diagnostic value over the KK in areas where both STHs and trematodes were co-endemic. The lower sensitivity of the MM would have an important impact on the administration of selective school-based treatment in this area since if only the MM were used, 36 (13.9%) children diagnosed with A. lumbricoides would have gone untreated.

Project description:BackgroundConventional microscopy of Kato-Katz (KK1.0) thick smears, the primary method for diagnosing soil-transmitted helminth (STH) infections, has limited sensitivity and is error-prone. Artificial intelligence-based digital pathology (AI-DP) may overcome the constraints of traditional microscopy-based diagnostics. This study in Ucayali, a remote Amazonian region of Peru, compares the performance of AI-DP-based Kato-Katz (KK2.0) method to KK1.0 at diagnosing STH infections in school-aged children (SAC).MethodsIn this prospective, non-interventional study, 510 stool samples from SAC (aged 5-14 years) were analyzed using KK1.0, KK2.0, and tube spontaneous sedimentation technique (TSET). KK1.0 and KK2.0 slides were evaluated at 30-minute and 24-hour timepoints for detection of Ascaris lumbricoides, Trichuris trichiura, and hookworms (at 30-minute only). Diagnostic performance was assessed by measuring STH eggs per gram of stool (EPG), sensitivity of methods, and agreement between the methods.ResultsKK2.0 detected more A. lumbricoides positive samples than KK1.0, with detection rates for T. trichiura and hookworms being comparable. At 30-minutes, 37.6%, 23.0%, and 2.6% of the samples tested positive based on KK1.0 for A. lumbricoides, T. trichiura, and hookworms, while this was 49.8%, 24.4%, and 1.9% for KK2.0. At 24-hours, 37.1% and 27.1% of the samples tested positive based on KK1.0 for A. lumbricoides and T. trichiura, while this was 45.8% and 24.1% for KK2.0. Mean EPG between KK2.0 and KK1.0 were not statistically different across STH species and timepoints, except for T. trichiura at 24-hours (higher mean EPG for KK1.0, p = 0.036). When considering infection intensity levels, KK2.0 identified 10% more of the total population as low-infection intensity samples of A. lumbricoides than KK1.0 (p ≤ 0.001, both timepoints) and similar to KK1.0 for T. trichiura and hookworms. Varying agreement existed between KK1.0 and KK2.0 in detecting STH eggs (A. lumbricoides: moderate; T. trichiura: substantial; hookworms: slight). However, these findings should be interpreted carefully as there are certain limitations that may have impacted the results of this study.ConclusionsThis study demonstrates the potential of the AI-DP-based method for STH diagnosis. While similar to KK1.0, the AI-DP-based method outperforms it in certain aspects. These findings underscore the potential of advancing the AI-DP KK2.0 prototype for dependable STH diagnosis and furthering the development of automated digital microscopes in accordance with WHO guidelines for STH diagnosis.

Project description:BackgroundSoil-transmitted helminths (STHs) infect over a billion individuals worldwide. In India, 241 million children are estimated to need deworming to avert the negative consequences STH infections can have on child health and development. In February-April 2011, 17 million children in Bihar State were dewormed during a government-led school-based deworming campaign. Prior to programme implementation, a study was conducted to assess STH prevalence in the school-age population to direct the programme. The study also investigated risk factors for STH infections, including caste, literacy, and defecation and hygiene practices, in order to inform the development of complementary interventions.MethodsA cross-sectional survey was conducted among children in 20 schools in Bihar. In addition to providing stool samples for identification of STH infections, children completed a short questionnaire detailing their usual defecation and hand-hygiene practices. Risk factors for STH infections were explored.ResultsIn January-February 2011, 1279 school children aged four to seventeen provided stool samples and 1157 children also completed the questionnaire. Overall, 68% of children (10-86% across schools) were infected with one or more soil-transmitted helminth species. The prevalence of ascariasis, hookworm and trichuriasis was 52%, 42% and 5% respectively. The majority of children (95%) practiced open defecation and reported most frequently cleansing hands with soil (61%). Increasing age, lack of maternal literacy and certain castes were independently associated with hookworm infection. Absence of a hand-washing station at the schools was also independently associated with A. lumbricoides infection.ConclusionsSTH prevalence in Bihar is high, and justifies mass deworming in school-aged children. Open defecation is common-place and hands are often cleansed using soil. The findings reported here can be used to help direct messaging appropriate to mothers with low levels of literacy and emphasise the importance of water and sanitation in the control of helminths and other diseases.

Dataset Information

Limitations of PCR detection of filarial DNA in human stools from subjects non-infected with soil-transmitted helminths.

Publications

Limitations of PCR detection of filarial DNA in human stools from subjects non-infected with soil-transmitted helminths.

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