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Schutte AHJ, Koelewijn R, Ajjampur SSR, Levecke B, McCarthy JS, Mejia R, Williams SA, Verweij JJ, van Lieshout L, van Hellemond JJ. Detection of soil-transmitted helminths and Schistosoma spp. by nucleic acid amplification test: Results of the first 5 years of the only international external quality assessment scheme. PLoS Negl Trop Dis 2024; 18:e0012404. [PMID: 39116195 DOI: 10.1371/journal.pntd.0012404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 07/25/2024] [Indexed: 08/10/2024] Open
Abstract
BACKGROUND Infections with soil-transmitted helminths (STH) and schistosomiasis (SCH) result in a significant global health burden, particularly in rural communities in low and middle-income countries. While microscopy remains the primary diagnostic method for STH and SCH in resource-limited settings, nucleic acid amplification tests (NAATs) are gaining prominence as tools for evaluation of public health control programs in endemic countries, and individual diagnosis in high-income countries. Despite the high sensitivity and specificity of NAATs, previous research has highlighted inter-laboratory variations, both in technical and clinical performance, justifying the need for continuous proficiency testing. METHODOLOGY Results from 5 rounds over a 5-year period of the so far only longitudinal international Helminth External Molecular Quality Assessment Scheme (HEMQAS), coordinated by the Dutch Foundation for Quality Assessment in Medical Laboratories (SKML), were examined in order to (i) assess the diagnostic proficiency of laboratories in detecting helminths in stool and (ii) identify potential factors contributing to variations in performance. OUTCOME AND CONCLUSIONS Thirty-six laboratories, from 18 countries and 5 continents, participated in HEMQAS. The overall diagnostic performances were satisfying, with remarkably low numbers (<2%) of false-positive results. False-negative results were more often reported for stool (15%) than for DNA (5%) samples. False-negative results varied largely between targets (the highest number (29%) for Trichuris trichiura). Twenty-five laboratories provided a sufficient number of results for a robust comparison between participating laboratories, which confirmed substantial inter-laboratory variability in quantitative NAAT results (Cq-values). This variability likely arises from differences in pre-treatment, DNA isolation and DNA-target amplification procedures. This study emphasizes the complexity of molecular diagnosis for STH and SCH, highlighting the critical role of proper stool preparation and DNA isolation methods. The results underscore the necessity for laboratory professionals and public health decision-makers to recognize these complexities and continuously undertake external quality assessment schemes to ensure accurate and reliable performance in molecular diagnosis.
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Affiliation(s)
- Annemiek H J Schutte
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Rob Koelewijn
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Sitara S R Ajjampur
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, Tamil Nadu, India
| | - Bruno Levecke
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
| | - James S McCarthy
- The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Australia
| | - Rojelio Mejia
- Department of Pediatrics-Tropical Medicine, Baylor College of Medicine, Houston, Texas, United States of America
| | - Steven A Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Jaco J Verweij
- Laboratory for Medical Microbiology and Immunology, Elisabeth-Tweesteden Hospital, Tilburg, the Netherlands
| | - Lisette van Lieshout
- Leiden University Center for Infectious Diseases (LU-CID); Parasitology group, Leiden University Medical Center, Leiden, The Netherlands
| | - Jaap J van Hellemond
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
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Wolstenholme AJ, Andersen EC, Choudhary S, Ebner F, Hartmann S, Holden-Dye L, Kashyap SS, Krücken J, Martin RJ, Midha A, Nejsum P, Neveu C, Robertson AP, von Samson-Himmelstjerna G, Walker R, Wang J, Whitehead BJ, Williams PDE. Getting around the roundworms: Identifying knowledge gaps and research priorities for the ascarids. ADVANCES IN PARASITOLOGY 2024; 123:51-123. [PMID: 38448148 PMCID: PMC11143470 DOI: 10.1016/bs.apar.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
The ascarids are a large group of parasitic nematodes that infect a wide range of animal species. In humans, they cause neglected diseases of poverty; many animal parasites also cause zoonotic infections in people. Control measures include hygiene and anthelmintic treatments, but they are not always appropriate or effective and this creates a continuing need to search for better ways to reduce the human, welfare and economic costs of these infections. To this end, Le Studium Institute of Advanced Studies organized a two-day conference to identify major gaps in our understanding of ascarid parasites with a view to setting research priorities that would allow for improved control. The participants identified several key areas for future focus, comprising of advances in genomic analysis and the use of model organisms, especially Caenorhabditis elegans, a more thorough appreciation of the complexity of host-parasite (and parasite-parasite) communications, a search for novel anthelmintic drugs and the development of effective vaccines. The participants agreed to try and maintain informal links in the future that could form the basis for collaborative projects, and to co-operate to organize future meetings and workshops to promote ascarid research.
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Affiliation(s)
- Adrian J Wolstenholme
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Université de Tours, ISP, Nouzilly, France.
| | - Erik C Andersen
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
| | - Shivani Choudhary
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Friederike Ebner
- Department of Molecular Life Sciences, School of Life Sciences, Technische Universität München, Freising, Germany
| | - Susanne Hartmann
- Institute for Immunology, Freie Universität Berlin, Berlin, Germany
| | - Lindy Holden-Dye
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Sudhanva S Kashyap
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Richard J Martin
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Ankur Midha
- Institute for Immunology, Freie Universität Berlin, Berlin, Germany
| | - Peter Nejsum
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Cedric Neveu
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Université de Tours, ISP, Nouzilly, France
| | - Alan P Robertson
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | | | - Robert Walker
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Jianbin Wang
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, United States
| | | | - Paul D E Williams
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
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Hon KL, Leung AKC. An update on the current and emerging pharmacotherapy for the treatment of human ascariasis. Expert Opin Pharmacother 2024. [PMID: 38372051 DOI: 10.1080/14656566.2024.2319686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 02/13/2024] [Indexed: 02/20/2024]
Abstract
INTRODUCTION Globally, Ascaris lumbricoides is the commonest helminthic infection that affects people in underdeveloped countries and returning immigrants in industrialized nations. This article aims to provide latest updates on the epidemiology, clinical manifestations, and pharmacotherapy of ascariasis. AREAS COVERED A PubMed search was conducted using Clinical Queries and the key terms 'human ascariasis' OR 'Ascaris lumbricoides.' Ascaris lumbricoides is highly endemic in tropical and subtropic regions and among returning immigrants in industrialized nations. Predisposing factors include poor sanitation and poverty. The prevalence is greatest in young children. Most infected patients are asymptomatic. Patients with A. lumbricoides infection should be treated with anti-helminthic drugs to prevent complications from migration of the worm. Mebendazole and albendazole are indicated for children and nonpregnant women. Pregnant individuals should be treated with pyrantel pamoate. EXPERT OPINION Cure rates with anthelmintic treatment are high. No emerging pharmacotherapy can replace these existing drugs of good efficacy, safety profile and low cost for public health. It is opinioned that advances in the management of ascariasis include diagnostic accuracy at affordable costs, Emodepside is highly effective in single doses against ascarids in mammals and in human trials. The drug could be registered for human use in multiple neglected tropical diseases.
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Affiliation(s)
- Kam Lun Hon
- Department of Paediatrics, The Chinese University of Hong Kong, and Department of Paediatrics and Adolescent Medicine, Hong Kong Children's Hospital, Hong Kong, China
| | - Alexander K C Leung
- Department of Pediatrics, The University of Calgary and the Alberta Children's Hospital, Calgary, Alberta, Canada
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Bradbury RS, Martin L, Malloch L, Martin M, Williams JM, Patterson K, Sanders C, Singh G, Arguello I, Rodriguez E, Byers P, Haynie L, Qvarnstrom Y, Hobbs CV. Surveillance for Soil-Transmitted Helminths in High-Risk County, Mississippi, USA. Emerg Infect Dis 2023; 29:2533-2537. [PMID: 37987591 PMCID: PMC10683803 DOI: 10.3201/eid2912.230709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023] Open
Abstract
Recent reports of hookworm infection in Alabama, USA, has prompted surveillance in Mississippi, given the states' similar environmental conditions. We collected stool specimens from 277 children in Rankin County, Mississippi. Kato-Katz microscopic smear, agar plate culture, and quantitative PCR indicated no soil-transmitted helminths. Nevertheless, further surveillance in other high-risk Mississippi counties is warranted.
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Doherty M, Grant JR, Pilotte N, Bennuru S, Fischer K, Fischer PU, Lustigman S, Nutman TB, Pfarr K, Hoerauf A, Unnasch TR, Hassan HK, Wanji S, Lammie PJ, Ottesen E, Mackenzie C, Williams SA. Optimized strategy for real-time qPCR detection of Onchocerca volvulus DNA in pooled Simulium sp. blackfly vectors. PLoS Negl Trop Dis 2023; 17:e0011815. [PMID: 38096317 PMCID: PMC10754622 DOI: 10.1371/journal.pntd.0011815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 12/28/2023] [Accepted: 11/22/2023] [Indexed: 12/30/2023] Open
Abstract
BACKGROUND Onchocerca volvulus is a filarial parasite that is a major cause of dermatitis and blindness in endemic regions primarily in sub-Saharan Africa. Widespread efforts to control the disease caused by O. volvulus infection (onchocerciasis) began in 1974 and in recent years, following successful elimination of transmission in much of the Americas, the focus of efforts in Africa has moved from control to the more challenging goal of elimination of transmission in all endemic countries. Mass drug administration (MDA) with ivermectin has reached more than 150 million people and elimination of transmission has been confirmed in four South American countries, with at least two African countries having now stopped MDA as they approach verification of elimination. It is essential that accurate data for active transmission are used to assist in making the critical decision to stop MDA, since missing low levels of transmission and infection can lead to continued spread or recrudescence of the disease. METHODOLOGY/PRINCIPAL FINDINGS Current World Health Organization guidelines for MDA stopping decisions and post-treatment surveillance include screening pools of the Simulium blackfly vector for the presence of O. volvulus larvae using a PCR-ELISA-based molecular technique. In this study, we address the potential of an updated, practical, standardized molecular diagnostic tool with increased sensitivity and species-specificity by comparing several candidate qPCR assays. When paired with heat-stable reagents, a qPCR assay with a mitochondrial DNA target (OvND5) was found to be more sensitive and species-specific than an O150 qPCR, which targets a non-protein coding repetitive DNA sequence. The OvND5 assay detected 19/20 pools of 100 blackfly heads spiked with a single L3, compared to 16/20 for the O150 qPCR assay. CONCLUSIONS/SIGNIFICANCE Given the improved sensitivity, species-specificity and resistance to PCR inhibitors, we identified OvND5 as the optimal target for field sample detection. All reagents for this assay can be shipped at room temperature with no loss of activity. The qPCR protocol we propose is also simpler, faster, and more cost-effective than the current end-point molecular assays.
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Affiliation(s)
- Mary Doherty
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Jessica R. Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Nils Pilotte
- Department of Biological Sciences, Quinnipiac University, Hamden, Connecticut, United States of America
| | - Sasisekhar Bennuru
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - Kerstin Fischer
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Peter U. Fischer
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - Thomas B. Nutman
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - Kenneth Pfarr
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), Partner-Site Bonn-Cologne, Bonn, Germany
| | - Achim Hoerauf
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), Partner-Site Bonn-Cologne, Bonn, Germany
| | - Thomas R. Unnasch
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida, United States of America
| | - Hassan K. Hassan
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida, United States of America
| | - Samuel Wanji
- Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and the Environment, Buea, Cameroon
| | - Patrick J. Lammie
- NTD-SC, Task Force for Global Health, Atlanta, Georgia, United States of America
| | - Eric Ottesen
- NTD-SC, Task Force for Global Health, Atlanta, Georgia, United States of America
| | - Charles Mackenzie
- NTD-SC, Task Force for Global Health, Atlanta, Georgia, United States of America
- RLMF, The END Fund, New York, New York, United States of America
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
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Poole C, Barker T, Bradbury R, Capone D, Chatham AH, Handali S, Rodriguez E, Qvarnstrom Y, Brown J. Cross-Sectional Study of Soil-Transmitted Helminthiases in Black Belt Region of Alabama, USA. Emerg Infect Dis 2023; 29:2461-2470. [PMID: 37987581 PMCID: PMC10683802 DOI: 10.3201/eid2912.230751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023] Open
Abstract
We conducted a cross-sectional study to determine the prevalence of soil-transmitted helminthiases (STH) in areas of rural Alabama, USA, that have sanitation deficits. We enrolled 777 children; 704 submitted stool specimens and 227 a dried blood spot sample. We microscopically examined stool specimens from all 704 children by using Mini-FLOTAC for helminth eggs. We tested a subset by using molecular techniques: real-time PCR analysis for 5 STH species, TaqMan Array Cards for enteric helminths, and digital PCR for Necator americanus hookworm. We analyzed dried blood spots for Strongyloides stercoralis and Toxocara spp. roundworms by using serologic testing. Despite 12% of our cohort reporting living in homes that directly discharge untreated domestic wastewater, stool testing for STH was negative; however, 5% of dried blood spots were positive for Toxocara spp. roundworms. Survey data suggests substantial numbers of children in this region may be exposed to raw sewage, which is itself a major public health concern.
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Bennuru S, Kodua F, Drame PM, Dahlstrom E, Nutman TB. A Novel, Highly Sensitive Nucleic Acid Amplification Test Assay for the Diagnosis of Loiasis and its Use for Detection of Circulating Cell-Free DNA. J Infect Dis 2023; 228:936-943. [PMID: 37243712 PMCID: PMC11009493 DOI: 10.1093/infdis/jiad186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/25/2023] [Accepted: 05/24/2023] [Indexed: 05/29/2023] Open
Abstract
Mass drug administration programs targeting filarial infections depend on diagnostic tools that are sensitive and specific. The coendemicity of Loa loa with other filarial species often hampers the control programs. LL2634 was identified as the most promising target among several highly repeated targets, with sensitivity between 500 ag and 1 fg of genomic DNA. Using DNA from infected individuals, LL2643 quantitative polymerase chain reaction (qPCR) was positive in all individuals. LL2643 was detected in plasma-derived circulating cell-free DNA (ccfDNA) from 48 of 53 microfilariae-positive patients. Detection of ccfDNA in urine was possible, but it occurred rarely among those tested. Importantly, LL2643 ccfDNA became undetectable within 1 month following diethylcarbamazine (DEC) treatment and remained negative for at least a year. LL2643 offers a more sensitive and specific target for detection of L. loa infection and would be easily configurable to a point-of-contact assay. Clinical Trials Registration. NCT00001230 and NCT00090662.
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Affiliation(s)
- Sasisekhar Bennuru
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Frimpong Kodua
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Papa Makhtar Drame
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Eric Dahlstrom
- Genomics Unit, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Thomas B Nutman
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Pilotte N, Thomas T, Zulch MF, Sirois AR, Minetti C, Reimer LJ, Williams SA, Saunders LJ. Targeting a highly repetitive genomic sequence for sensitive and specific molecular detection of the filarial parasite Mansonella perstans from human blood and mosquitoes. PLoS Negl Trop Dis 2022; 16:e0010615. [PMID: 36580452 PMCID: PMC9833530 DOI: 10.1371/journal.pntd.0010615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 01/11/2023] [Accepted: 12/15/2022] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Mansonella perstans is among the most neglected of the neglected tropical diseases and is believed to cause more human infections than any other filarial pathogen in Africa. Based largely upon assumptions of limited infection-associated morbidity, this pathogen remains understudied, and many basic questions pertaining to its pathogenicity, distribution, prevalence, and vector-host relationships remain unanswered. However, in recent years, mounting evidence of the potential for increased Mansonella infection-associated disease has sparked a renewal in research interest. This, in turn, has produced a need for improved diagnostics, capable of providing more accurate pictures of infection prevalence, pathogen distribution, and vector-host interactions. METHODOLOGY/PRINCIPAL FINDINGS Utilizing a previously described pipeline for the discovery of optimal molecular diagnostic targets, we identified a repetitive DNA sequence, and developed a corresponding assay, which allows for the sensitive and species-specific identification of M. perstans in human blood samples. Testing also demonstrated the ability to utilize this assay for the detection of M. perstans in field-collected mosquito samples. When testing both sample types, our repeat-targeting index assay outperformed a ribosomal sequence-targeting reference assay, facilitating the identification of additional M. perstans-positive samples falsely characterized as "negative" using the less sensitive detection method. CONCLUSIONS/SIGNIFICANCE Through the development of an assay based upon the systematic identification of an optimal DNA target sequence, our novel diagnostic assay will provide programmatic efforts with a sensitive and specific testing platform that is capable of accurately mapping M. perstans infection and determining prevalence. Furthermore, with the added ability to identify the presence of M. perstans in mosquito samples, this assay will help to define our knowledge of the relationships that exist between this pathogen and the various geographically relevant mosquito species, which have been surmised to represent potential secondary vectors under certain conditions. Detection of M. perstans in mosquitoes will also demonstrate proof-of-concept for the mosquito-based monitoring of filarial pathogens not vectored primarily by mosquitoes, an approach expanding opportunities for integrated surveillance.
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Affiliation(s)
- Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Department of Biological Sciences, Quinnipiac University, Hamden, Connecticut, United States of America
| | - Tamara Thomas
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Michael F. Zulch
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Allison R. Sirois
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Corrado Minetti
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Lisa J. Reimer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Lori J. Saunders
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
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Rinaldi L, Krücken J, Martinez-Valladares M, Pepe P, Maurelli MP, de Queiroz C, Castilla Gómez de Agüero V, Wang T, Cringoli G, Charlier J, Gilleard JS, von Samson-Himmelstjerna G. Advances in diagnosis of gastrointestinal nematodes in livestock and companion animals. ADVANCES IN PARASITOLOGY 2022; 118:85-176. [PMID: 36088084 DOI: 10.1016/bs.apar.2022.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Diagnosis of gastrointestinal nematodes in livestock and companion animals has been neglected for years and there has been an historical underinvestment in the development and improvement of diagnostic tools, undermining the undoubted utility of surveillance and control programmes. However, a new impetus by the scientific community and the quickening pace of technological innovations, are promoting a renaissance of interest in developing diagnostic capacity for nematode infections in veterinary parasitology. A cross-cutting priority for diagnostic tools is the development of pen-side tests and associated decision support tools that rapidly inform on the levels of infection and morbidity. This includes development of scalable, parasite detection using artificial intelligence for automated counting of parasitic elements and research towards establishing biomarkers using innovative molecular and proteomic methods. The aim of this review is to assess the state-of-the-art in the diagnosis of helminth infections in livestock and companion animals and presents the current advances of diagnostic methods for intestinal parasites harnessing (i) automated methods for copromicroscopy based on artificial intelligence, (ii) immunodiagnosis, and (iii) molecular- and proteome-based approaches. Regardless of the method used, multiple factors need to be considered before diagnostics test results can be interpreted in terms of control decisions. Guidelines on how to apply diagnostics and how to interpret test results in different animal species are increasingly requested and some were recently made available in veterinary parasitology for the different domestic species.
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Affiliation(s)
- Laura Rinaldi
- Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Naples, Italy.
| | - J Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Veterinary Centre for Resistance Research, Freie Universität Berlin, Berlin, Germany
| | - M Martinez-Valladares
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de León, León, Spain
| | - P Pepe
- Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Naples, Italy
| | - M P Maurelli
- Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Naples, Italy
| | - C de Queiroz
- Faculty of Veterinary Medicine, 3331 Hospital Drive, Host-Parasite Interactions (HPI) Program University of Calgary, Calgary, Alberta, Canada; Faculty of Veterinary Medicine, St Georges University, Grenada
| | - V Castilla Gómez de Agüero
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de León, León, Spain
| | - T Wang
- Kreavet, Kruibeke, Belgium
| | - Giuseppe Cringoli
- Department of Veterinary Medicine and Animal Production, University of Naples "Federico II", Naples, Italy
| | | | - J S Gilleard
- Faculty of Veterinary Medicine, 3331 Hospital Drive, Host-Parasite Interactions (HPI) Program University of Calgary, Calgary, Alberta, Canada
| | - G von Samson-Himmelstjerna
- Institute for Parasitology and Tropical Veterinary Medicine, Veterinary Centre for Resistance Research, Freie Universität Berlin, Berlin, Germany
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Sears WJ, Cardenas J, Kubofcik J, Nutman TB, Cooper PJ. Zoonotic Ancylostoma ceylanicum Hookworm Infections, Ecuador. Emerg Infect Dis 2022; 28:1867-1869. [PMID: 35997627 PMCID: PMC9423896 DOI: 10.3201/eid2809.220248] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Ancylostoma ceylanicum hookworms are zoonotic parasites that can infect humans. To detect autochthonous transmission, we analyzed human fecal samples collected in 2000. Multiparallel quantitative PCR detected infection in persons who had never traveled outside Ecuador. These data indicate human transmission of A. ceylanicum in the Americas, although endemicity remains unknown.
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11
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Papaiakovou M, Littlewood DTJ, Doyle SR, Gasser RB, Cantacessi C. Worms and bugs of the gut: the search for diagnostic signatures using barcoding, and metagenomics-metabolomics. Parasit Vectors 2022; 15:118. [PMID: 35365192 PMCID: PMC8973539 DOI: 10.1186/s13071-022-05225-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 02/25/2022] [Indexed: 02/07/2023] Open
Abstract
Gastrointestinal (GI) helminth infections cause significant morbidity in both humans and animals worldwide. Specific and sensitive diagnosis is central to the surveillance of such infections and to determine the effectiveness of treatment strategies used to control them. In this article, we: (i) assess the strengths and limitations of existing methods applied to the diagnosis of GI helminth infections of humans and livestock; (ii) examine high-throughput sequencing approaches, such as targeted molecular barcoding and shotgun sequencing, as tools to define the taxonomic composition of helminth infections; and (iii) discuss the current understanding of the interactions between helminths and microbiota in the host gut. Stool-based diagnostics are likely to serve as an important tool well into the future; improved diagnostics of helminths and their environment in the gut may assist the identification of biomarkers with the potential to define the health/disease status of individuals and populations, and to identify existing or emerging anthelmintic resistance.
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Affiliation(s)
- Marina Papaiakovou
- Department of Veterinary Medicine, University of Cambridge, Cambridge, CB3 0ES UK
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | | | | | - Robin B. Gasser
- Melbourne Veterinary School, The University of Melbourne, Parkville, VIC 3010 Australia
| | - Cinzia Cantacessi
- Department of Veterinary Medicine, University of Cambridge, Cambridge, CB3 0ES UK
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12
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Halili S, Grant JR, Pilotte N, Gordon CA, Williams SA. Development of a novel real-time polymerase chain reaction assay for the sensitive detection of Schistosoma japonicum in human stool. PLoS Negl Trop Dis 2021; 15:e0009877. [PMID: 34695134 PMCID: PMC8568117 DOI: 10.1371/journal.pntd.0009877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 11/04/2021] [Accepted: 10/06/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Elimination and control of Schistosoma japonicum, the most virulent of the schistosomiasis-causing blood flukes, requires the development of sensitive and specific diagnostic tools capable of providing an accurate measurement of the infection prevalence in endemic areas. Typically, detection of S. japonicum has occurred using the Kato-Katz technique, but this methodology, which requires skilled microscopists, has been shown to radically underestimate levels of infection. With the ever-improving capabilities of next-generation sequencing and bioinformatic analysis tools, identification of satellite sequences and other highly repetitive genomic elements for use as real-time PCR diagnostic targets is becoming increasingly common. Assays developed using these targets have the ability to improve the sensitivity and specificity of results for epidemiological studies that can in turn be used to inform mass drug administration and programmatic decision making. METHODOLOGY/PRINCIPAL FINDINGS Utilizing Tandem Repeat Analyzer (TAREAN) and RepeatExplorer2, a cluster-based analysis of the S. japonicum genome was performed and a tandemly arranged genomic repeat, which we named SjTR1 (Schistosoma japonicum Tandem Repeat 1), was selected as the target for a real-time PCR diagnostic assay. Based on these analyses, a primer/probe set was designed and the assay was optimized. The resulting real-time PCR test was shown to reliably detect as little as 200 ag of S. japonicum genomic DNA and as little as 1 egg per gram of human stool. Based on these results, the index assay reported in this manuscript is more sensitive than previously published real-time PCR assays for the detection of S. japonicum. CONCLUSIONS/SIGNIFICANCE The extremely sensitive and specific diagnostic assay described in this manuscript will facilitate the accurate detection of S. japonicum, particularly in regions with low levels of endemicity. This assay will be useful in providing data to inform programmatic decision makers, aiding disease control and elimination efforts.
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Affiliation(s)
- Sara Halili
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Program in Biochemistry, Smith College, Northampton, Massachusetts, United States of America
| | - Jessica R. Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Department of Biological Sciences, Quinnipiac University, Hamden, Connecticut, United States of America
| | - Catherine A. Gordon
- QIMR Berghofer Institute of Medical Research, Molecular Parasitology Laboratory, Brisbane, Australia
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Program in Biochemistry, Smith College, Northampton, Massachusetts, United States of America
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
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13
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Braseth AL, Elliott DE, Ince MN. Parasitic Infections of the Gastrointestinal Track and Liver. Gastroenterol Clin North Am 2021; 50:361-381. [PMID: 34024446 PMCID: PMC11095845 DOI: 10.1016/j.gtc.2021.02.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Parasites have coevolved with humans. Several of them colonize the human body and establish a symbiotic relationship. Other parasites cause severe and lethal diseases. Prevalence of parasitic infections is decreased in highly industrialized countries, largely due to enforced hygienic practices. In contrast, parasites cause significant morbidity and mortality in parts of the world with barriers to effective public hygiene. Some parasites have emerged as potent pathogens in specific patient populations, such as immune suppressed individuals, regardless of sanitation. This article reviews common parasites encountered in clinical practice and, in the setting of host-parasite symbiosis, discusses their immune regulatory role.
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Affiliation(s)
- Annie L Braseth
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Iowa, Carver College of Medicine, Iowa City, IA 52242, USA
| | - David E Elliott
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Iowa, Carver College of Medicine, 4546 JCP, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - M Nedim Ince
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Iowa, Carver College of Medicine, 4546 JCP, 200 Hawkins Drive, Iowa City, IA 52242, USA.
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14
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Papaiakovou M, Littlewood DTJ, Gasser RB, Anderson RM. How qPCR complements the WHO roadmap (2021-2030) for soil-transmitted helminths. Trends Parasitol 2021; 37:698-708. [PMID: 33931342 DOI: 10.1016/j.pt.2021.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/02/2021] [Accepted: 04/08/2021] [Indexed: 12/19/2022]
Abstract
Complementing the launch of the World Health Organization (WHO) roadmap (2021-2030) we explore key elements needing attention before recruitment of qPCR as the main diagnostics tool to confirm reduction or elimination of soil-transmitted helminth (STH) transmission in both control and elimination programmes. Given the performance limitations of conventional methods, a proposed harmonised qPCR will provide a diagnostic tool, with the sensitivity and specificity required to monitor low-intensity infections, following mass drug administration (MDA). Technical and logistical challenges associated with introducing qPCR as a stand-alone tool are highlighted, and a decision-making scheme on how qPCR can support surveillance, resistance detection, and elimination is presented. An accurate point-of-care (POC) diagnostic test needs to be developed to support STH control in the field, and STH biorepositories need to be established and maintained to ensure that reference materials are available for research and validation.
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Affiliation(s)
- Marina Papaiakovou
- Department of Infectious Disease Epidemiology, St Mary's Campus, Imperial College London, London, UK; London Centre for Neglected Tropical Disease Research (LCNTDR), Imperial College London, London, UK.
| | - D Timothy J Littlewood
- Science Directorate, Natural History Museum, London, UK; London Centre for Neglected Tropical Disease Research (LCNTDR), Imperial College London, London, UK
| | - Robin B Gasser
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Roy M Anderson
- Department of Infectious Disease Epidemiology, St Mary's Campus, Imperial College London, London, UK; London Centre for Neglected Tropical Disease Research (LCNTDR), Imperial College London, London, UK
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15
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Wang J. Genomics of the Parasitic Nematode Ascaris and Its Relatives. Genes (Basel) 2021; 12:493. [PMID: 33800545 PMCID: PMC8065839 DOI: 10.3390/genes12040493] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/22/2021] [Accepted: 03/26/2021] [Indexed: 12/18/2022] Open
Abstract
Nematodes of the genus Ascaris are important parasites of humans and swine, and the phylogenetically related genera (Parascaris, Toxocara, and Baylisascaris) infect mammals of veterinary interest. Over the last decade, considerable genomic resources have been established for Ascaris, including complete germline and somatic genomes, comprehensive mRNA and small RNA transcriptomes, as well as genome-wide histone and chromatin data. These datasets provide a major resource for studies on the basic biology of these parasites and the host-parasite relationship. Ascaris and its relatives undergo programmed DNA elimination, a highly regulated process where chromosomes are fragmented and portions of the genome are lost in embryonic cells destined to adopt a somatic fate, whereas the genome remains intact in germ cells. Unlike many model organisms, Ascaris transcription drives early development beginning prior to pronuclear fusion. Studies on Ascaris demonstrated a complex small RNA network even in the absence of a piRNA pathway. Comparative genomics of these ascarids has provided perspectives on nematode sex chromosome evolution, programmed DNA elimination, and host-parasite coevolution. The genomic resources enable comparison of proteins across diverse species, revealing many new potential drug targets that could be used to control these parasitic nematodes.
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Affiliation(s)
- Jianbin Wang
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA;
- UT-Oak Ridge National Laboratory Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA
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16
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Leung AK, Leung AA, Wong AH, Hon KL. Human Ascariasis: An Updated Review. ACTA ACUST UNITED AC 2021; 14:133-145. [DOI: 10.2174/1872213x14666200705235757] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 05/25/2020] [Accepted: 06/11/2020] [Indexed: 11/22/2022]
Abstract
Background:
Ascaris lumbricoides is the most common helminthic infection. More than
1.2 billion people have ascariasis worldwide.
Objective:
This article aimed to provide an update on the evaluation, diagnosis, and treatment of ascariasis.
Methods:
A PubMed search was conducted in February 2020 in Clinical Queries using the key
terms “ascariasis” OR “Ascaris lumbricoides”. The search strategy included meta-analyses, randomized
controlled trials, clinical trials, observational studies, and reviews published within the
past 10 years. The search was restricted to English literature. The information retrieved from the
above search was used in the compilation of the present article. Patents were searched using the
key term “ascariasis” OR “Ascaris lumbricoides” in www.freepatentsonline.com.
Results:
Ascaris lumbricoides is transmitted through the ingestion of embryonated eggs from fecal-
contaminated material. Ascariasis has high endemicity in tropical and subtropical areas. Predisposing
factors include poverty, poor sanitation, inadequate sewage disposal, and poor personal hygiene.
The prevalence is greatest in children younger than 5 years of age. The majority of patients
with intestinal ascariasis are asymptomatic. For those with symptoms, anorexia, nausea, bloating,
abdominal discomfort, recurrent abdominal pain, abdominal distension, and intermittent diarrhea
are not uncommon. Other clinical manifestations vary widely, depending on the underlying complications.
Complications include Löeffler syndrome, intestinal obstruction, biliary colic, recurrent
pyogenic cholangitis, cholecystitis, acalculous cholecystitis, obstructive jaundice, cholelithiasis,
pancreatitis, and malnutrition. The diagnosis is best established by microscopic examination of fecal
smears or following concentration techniques for the characteristic ova. Patients with A. lumbricoides
infection warrant anthelminthic treatment, even if they are asymptomatic, to prevent complications
from migration of the parasite. Albendazole and mebendazole are the drugs of choice for
children and nonpregnant individuals with ascariasis. Pregnant women with ascariasis should be
treated with pyrantel pamoate. Recent patents related to the management of ascariasis are also discussed.
Conclusion:
The average cure rate with anthelminthic treatment is over 95%. Unfortunately, most
treated patients in endemic areas become re-infected within months. Health education, personal hygiene,
improved sanitary conditions, proper disposal of human excreta, and discontinuing the use
of human fecal matter as a fertilizer are effective long-term preventive measures. Targeting deworming
treatment and mass anthelminthic treatment should be considered in regions where A. lumbricoides
is prevalent.
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Affiliation(s)
- Alexander K.C. Leung
- Department of Pediatrics, The University of Calgary, Alberta Children’s Hospital, Calgary, Alberta, Canada
| | - Amy A.M. Leung
- Department of Family Medicine, The University of Alberta, Edmonton, Alberta, Canada
| | - Alex H.C. Wong
- Department of Family Medicine, The University of Calgary, Calgary, Alberta, Canada
| | - Kam L. Hon
- Department of Paediatrics, The Chinese University of Hong Kong, and Department of Paediatrics and Adolescent Medicine, Hong Kong Children’s Hospital, Shatin, Hong Kong
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17
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Sears WJ, Qvarnstrom Y, Dahlstrom E, Snook K, Kaluna L, Baláž V, Feckova B, Šlapeta J, Modry D, Jarvi S, Nutman TB. AcanR3990 qPCR: a novel, highly sensitive, bioinformatically-informed assay to detect Angiostrongylus cantonensis infections. Clin Infect Dis 2020; 73:e1594-e1600. [PMID: 33252651 DOI: 10.1093/cid/ciaa1791] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 11/26/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Angiostrongylus cantonensis (Ac), or the rat lungworm, is a major cause of eosinophilic meningitis. Humans are infected by ingesting the 3 rd stage larvae from primary hosts, snails and slugs, or paratenic hosts. The currently used molecular test is a qPCR assay targeting the ITS1 rDNA region (ITS1) of Ac. METHODS In silico design of a more sensitive qPCR assay was performed based on tandem repeats predicted to be the most abundant by the RepeatExplorer algorithm. Genomic DNA (gDNA) of Ac were used to determine the analytical sensitivity and specificity of the best primer/probe combination. This assay was then applied to clinical and environmental samples. RESULTS The limit of detection of the best performing assay, AcanR3990, was 1 fg (the DNA equivalent of 1/100,000 dilution of a single 3 rd stage larvae). Out of 127 CDC archived CSF samples from varied geographic locations, the AcanR3990 qPCR detected the presence of Ac in 49/49 ITS1 confirmed angiostrongyliasis patients along with 15/73 samples previously negative by ITS1 qPCR despite strong clinical suspicion for angiostrongyliasis. Intermediate hosts (gastropods) and an accidental host, a symptomatic horse, were also tested with similar improvement in detection observed. AcanR3990 qPCR did not cross-react in five CSF from patients with proven neurocysticercosis, toxocariasis, gnathostomiasis and baylisascariasis. AcanR3990 qPCR failed to amplify genomic DNA from the other related Angiostrongylus species tested except for A. mackerrasae (Am), a neurotropic species limited to Australia that would be expected to present with a clinical syndrome indistinguishable from Ac. CONCLUSION These results suggest AcanR3990 qPCR assay is highly sensitive and specific with potential wide applicability as a One Health detection method for Ac and Am.
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Affiliation(s)
- William J Sears
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD
| | - Yvonne Qvarnstrom
- Parasitic Disease Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Eric Dahlstrom
- RML Genomics Unit, Research Technology Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Kirsten Snook
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Hawai'i at Hilo, Hilo, HI, USA
| | - Lisa Kaluna
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Hawai'i at Hilo, Hilo, HI, USA
| | - Vojtech Baláž
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic.,Department of Ecology and Diseases of Zoo Animals, Game, Fish and Bees, Faculty of Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - Barbora Feckova
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic.,Department of Pathology and Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - Jan Šlapeta
- Laboratory of Veterinary Parasitology, Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales, Australia
| | - David Modry
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic.,Department of Pathology and Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic.,Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Susan Jarvi
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Hawai'i at Hilo, Hilo, HI, USA
| | - Thomas B Nutman
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD
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18
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Bradbury RS, Arguello I, Lane M, Cooley G, Handali S, Dimitrova SD, Nascimento FS, Jameson S, Hellmann K, Tharp M, Byers P, Montgomery SP, Haynie L, Kirmse B, Pilotte N, Williams SA, Hobbs CV. Parasitic Infection Surveillance in Mississippi Delta Children. Am J Trop Med Hyg 2020; 103:1150-1153. [PMID: 32588796 PMCID: PMC7470556 DOI: 10.4269/ajtmh.20-0026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Some recent studies suggest ongoing transmission of parasitic diseases in the American South; however, surveys in Mississippi children are lacking. We enrolled 166 children (median age 8 years, range 4-13 years) from the Mississippi Delta region and carried out multi-parallel real-time polymerase chain reaction (PCR) for Necator americanus, Ascaris lumbricoides, and Strongyloides stercoralis on their stool samples. Dried blood spots were obtained for multiplex serology antibody detection. Of 166 children, all reported having flushable toilets, 11% had soil exposure, and 34% had a pet dog or cat. None had prior diagnosis or treatment of parasitic disease. Multi-parallel real-time PCRs were negative on the 89 stool DNA extracts available for testing. Dried blood spot testing of all 166 children determined the seroprevalence of IgG antibodies to Toxocara spp. (3.6%), Cryptosporidium (2.4%), S. stercoralis, Fasciola hepatica, and Giardia duodenalis (all 0%). In conclusion, parasitic infections and exposure were scarce in this population. Larger studies of at-risk populations are needed.
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Affiliation(s)
- Richard S Bradbury
- School of Health and Life Sciences, Federation University, Berwick Campus, Melbourne, Australia.,Division of Parasitic Diseases and Malaria, Parasitic Diseases Branch, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Irene Arguello
- Department of Pediatrics, Division of Infectious Diseases, Children's of Mississippi, Jackson, Mississippi
| | - Meredith Lane
- Division of Parasitic Diseases and Malaria, Parasitic Diseases Branch, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Gretchen Cooley
- Division of Parasitic Diseases and Malaria, Parasitic Diseases Branch, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Sukwan Handali
- Division of Parasitic Diseases and Malaria, Parasitic Diseases Branch, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Silvia D Dimitrova
- Division of Parasitic Diseases and Malaria, Parasitic Diseases Branch, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Fernanda S Nascimento
- Division of Parasitic Diseases and Malaria, Parasitic Diseases Branch, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Sam Jameson
- Department of Pediatrics, Division of Infectious Diseases, Children's of Mississippi, Jackson, Mississippi
| | - Kathryn Hellmann
- Department of Pediatrics, Division of Infectious Diseases, Children's of Mississippi, Jackson, Mississippi
| | - Michelle Tharp
- The Delta Mercy Project, School of Nursing, University of Mississippi Medical Center, Jackson, Mississippi.,Division of Genetics, Department of Pediatrics, University of Mississippi Medical Center, Jackson, Mississippi
| | - Paul Byers
- Mississippi State Department of Health, Jackson, Mississippi
| | - Susan P Montgomery
- Division of Parasitic Diseases and Malaria, Parasitic Diseases Branch, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Lisa Haynie
- The Delta Mercy Project, School of Nursing, University of Mississippi Medical Center, Jackson, Mississippi
| | - Brian Kirmse
- Division of Genetics, Department of Pediatrics, University of Mississippi Medical Center, Jackson, Mississippi
| | - Nils Pilotte
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts.,Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Steven A Williams
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts.,Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Charlotte V Hobbs
- Department of Microbiology, University of Mississippi Medical Center, Jackson, Mississippi.,Department of Pediatrics, Division of Infectious Diseases, Children's of Mississippi, Jackson, Mississippi
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19
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Maasch JRMA, Arzika AM, Cook C, Lebas E, Pilotte N, Grant JR, Williams SA, Keenan JD, Lietman TM, Aiemjoy K. Rectal Swabs as an Alternative Sample Collection Method to Bulk Stool for the Real-Time PCR Detection of Giardia duodenalis. Am J Trop Med Hyg 2020; 103:1276-1282. [PMID: 32524959 PMCID: PMC7470573 DOI: 10.4269/ajtmh.19-0909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 05/02/2020] [Indexed: 12/19/2022] Open
Abstract
Though bulk stool remains the gold standard specimen type for enteropathogen diagnosis, rectal swabs may offer comparable sensitivity with greater ease of collection for select pathogens. This study sought to evaluate the validity and reproducibility of rectal swabs as a sample collection method for the molecular diagnosis of Giardia duodenalis. Paired rectal swab and bulk stool samples were collected from 86 children ages 0-4 years living in southwest Niger, with duplicate samples collected among a subset of 50 children. Infection was detected using a previously validated real-time PCR diagnostic targeting the small subunit ribosomal RNA gene. Giardia duodenalis was detected in 65.5% (55/84) of bulk stool samples and 44.0% (37/84) of swab samples. The kappa evaluating test agreement was 0.81 (95% CI: 0.54-1.00) among duplicate stool samples (N = 49) and 0.75 (95% CI: 0.47-1.00) among duplicate rectal swabs (N = 48). Diagnostic sensitivity was 93% (95% CI: 84-98) by bulk stool and 63% (95% CI: 49-75) by rectal swabs. When restricting to the lowest three quartiles of bulk stool quantitation cycle values (an indication of relatively high parasite load), sensitivity by rectal swabs increased to 78.0% (95% CI: 64-89, P < 0.0001). These findings suggest that rectal swabs provide less sensitive and reproducible results than bulk stool for the real-time PCR diagnosis of G. duodenalis. However, their fair sensitivity for higher parasite loads suggests that swabs may be a useful tool for detecting higher burden infections when stool collection is excessively expensive or logistically challenging.
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Affiliation(s)
| | | | - Catherine Cook
- Proctor Foundation, University of California San Francisco, San Francisco, California
| | - Elodie Lebas
- Proctor Foundation, University of California San Francisco, San Francisco, California
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts
| | - Jessica R. Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts
| | - Jeremy D. Keenan
- Proctor Foundation, University of California San Francisco, San Francisco, California
| | - Thomas M. Lietman
- Proctor Foundation, University of California San Francisco, San Francisco, California
| | - Kristen Aiemjoy
- Proctor Foundation, University of California San Francisco, San Francisco, California
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California
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20
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Aiemjoy K, Arzika AM, Cook C, Lebas E, Pilotte N, Grant JR, Williams SA, Lietman TM, Keenan JD. Molecular detection of intestinal helminths and protozoa among young children in Dosso Region, Niger. Gates Open Res 2020; 4:38. [PMID: 32923983 PMCID: PMC7468184 DOI: 10.12688/gatesopenres.13124.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2020] [Indexed: 11/29/2022] Open
Abstract
Eukaryotic parasites are significant contributors to childhood illness in Niger. While helminthiases have received national attention through mass deworming efforts, the epidemiology of intestinal protozoa in Niger remains underexamined. This study employed real-time PCR diagnostics to describe the prevalence of two schistosomes, four soil-transmitted helminths, and one protozoan parasite in Boboye Department, Dosso Region. Prevalence was assessed using bulk stool specimens collected from a population-based sample of 86 children residing in 9 communities. Anthropometric measurements were used to calculate child growth z-scores and stool consistency was graded. Helminths were absent from the study population, with the exception of a single Schistosoma haematobium infection (1/86; 1.2%). Giardia duodenalis was the only protozoa present, detected in 65% (56/86) of children. Prevalence of G. duodenalis peaked in 2-year-olds with 88% (15/17) positivity. The population was generally undernourished, though growth indices did not differ significantly between children with and without G. duodenalis infection.
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Affiliation(s)
- Kristen Aiemjoy
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| | | | - Catherine Cook
- Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, USA
| | - Elodie Lebas
- Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, USA
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA
- Department of Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Jessica R. Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA
- Department of Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Thomas M. Lietman
- Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, USA
| | - Jeremy D. Keenan
- Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, USA
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21
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Williams KM, Fessler MK, Bloomfield RA, Sandke WD, Malekshahi CR, Keroack CD, Duignan PJ, Torquato SD, Williams SA. A novel quantitative real-time PCR diagnostic assay for fecal and nasal swab detection of an otariid lungworm, Parafilaroides decorus. INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE 2020; 12:85-92. [PMID: 32489853 PMCID: PMC7256429 DOI: 10.1016/j.ijppaw.2020.04.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/30/2020] [Accepted: 04/30/2020] [Indexed: 01/08/2023]
Abstract
Parafilaroides decorus, also known as sea lion lungworm, is a metastrongyloid nematode that infects otariid hosts, such as the charismatic California sea lion, Zalophus californianus. P. decorus causes bronchointerstitial pneumonia, respiratory distress, reduced ability to swim, dive and hunt and as a result, increased mortality particularly in young animals. Respiratory disease is a leading cause of stranding and admission to rehabilitation centers on the Pacific coast. Low-coverage genomic sequencing of four P. decorus individuals analyzed through Galaxy's RepeatExplorer identified a novel repeat DNA family we employed to design a sensitive quantitative PCR (qPCR) assay for diagnosing infections from fecal or sputum samples. The assay detects as little as 10 fg of P. decorus DNA and a linear regression model developed using a standard curve can be used to estimate the concentration of P. decorus DNA in a sample, ± 0.015 ng. This knowledge can be leveraged to estimate the level of parasite burden, which can be used to design improved treatments for animals in rehabilitation. Improved treatment of infections will aid in more animals being successfully released back into the wild. Developed qPCR assay for P. decorus. Sensitive to 10 fg. Applicable for feces or sputum.
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Affiliation(s)
- Kalani M Williams
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - M K Fessler
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - R A Bloomfield
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - William D Sandke
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - Clara R Malekshahi
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - Caroline D Keroack
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | | | - Samantha D Torquato
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - Steven A Williams
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA.,University of Massachusetts, Molecular and Cellular Biology Program, Amherst, MA, 01003, USA
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22
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Zulch MF, Pilotte N, Grant JR, Minetti C, Reimer LJ, Williams SA. Selection and exploitation of prevalent, tandemly repeated genomic targets for improved real-time PCR-based detection of Wuchereria bancrofti and Plasmodium falciparum in mosquitoes. PLoS One 2020; 15:e0232325. [PMID: 32357154 PMCID: PMC7194414 DOI: 10.1371/journal.pone.0232325] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/12/2020] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Optimization of polymerase chain reaction (PCR)-based diagnostics requires the careful selection of molecular targets that are both highly repetitive and pathogen-specific. Advances in both next-generation sequencing (NGS) technologies and bioinformatics-based analysis tools are facilitating this selection process, informing target choices and reducing labor. Once developed, such assays provide disease control and elimination programs with an additional set of tools capable of evaluating and monitoring intervention successes. The importance of such tools is heightened as intervention efforts approach their endpoints, as accurate and complete information is an essential component of the informed decision-making process. As global efforts for the control and elimination of both lymphatic filariasis and malaria continue to make significant gains, the benefits of diagnostics with improved analytical and clinical/field-based sensitivities and specificities will become increasingly apparent. METHODOLOGY/PRINCIPAL FINDINGS Coupling Illumina-based NGS with informatics approaches, we have successfully identified the tandemly repeated elements in both the Wuchereria bancrofti and Plasmodium falciparum genomes of putatively greatest copy number. Utilizing these sequences as quantitative real-time PCR (qPCR)-based targets, we have developed assays capable of exploiting the most abundant tandem repeats for both organisms. For the detection of P. falciparum, analysis and development resulted in an assay with improved analytical and field-based sensitivity vs. an established ribosomal sequence-targeting assay. Surprisingly, analysis of the W. bancrofti genome predicted a ribosomal sequence to be the genome's most abundant tandem repeat. While resulting cycle quantification values comparing a qPCR assay targeting this ribosomal sequence and a commonly targeted repetitive DNA sequence from the literature supported our finding that this ribosomal sequence was the most prevalent tandemly repeated target in the W. bancrofti genome, the resulting assay did not significantly improve detection sensitivity in conjunction with field sample testing. CONCLUSIONS/SIGNIFICANCE Examination of pathogen genomes facilitates the development of PCR-based diagnostics targeting the most abundant and specific genomic elements. While in some instances currently available tools may deliver equal or superior performance, systematic analysis of potential targets provides confidence that the selected assays represent the most advantageous options available and that informed assay selection is occurring in the context of a particular study's objectives.
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Affiliation(s)
- Michael F Zulch
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America.,Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Jessica R Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Corrado Minetti
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Lisa J Reimer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Steven A Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America.,Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
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23
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Benjamin-Chung J, Pilotte N, Ercumen A, Grant JR, Maasch JRMA, Gonzalez AM, Ester AC, Arnold BF, Rahman M, Haque R, Hubbard AE, Luby SP, Williams SA, Colford JM. Comparison of multi-parallel qPCR and double-slide Kato-Katz for detection of soil-transmitted helminth infection among children in rural Bangladesh. PLoS Negl Trop Dis 2020; 14:e0008087. [PMID: 32330127 PMCID: PMC7202662 DOI: 10.1371/journal.pntd.0008087] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 05/06/2020] [Accepted: 01/24/2020] [Indexed: 01/08/2023] Open
Abstract
There is growing interest in local elimination of soil-transmitted helminth (STH) infection in endemic settings. In such settings, highly sensitive diagnostics are needed to detect STH infection. We compared double-slide Kato-Katz, the most commonly used copromicroscopic detection method, to multi-parallel quantitative polymerase chain reaction (qPCR) in 2,799 stool samples from children aged 2–12 years in a setting in rural Bangladesh with predominantly low STH infection intensity. We estimated the sensitivity and specificity of each diagnostic using Bayesian latent class analysis. Compared to double-slide Kato-Katz, STH prevalence using qPCR was almost 3-fold higher for hookworm species and nearly 2-fold higher for Trichuris trichiura. Ascaris lumbricoides prevalence was lower using qPCR, and 26% of samples classified as A. lumbricoides positive by Kato-Katz were negative by qPCR. Amplicon sequencing of the 18S rDNA from 10 samples confirmed that A. lumbricoides was absent in samples classified as positive by Kato-Katz and negative by qPCR. The sensitivity of Kato-Katz was 49% for A. lumbricoides, 32% for hookworm, and 52% for T. trichiura; the sensitivity of qPCR was 79% for A. lumbricoides, 93% for hookworm, and 90% for T. trichiura. Specificity was ≥ 97% for both tests for all STH except for Kato-Katz for A. lumbricoides (specificity = 68%). There were moderate negative, monotonic correlations between qPCR cycle quantification values and eggs per gram quantified by Kato-Katz. While it is widely assumed that double-slide Kato-Katz has few false positives, our results indicate otherwise and highlight inherent limitations of the Kato-Katz technique. qPCR had higher sensitivity than Kato-Katz in this low intensity infection setting. Soil-transmitted helminth infections (STH) (e.g., Ascaris, hookworm, Trichuris) contribute to a large burden of disease among children in low- and middle-income countries. There is increasing interest in implementing large-scale deworming programs to eliminate STH in certain settings. Efforts to monitor whether local elimination has occurred require sensitive diagnostic tests that will not miss positive cases. Kato-Katz, a microscopy-based diagnostic test, has commonly been used to identify STH eggs in stool, but in settings where infection intensity is low, this method frequently misses positive samples because it requires visual identification of small numbers of eggs, and hookworm eggs may degrade prior to visualization. Quantitative polymerase chain reaction (qPCR) is a molecular diagnostic method for detecting STH. It may detect more low intensity infections than Kato-Katz because it identifies STH DNA in stool; DNA can be detected in very small quantities and is less likely to degrade than STH ova. Thus, qPCR is likely to be more accurate than Kato-Katz. This study compared the performance of double-slide Kato-Katz and qPCR using 2,799 stool samples from children aged 2–12 years in a setting in rural Bangladesh with predominantly low STH infection intensity. qPCR was more sensitive than Kato-Katz for hookworm and Trichuris infections. 26% of samples were classified as Ascaris positive by Kato-Katz and negative by qPCR. DNA sequencing of 10 samples confirmed that Ascaris was absent in samples classified as positive by Kato-Katz and negative by qPCR. We conclude that Kato-Katz likely produced false positive results for Ascaris and that qPCR had a higher sensitivity than double-slide Kato-Katz in this low infection intensity setting.
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Affiliation(s)
- Jade Benjamin-Chung
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail:
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Ayse Ercumen
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, California, United States of America
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Jessica R. Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | | | - Andrew M. Gonzalez
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Ashanta C. Ester
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Benjamin F. Arnold
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, California, United States of America
| | - Mahbubur Rahman
- Infectious Disease Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Rashidul Haque
- Infectious Disease Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Alan E. Hubbard
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, California, United States of America
| | - Stephen P. Luby
- Infectious Diseases & Geographic Medicine, Stanford University, Stanford, California, United States of America
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - John M. Colford
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, California, United States of America
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24
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Aiemjoy K, Arzika AM, Cook C, Lebas E, Pilotte N, Grant JR, Williams SA, Lietman TM, Keenan JD. Molecular detection of intestinal helminths and protozoa among young children in Dosso Region, Niger. Gates Open Res 2020; 4:38. [PMID: 32923983 PMCID: PMC7468184 DOI: 10.12688/gatesopenres.13124.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2020] [Indexed: 07/29/2023] Open
Abstract
Eukaryotic parasites are significant contributors to childhood illness in Niger. While helminthiases have received national attention through mass deworming efforts, the epidemiology of intestinal protozoa in Niger remains underexamined. This study employed real-time PCR diagnostics to describe the prevalence of two schistosomes, four soil-transmitted helminths, and one protozoan parasite in Boboye Department, Dosso Region. Prevalence was assessed using bulk stool specimens collected from a population-based sample of 86 children residing in 9 communities. Anthropometric measurements were used to calculate child growth z-scores and stool consistency was graded. Helminths were absent from the study population, with the exception of a single Schistosoma haematobium infection (1/86; 1.2%). Giardia duodenalis was the only protozoa present, detected in 65% (56/86) of children. Prevalence of G. duodenalis peaked in 2-year-olds with 88% (15/17) positivity. The population was generally undernourished, though growth indices did not differ significantly between children with and without G. duodenalis infection.
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Affiliation(s)
- Kristen Aiemjoy
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| | | | - Catherine Cook
- Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, USA
| | - Elodie Lebas
- Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, USA
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA
- Department of Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Jessica R. Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA
- Department of Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Thomas M. Lietman
- Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, USA
| | - Jeremy D. Keenan
- Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, USA
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