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Ding X, Yang Y, Zhang Y, Zhang Q, Mao F, Dai Y. Establishment of a Simple and Rapid Nucleic Acid Detection Method for Hookworm Identification. Pathogens 2023; 12:pathogens12040630. [PMID: 37111516 PMCID: PMC10142964 DOI: 10.3390/pathogens12040630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
Hookworm infection is one of the most common neglected tropical diseases and is mainly found in tropical and subtropical areas. Two species of human hookworm are distributed in China, i.e., Ancylostoma duodenale (AD) and Necator americanus (NA). BACKGROUND Traditional microscopic technology such as the Kato-Katz method is not suitable for hookworm diagnosis due to the rapid degeneration of fragile hookworm eggs or for species identification of hookworm infection. The aim of the present study was to establish and evaluate a novel nucleic acid detection method based on recombinase-aided isothermal amplification (RAA) for the detection of hookworm infections and species identification. METHODS Based on the specific target gene sequences of hookworms (5.8S rRNA for AD and ITS2 for NA, respectively), we designed and synthesized amplification primers and fluorescence probes referring to the principle of the fluorescence recombinase-aided amplification (RAA) technique. RESULTS Each assay provided specific amplification of larval DNA from AD and NA by fluorescence RAA, and the detection limits in plasmids reached 102 copies and 10 copies, respectively. Genomic DNA of two hookworm species was successfully detected at a concentration of 0.1 pg/μL, revealing a high detection sensitivity. No positive amplification occurred for genomic DNA from crossed hookworm species and genomic DNA from Cryptosporidium, Giardia lamblia, Strongyloides stercoralis, Schistosoma japonicum, Ascaris lumbricoides, and Clonorchis sinensis, revealing a satisfactory specificity. Fecal sample detection results demonstrated a similar efficacy to the Kato-Katz method; however, it had a greater sensitivity than the larvae culture method. CONCLUSION A simple and rapid nucleic acid method was successfully established based on RAA, which improved the detection efficacy and species identification for human hookworm infections.
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Affiliation(s)
- Xin Ding
- Key Laboratory of National Health Commission on Parasitic Disease Control and Prevention, Key Laboratory of Jiangsu Province on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi 214064, China
| | - Yougui Yang
- School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - Yingshu Zhang
- School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - Qiang Zhang
- Key Laboratory of National Health Commission on Parasitic Disease Control and Prevention, Key Laboratory of Jiangsu Province on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi 214064, China
| | - Fanzhen Mao
- Key Laboratory of National Health Commission on Parasitic Disease Control and Prevention, Key Laboratory of Jiangsu Province on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi 214064, China
| | - Yang Dai
- Key Laboratory of National Health Commission on Parasitic Disease Control and Prevention, Key Laboratory of Jiangsu Province on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi 214064, China
- School of Public Health, Nanjing Medical University, Nanjing 211166, China
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Malizia V, Giardina F, de Vlas SJ, Coffeng LE. Appropriateness of the current parasitological control target for hookworm morbidity: A statistical analysis of individual-level data. PLoS Negl Trop Dis 2022; 16:e0010279. [PMID: 35763498 PMCID: PMC9239476 DOI: 10.1371/journal.pntd.0010279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/25/2022] [Indexed: 11/18/2022] Open
Abstract
Background
Soil-transmitted helminths affect almost 2 billion people globally. Hookworm species contribute to most of the related morbidity. Hookworms mainly cause anaemia, due to blood loss at the site of the attachment of the adult worms to the human intestinal mucosa. The World Health Organization (WHO) aims to eliminate hookworm morbidity by 2030 through achieving a prevalence of moderate and heavy intensity (M&HI) infections below 2%. In this paper, we aim to assess the suitability of this threshold to reflect hookworm-attributable morbidity.
Methodology/Principal findings
We developed a hierarchical statistical model to simulate individual haemoglobin concentrations in association with hookworm burdens, accounting for low haemoglobin values attributable to other causes. The model was fitted to individual-level data within a Bayesian framework. Then, we generated different endemicity settings corresponding to infection prevalence ranging from 10% to 90% (0% to 55% M&HI prevalence), using 1, 2 or 4 Kato-Katz slides. For each scenario, we estimated the prevalence of anaemia due to hookworm. Our results showed that on average, haemoglobin falls below the WHO threshold for anaemia when intensities are above 2000 eggs per gram of faeces. For the different simulated scenarios, the estimated prevalence of anaemia attributable to hookworm ranges from 0% to 30% (95%-PI: 24% - 36%) being mainly associated to the prevalence of M&HI infections. Simulations show that a 2% prevalence of M&HI infections in adults corresponds to a prevalence of hookworm-attributable anaemia lower than 1%.
Conclusions/Significance
Our results support the use of the current WHO thresholds of 2% prevalence of M&HI as a proxy for hookworm morbidity. A single Kato-Katz slide may be sufficient to assess the achievement of the morbidity target. Further studies are needed to elucidate haemoglobin dynamics pre- and post- control, ideally using longitudinal data in adults and children.
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Affiliation(s)
- Veronica Malizia
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Department for Health Evidence, Biostatistics Research Group, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- * E-mail: (VM); (LEC)
| | - Federica Giardina
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- Department for Health Evidence, Biostatistics Research Group, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Sake J. de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Luc E. Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- * E-mail: (VM); (LEC)
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Human hookworms from Argentina: Differential diagnosis of Necator americanus and Ancylostoma duodenale in endemic populations from Buenos Aires and Misiones. Rev Argent Microbiol 2022; 54:268-281. [DOI: 10.1016/j.ram.2022.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/23/2021] [Accepted: 05/02/2022] [Indexed: 11/22/2022] Open
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Clements ACA, Addis Alene K. Global distribution of human hookworm species and differences in their morbidity effects: a systematic review. THE LANCET MICROBE 2022; 3:e72-e79. [DOI: 10.1016/s2666-5247(21)00181-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 06/30/2021] [Accepted: 07/02/2021] [Indexed: 11/24/2022] Open
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Dorsey A, Thompson AL. Child, caretaker, and community: Testing predictors of anemia and response to iron supplementation in Peruvian preschool-aged children. Am J Hum Biol 2021; 33:e23538. [PMID: 33200848 PMCID: PMC8126576 DOI: 10.1002/ajhb.23538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 10/02/2020] [Accepted: 11/03/2020] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVES Despite repeated governmental and nongovernmental interventions, anemia remains a widespread public health concern in Peru. This article examines nutritional and disease factors associated with the prevalence of anemia and response to iron supplementation in Peruvian children, with the aim of understanding the lack of success of national programs. METHODS Data come from children, aged 2-5 years (n = 102), living in peri-urban Lima. Predictors of anemia and response to iron supplementation were explored at the individual, maternal, household, and environmental levels using logistic regression models, adjusted for clustering by household. RESULTS Half of the children in this sample were anemic and 50% of the anemic children responded to iron supplementation. We identified several factors that were associated with child anemia status and response to iron supplementation. Lower weight-for-age z-scores and the winter season were strong predictors of child anemia status and nonresponse to iron supplementation. Living with paternal grandparents was protective against anemia and elevated C-reactive protein at the time of the final interview was associated with a lack of response to iron supplementation. CONCLUSIONS The findings of this study document an association between children's anemia status and their nutritional and ecological environment, highlighting the importance of examining anemia within a specific context to better understand the factors driving this important health problem.
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Affiliation(s)
- Achsah Dorsey
- Department of Anthropology, University of Massachusetts, Amherst, USA
| | - Amanda L. Thompson
- Carolina Population Center, University of North Carolina, Chapel Hill, USA
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, USA
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Westgard CM, Orrego-Ferreyros LA, Calderón LF, Rogers AM. Dietary intake, intestinal infection, and safe drinking water among children with anemia in Peru: a cross-sectional analysis. BMC Nutr 2021; 7:11. [PMID: 34078476 PMCID: PMC8173807 DOI: 10.1186/s40795-021-00417-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 03/04/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Anemia is a major public health concern that is present in 41.7% of children under 5 worldwide. The prevalence of anemia in Peru was 43.6% in 2017, a decrease by only 6.8% in 8 years. Despite great efforts made by the government to reduce anemia by distributing free multi-micronutrient supplements and promote the consumption of iron rich foods, progress has been slow. The current study sought to better understand why the prevalence remains high by analyzing the dietary intake, incidence of intestinal infectious disease, and access to safe drinking water by children with anemia in Peru. METHODS A cross-sectional analysis was conducted using data from two national surveys that were combined by child ID. Descriptive statistics was analyzed to understand the experience of children with anemia in comparison to child without anemia. Logistic multivariate regression analyses were conducted to test the associations between anemia and dietary intake, intestinal infection, and access to safe drinking water. RESULTS The sample included 586 children between 6 and 35 months. The prevalence of anemia in this population was 53%. The portion of children that consumed sufficient iron to meet the recommendation for their age was 62%. Of the children with anemia, 52% consumed sufficient iron to meet their recommendation, vs. 72% of children without anemia (p < 0.001). The children with anemia were more likely to have an intestinal infection during the previous year (35% vs. 26%, p = 0.057) and less likely to have access to safe drinking water (77% vs. 86%, p = 0.002) than those without anemia. The logistic analysis revealed that having an intestinal infection increased the odds of having anemia (OR = 1.64, CI 95% [1.041-2.584]), and having access to safe drinking waters decreased the odds of having anemia (OR = 0.578, [0.334-0.998]). CONCLUSIONS More than half of the children with anemia in Peru already consume sufficient iron to meet their daily requirement. However, they continue to have anemia, likely due to intestinal infection, such as diarrhea and parasites, from a lack of access to safe drinking water and hygienic practices.
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Affiliation(s)
- Christopher M Westgard
- Department of Research and Innovation, Elementos, Lima, Peru.
- Department of Maternal and Child Health, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Luis A Orrego-Ferreyros
- Department of Research and Innovation, Elementos, Lima, Peru
- Faculty of Public Health and Administration, Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - Alexandra M Rogers
- Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
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Ajjampur SSR, Kaliappan SP, Halliday KE, Palanisamy G, Farzana J, Manuel M, Abraham D, Laxmanan S, Aruldas K, Rose A, Kennedy DS, Oswald WE, Pullan RL, Galagan SR, Ásbjörnsdóttir K, Anderson RM, Muliyil J, Sarkar R, Kang G, Walson JL. Epidemiology of soil transmitted helminths and risk analysis of hookworm infections in the community: Results from the DeWorm3 Trial in southern India. PLoS Negl Trop Dis 2021; 15:e0009338. [PMID: 33930024 PMCID: PMC8184002 DOI: 10.1371/journal.pntd.0009338] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 06/07/2021] [Accepted: 03/29/2021] [Indexed: 12/17/2022] Open
Abstract
Since 2015, India has coordinated the largest school-based deworming program globally, targeting soil-transmitted helminths (STH) in ~250 million children aged 1 to 19 years twice yearly. Despite substantial progress in reduction of morbidity associated with STH, reinfection rates in endemic communities remain high. We conducted a community based parasitological survey in Tamil Nadu as part of the DeWorm3 Project—a cluster-randomised trial evaluating the feasibility of interrupting STH transmission at three geographically distinct sites in Africa and Asia—allowing the estimation of STH prevalence and analysis of associated factors. In India, following a comprehensive census, enumerating 140,932 individuals in 36,536 households along with geospatial mapping of households, an age-stratified sample of individuals was recruited into a longitudinal monitoring cohort (December 2017-February 2018) to be followed for five years. At enrolment, a total of 6089 consenting individuals across 40 study clusters provided a single adequate stool sample for analysis using the Kato-Katz method, as well as answering a questionnaire covering individual and household level factors. The unweighted STH prevalence was 17.0% (95% confidence interval [95%CI]: 16.0–17.9%), increasing to 21.4% when weighted by age and cluster size. Hookworm was the predominant species, with a weighted infection prevalence of 21.0%, the majority of which (92.9%) were light intensity infections. Factors associated with hookworm infection were modelled using mixed-effects multilevel logistic regression for presence of infection and mixed-effects negative binomial regression for intensity. The prevalence of both Ascaris lumbricoides and Trichuris trichiura infections were rare (<1%) and risk factors were therefore not assessed. Increasing age (multivariable odds ratio [mOR] 21.4, 95%CI: 12.3–37.2, p<0.001 for adult age-groups versus pre-school children) and higher vegetation were associated with an increased odds of hookworm infection, whereas recent deworming (mOR 0.3, 95%CI: 0.2–0.5, p<0.001) and belonging to households with higher socioeconomic status (mOR 0.3, 95%CI: 0.2–0.5, p<0.001) and higher education level of the household head (mOR 0.4, 95%CI: 0.3–0.6, p<0.001) were associated with lower odds of hookworm infection in the multilevel model. The same factors were associated with intensity of infection, with the use of improved sanitation facilities also correlated to lower infection intensities (multivariable infection intensity ratio [mIIR] 0.6, 95%CI: 0.4–0.9, p<0.016). Our findings suggest that a community-based approach is required to address the high hookworm burden in adults in this setting. Socioeconomic, education and sanitation improvements alongside mass drug administration would likely accelerate the drive to elimination in these communities. Trial Registration:NCT03014167. Approximately 1 in 5 people in India are infected with soil transmitted helminths (STH), leading to anaemia and malnutrition. To tackle this large burden of infection, the government of India launched one of the world’s largest school-based deworming programs in 2015 aiming to deworm all pre-school and school-aged children between 1 to 19 years of age twice yearly on the National Deworming Days. Deworming programs, including those in India, are focused on pre-school aged children, school aged children and women of reproductive age group. However, prevailing environmental and socioeconomic conditions, including poor sanitation, can contribute to high rates of reinfection from untreated adults and children. The DeWorm3 Project is a cluster-randomised trial evaluating the feasibility of interrupting STH transmission with community wide deworming of all individuals aged one to 99 years of age or older. As part of the study, we conducted a parasitological survey in the Deworm3 trial site in rural Tamil Nadu. Here we present the factors associated with STH infection and burden in these communities.
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Affiliation(s)
- Sitara S. R. Ajjampur
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
- * E-mail:
| | | | - Katherine E. Halliday
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
- The DeWorm3 Project, University of Washington, Seattle, Washington, United States of America
| | - Gokila Palanisamy
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Jasmine Farzana
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Malathi Manuel
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Dilip Abraham
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Selvi Laxmanan
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Kumudha Aruldas
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Anuradha Rose
- Department of Community Medicine, Christian Medical College, Vellore, India
| | - David S. Kennedy
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - William E. Oswald
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Rachel L. Pullan
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Sean R. Galagan
- The DeWorm3 Project, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Kristjana Ásbjörnsdóttir
- The DeWorm3 Project, University of Washington, Seattle, Washington, United States of America
- Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
| | - Roy M. Anderson
- School of Public Health, Faculty of Medicine, Imperial College, London, United Kingdom
| | - Jayaprakash Muliyil
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Rajiv Sarkar
- Indian Institute of Public Health, Shillong, India
| | - Gagandeep Kang
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Judd L. Walson
- The DeWorm3 Project, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- Department of Medicine (Infectious Diseases) and Pediatrics, University of Washington, Seattle, Washington, United States of America
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Karunaratne R, Sturgeon JP, Patel R, Prendergast AJ. Predictors of inpatient mortality among children hospitalized for severe acute malnutrition: a systematic review and meta-analysis. Am J Clin Nutr 2020; 112:1069-1079. [PMID: 32885807 PMCID: PMC7528552 DOI: 10.1093/ajcn/nqaa182] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 06/12/2020] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Malnutrition underlies 45% of under-5 deaths globally. Severe acute malnutrition (SAM) is the most serious form of undernutrition, characterized by wasting with or without edema. Mortality remains high (10%-40%) among children requiring hospitalization for complicated SAM. OBJECTIVES We aimed to systematically document the factors independently associated with inpatient mortality in children with SAM. METHODS Embase, Ovid MEDINE, the Cochrane Library, and clinicaltrials.gov were searched for articles published between January 2000 and January 2020, using a prespecified protocol. Eligible studies included children aged ≤59 mo hospitalized with SAM and used multivariable analysis to assess the baseline factors independently associated with inpatient mortality. Random-effects meta-analysis, stratified by the stated measure of effect, was used where >20% of studies included the same factor in analyses. RESULTS Twenty-eight of 1432 studies fulfilled inclusion criteria: 19 studies included all children with SAM and 9 included specific subgroups of children with SAM. All 19 main studies were from 8 countries across Africa, with a median of 400 children/study. The mean inpatient mortality was 15.7% (95% CI: 10.4%, 21.0%) and HIV prevalence ranged from 2.1% to 51%. Nine factors were included in the meta-analysis, stratified by HR and OR. HIV infection (HR: 4.32; 95% CI: 2.31, 8.08), weight-for-height z score (WHZ) (OR: 0.44; 95% CI: 0.24, 0.80), diarrhea (HR: 2.84; 95% CI: 1.40, 5.75), pneumonia (HR: 1.89; 95% CI: 1.19, 3.02), presence of shock (HR: 3.67; 95% CI: 2.24, 6.03), and lack of appetite (HR: 2.16; 95% CI: 1.48, 3.16) were associated with increased mortality, whereas child age and sex were not. The association between edema and mortality was difficult to ascertain from the available studies. CONCLUSIONS HIV infection, diarrhea, pneumonia, shock, lack of appetite, and lower WHZ are independent predictors of inpatient mortality in children with SAM. These factors may help to risk-stratify children being hospitalized with complicated SAM.This systematic review/meta-analysis protocol was registered at www.crd.york.ac.uk/prospero as CRD42019152267.
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Affiliation(s)
| | - Jonathan P Sturgeon
- Zvitambo Institute for Maternal and Child Health Research, Harare, Zimbabwe
- Centre for Genomics and Child Health, Blizard Institute, Queen Mary University of London, London, United Kingdom
| | - Rajvi Patel
- Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Andrew J Prendergast
- Zvitambo Institute for Maternal and Child Health Research, Harare, Zimbabwe
- Centre for Genomics and Child Health, Blizard Institute, Queen Mary University of London, London, United Kingdom
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Prevalence of inherited blood disorders and associations with malaria and anemia in Malawian children. Blood Adv 2019; 2:3035-3044. [PMID: 30425067 DOI: 10.1182/bloodadvances.2018023069] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 09/10/2018] [Indexed: 12/23/2022] Open
Abstract
In sub-Saharan Africa, inherited causes of anemia are common, but data are limited regarding the geographical prevalence and coinheritance of these conditions and their overall contributions to childhood anemia. To address these questions in Malawi, we performed a secondary analysis of the 2015-2016 Malawi Micronutrient Survey, a nationally and regionally representative survey that estimated the prevalence of micronutrient deficiencies and evaluated both inherited and noninherited determinants of anemia. Children age 6 to 59 months were sampled from 105 clusters within the 2015-2016 Malawi Demographic Health Survey. Hemoglobin, ferritin, retinol binding protein, malaria, and inflammatory biomarkers were measured from venous blood. Molecular studies were performed using dried blood spots to determine the presence of sickle cell disease or trait, α-thalassemia trait, and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Of 1279 eligible children, 1071 were included in the final analysis. Anemia, iron deficiency, and malaria were common, affecting 30.9%, 21.5%, and 27.8% of the participating children, respectively. α-Thalassemia trait was common (>40% of children demonstrating deletion of 1 [33.1%] or 2 [10.0%] α-globin genes) and associated with higher prevalence of anemia (P < .001). Approximately 20% of males had G6PD deficiency, which was associated with a 1.0 g/dL protection in hemoglobin decline during malaria infection (P = .02). These data document that inherited blood disorders are common and likely play an important role in the prevalence of anemia and malaria in Malawian children.
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Hii SF, Senevirathna D, Llewellyn S, Inpankaew T, Odermatt P, Khieu V, Muth S, McCarthy J, Traub RJ. Development and Evaluation of a Multiplex Quantitative Real-Time Polymerase Chain Reaction for Hookworm Species in Human Stool. Am J Trop Med Hyg 2019; 99:1186-1193. [PMID: 30226132 PMCID: PMC6221243 DOI: 10.4269/ajtmh.18-0276] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Hookworm disease caused by Necator americanus, Ancylostoma duodenale, and Ancylostoma ceylanicum affects half a billion people worldwide. The prevalence and intensity of infection of individual hookworm species are vital for assessing morbidity and generating targeted intervention programs for their control. The present study aims to evaluate a multiplex real-time quantitative PCR (qPCR) assay to determine the prevalence and egg intensity of all three hookworm species and compare this with standard microscopy and published genus-based conventional and real-time multiplex qPCRs. Performance of the diagnostic assays was evaluated using DNA extracted from 192 fecal samples collected as part of a soil-transmitted helminth (STH) survey in northern Cambodia. The prevalence of hookworms as detected by the multiplex hookworm qPCR of 84/192 (43.8%) was significantly higher than that using microscopy of 49/192 (25.5%). The hookworm multiplex qPCR showed very good agreement for the detection of both N. americanus (Kappa 0.943) and Ancylostoma spp. (Kappa 0.936) with a multiplex STH qPCR. A strong and moderate quantitative correlation between cycle threshold and eggs per gram (EPG) feces was obtained for the hookworm qPCR for seeded DNA egg extracts (R 2 ≥ 0.9004) and naturally egg-infected individuals (R 2 = 0.6848), respectively. The newly developed hookworm quantitative multiplex qPCR has the potential for application in anthelmintic efficacy trials and for monitoring the success of mass deworming programs targeting individual species of anthroponotic and zoonotic hookworms.
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Affiliation(s)
- Sze Fui Hii
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Australia
| | - Dammika Senevirathna
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Australia
| | - Stacey Llewellyn
- Clinical Tropical Medicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | - Tawin Inpankaew
- Department of Parasitology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand
| | - Peter Odermatt
- University of Basel, Basel, Switzerland.,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Virak Khieu
- National Centre for Parasitology, Entomology, and Malaria Control, Phnom Penh, Cambodia
| | - Sinoun Muth
- National Centre for Parasitology, Entomology, and Malaria Control, Phnom Penh, Cambodia
| | - James McCarthy
- Clinical Tropical Medicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | - Rebecca J Traub
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Australia
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Cools P, Vlaminck J, Albonico M, Ame S, Ayana M, José Antonio BP, Cringoli G, Dana D, Keiser J, Maurelli MP, Maya C, Matoso LF, Montresor A, Mekonnen Z, Mirams G, Corrêa-Oliveira R, Pinto SA, Rinaldi L, Sayasone S, Thomas E, Verweij JJ, Vercruysse J, Levecke B. Diagnostic performance of a single and duplicate Kato-Katz, Mini-FLOTAC, FECPAKG2 and qPCR for the detection and quantification of soil-transmitted helminths in three endemic countries. PLoS Negl Trop Dis 2019; 13:e0007446. [PMID: 31369558 PMCID: PMC6675048 DOI: 10.1371/journal.pntd.0007446] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/07/2019] [Indexed: 12/20/2022] Open
Abstract
Background Because the success of deworming programs targeting soil-transmitted helminths (STHs) is evaluated through the periodically assessment of prevalence and infection intensities, the use of the correct diagnostic method is of utmost importance. The STH community has recently published for each phase of a deworming program the minimal criteria that a potential diagnostic method needs to meet, the so-called target product profiles (TPPs). Methodology We compared the diagnostic performance of a single Kato-Katz (reference method) with that of other microscopy-based methods (duplicate Kato-Katz, Mini-FLOTAC and FECPAKG2) and one DNA-based method (qPCR) for the detection and quantification of STH infections in three drug efficacy trials in Ethiopia, Lao PDR, and Tanzania. Furthermore, we evaluated a selection of minimal diagnostic criteria of the TPPs. Principal findings All diagnostic methods showed a clinical sensitivity of ≥90% for all STH infections of moderate-to-heavy intensities. For infections of very low intensity, only qPCR resulted in a sensitivity that was superior to a single Kato-Katz for all STHs. Compared to the reference method, both Mini-FLOTAC and FECPAKG2 resulted in significantly lower fecal egg counts for some STHs, leading to a substantial underestimation of the infection intensity. For qPCR, there was a positive significant correlation between the egg counts of a single Kato-Katz and the DNA concentration. Conclusions/Significance Our results indicate that the diagnostic performance of a single Kato-Katz is underestimated by the community and that diagnostic specific thresholds to classify intensity of infection are warranted for Mini-FLOTAC, FECPAKG2 and qPCR. When we strictly apply the TPPs, Kato-Katz is the only microscopy-based method that meets the minimal diagnostic criteria for application in the planning, monitoring and evaluation phase of an STH program. qPCR is the only method that could be considered in the phase that aims to seek confirmation for cessation of program. Trial registration ClinicalTrials.gov NCT03465488 To control the burden caused by intestinal worms, the World Health Organization recommends large-scale deworming programs where anti-worm drugs are administered to at-risk populations. The decision to scale down drug distribution is based on the periodically assessment of prevalence and intensity of infections using a standard diagnostic method. Today, the scientific community strongly doubts whether this method can be used throughout the program. This is in particular when it fails to detect infections of low intensity, and hence may result in prematurely stopping the distribution of drugs. We compared the diagnostic performance of alternative diagnostic methods in three drug efficacy trials in two African and one Asian country. The diagnostic methods were based on demonstration of worm eggs or worm DNA in stool. We also checked the results with minimal diagnostic criteria which have been recently been proposed by the scientific community. Our results indicate that of all diagnostic methods based on demonstration of worm eggs, only the current standard method fulfills the diagnostic criteria for planning, monitoring and evaluation phases of deworming program. Furthermore, we showed that DNA-based methods could be considered in the phase that aims to seek confirmation for cessation of the deworming program.
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Affiliation(s)
- Piet Cools
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Johnny Vlaminck
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Marco Albonico
- Center for Tropical Diseases, Sacro Cuore Don Calabria Hospital, Negrar, Italy
- Department of Life Sciences and Systems Biology, University of Turin, Italy
| | - Shaali Ame
- Public Health Laboratory-Ivo de Carneri, Chake Chake, United Republic of Tanzania
| | - Mio Ayana
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | | | - Giuseppe Cringoli
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples, Italy
| | - Daniel Dana
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | - Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Maria P. Maurelli
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples, Italy
| | - Catalina Maya
- Engineering Institute of National Autonomous University of Mexico, Mexico City, Mexico
| | - Leonardo F. Matoso
- Laboratory of Molecular and Cellular Immunology, Research Center René Rachou—FIOCRUZ, Belo Horizonte, Brazil
| | - Antonio Montresor
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Zeleke Mekonnen
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | | | - Rodrigo Corrêa-Oliveira
- Laboratory of Molecular and Cellular Immunology, Research Center René Rachou—FIOCRUZ, Belo Horizonte, Brazil
| | - Simone A. Pinto
- Laboratory of Molecular and Cellular Immunology, Research Center René Rachou—FIOCRUZ, Belo Horizonte, Brazil
| | - Laura Rinaldi
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples, Italy
| | - Somphou Sayasone
- Lao Tropical and Public Health Institute, Ministry of Health, Vientiane, Lao People’s Democratic Republic
| | | | - Jaco J. Verweij
- Laboratory for Medical Microbiology and Immunology, Elisabeth-Tweesteden Hospital, Tilburg, The Netherlands
| | - Jozef Vercruysse
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Bruno Levecke
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
- * E-mail:
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O'Connell EM, Mitchell T, Papaiakovou M, Pilotte N, Lee D, Weinberg M, Sakulrak P, Tongsukh D, Oduro-Boateng G, Harrison S, Williams SA, Stauffer WM, Nutman TB. Ancylostoma ceylanicum Hookworm in Myanmar Refugees, Thailand, 2012-2015. Emerg Infect Dis 2019; 24. [PMID: 30014834 PMCID: PMC6056130 DOI: 10.3201/eid2408.180280] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
This hookworm, uncommonly found in humans, has a higher cure rate than that for Necator americanus hookworm. During 2012–2015, US-bound refugees living in Myanmar–Thailand border camps (n = 1,839) were surveyed for hookworm infection and treatment response by using quantitative PCR. Samples were collected at 3 time points: after each of 2 treatments with albendazole and after resettlement in the United States. Baseline prevalence of Necator americanus hookworm was 25.4%, Ancylostoma duodenale 0%, and Ancylostoma ceylanicum (a zoonosis) 5.4%. Compared with N. americanus prevalence, A. ceylanicum hookworm prevalence peaked in younger age groups, and blood eosinophil concentrations during A. ceylanicum infection were higher than those for N. americanus infection. Female sex was associated with a lower risk for either hookworm infection. Cure rates after 1 dose of albendazole were greater for A. ceylanicum (93.3%) than N. americanus (65.9%) hookworm (p<0.001). Lower N. americanus hookworm cure rates were unrelated to β-tubulin single-nucleotide polymorphisms at codons 200 or 167. A. ceylanicum hookworm infection might be more common in humans than previously recognized.
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Hu Z, Chen H, Huang L, Chen S, Huang Z, Qin S, Zhong J, Qin X, Li S. Correlation between hematological parameters and ancylostomiasis: A retrospective study. J Clin Lab Anal 2018; 33:e22705. [PMID: 30390342 DOI: 10.1002/jcla.22705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/05/2018] [Accepted: 10/05/2018] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVE Our aim intended to determine the relationship between hematological parameters (neutrophil-to-lymphocyte ratio [NLR], platelet-to-lymphocyte ratio [PLR], and eosinophil-to-lymphocyte ratio [ELR]) and ancylostomiasis. METHODS There were 140 patients with ancylostomiasis and 159 healthy controls enrolled in this study. All data were collected from electronic medical records of the First Affiliated Hospital of Guangxi Medical University. RESULTS The levels of NLR, PLR, and ELR in ancylostomiasis patients were significantly higher than those in the healthy controls (all P = 0.000). A receiver operating characteristic curve was generated to assess the diagnostic efficacy of these three hematological parameters. ELR (AUC = 0.850; sensitivity = 75.00%; specificity = 86.80%) showed the superior AUC than those of NLR (AUC = 0.718; sensitivity = 53.57%; specificity = 88.68%) and PLR (AUC = 0.806; sensitivity = 68.57%; specificity = 86.79%), respectively. A multivariate regression model using the two selected indices (RBC and ELR) was established with the model's sensitivity and specificity reached 82.86% and 96.23%, respectively. In the ancylostomiasis patient group, NLR (r = -0.452, P = 0.000) and PLR (r = -0.357, P = 0.000) were reversely associated with eosinophils. CONCLUSION The pretreatment levels of the three hematological parameters (NLR, PLR, and ELR) may serve as valuable indicators for distinguishing patients with ancylostomiasis from healthy controls. NLR and PLR are negatively associated with the previous indicator, eosinophils.
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Affiliation(s)
- Zuojian Hu
- Department of Laboratory Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Huaping Chen
- Department of Laboratory Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Li Huang
- Department of Laboratory Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Siyuan Chen
- Department of Laboratory Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Zhili Huang
- Department of Laboratory Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Shanzi Qin
- Department of Laboratory Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Jianing Zhong
- Department of Laboratory Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Xue Qin
- Department of Laboratory Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Shan Li
- Department of Laboratory Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning, China
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Squire SA, Yang R, Robertson I, Ayi I, Squire DS, Ryan U. Gastrointestinal helminths in farmers and their ruminant livestock from the Coastal Savannah zone of Ghana. Parasitol Res 2018; 117:3183-3194. [PMID: 30030626 DOI: 10.1007/s00436-018-6017-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 07/12/2018] [Indexed: 01/08/2023]
Abstract
To identify the gastrointestinal helminths of veterinary, zoonotic and public health importance in farmers and their ruminant livestock in Ghana, faecal samples were collected from 95 farmers and their livestock (cattle = 328, sheep = 285 and goats = 217) and examined by microscopy and/or molecular techniques. Overall, 21 farmers tested positive for at least one gastrointestinal helminth, 80.9% of which were single infections and 19.0% co-infections. The parasites identified in the farmers consisted of hookworms (n = 13) (9 were Necator americanus and the other 4 could not be amplified by PCR), Trichostrongylus spp. (n = 9), Schistosoma mansoni (n = 1), Schistosoma haematobium (n = 1) and Diphyllobothrium latum (n = 1). In livestock, strongylid nematodes were dominant (56.6%), followed by Paramphistomum spp. (16.9%), Dicrocoelium spp. (7.1%), Thysaniezia spp. (5.8%), Trichuris spp. (3.3%), Moniezia spp. (3.1%), Fasciola spp. (2.8%), Toxocara spp. (1.1%) and Schistosoma spp. (0.2%). Genotyping of Trichostrongylus spp. in the farmer's stools identified six T. colubriformis similar to T. colubriformis detected in cattle, sheep and goats in the study, two Trichostrongylus spp. with 98.3% and 99.2% genetic similarity to T. probolurus respectively and one Trichostrongylus spp. which showed 96.6% similarity to both T. probolurus and T. rugatus. Trichostrongylus axei was also identified in cattle, sheep and goats. This is the first molecular characterisation of Trichostrongylus spp. in Ghana and the species identified in the present study suggests zoonotic transmission from cattle, sheep and goats. Further studies involving larger numbers of farmers and their household members are essential to understand the transmission dynamics and impact of these parasites on farming communities in Ghana.
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Affiliation(s)
- Sylvia Afriyie Squire
- School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia. .,Council for Scientific and Industrial Research, Animal Research Institute, P. O. Box AH 20, Achimota, Accra, Ghana.
| | - Rongchang Yang
- School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia
| | - Ian Robertson
- School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia.,China-Australia Joint Research and Training Center for Veterinary Epidemiology, Huazhong Agricultural University, Wuhan, China
| | - Irene Ayi
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG 581, Legon, Accra, Ghana
| | - Daniel Sai Squire
- School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia.,Usher Polyclinic, Ghana Health Service, P. O. Box GP 2105, Accra, Ghana
| | - Una Ryan
- School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia
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High frequency of Polio-like Enterovirus C strains with differential clustering of CVA-13 and EV-C99 subgenotypes in a cohort of Malawian children. Arch Virol 2018; 163:2645-2653. [PMID: 29808442 PMCID: PMC6132918 DOI: 10.1007/s00705-018-3878-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 03/08/2018] [Indexed: 01/02/2023]
Abstract
Enteroviruses (EVs) are among the most commonly detected viruses infecting humans worldwide. Although the prevalence of EVs is widely studied, the status of EV prevalence in sub-Saharan Africa remains largely unknown. The objective of our present study was therefore to increase our knowledge on EV circulation in sub-Saharan Africa. We obtained 749 fecal samples from a cross-sectional study conducted on Malawian children aged 6 to 60 months. We tested the samples for the presence of EVs using real time PCR, and typed the positive samples based on partial viral protein 1 (VP1) sequences. A large proportion of the samples was EV positive (89.9%). 12.9% of the typed samples belonged to EV species A (EV-A), 48.6% to species B (EV-B) and 38.5% to species C (EV-C). More than half of the EV-C strains (53%) belonged to subgroup C containing, among others, Poliovirus (PV) 1-3. The serotype most frequently isolated in our study was CVA-13, followed by EV-C99. The strains of CVA-13 showed a vast genetic diversity, possibly representing a new cluster, 'F'. The majority of the EV-C99 strains grouped together as cluster B. In conclusion, this study showed a vast circulation of EVs among Malawian children, with an EV prevalence of 89.9%. Identification of prevalences for species EV-C comparable to our study (38.5%) have only previously been reported in sub-Saharan Africa, and EV-C is rarely found outside of this region. The data found in this study are an important contribution to our current knowledge of EV epidemiology within sub-Saharan Africa.
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Accinelli RA, Leon-Abarca JA. Solid fuel use is associated with anemia in children. ENVIRONMENTAL RESEARCH 2017; 158:431-435. [PMID: 28689034 DOI: 10.1016/j.envres.2017.06.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 05/20/2017] [Accepted: 06/26/2017] [Indexed: 06/07/2023]
Abstract
Over 3 billion people use solid fuels as a means of energy and heating source, and ~ 50% of households burn them in inefficient, poorly ventilated stoves. In 2010, ~ 43% of the 640 million preschool children in 220 countries suffered from a certain degree of anemia, with iron deficiency as the main cause in developed countries whereas its causes remained multifactorial in the undeveloped group. In this study, we explore the relations of country-wide variables that might affect the people's health status (from socioeconomic status to more specific variables such as water access). We found independent relationship between solid fuel use and anemia in children under five years old (p < 0.0001), taking into account the prevalence of anemia in pregnant woman and the access to improved water sources. Countries in which the population uses solid fuel the most have over three times higher anemia rates in children than countries with the lowest prevalence of solid fuels use. There is still a complex relationship between solid fuels use and anemia, as reflected in its worldwide significance (p < 0.05) controlled for measles immunization, tobacco consumption, anemia in pregnant mothers, girl's primary education, life expectancy and improved water access but not (p > 0.05) when weighing for sanitation access or income per capita.
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Affiliation(s)
- Roberto A Accinelli
- Hospital Cayetano Heredia, Peru; Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru.
| | - Juan A Leon-Abarca
- Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru
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Papaiakovou M, Pilotte N, Grant JR, Traub RJ, Llewellyn S, McCarthy JS, Krolewiecki AJ, Cimino R, Mejia R, Williams SA. A novel, species-specific, real-time PCR assay for the detection of the emerging zoonotic parasite Ancylostoma ceylanicum in human stool. PLoS Negl Trop Dis 2017; 11:e0005734. [PMID: 28692668 PMCID: PMC5519186 DOI: 10.1371/journal.pntd.0005734] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 07/20/2017] [Accepted: 06/21/2017] [Indexed: 11/18/2022] Open
Abstract
Background Molecular-based surveys have indicated that Ancylostoma ceylanicum, a zoonotic hookworm, is likely the second most prevalent hookworm species infecting humans in Asia. Most current PCR-based diagnostic options for the detection of Ancylostoma species target the Internal Transcribed Spacer (ITS) regions of the ribosomal gene cluster. These regions possess a considerable degree of conservation among the species of this genus and this conservation can lead to the misidentification of infecting species or require additional labor for accurate species-level determination. We have developed a novel, real-time PCR-based assay for the sensitive and species-specific detection of A. ceylanicum that targets a non-coding, highly repetitive genomic DNA element. Comparative testing of this PCR assay with an assay that targets ITS sequences was conducted on field-collected samples from Argentina and Timor-Leste to provide further evidence of the sensitivity and species-specificity of this assay. Methods/Principal findings A previously described platform for the design of primers/probe targeting non-coding highly repetitive regions was used for the development of this novel assay. The assay’s limits of detection (sensitivity) and cross-reactivity with other soil-transmitted helminth species (specificity) were assessed with real-time PCR experiments. The assay was successfully used to identify infections caused by A. ceylanicum that were previously only identified to the genus level as Ancylostoma spp. when analyzed using other published primer-probe pairings. Further proof of sensitive, species-specific detection was provided using a published, semi-nested restriction fragment length polymorphism-PCR assay that differentiates between Ancylostoma species. Conclusions/Significance Due to the close proximity of people and domestic/wild animals in many regions of the world, the potential for zoonotic infections is substantial. Sensitive tools enabling the screening for different soil-transmitted helminth infections are essential to the success of mass deworming efforts and facilitate the appropriate interpretation of data. This study describes a novel, species-specific, real-time PCR-based assay for the detection of A. ceylanicum that will help to address the need for such tools in integrated STH deworming programs. Trial registration ANZCTR.org.au ACTRN12614000680662 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 laborious 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 diagnostic tool that will facilitate the accurate mapping of disease endemicity and will aid in the evaluation of progress of programmatic deworming efforts.
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Affiliation(s)
- Marina Papaiakovou
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, 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
| | - Jessica R. Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Rebecca J. Traub
- Faculty of Veterinary and Agricultural Science, University of Melbourne, Parkville, Australia
| | - Stacey Llewellyn
- Clinical Medical Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - James S. McCarthy
- Clinical Medical Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Alejandro J. Krolewiecki
- Instituto de Investigaciones en Enfermedades Tropicales, Universidad Nacional de Salta/CONICET, Orán, Argentina
- Instituto de Patología Experimental (IPE-CONICET), Facultad de Ciencias de la Salud, Universidad Nacional de Salta, Salta, Argentina
| | - Rubén Cimino
- Instituto de Investigaciones en Enfermedades Tropicales, Universidad Nacional de Salta/CONICET, Orán, Argentina
| | - Rojelio Mejia
- National School of 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
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Madinga J, Polman K, Kanobana K, van Lieshout L, Brienen E, Praet N, Kabwe C, Gabriël S, Dorny P, Lutumba P, Speybroeck N. Epidemiology of polyparasitism with Taenia solium, schistosomes and soil-transmitted helminths in the co-endemic village of Malanga, Democratic Republic of Congo. Acta Trop 2017; 171:186-193. [PMID: 28336269 DOI: 10.1016/j.actatropica.2017.03.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 03/10/2017] [Accepted: 03/18/2017] [Indexed: 11/27/2022]
Abstract
Helminth co-infections are common in sub-Saharan Africa. However, little is known about the distribution and determinants of co-infections with Taenia solium taeniasis/cysticercosis. Building on a previous community-based study on human cysticercosis in Malanga village, we investigated co-infections with Taenia solium, soil-transmitted helminths (STHs) and Schistosoma spp and associated risk factors in a random subsample of 330 participants. Real time PCR assays were used to detect DNA of soil-transmitted helminths (STHs), T. solium and Schistosoma in stool samples and Schistosoma DNA in urine samples. Serum samples were tested for T. solium cysticercosis using the B158/B60 monoclonal antibody-based antigen ELISA. Bivariate analysis and logistic regression were applied to assess associations of single and co-infections with common risk factors (age, sex, area, hygiene) as well as pair wise associations between helminth species. Overall, 240 (72.7%) participants were infected with at least one helminth species; 128 (38.8%) harbored at least two helminth species (16.1% with STHs-Schistosoma, 14.5% with STHs-T. solium taeniasis/cysticercosis and 8.2% with Schistosoma-T. solium taeniasis/cysticercosis co-infections). No significant associations were found between Schistosoma-T. solium taeniasis/cysticercosis co-infection and any of the risk factors studied. Males (OR=2 (95%CI=1.1-5), p=0.03) and open defecation behavior (OR=3.8 (95%CI=1.1-6.5), p=0.04) were associated with higher odds of STHs-T. solium taeniasis/cysticercosis co-infection. Village districts that were found at high risk of T. solium taeniasis/cysticercosis were also at high risk of co-infection with STHs and T. solium taeniasis/cysticercosis (OR=3.2 (95%CI=1.1-7.8), p=0.03). Significant pair-wise associations were found between T. solium cysticerci and Necator americanus (OR=2.2 (95%CI=1.2-3.8), p<0.01) as well as Strongyloides stercoralis (OR=2.7 (95%CI=1.1-6.5), p=0.02). These findings show that co-infections with T. solium are common in this polyparasitic community in DRC. Our results on risk factors of helminth co-infections and specific associations between helminths may contribute to a better integration of control within programmes that target more than one NTD.
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Campbell SJ, Nery SV, D’Este CA, Gray DJ, McCarthy JS, Traub RJ, Andrews RM, Llewellyn S, Vallely AJ, Williams GM, Clements ACA. Investigations into the association between soil-transmitted helminth infections, haemoglobin and child development indices in Manufahi District, Timor-Leste. Parasit Vectors 2017; 10:192. [PMID: 28424091 PMCID: PMC5395746 DOI: 10.1186/s13071-017-2084-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 03/09/2017] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Timor-Leste has a high prevalence of soil-transmitted helminth (STH) infections. High proportions of the population have been reported as being anaemic, and extremely high proportions of children as stunted or wasted. There have been no published analyses of the contributions of STH to these morbidity outcomes in Timor-Leste. METHODS Using baseline cross-sectional data from 24 communities (18 communities enrolled in a cluster randomised controlled trial, and identically-collected data from six additional communities), analyses of the association between STH infections and community haemoglobin and child development indices were undertaken. Stool samples were assessed for STH using qPCR and participant haemoglobin, heights and weights were measured. Questionnaires were administered to collect demographic and socioeconomic data. Intensity of infection was categorised using correlational analysis between qPCR quantification cycle values and eggs per gram of faeces equivalents, with algorithms generated from seeding experiments. Mixed-effects logistic and multinomial regression were used to assess the association between STH infection intensity classes and anaemia, and child stunting, wasting and underweight. RESULTS Very high stunting (60%), underweight (60%), and wasting (20%) in children, but low anaemia prevalence (15%), were found in the study communities. STH were not significantly associated with morbidity outcomes. Male children and those in the poorest socioeconomic quintile were significantly more likely to be moderately and severely stunted. Male children were significantly more likely than female children to be severely underweight. Increasing age was also a risk factor for being underweight. Few risk factors emerged for wasting in these analyses. CONCLUSIONS According to World Health Organization international reference standards, levels of child morbidity in this population constitute a public health emergency, although the international reference standards need to be critically evaluated for their applicability in Timor-Leste. Strategies to improve child development and morbidity outcomes, for example via nutrition and iron supplementation programmes, are recommended for these communities. Despite the apparent lack of an association from STH in driving anaemia, stunting, wasting and underweight, high endemicity suggests a need for STH control strategies. TRIAL REGISTRATION Australian and New Zealand Clinical Trials Registry ACTRN12614000680662 ; retrospectively registered.
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Affiliation(s)
- Suzy J. Campbell
- Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, 62 Mills Rd, Acton, ACT 2601 Australia
| | - Susana V. Nery
- Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, 62 Mills Rd, Acton, ACT 2601 Australia
| | - Catherine A. D’Este
- Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, 62 Mills Rd, Acton, ACT 2601 Australia
| | - Darren J. Gray
- Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, 62 Mills Rd, Acton, ACT 2601 Australia
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Rd, Brisbane, QLD 4006 Australia
- School of Public Health, University of Queensland, Herston Rd, Brisbane, QLD 4006 Australia
| | - James S. McCarthy
- School of Public Health, University of Queensland, Herston Rd, Brisbane, QLD 4006 Australia
- Clinical Tropical Medicine Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Rd, Brisbane, QLD 4006 Australia
| | - Rebecca J. Traub
- Faculty of Veterinary and Agricultural Science, The University of Melbourne, Parkville, VIC 3010 Australia
| | - Ross M. Andrews
- Menzies School of Health Research, Charles Darwin University, Ellengowan Dr, Casuarina, NT 0810 Australia
| | - Stacey Llewellyn
- Clinical Tropical Medicine Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Rd, Brisbane, QLD 4006 Australia
| | - Andrew J. Vallely
- Kirby Institute, University of New South Wales, Wallace Wurth Building, High St, Kensington, NSW 2052 Australia
| | - Gail M. Williams
- School of Public Health, University of Queensland, Herston Rd, Brisbane, QLD 4006 Australia
| | - Archie C. A. Clements
- Research School of Population Health, College of Medicine, Biology and Environment, The Australian National University, 62 Mills Rd, Acton, ACT 2601 Australia
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Jonker FAM, Te Poel E, Bates I, Boele van Hensbroek M. Anaemia, iron deficiency and susceptibility to infection in children in sub-Saharan Africa, guideline dilemmas. Br J Haematol 2017; 177:878-883. [PMID: 28397964 DOI: 10.1111/bjh.14593] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/15/2017] [Accepted: 01/15/2017] [Indexed: 12/31/2022]
Abstract
Globally, anaemia, iron deficiency and infections are responsible for a majority of the morbidity and mortality that occurs among children. As iron is essential for erythropoiesis and the human immune system, as well as a crucial element for many pathogens, these three conditions often interact. This article considers the question - have the studies conducted so far unravelled the potential complex interaction between these factors sufficiently enough to be able to develop universally applicable guidelines about iron treatment in children? It is possible, however, that the area is too complex and diverse, with many sub-populations, and that not universal, but tailor-made guidelines are needed based on some agreed principles.
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Affiliation(s)
- Femkje A M Jonker
- Global Child Health Group, Emma Children's Hospital, Academic Medical Centre, Amsterdam, The Netherlands
| | - Elodie Te Poel
- Global Child Health Group, Emma Children's Hospital, Academic Medical Centre, Amsterdam, The Netherlands
| | - Imelda Bates
- Liverpool School of Tropical Medicine, University of Liverpool, Liverpool, United Kingdom
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Meurs L, Polderman AM, Vinkeles Melchers NVS, Brienen EAT, Verweij JJ, Groosjohan B, Mendes F, Mechendura M, Hepp DH, Langenberg MCC, Edelenbosch R, Polman K, van Lieshout L. Diagnosing Polyparasitism in a High-Prevalence Setting in Beira, Mozambique: Detection of Intestinal Parasites in Fecal Samples by Microscopy and Real-Time PCR. PLoS Negl Trop Dis 2017; 11:e0005310. [PMID: 28114314 PMCID: PMC5289637 DOI: 10.1371/journal.pntd.0005310] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 02/02/2017] [Accepted: 01/09/2017] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Many different intestinal parasite species can co-occur in the same population. However, classic diagnostic tools can only frame a particular group of intestinal parasite species. Hence, one or two tests do not suffice to provide a complete picture of infecting parasite species in a given population. The present study investigated intestinal parasitic infections in Beira, Mozambique, i.e. in the informal settlement of Inhamudima. Diagnostic accuracy of five classical microscopy techniques and real-time PCR for the detection of a broad spectrum of parasites was compared. METHODOLOGY/PRINCIPAL FINDINGS A cross-sectional population-based survey was performed. One stool sample per participant (n = 303) was examined by direct smear, formal-ether concentration (FEC), Kato smear, Baermann method, coproculture and real-time PCR. We found that virtually all people (96%) harbored at least one helminth, and that almost half (49%) harbored three helminths or more. Remarkably, Strongyloides stercoralis infections were widespread with a prevalence of 48%, and Ancylostoma spp. prevalence was higher than that of Necator americanus (25% versus 15%), the hookworm species that is often assumed to prevail in East-Africa. Among the microscopic techniques, FEC was able to detect the broadest spectrum of parasite species. However, FEC also missed a considerable number of infections, notably S. stercoralis, Schistosoma mansoni and G. intestinalis. PCR outperformed microscopy in terms of sensitivity and range of parasite species detected. CONCLUSIONS/SIGNIFICANCE We showed intestinal parasites-especially helminths-to be omnipresent in Inhamudima, Beira. However, it is a challenge to achieve high diagnostic sensitivity for all species. Classical techniques such as FEC are useful for the detection of some intestinal helminth species, but they lack sensitivity for other parasite species. PCR can detect intestinal parasites more accurately but is generally not feasible in resource-poor settings, at least not in peripheral labs. Hence, there is a need for a more field-friendly, sensitive approach for on-the-spot diagnosis of parasitic infections.
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Affiliation(s)
- Lynn Meurs
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Anton M. Polderman
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Eric A. T. Brienen
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jaco J. Verweij
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Bernhard Groosjohan
- Faculty of Health Science, Catholic University of Mozambique, Beira, Mozambique
| | - Felisberto Mendes
- Faculty of Health Science, Catholic University of Mozambique, Beira, Mozambique
| | - Manito Mechendura
- Faculty of Health Science, Catholic University of Mozambique, Beira, Mozambique
| | - Dagmar H. Hepp
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Rosanne Edelenbosch
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Katja Polman
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Lisette van Lieshout
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
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Hawkins KR, Cantera JL, Storey HL, Leader BT, de los Santos T. Diagnostic Tests to Support Late-Stage Control Programs for Schistosomiasis and Soil-Transmitted Helminthiases. PLoS Negl Trop Dis 2016; 10:e0004985. [PMID: 28005900 PMCID: PMC5179049 DOI: 10.1371/journal.pntd.0004985] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Global efforts to address schistosomiasis and soil-transmitted helminthiases (STH) include deworming programs for school-aged children that are made possible by large-scale drug donations. Decisions on these mass drug administration (MDA) programs currently rely on microscopic examination of clinical specimens to determine the presence of parasite eggs. However, microscopy-based methods are not sensitive to the low-intensity infections that characterize populations that have undergone MDA. Thus, there has been increasing recognition within the schistosomiasis and STH communities of the need for improved diagnostic tools to support late-stage control program decisions, such as when to stop or reduce MDA. Failure to adequately address the need for new diagnostics could jeopardize achievement of the 2020 London Declaration goals. In this report, we assess diagnostic needs and landscape potential solutions and determine appropriate strategies to improve diagnostic testing to support control and elimination programs. Based upon literature reviews and previous input from experts in the schistosomiasis and STH communities, we prioritized two diagnostic use cases for further exploration: to inform MDA-stopping decisions and post-MDA surveillance. To this end, PATH has refined target product profiles (TPPs) for schistosomiasis and STH diagnostics that are applicable to these use cases. We evaluated the limitations of current diagnostic methods with regards to these use cases and identified candidate biomarkers and diagnostics with potential application as new tools. Based on this analysis, there is a need to develop antigen-detecting rapid diagnostic tests (RDTs) with simplified, field-deployable sample preparation for schistosomiasis. Additionally, there is a need for diagnostic tests that are more sensitive than the current methods for STH, which may include either a field-deployable molecular test or a simple, low-cost, rapid antigen-detecting test.
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Affiliation(s)
- Kenneth R. Hawkins
- Diagnostics Program, PATH, Seattle, Washington, United States of America
- * E-mail:
| | - Jason L. Cantera
- Diagnostics Program, PATH, Seattle, Washington, United States of America
| | - Helen L. Storey
- Diagnostics Program, PATH, Seattle, Washington, United States of America
| | - Brandon T. Leader
- Diagnostics Program, PATH, Seattle, Washington, United States of America
| | - Tala de los Santos
- Diagnostics Program, PATH, Seattle, Washington, United States of America
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Wang H, Naghavi M, Allen C, Barber RM, Bhutta ZA, Carter A, Casey DC, Charlson FJ, Chen AZ, Coates MM, Coggeshall M, Dandona L, Dicker DJ, Erskine HE, Ferrari AJ, Fitzmaurice C, Foreman K, Forouzanfar MH, Fraser MS, Fullman N, Gething PW, Goldberg EM, Graetz N, Haagsma JA, Hay SI, Huynh C, Johnson CO, Kassebaum NJ, Kinfu Y, Kulikoff XR, Kutz M, Kyu HH, Larson HJ, Leung J, Liang X, Lim SS, Lind M, Lozano R, Marquez N, Mensah GA, Mikesell J, Mokdad AH, Mooney MD, Nguyen G, Nsoesie E, Pigott DM, Pinho C, Roth GA, Salomon JA, Sandar L, Silpakit N, Sligar A, Sorensen RJD, Stanaway J, Steiner C, Teeple S, Thomas BA, Troeger C, VanderZanden A, Vollset SE, Wanga V, Whiteford HA, Wolock T, Zoeckler L, Abate KH, Abbafati C, Abbas KM, Abd-Allah F, Abera SF, Abreu DMX, Abu-Raddad LJ, Abyu GY, Achoki T, Adelekan AL, Ademi Z, Adou AK, Adsuar JC, Afanvi KA, Afshin A, Agardh EE, Agarwal A, Agrawal A, Kiadaliri AA, Ajala ON, Akanda AS, Akinyemi RO, Akinyemiju TF, Akseer N, Lami FHA, Alabed S, Al-Aly Z, Alam K, Alam NKM, Alasfoor D, Aldhahri SF, Aldridge RW, Alegretti MA, Aleman AV, Alemu ZA, Alexander LT, Alhabib S, Ali R, Alkerwi A, Alla F, Allebeck P, Al-Raddadi R, Alsharif U, Altirkawi KA, Martin EA, Alvis-Guzman N, Amare AT, Amegah AK, Ameh EA, Amini H, Ammar W, Amrock SM, Andersen HH, Anderson BO, Anderson GM, Antonio CAT, Aregay AF, Ärnlöv J, Arsenijevic VSA, Artaman A, Asayesh H, Asghar RJ, Atique S, Avokpaho EFGA, Awasthi A, Azzopardi P, Bacha U, Badawi A, Bahit MC, Balakrishnan K, Banerjee A, Barac A, Barker-Collo SL, Bärnighausen T, Barregard L, Barrero LH, Basu A, Basu S, Bayou YT, Bazargan-Hejazi S, Beardsley J, Bedi N, Beghi E, Belay HA, Bell B, Bell ML, Bello AK, Bennett DA, Bensenor IM, Berhane A, Bernabé E, Betsu BD, Beyene AS, Bhala N, Bhalla A, Biadgilign S, Bikbov B, Abdulhak AAB, Biroscak BJ, Biryukov S, Bjertness E, Blore JD, Blosser CD, Bohensky MA, Borschmann R, Bose D, Bourne RRA, Brainin M, Brayne CEG, Brazinova A, Breitborde NJK, Brenner H, Brewer JD, Brown A, Brown J, Brugha TS, Buckle GC, Butt ZA, Calabria B, Campos-Nonato IR, Campuzano JC, Carapetis JR, Cárdenas R, Carpenter DO, Carrero JJ, Castañeda-Orjuela CA, Rivas JC, Catalá-López F, Cavalleri F, Cercy K, Cerda J, Chen W, Chew A, Chiang PPC, Chibalabala M, Chibueze CE, Chimed-Ochir O, Chisumpa VH, Choi JYJ, Chowdhury R, Christensen H, Christopher DJ, Ciobanu LG, Cirillo M, Cohen AJ, Colistro V, Colomar M, Colquhoun SM, Cooper C, Cooper LT, Cortinovis M, Cowie BC, Crump JA, Damsere-Derry J, Danawi H, Dandona R, Daoud F, Darby SC, Dargan PI, das Neves J, Davey G, Davis AC, Davitoiu DV, de Castro EF, de Jager P, Leo DD, Degenhardt L, Dellavalle RP, Deribe K, Deribew A, Dharmaratne SD, Dhillon PK, Diaz-Torné C, Ding EL, dos Santos KPB, Dossou E, Driscoll TR, Duan L, Dubey M, Duncan BB, Ellenbogen RG, Ellingsen CL, Elyazar I, Endries AY, Ermakov SP, Eshrati B, Esteghamati A, Estep K, Faghmous IDA, Fahimi S, Faraon EJA, Farid TA, Farinha CSES, Faro A, Farvid MS, Farzadfar F, Feigin VL, Fereshtehnejad SM, Fernandes JG, Fernandes JC, Fischer F, Fitchett JRA, Flaxman A, Foigt N, Fowkes FGR, Franca EB, Franklin RC, Friedman J, Frostad J, Fürst T, Futran ND, Gall SL, Gambashidze K, Gamkrelidze A, Ganguly P, Gankpé FG, Gebre T, Gebrehiwot TT, Gebremedhin AT, Gebru AA, Geleijnse JM, Gessner BD, Ghoshal AG, Gibney KB, Gillum RF, Gilmour S, Giref AZ, Giroud M, Gishu MD, Giussani G, Glaser E, Godwin WW, Gomez-Dantes H, Gona P, Goodridge A, Gopalani SV, Gosselin RA, Gotay CC, Goto A, Gouda HN, Greaves F, Gugnani HC, Gupta R, Gupta R, Gupta V, Gutiérrez RA, Hafezi-Nejad N, Haile D, Hailu AD, Hailu GB, Halasa YA, Hamadeh RR, Hamidi S, Hancock J, Handal AJ, Hankey GJ, Hao Y, Harb HL, Harikrishnan S, Haro JM, Havmoeller R, Heckbert SR, Heredia-Pi IB, Heydarpour P, Hilderink HBM, Hoek HW, Hogg RS, Horino M, Horita N, Hosgood HD, Hotez PJ, Hoy DG, Hsairi M, Htet AS, Htike MMT, Hu G, Huang C, Huang H, Huiart L, Husseini A, Huybrechts I, Huynh G, Iburg KM, Innos K, Inoue M, Iyer VJ, Jacobs TA, Jacobsen KH, Jahanmehr N, Jakovljevic MB, James P, Javanbakht M, Jayaraman SP, Jayatilleke AU, Jeemon P, Jensen PN, Jha V, Jiang G, Jiang Y, Jibat T, Jimenez-Corona A, Jonas JB, Joshi TK, Kabir Z, Kamal R, Kan H, Kant S, Karch A, Karema CK, Karimkhani C, Karletsos D, Karthikeyan G, Kasaeian A, Katibeh M, Kaul A, Kawakami N, Kayibanda JF, Keiyoro PN, Kemmer L, Kemp AH, Kengne AP, Keren A, Kereselidze M, Kesavachandran CN, Khader YS, Khalil IA, Khan AR, Khan EA, Khang YH, Khera S, Khoja TAM, Kieling C, Kim D, Kim YJ, Kissela BM, Kissoon N, Knibbs LD, Knudsen AK, Kokubo Y, Kolte D, Kopec JA, Kosen S, Koul PA, Koyanagi A, Krog NH, Defo BK, Bicer BK, Kudom AA, Kuipers EJ, Kulkarni VS, Kumar GA, Kwan GF, Lal A, Lal DK, Lalloo R, Lallukka T, Lam H, Lam JO, Langan SM, Lansingh VC, Larsson A, Laryea DO, Latif AA, Lawrynowicz AEB, Leigh J, Levi M, Li Y, Lindsay MP, Lipshultz SE, Liu PY, Liu S, Liu Y, Lo LT, Logroscino G, Lotufo PA, Lucas RM, Lunevicius R, Lyons RA, Ma S, Machado VMP, Mackay MT, MacLachlan JH, Razek HMAE, Magdy M, Razek AE, Majdan M, Majeed A, Malekzadeh R, Manamo WAA, Mandisarisa J, Mangalam S, Mapoma CC, Marcenes W, Margolis DJ, Martin GR, Martinez-Raga J, Marzan MB, Masiye F, Mason-Jones AJ, Massano J, Matzopoulos R, Mayosi BM, McGarvey ST, McGrath JJ, McKee M, McMahon BJ, Meaney PA, Mehari A, Mehndiratta MM, Mejia-Rodriguez F, Mekonnen AB, Melaku YA, Memiah P, Memish ZA, Mendoza W, Meretoja A, Meretoja TJ, Mhimbira FA, Micha R, Millear A, Miller TR, Mirarefin M, Misganaw A, Mock CN, Mohammad KA, Mohammadi A, Mohammed S, Mohan V, Mola GLD, Monasta L, Hernandez JCM, Montero P, Montico M, Montine TJ, Moradi-Lakeh M, Morawska L, Morgan K, Mori R, Mozaffarian D, Mueller UO, Murthy GVS, Murthy S, Musa KI, Nachega JB, Nagel G, Naidoo KS, Naik N, Naldi L, Nangia V, Nash D, Nejjari C, Neupane S, Newton CR, Newton JN, Ng M, Ngalesoni FN, de Dieu Ngirabega J, Nguyen QL, Nisar MI, Pete PMN, Nomura M, Norheim OF, Norman PE, Norrving B, Nyakarahuka L, Ogbo FA, Ohkubo T, Ojelabi FA, Olivares PR, Olusanya BO, Olusanya JO, Opio JN, Oren E, Ortiz A, Osman M, Ota E, Ozdemir R, PA M, Pain A, Pandian JD, Pant PR, Papachristou C, Park EK, Park JH, Parry CD, Parsaeian M, Caicedo AJP, Patten SB, Patton GC, Paul VK, Pearce N, Pedro JM, Stokic LP, Pereira DM, Perico N, Pesudovs K, Petzold M, Phillips MR, Piel FB, Pillay JD, Plass D, Platts-Mills JA, Polinder S, Pope CA, Popova S, Poulton RG, Pourmalek F, Prabhakaran D, Qorbani M, Quame-Amaglo J, Quistberg DA, Rafay A, Rahimi K, Rahimi-Movaghar V, Rahman M, Rahman MHU, Rahman SU, Rai RK, Rajavi Z, Rajsic S, Raju M, Rakovac I, Rana SM, Ranabhat CL, Rangaswamy T, Rao P, Rao SR, Refaat AH, Rehm J, Reitsma MB, Remuzzi G, Resnikoff S, Ribeiro AL, Ricci S, Blancas MJR, Roberts B, Roca A, Rojas-Rueda D, Ronfani L, Roshandel G, Rothenbacher D, Roy A, Roy NK, Ruhago GM, Sagar R, Saha S, Sahathevan R, Saleh MM, Sanabria JR, Sanchez-Niño MD, Sanchez-Riera L, Santos IS, Sarmiento-Suarez R, Sartorius B, Satpathy M, Savic M, Sawhney M, Schaub MP, Schmidt MI, Schneider IJC, Schöttker B, Schutte AE, Schwebel DC, Seedat S, Sepanlou SG, Servan-Mori EE, Shackelford KA, Shaddick G, Shaheen A, Shahraz S, Shaikh MA, Shakh-Nazarova M, Sharma R, She J, Sheikhbahaei S, Shen J, Shen Z, Shepard DS, Sheth KN, Shetty BP, Shi P, Shibuya K, Shin MJ, Shiri R, Shiue I, Shrime MG, Sigfusdottir ID, Silberberg DH, Silva DAS, Silveira DGA, Silverberg JI, Simard EP, Singh A, Singh GM, Singh JA, Singh OP, Singh PK, Singh V, Soneji S, Søreide K, Soriano JB, Sposato LA, Sreeramareddy CT, Stathopoulou V, Stein DJ, Stein MB, Stranges S, Stroumpoulis K, Sunguya BF, Sur P, Swaminathan S, Sykes BL, Szoeke CEI, Tabarés-Seisdedos R, Tabb KM, Takahashi K, Takala JS, Talongwa RT, Tandon N, Tavakkoli M, Taye B, Taylor HR, Ao BJT, Tedla BA, Tefera WM, Have MT, Terkawi AS, Tesfay FH, Tessema GA, Thomson AJ, Thorne-Lyman AL, Thrift AG, Thurston GD, Tillmann T, Tirschwell DL, Tonelli M, Topor-Madry R, Topouzis F, Towbin JA, Traebert J, Tran BX, Truelsen T, Trujillo U, Tura AK, Tuzcu EM, Uchendu US, Ukwaja KN, Undurraga EA, Uthman OA, Dingenen RV, van Donkelaar A, Vasankari T, Vasconcelos AMN, Venketasubramanian N, Vidavalur R, Vijayakumar L, Villalpando S, Violante FS, Vlassov VV, Wagner JA, Wagner GR, Wallin MT, Wang L, Watkins DA, Weichenthal S, Weiderpass E, Weintraub RG, Werdecker A, Westerman R, White RA, Wijeratne T, Wilkinson JD, Williams HC, Wiysonge CS, Woldeyohannes SM, Wolfe CDA, Won S, Wong JQ, Woolf AD, Xavier D, Xiao Q, Xu G, Yakob B, Yalew AZ, Yan LL, Yano Y, Yaseri M, Ye P, Yebyo HG, Yip P, Yirsaw BD, Yonemoto N, Yonga G, Younis MZ, Yu S, Zaidi Z, Zaki MES, Zannad F, Zavala DE, Zeeb H, Zeleke BM, Zhang H, Zodpey S, Zonies D, Zuhlke LJ, Vos T, Lopez AD, Murray CJL. Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet 2016; 388:1459-1544. [PMID: 27733281 PMCID: PMC5388903 DOI: 10.1016/s0140-6736(16)31012-1] [Citation(s) in RCA: 4031] [Impact Index Per Article: 503.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Improving survival and extending the longevity of life for all populations requires timely, robust evidence on local mortality levels and trends. The Global Burden of Disease 2015 Study (GBD 2015) provides a comprehensive assessment of all-cause and cause-specific mortality for 249 causes in 195 countries and territories from 1980 to 2015. These results informed an in-depth investigation of observed and expected mortality patterns based on sociodemographic measures. METHODS We estimated all-cause mortality by age, sex, geography, and year using an improved analytical approach originally developed for GBD 2013 and GBD 2010. Improvements included refinements to the estimation of child and adult mortality and corresponding uncertainty, parameter selection for under-5 mortality synthesis by spatiotemporal Gaussian process regression, and sibling history data processing. We also expanded the database of vital registration, survey, and census data to 14 294 geography-year datapoints. For GBD 2015, eight causes, including Ebola virus disease, were added to the previous GBD cause list for mortality. We used six modelling approaches to assess cause-specific mortality, with the Cause of Death Ensemble Model (CODEm) generating estimates for most causes. We used a series of novel analyses to systematically quantify the drivers of trends in mortality across geographies. First, we assessed observed and expected levels and trends of cause-specific mortality as they relate to the Socio-demographic Index (SDI), a summary indicator derived from measures of income per capita, educational attainment, and fertility. Second, we examined factors affecting total mortality patterns through a series of counterfactual scenarios, testing the magnitude by which population growth, population age structures, and epidemiological changes contributed to shifts in mortality. Finally, we attributed changes in life expectancy to changes in cause of death. We documented each step of the GBD 2015 estimation processes, as well as data sources, in accordance with Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER). FINDINGS Globally, life expectancy from birth increased from 61·7 years (95% uncertainty interval 61·4-61·9) in 1980 to 71·8 years (71·5-72·2) in 2015. Several countries in sub-Saharan Africa had very large gains in life expectancy from 2005 to 2015, rebounding from an era of exceedingly high loss of life due to HIV/AIDS. At the same time, many geographies saw life expectancy stagnate or decline, particularly for men and in countries with rising mortality from war or interpersonal violence. From 2005 to 2015, male life expectancy in Syria dropped by 11·3 years (3·7-17·4), to 62·6 years (56·5-70·2). Total deaths increased by 4·1% (2·6-5·6) from 2005 to 2015, rising to 55·8 million (54·9 million to 56·6 million) in 2015, but age-standardised death rates fell by 17·0% (15·8-18·1) during this time, underscoring changes in population growth and shifts in global age structures. The result was similar for non-communicable diseases (NCDs), with total deaths from these causes increasing by 14·1% (12·6-16·0) to 39·8 million (39·2 million to 40·5 million) in 2015, whereas age-standardised rates decreased by 13·1% (11·9-14·3). Globally, this mortality pattern emerged for several NCDs, including several types of cancer, ischaemic heart disease, cirrhosis, and Alzheimer's disease and other dementias. By contrast, both total deaths and age-standardised death rates due to communicable, maternal, neonatal, and nutritional conditions significantly declined from 2005 to 2015, gains largely attributable to decreases in mortality rates due to HIV/AIDS (42·1%, 39·1-44·6), malaria (43·1%, 34·7-51·8), neonatal preterm birth complications (29·8%, 24·8-34·9), and maternal disorders (29·1%, 19·3-37·1). Progress was slower for several causes, such as lower respiratory infections and nutritional deficiencies, whereas deaths increased for others, including dengue and drug use disorders. Age-standardised death rates due to injuries significantly declined from 2005 to 2015, yet interpersonal violence and war claimed increasingly more lives in some regions, particularly in the Middle East. In 2015, rotaviral enteritis (rotavirus) was the leading cause of under-5 deaths due to diarrhoea (146 000 deaths, 118 000-183 000) and pneumococcal pneumonia was the leading cause of under-5 deaths due to lower respiratory infections (393 000 deaths, 228 000-532 000), although pathogen-specific mortality varied by region. Globally, the effects of population growth, ageing, and changes in age-standardised death rates substantially differed by cause. Our analyses on the expected associations between cause-specific mortality and SDI show the regular shifts in cause of death composition and population age structure with rising SDI. Country patterns of premature mortality (measured as years of life lost [YLLs]) and how they differ from the level expected on the basis of SDI alone revealed distinct but highly heterogeneous patterns by region and country or territory. Ischaemic heart disease, stroke, and diabetes were among the leading causes of YLLs in most regions, but in many cases, intraregional results sharply diverged for ratios of observed and expected YLLs based on SDI. Communicable, maternal, neonatal, and nutritional diseases caused the most YLLs throughout sub-Saharan Africa, with observed YLLs far exceeding expected YLLs for countries in which malaria or HIV/AIDS remained the leading causes of early death. INTERPRETATION At the global scale, age-specific mortality has steadily improved over the past 35 years; this pattern of general progress continued in the past decade. Progress has been faster in most countries than expected on the basis of development measured by the SDI. Against this background of progress, some countries have seen falls in life expectancy, and age-standardised death rates for some causes are increasing. Despite progress in reducing age-standardised death rates, population growth and ageing mean that the number of deaths from most non-communicable causes are increasing in most countries, putting increased demands on health systems. FUNDING Bill & Melinda Gates Foundation.
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O'Connell EM, Nutman TB. Molecular Diagnostics for Soil-Transmitted Helminths. Am J Trop Med Hyg 2016; 95:508-513. [PMID: 27481053 PMCID: PMC5014250 DOI: 10.4269/ajtmh.16-0266] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/29/2016] [Indexed: 12/18/2022] Open
Abstract
Historically, the diagnosis of soil-transmitted helminths (STHs) (e.g., Strongyloides stercoralis, Trichuris trichiura, Ancylostoma duodenale, Necator americanus, and Ascaris lumbricoides) has relied on often-insensitive microscopy techniques. Over the past several years, there has been an effort to use molecular diagnostics, particularly quantitative polymerase chain reaction (qPCR), to detect intestinal pathogens. While some platforms have been approved by regulatory bodies (e.g., Food and Drug Administration) to detect intestinal bacteria, viruses, and protozoa, there are no approved tests currently available for STH. Although studies comparing qPCR to microscopy methods for STH are imperfect, due in large part to a lack of a sufficient gold standard, they do show a significant increase in sensitivity and specificity of qPCR compared with microscopic techniques. These studies, as well as the advantages and disadvantages of using qPCR for STH diagnosis, are discussed. Guidelines for those designing future studies utilizing qPCR are proposed for optimizing results, as is the proposition for using standardized molecular diagnostics routinely for STH in clinical laboratories and for field-based studies when possible.
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Affiliation(s)
- Elise M O'Connell
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Thomas B Nutman
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
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Molecular testing for clinical diagnosis and epidemiological investigations of intestinal parasitic infections. Clin Microbiol Rev 2016; 27:371-418. [PMID: 24696439 DOI: 10.1128/cmr.00122-13] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.
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Abstract
Anaemia affects roughly a third of the world's population; half the cases are due to iron deficiency. It is a major and global public health problem that affects maternal and child mortality, physical performance, and referral to health-care professionals. Children aged 0-5 years, women of childbearing age, and pregnant women are particularly at risk. Several chronic diseases are frequently associated with iron deficiency anaemia--notably chronic kidney disease, chronic heart failure, cancer, and inflammatory bowel disease. Measurement of serum ferritin, transferrin saturation, serum soluble transferrin receptors, and the serum soluble transferrin receptors-ferritin index are more accurate than classic red cell indices in the diagnosis of iron deficiency anaemia. In addition to the search for and treatment of the cause of iron deficiency, treatment strategies encompass prevention, including food fortification and iron supplementation. Oral iron is usually recommended as first-line therapy, but the most recent intravenous iron formulations, which have been available for nearly a decade, seem to replenish iron stores safely and effectively. Hepcidin has a key role in iron homoeostasis and could be a future diagnostic and therapeutic target. In this Seminar, we discuss the clinical presentation, epidemiology, pathophysiology, diagnosis, and acute management of iron deficiency anaemia, and outstanding research questions for treatment.
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Affiliation(s)
- Anthony Lopez
- Department of Hepato-Gastroenterology and Inserm U954, University Hospital of Nancy, Lorraine University, Vandoeuvre-lès-Nancy, France
| | - Patrice Cacoub
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7211, Paris, France; Inflammation-Immunopathology-Biotherapy Department, F-75005, Paris, France; AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Department of Internal Medicine and Clinical Immunology, F-75013, Paris, France
| | | | - Laurent Peyrin-Biroulet
- Department of Hepato-Gastroenterology and Inserm U954, University Hospital of Nancy, Lorraine University, Vandoeuvre-lès-Nancy, France.
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Easton AV, Oliveira RG, O'Connell EM, Kepha S, Mwandawiro CS, Njenga SM, Kihara JH, Mwatele C, Odiere MR, Brooker SJ, Webster JP, Anderson RM, Nutman TB. Multi-parallel qPCR provides increased sensitivity and diagnostic breadth for gastrointestinal parasites of humans: field-based inferences on the impact of mass deworming. Parasit Vectors 2016; 9:38. [PMID: 26813411 PMCID: PMC4729172 DOI: 10.1186/s13071-016-1314-y] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 01/05/2016] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Although chronic morbidity in humans from soil transmitted helminth (STH) infections can be reduced by anthelmintic treatment, inconsistent diagnostic tools make it difficult to reliably measure the impact of deworming programs and often miss light helminth infections. METHODS Cryopreserved stool samples from 796 people (aged 2-81 years) in four villages in Bungoma County, western Kenya, were assessed using multi-parallel qPCR for 8 parasites and compared to point-of-contact assessments of the same stools by the 2-stool 2-slide Kato-Katz (KK) method. All subjects were treated with albendazole and all Ascaris lumbricoides expelled post-treatment were collected. Three months later, samples from 633 of these people were re-assessed by both qPCR and KK, re-treated with albendazole and the expelled worms collected. RESULTS Baseline prevalence by qPCR (n = 796) was 17 % for A. lumbricoides, 18 % for Necator americanus, 41 % for Giardia lamblia and 15% for Entamoeba histolytica. The prevalence was <1% for Trichuris trichiura, Ancylostoma duodenale, Strongyloides stercoralis and Cryptosporidium parvum. The sensitivity of qPCR was 98% for A. lumbricoides and N. americanus, whereas KK sensitivity was 70% and 32%, respectively. Furthermore, qPCR detected infections with T. trichiura and S. stercoralis that were missed by KK, and infections with G. lamblia and E. histolytica that cannot be detected by KK. Infection intensities measured by qPCR and by KK were correlated for A. lumbricoides (r = 0.83, p < 0.0001) and N. americanus (r = 0.55, p < 0.0001). The number of A. lumbricoides worms expelled was correlated (p < 0.0001) with both the KK (r = 0.63) and qPCR intensity measurements (r = 0.60). CONCLUSIONS KK may be an inadequate tool for stool-based surveillance in areas where hookworm or Strongyloides are common or where intensity of helminth infection is low after repeated rounds of chemotherapy. Because deworming programs need to distinguish between populations where parasitic infection is controlled and those where further treatment is required, multi-parallel qPCR (or similar high throughput molecular diagnostics) may provide new and important diagnostic information.
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Affiliation(s)
- Alice V Easton
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, MD, USA.
- Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK.
| | - Rita G Oliveira
- Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK.
| | - Elise M O'Connell
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, MD, USA. elise.o'
| | - Stella Kepha
- School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda.
| | - Charles S Mwandawiro
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya.
| | - Sammy M Njenga
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya.
| | - Jimmy H Kihara
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya.
| | - Cassian Mwatele
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya.
| | - Maurice R Odiere
- Neglected Tropical Diseases Research Unit, Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.
| | - Simon J Brooker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
| | - Joanne P Webster
- Royal Veterinary College, University of London, Hertfordshire, UK.
| | - Roy M Anderson
- Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK.
| | - Thomas B Nutman
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, MD, USA.
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Becker SL, Piraisoody N, Kramme S, Marti H, Silué KD, Panning M, Nickel B, Kern WV, Herrmann M, Hatz CF, N’Goran EK, Utzinger J, von Müller L. Real-time PCR for detection of Strongyloides stercoralis in human stool samples from Côte d'Ivoire: diagnostic accuracy, inter-laboratory comparison and patterns of hookworm co-infection. Acta Trop 2015. [PMID: 26215130 DOI: 10.1016/j.actatropica.2015.07.019] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Human infections with the helminth species Strongyloides stercoralis encompass a wide clinical spectrum, ranging from asymptomatic carriage to life-threatening disease. The diagnosis of S. stercoralis is cumbersome and the sensitivity of conventional stool microscopy is low. New molecular tools have been developed to increase sensitivity. We compared the diagnostic accuracy of real-time PCR with microscopy for the detection of S. stercoralis and hookworm in human stool samples, and investigated the inter-laboratory agreement of S. stercoralis-specific real-time PCR in two European laboratories. Stool specimens from 256 randomly selected individuals in rural Côte d'Ivoire were examined using three microscopic techniques (i.e. Kato-Katz, Koga agar plate (KAP) and Baermann (BM)). Additionally, ethanol-fixed stool aliquots were subjected to molecular diagnosis. The prevalence of S. stercoralis and hookworm infection was 21.9% and 52.0%, respectively, whilst co-infections were detected in 35 (13.7%) participants. The diagnostic agreement between real-time PCR and microscopy was excellent when both KAP and BM tested positive for S. stercoralis, but was considerably lower when only one microscopic technique was positive. The sensitivity of KAP, BM and real-time PCR for detection of S. stercoralis as compared to a combination of all diagnostic techniques was 21.4%, 37.5% and 76.8%, respectively. The inter-laboratory agreement of S. stercoralis-specific PCR was substantial (κ=0.63, p<0.001). We conclude that a combination of real-time PCR and stool microscopy shows high accuracy for S. stercoralis diagnosis. Besides high sensitivity, PCR may also enhance specificity by reducing microscopic misdiagnosis of morphologically similar helminth larvae (i.e. hookworm and S. stercoralis) in settings where both helminth species co-exist.
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Montresor A, Addiss D, Albonico M, Ali SM, Ault SK, Gabrielli AF, Garba A, Gasimov E, Gyorkos T, Jamsheed MA, Levecke B, Mbabazi P, Mupfasoni D, Savioli L, Vercruysse J, Yajima A. Methodological Bias Can Lead the Cochrane Collaboration to Irrelevance in Public Health Decision-Making. PLoS Negl Trop Dis 2015; 9:e0004165. [PMID: 26492178 PMCID: PMC4619606 DOI: 10.1371/journal.pntd.0004165] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Antonio Montresor
- Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - David Addiss
- Children Without Worms, Task Force for Global Health, Decatur, Georgia, United States of America
| | - Marco Albonico
- WHO Collaborating Centre for Neglected Tropical Diseases, Public Health Laboratory Ivo de Carneri, Zanzibar, United Republic of Tanzania
| | - Said Mohammed Ali
- WHO Collaborating Centre for Neglected Tropical Diseases, Public Health Laboratory Ivo de Carneri, Zanzibar, United Republic of Tanzania
| | - Steven K. Ault
- Neglected Infectious Diseases, Pan American Health Organization, World Health Regional Office for the Americas, Washington, DC, United States of America
| | - Albis-Francesco Gabrielli
- Neglected Tropical Diseases, World Health Organization Regional Office for the Eastern Mediterranean, Cairo, Egypt
| | - Amadou Garba
- Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Elkhan Gasimov
- Malaria, Other Vectorborne and Parasitic Diseases, World Health Organization Regional Office for Europe, Copenhagen, Denmark
| | - Theresa Gyorkos
- WHO Collaborating Centre for Research and Training in Parasite Epidemiology and Control, Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada
| | - Mohamed Ahmed Jamsheed
- Vector-Borne and Neglected Tropical Diseases Control, World Health Organization Regional Office for South-East Asia, New Delhi, India
| | - Bruno Levecke
- WHO Collaborating Centre for the Monitoring of Anthelminthic Drug Efficacy for Soil-Transmitted Helminthiasis, Department of Virology, Parasitology and Immunology, University of Ghent, Ghent, Belgium
| | - Pamela Mbabazi
- Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Denise Mupfasoni
- Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Lorenzo Savioli
- Global Schistosomiasis Alliance and Public Health Laboratory Ivo de Carneri, Zanzibar, United Republic of Tanzania
| | - Jozef Vercruysse
- WHO Collaborating Centre for the Monitoring of Anthelminthic Drug Efficacy for Soil-Transmitted Helminthiasis, Department of Virology, Parasitology and Immunology, University of Ghent, Ghent, Belgium
| | - Aya Yajima
- Malaria, Other Vectorborne and Parasitic Diseases, World Health Organization, Regional Office for Western Pacific, Manila, Philippines
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Cimino RO, Jeun R, Juarez M, Cajal PS, Vargas P, Echazú A, Bryan PE, Nasser J, Krolewiecki A, Mejia R. Identification of human intestinal parasites affecting an asymptomatic peri-urban Argentinian population using multi-parallel quantitative real-time polymerase chain reaction. Parasit Vectors 2015; 8:380. [PMID: 26183074 PMCID: PMC4504406 DOI: 10.1186/s13071-015-0994-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 07/07/2015] [Indexed: 11/29/2022] Open
Abstract
Background In resource-limited countries, stool microscopy is the diagnostic test of choice for intestinal parasites (soil-transmitted helminths and/or intestinal protozoa). However, sensitivity and specificity is low. Improved diagnosis of intestinal parasites is especially important for accurate measurements of prevalence and intensity of infections in endemic areas. Methods The study was carried out in Orán, Argentina. A total of 99 stool samples from a local surveillance campaign were analyzed by concentration microscopy and McMaster egg counting technique compared to the analysis by multi-parallel quantitative real-time polymerase chain reaction (qPCR). This study compared the performance of qPCR assay and stool microscopy for 8 common intestinal parasites that infect humans including the helminths Ascaris lumbricoides, Ancylostoma duodenale, Necator americanus, Strongyloides stercoralis, Trichuris trichiura, and the protozoa Giardia lamblia, Cryptosporidium parvum/hominis, and Entamoeba histolytica, and investigated the prevalence of polyparasitism in an endemic area. Results qPCR showed higher detection rates for all parasites as compared to stool microscopy except T. trichiura. Species-specific primers and probes were able to distinguish between A. duodenale (19.1 %) and N. americanus (36.4 %) infections. There were 48.6 % of subjects co-infected with both hookworms, and a significant increase in hookworm DNA for A. duodenale versus N. americanus (119.6 fg/μL: 0.63 fg/μL, P < 0.001) respectively. qPCR outperformed microscopy by the largest margin in G. lamblia infections (63.6 % versus 8.1 %, P < 0.05). Polyparasitism was detected more often by qPCR compared to microscopy (64.7 % versus 24.2 %, P < 0.05). Conclusions Multi-parallel qPCR is a quantitative molecular diagnostic method for common intestinal parasites in an endemic area that has improved diagnostic accuracy compared to stool microscopy. This first time use of multi-parallel qPCR in Argentina has demonstrated the high prevalence of intestinal parasites in a peri-urban area. These results will contribute to more accurate epidemiological survey, refined treatment strategies on a public scale, and better health outcomes in endemic settings.
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Affiliation(s)
- Rubén O Cimino
- Instituto de Investigaciones en Enfermedades Tropicales - Universidad Nacional de Salta/CONICET, Oran, Argentina. .,Cátedra de Química Biológica, Facultad de Ciencias Naturales, Universidad Nacional de Salta, Oran, Argentina.
| | - Rebecca Jeun
- National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA.
| | - Marisa Juarez
- Instituto de Investigaciones en Enfermedades Tropicales - Universidad Nacional de Salta/CONICET, Oran, Argentina. .,Fundación Mundo Sano, Buenos Aires, Argentina.
| | - Pamela S Cajal
- Instituto de Investigaciones en Enfermedades Tropicales - Universidad Nacional de Salta/CONICET, Oran, Argentina.
| | - Paola Vargas
- Instituto de Investigaciones en Enfermedades Tropicales - Universidad Nacional de Salta/CONICET, Oran, Argentina.
| | - Adriana Echazú
- Instituto de Investigaciones en Enfermedades Tropicales - Universidad Nacional de Salta/CONICET, Oran, Argentina.
| | - Patricia E Bryan
- National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA.
| | - Julio Nasser
- Instituto de Investigaciones en Enfermedades Tropicales - Universidad Nacional de Salta/CONICET, Oran, Argentina. .,Cátedra de Química Biológica, Facultad de Ciencias Naturales, Universidad Nacional de Salta, Oran, Argentina.
| | - Alejandro Krolewiecki
- Instituto de Investigaciones en Enfermedades Tropicales - Universidad Nacional de Salta/CONICET, Oran, Argentina.
| | - Rojelio Mejia
- Cátedra de Química Biológica, Facultad de Ciencias Naturales, Universidad Nacional de Salta, Oran, Argentina. .,National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA.
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Prevalence of Necator americanus infection and risk factors among school-age children in Mirab Abaya District, South Ethiopia. ASIAN PACIFIC JOURNAL OF TROPICAL DISEASE 2015. [DOI: 10.1016/s2222-1808(14)60798-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Anaemia, iron deficiency and susceptibility to infections. J Infect 2014; 69 Suppl 1:S23-7. [DOI: 10.1016/j.jinf.2014.08.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2014] [Indexed: 12/11/2022]
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Spottiswoode N, Duffy PE, Drakesmith H. Iron, anemia and hepcidin in malaria. Front Pharmacol 2014; 5:125. [PMID: 24910614 PMCID: PMC4039013 DOI: 10.3389/fphar.2014.00125] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 05/11/2014] [Indexed: 12/21/2022] Open
Abstract
Malaria and iron have a complex but important relationship. Plasmodium proliferation requires iron, both during the clinically silent liver stage of growth and in the disease-associated phase of erythrocyte infection. Precisely how the protozoan acquires its iron from its mammalian host remains unclear, but iron chelators can inhibit pathogen growth in vitro and in animal models. In humans, iron deficiency appears to protect against severe malaria, while iron supplementation increases risks of infection and disease. Malaria itself causes profound disturbances in physiological iron distribution and utilization, through mechanisms that include hemolysis, release of heme, dyserythropoiesis, anemia, deposition of iron in macrophages, and inhibition of dietary iron absorption. These effects have significant consequences. Malarial anemia is a major global health problem, especially in children, that remains incompletely understood and is not straightforward to treat. Furthermore, the changes in iron metabolism during a malaria infection may modulate susceptibility to co-infections. The release of heme and accumulation of iron in granulocytes may explain increased vulnerability to non-typhoidal Salmonella during malaria. The redistribution of iron away from hepatocytes and into macrophages may confer host resistance to superinfection, whereby blood-stage parasitemia prevents the development of a second liver-stage Plasmodium infection in the same organism. Key to understanding the pathophysiology of iron metabolism in malaria is the activity of the iron regulatory hormone hepcidin. Hepcidin is upregulated during blood-stage parasitemia and likely mediates much of the iron redistribution that accompanies disease. Understanding the regulation and role of hepcidin may offer new opportunities to combat malaria and formulate better approaches to treat anemia in the developing world.
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Affiliation(s)
- Natasha Spottiswoode
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of HealthBethesda, MD, USA
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of OxfordOxford, UK
| | - Patrick E. Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of HealthBethesda, MD, USA
| | - Hal Drakesmith
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of OxfordOxford, UK
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Application of PCR-based methods for diagnosis of intestinal parasitic infections in the clinical laboratory. Parasitology 2014; 141:1863-72. [DOI: 10.1017/s0031182014000419] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
SUMMARYFor many years PCR- and other DNA-based methods of pathogen detection have been available in most clinical microbiology laboratories; however, until recently these tools were not routinely exploited for the diagnosis of parasitic infections. Laboratories were initially reluctant to implement PCR as incorporation of such assays within the algorithm of tools available for the most accurate diagnosis of a large variety of parasites was unclear. With regard to diagnosis of intestinal parasitic infections, the diversity of parasites that one can expect in most settings is far less than the parasitological textbooks would have you believe, hence developing a simplified diagnostic triage is feasible. Therefore the classical algorithm based on population, patient groups, use of immuno-suppressive drugs, travel history etc. is also applicable to decide when to perform and which additional techniques are to be used, if a multiplex PCR panel is used as a first-line screening diagnostic.
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Staudacher O, Heimer J, Steiner F, Kayonga Y, Havugimana JM, Ignatius R, Musemakweri A, Ngabo F, Harms G, Gahutu JB, Mockenhaupt FP. Soil-transmitted helminths in southern highland Rwanda: associated factors and effectiveness of school-based preventive chemotherapy. Trop Med Int Health 2014; 19:812-24. [PMID: 24750543 DOI: 10.1111/tmi.12321] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVES Preventive chemotherapy of schoolchildren against soil-transmitted helminths (STHs) is widely implemented in Rwanda. However, data on its actual efficacy are lacking. We assessed prevalence, associated factors and manifestation of STH infection among schoolchildren in southern highland Rwanda as well as cure and reinfection rates. METHODS Six hundred and twenty-two children (rural, 301; urban, 321) were included preceding the administration of a single dose of 500 mg mebendazole. Before treatment, and after 2 and 15 weeks, STH infection was determined by Kato-Katz smears and by PCR assays for Ascaris lumbricoides. Clinical and anthropometric data, socio-economic status and factors potentially associated with STH infection were assessed. RESULTS Soil-transmitted helminth (STH) infection was present in 38% of rural and in 13% of urban schoolchildren. Ascaris lumbricoides accounted for 96% of infections. Of these, one-third was detected by PCR exclusively. Factors associated with STH infection differed greatly between rural and urban children. Likewise, STH infection was associated with stunting and anaemia only among urban children. The cure rate after 2 weeks was 92%. Among eight non-cleared A. lumbricoides infections, seven were submicroscopic. Reinfection within 3 months occurred in 7%, but the rate was higher among rural children, and with initially present infection, particularly at comparatively high intensity. CONCLUSIONS The rural-urban difference in factors associated with STH infection and in reinfection rates highlights the need for targeted interventions to reduce transmission. PCR assays may help in detecting low-level infections persisting after treatment. In southern Rwanda, mebendazole is highly effective against the STH infections predominated by A. lumbricoides.
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Affiliation(s)
- Olga Staudacher
- Institute of Tropical Medicine and International Health, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Hawdon JM. Controlling Soil-Transmitted Helminths: Time to Think Inside the Box? J Parasitol 2014; 100:166-88. [DOI: 10.1645/13-412.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Arndt MB, John-Stewart G, Richardson BA, Singa B, van Lieshout L, Verweij JJ, Sangaré LR, Mbogo LW, Naulikha JM, Walson JL. Impact of helminth diagnostic test performance on estimation of risk factors and outcomes in HIV-positive adults. PLoS One 2013; 8:e81915. [PMID: 24324729 PMCID: PMC3852669 DOI: 10.1371/journal.pone.0081915] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/18/2013] [Indexed: 11/18/2022] Open
Abstract
Background Traditional methods using microscopy for the detection of helminth infections have limited sensitivity. Polymerase chain reaction (PCR) assays enhance detection of helminths, particularly low burden infections. However, differences in test performance may modify the ability to detect associations between helminth infection, risk factors, and sequelae. We compared these associations using microscopy and PCR. Methods This cross-sectional study was nested within a randomized clinical trial conducted at 3 sites in Kenya. We performed microscopy and real-time multiplex PCR for the stool detection and quantification of Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis, and Schistosoma species. We utilized regression to evaluate associations between potential risk factors or outcomes and infection as detected by either method. Results Of 153 HIV-positive adults surveyed, 55(36.0%) and 20(13.1%) were positive for one or more helminth species by PCR and microscopy, respectively (p<0.001). PCR-detected infections were associated with farming (Prevalence Ratio 1.57, 95% CI: 1.02, 2.40), communal water source (PR 3.80, 95% CI: 1.01, 14.27), and no primary education (PR 1.54, 95% CI: 1.14, 2.33), whereas microscopy-detected infections were not associated with any risk factors under investigation. Microscopy-detected infections were associated with significantly lower hematocrit and hemoglobin (means of -3.56% and -0.77 g/dl) and a 48% higher risk of anemia (PR 1.48, 95% CI: 1.17, 1.88) compared to uninfected. Such associations were absent for PCR-detected infections unless infection intensity was considered, Infections diagnosed with either method were associated with increased risk of eosinophilia (PCR PR 2.42, 95% CI: 1.02, 5.76; microscopy PR 2.92, 95% CI: 1.29, 6.60). Conclusion Newer diagnostic methods, including PCR, improve the detection of helminth infections. This heightened sensitivity may improve the identification of risk factors for infection while reducing ability to discriminate infections associated with adverse clinical outcomes. Quantitative assays can be used to differentiate infection loads and discriminate infections associated with sequelae.
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Affiliation(s)
- Michael B. Arndt
- Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| | - Grace John-Stewart
- Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Pediatrics, University of Washington, Seattle, Washington, United States of America
- Department of Allergy and Infectious Disease, University of Washington, Seattle, Washington, United States of America
| | - Barbra A. Richardson
- Department of Biostatistics, University of Washington, Seattle, Washington, United States of America
| | - Benson Singa
- Centre for Clinical Research, Kenya Medical Research Institute, Nairobi, Kenya
- Centre for Reproductive Health, Kenya Medical Research Institute, Nairobi, Kenya
| | - Lisette van Lieshout
- Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Jaco J. Verweij
- Department of Parasitology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Laura R. Sangaré
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Loice W. Mbogo
- Centre for Clinical Research, Kenya Medical Research Institute, Nairobi, Kenya
| | | | - Judd L. Walson
- Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Pediatrics, University of Washington, Seattle, Washington, United States of America
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40
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Wang JX, Pan CS, Cui LW. Application of a real-time PCR method for detecting and monitoring hookworm Necator americanus infections in Southern China. Asian Pac J Trop Biomed 2012; 2:925-9. [PMID: 23593570 PMCID: PMC3621466 DOI: 10.1016/s2221-1691(13)60001-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 11/17/2012] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVE To develop a quantitative PCR method for detecting hookworm infection and quantification. METHODS A real-time PCR method was designed based on the intergenic region II of ribosomal DNA of the hookworm Necator americanus. The detection limit of this method was compared with the microscopy-based Kato-Katz method. The real-time PCR method was used to conduct an epidemiological survey of hookworm infection in southern Fujian Province of China. RESULTS The real-time PCR method was specific for detecting Necator americanus infection, and was more sensitive than conventional PCR or microscopy-based method. A preliminary survey for hookworm infection in villages of Fujian Province confirmed the high prevalence of hookworm infections in the resident populations. In addition, the infection rate in women was significantly higher than that of in men. CONCLUSIONS A real-time PCR method is designed, which has increased detection sensitivity for more accurate epidemiological studies of hookworm infections, especially when intensity of the infection needs to be considered.
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Affiliation(s)
- Jia-Xu Wang
- Department of Microbiology, Xiamen Centre for Disease Control and Prevention, Xiamen 361021, Fujian, China
- School of Life Science, Xiamen University, Xiamen 361005, Fujian, China
| | - Cang-Sang Pan
- School of Life Science, Xiamen University, Xiamen 361005, Fujian, China
| | - Li-Wang Cui
- Department of Entomology, the Pennsylvania State University, 501 ASI Building, University Park, PA 16802, USA
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41
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Jonker FAM, Calis JCJ, van Hensbroek MB, Phiri K, Geskus RB, Brabin BJ, Leenstra T. Iron status predicts malaria risk in Malawian preschool children. PLoS One 2012; 7:e42670. [PMID: 22916146 PMCID: PMC3420896 DOI: 10.1371/journal.pone.0042670] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 07/10/2012] [Indexed: 11/30/2022] Open
Abstract
Introduction Iron deficiency is highly prevalent in pre-school children in developing countries and an important health problem in sub-Saharan Africa. A debate exists on the possible protective effect of iron deficiency against malaria and other infections; yet consensus is lacking due to limited data. Recent studies have focused on the risks of iron supplementation but the effect of an individual's iron status on malaria risk remains unclear. Studies of iron status in areas with a high burden of infections often are exposed to bias. The aim of this study was to assess the predictive value of baseline iron status for malaria risk explicitly taking potential biases into account. Methods and materials We prospectively assessed the relationship between baseline iron deficiency (serum ferritin <30 µg/L) and malaria risk in a cohort of 727 Malawian preschool children during a year of follow-up. Data were analyzed using marginal structural Cox regression models and confounders were selected using causal graph theory. Sensitivity of results to bias resulting from misclassification of iron status by concurrent inflammation and to bias from unmeasured confounding were assessed using modern causal inference methods. Results and Conclusions The overall incidence of malaria parasitemia and clinical malaria was 1.9 (95% CI 1.8–2.0) and 0.7 (95% CI 0.6–0.8) events per person-year, respectively. Children with iron deficiency at baseline had a lower incidence of malaria parasitemia and clinical malaria during a year of follow-up; adjusted hazard ratio's 0.55 (95%-CI:0.41–0.74) and 0.49 (95%-CI:0.33–0.73), respectively. Our results suggest that iron deficiency protects against malaria parasitemia and clinical malaria in young children. Therefore the clinical importance of treating iron deficiency in a pre-school child should be weighed carefully against potential harms. In malaria endemic areas treatment of iron deficiency in children requires sustained prevention of malaria.
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Affiliation(s)
- Femkje A M Jonker
- Global Child Health Group, Emma Children's Hospital, Academic Medical Centre, Amsterdam, The Netherlands.
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