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Costa AS, Comesaña M, Soares AP. PHOR-in-One: A multilingual lexical database with PHonological, ORthographic and PHonographic word similarity estimates in four languages. Behav Res Methods 2023; 55:3699-3725. [PMID: 36344773 DOI: 10.3758/s13428-022-01985-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2022] [Indexed: 11/09/2022]
Abstract
A large body of research seeking to explore how form affects lexical processing in bilinguals has suggested that orthographically similar translations (e.g., English-Portuguese "paper-papel") are responded to more quickly and accurately than words with little to no overlap (e.g., English-Portuguese "house-casa"). One of the most prominent algorithms to estimate orthographic similarity, the normalized Levenshtein distance (NLD), returns an index of the proportion of identical characters of two strings, and is an efficient and invaluable tool for the selection, manipulation, and control of verbal stimuli. Notwithstanding its many advantages for second-language research, the absence of a comparable measure for phonology has resulted in the adoption of different strategies to assess the degree of interlanguage phonological similarity across the literature, with profound implications for the interpretation of results on the relative role of orthographic and phonological similarity in bilingual lexical access. In the present work, we introduce PHOR-in-One, a multilingual lexical database with a set of phonological and orthographic NLD estimates for 6160 translation equivalents in American and British English, European Portuguese, German and Spanish in a total of 30,800 words. We also propose a new measure of phonographic NLD, a pooled index of orthographic and phonological similarity, particularly useful for researchers interested in controlling for and/or manipulating both estimates at once. PHOR-in-One includes a comprehensive characterization of its lexical entries, namely Part-of-Speech-dependent and independent frequency counts, number of letters and phonemes, and phonetic transcription. PHOR-in-One is thus a valuable tool to support bilingual and multilingual research.
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Affiliation(s)
- Ana Santos Costa
- Research Unit in Human Cognition, CIPsi, School of Psychology, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal.
| | - Montserrat Comesaña
- Research Unit in Human Cognition, CIPsi, School of Psychology, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
- Centro de Investigación Nebrija en Cognición (CINC), Universidad Nebrija, Madrid, Spain
| | - Ana Paula Soares
- Research Unit in Human Cognition, CIPsi, School of Psychology, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
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Thompson JA, Leurent B, Nash S, Moulton LH, Hayes RJ. Cluster randomized controlled trial analysis at the cluster level: The clan command. THE STATA JOURNAL 2023; 23:754-773. [PMID: 37850046 PMCID: PMC7615216 DOI: 10.1177/1536867x231196294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2023]
Abstract
In this article, we introduce a new command, clan, that conducts a cluster-level analysis of cluster randomized trials. The command simplifies adjusting for individual- and cluster-level covariates and can also account for a stratified design. It can be used to analyze a continuous, binary, or rate outcome.
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Affiliation(s)
- Jennifer A. Thompson
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, U.K
| | - Baptiste Leurent
- Medical Statistics Department, London School of Hygiene and Tropical Medicine, London, U.K.; Department of Statistical Science University College London London, U.K
| | - Stephen Nash
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine London, U.K
| | - Lawrence H. Moulton
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | - Richard J. Hayes
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine London, U.K
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Doan T, Gebre T, Ayele B, Zerihun M, Hinterwirth A, Zhong L, Chen C, Ruder K, Zhou Z, Emerson PM, Porco TC, Keenan JD, Lietman TM. Effect of Azithromycin on the Ocular Surface Microbiome of Children in a High Prevalence Trachoma Area. Cornea 2022; 41:1260-1264. [PMID: 34483276 PMCID: PMC8894504 DOI: 10.1097/ico.0000000000002863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 06/30/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE The aim of this study was to evaluate the effect of the 4 times per year mass azithromycin distributions on the ocular surface microbiome of children in a trachoma endemic area. METHODS In this cluster-randomized controlled trial, children aged 1 to 10 years in rural communities in the Goncha Seso Enesie district of Ethiopia were randomized to either no treatment or treatment with a single dose of oral azithromycin (height-based dosing to approximate 20 mg/kg) every 3 months for 1 year. Post hoc analysis of ocular surface Chlamydia trachomatis load, microbial community diversity, and macrolide resistance determinants was performed to evaluate differences between treatment arms. RESULTS One thousand two hundred fifty-five children from 24 communities were included in the study. The mean azithromycin coverage in the treated communities was 80% (95% CI: 73%-86%). The average age was 5 years (95% CI: 4-5). Ocular surface C. trachomatis load was reduced in children treated with the 4 times per year azithromycin ( P = 0.0003). Neisseria gonorrhoeae , Neisseria lactamica , and Neisseria meningitidis were more abundant in the no-treatment arm compared with the treated arm. The macrolide resistance gene ermB was not different between arms ( P = 0.63), but mefA / E was increased ( P = 0.04) in the azithromycin-treated arm. CONCLUSIONS We found a reduction in the load of C. trachomatis and 3 Neisseria species in communities treated with azithromycin. These benefits came at the cost of selection for macrolide resistance.
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Affiliation(s)
- Thuy Doan
- Francis I Proctor Foundation, University of California San Francisco, USA
- Department of Ophthalmology, University of California San Francisco, USA
| | | | - Berhan Ayele
- The Carter Center Ethiopia, Addis Ababa, Ethiopia
| | | | - Armin Hinterwirth
- Francis I Proctor Foundation, University of California San Francisco, USA
| | - Lina Zhong
- Francis I Proctor Foundation, University of California San Francisco, USA
| | - Cindi Chen
- Francis I Proctor Foundation, University of California San Francisco, USA
| | - Kevin Ruder
- Francis I Proctor Foundation, University of California San Francisco, USA
| | - Zhaoxia Zhou
- Francis I Proctor Foundation, University of California San Francisco, USA
| | - Paul M. Emerson
- International Trachoma Initiative, Addis Ababa, Ethiopia
- International Trachoma Initiative, Atlanta, Georgia, USA
| | - Travis C. Porco
- Francis I Proctor Foundation, University of California San Francisco, USA
- Department of Ophthalmology, University of California San Francisco, USA
- Department of Epidemiology and Biostatistics, University of California San Francisco, USA
| | - Jeremy D. Keenan
- Francis I Proctor Foundation, University of California San Francisco, USA
- Department of Ophthalmology, University of California San Francisco, USA
| | - Thomas M. Lietman
- Francis I Proctor Foundation, University of California San Francisco, USA
- Department of Ophthalmology, University of California San Francisco, USA
- Department of Epidemiology and Biostatistics, University of California San Francisco, USA
- Institute for Global Health Sciences, University of California San Francisco, USA
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Last A, Burr S, Alexander N, Harding-Esch E, Roberts CH, Nabicassa M, Cassama ETDS, Mabey D, Holland M, Bailey R. Spatial clustering of high load ocular Chlamydia trachomatis infection in trachoma: a cross-sectional population-based study. Pathog Dis 2018; 75:3791466. [PMID: 28472466 PMCID: PMC5808645 DOI: 10.1093/femspd/ftx050] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 05/02/2017] [Indexed: 11/12/2022] Open
Abstract
Chlamydia trachomatis (Ct) is the most common cause of bacterial sexually transmitted infection and infectious cause of blindness (trachoma) worldwide. Understanding the spatial distribution of Ct infection may enable us to identify populations at risk and improve our understanding of Ct transmission. In this study, we sought to investigate the spatial distribution of Ct infection and the clinical features associated with high Ct load in trachoma-endemic communities on the Bijagós Archipelago (Guinea Bissau). We collected 1507 conjunctival samples and corresponding detailed clinical data during a cross-sectional population-based geospatially representative trachoma survey. We used droplet digital PCR to estimate Ct load on conjunctival swabs. Geostatistical tools were used to investigate clustering of ocular Ct infections. Spatial clusters (independent of age and gender) of individuals with high Ct loads were identified using local indicators of spatial association. We did not detect clustering of individuals with low load infections. These data suggest that infections with high bacterial load may be important in Ct transmission. These geospatial tools may be useful in the study of ocular Ct transmission dynamics and as part of trachoma surveillance post-treatment, to identify clusters of infection and thresholds of Ct load that may be important foci of re-emergent infection in communities.
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Affiliation(s)
- Anna Last
- Clinical Research Department, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Sarah Burr
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia, PO Box 273 Banjul, Atlantic Boulevard, Fajara, The Gambia
| | - Neal Alexander
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Emma Harding-Esch
- Clinical Research Department, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Chrissy H Roberts
- Clinical Research Department, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Meno Nabicassa
- Programa Nacional de Saúde de Visão, Ministério de Saúde Publica, PO Box 50, Avenida de Unidade Africana, Bisssau, Guiné Bissau
| | | | - David Mabey
- Clinical Research Department, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Martin Holland
- Clinical Research Department, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Robin Bailey
- Clinical Research Department, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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Butcher R, Houghton J, Derrick T, Ramadhani A, Herrera B, Last AR, Massae PA, Burton MJ, Holland MJ, Roberts CH. Reduced-cost Chlamydia trachomatis-specific multiplex real-time PCR diagnostic assay evaluated for ocular swabs and use by trachoma research programmes. J Microbiol Methods 2017; 139:95-102. [PMID: 28487054 PMCID: PMC5496587 DOI: 10.1016/j.mimet.2017.04.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/21/2017] [Accepted: 04/22/2017] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Trachoma, caused by the intracellular bacterium Chlamydia trachomatis (Ct), is the leading infectious cause of preventable blindness. Many commercial platforms are available that provide highly sensitive and specific detection of Ct DNA. However, the majority of these commercial platforms are inaccessible for population-level surveys in resource-limited settings typical to trachoma control programmes. We developed two low-cost quantitative PCR (qPCR) tests for Ct using readily available reagents on standard real-time thermocyclers. METHODS Each multiplex qPCR test targets one genomic and one plasmid Ct target in addition to an endogenous positive control for Homo sapiens DNA. The quantitative performance of the qPCR assays in clinical samples was determined by comparison to a previously evaluated droplet digital PCR (ddPCR) test. The diagnostic performance of the qPCR assays were evaluated against a commercial assay (artus C. trachomatis Plus RG PCR, Qiagen) using molecular diagnostics quality control standards and clinical samples. We examined the yield of Ct DNA prepared from five different DNA extraction kits and a cold chain-free dry-sample preservation method using swabs spiked with fixed concentrations of human and Ct DNA. RESULTS The qPCR assay was highly reproducible (Ct plasmid and genomic targets mean total coefficients of variance 41.5% and 48.3%, respectively). The assay detected 8/8 core specimens upon testing of a quality control panel and performed well in comparison to commercially marketed comparator test (sensitivity and specificity>90%). Optimal extraction and sample preservation methods for research applications were identified. CONCLUSION We describe a pipeline from collection to diagnosis providing the most efficient sample preservation and extraction with significant per test cost savings over a commercial qPCR diagnostic assay. The assay and its evaluation should allow control programs wishing to conduct independent research within the context of trachoma control, access to an affordable test with defined performance characteristics.
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Affiliation(s)
- Robert Butcher
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom.
| | - Jo Houghton
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Tamsyn Derrick
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom; Kilimanjaro Christian Medical Centre, Moshi, Tanzania
| | - Athumani Ramadhani
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom; Kilimanjaro Christian Medical Centre, Moshi, Tanzania
| | - Beatriz Herrera
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Anna R Last
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom
| | | | - Matthew J Burton
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Martin J Holland
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Chrissy H Roberts
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom
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Roberts CH, Last A, Burr SE, Bailey RL, Mabey DC, Holland MJ. Will droplet digital PCR become the test of choice for detecting and quantifying ocularChlamydia trachomatisinfection? Maybe. Expert Rev Mol Diagn 2014; 14:253-6. [DOI: 10.1586/14737159.2014.897609] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Abstract
OBJECTIVE To review methods for the statistical analysis of parasite and other skewed count data. METHODS Statistical methods for skewed count data are described and compared, with reference to a 10-year period of Tropical Medicine and International Health (TMIH). Two parasitological datasets are used for illustration. RESULTS The review of TMIH found 90 articles, of which 89 used descriptive methods and 60 used inferential analysis. A lack of clarity is noted in identifying the measures of location, in particular the Williams and geometric means. The different measures are compared, emphasising the legitimacy of the arithmetic mean for the skewed data. In the published articles, the t test and related methods were often used on untransformed data, which is likely to be invalid. Several approaches to inferential analysis are described, emphasising (1) non-parametric methods, while noting that they are not simply comparisons of medians, and (2) generalised linear modelling, in particular with the negative binomial distribution. Additional methods, such as the bootstrap, with potential for greater use are described. CONCLUSIONS Clarity is recommended when describing transformations and measures of location. It is suggested that non-parametric methods and generalised linear models are likely to be sufficient for most analyses.
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Affiliation(s)
- Neal Alexander
- London School of Hygiene and Tropical Medicine, London, UK.
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Goldschmidt P, Benallaoua D, Amza A, Einterz E, Huguet P, Poisson F, Bilinkai AB, Ismaila M, Bensaid P, Bella L, Chaumeil C. Clinical and microbiological assessment of trachoma in the kolofata health district, far north region, cameroon. Trop Med Health 2012; 40:7-14. [PMID: 22949801 PMCID: PMC3426829 DOI: 10.2149/tmh.2011-26] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 12/01/2011] [Indexed: 12/04/2022] Open
Abstract
Background and aims: Trachoma is a sight-threatening process triggered by the infection of the conjunctiva with Chlamydiae. Blindness associated with trachoma was reported in Sahelian areas of Cameroon. However, data on the prevalence of this neglected infection in the Far North Region are not available. The aim of this study was a) to assess clinical trachoma and b) to detect Chlamydia in the conjunctiva of trachomatous populations living in the Far North Regions of Cameroon. Methods: A total of 2,423 randomly selected children (1–10 years) and 1,590 women over 14 from randomly selected villages from the Kolofata Health District (115,000 inhabitants) were included in a cross-sectional study in February 2009. Trained staff examined and obtained conjunctival swabs from trachomatous subjects. DNA was extracted and amplified to detect Chlamydia DNA by real-time PCR. The quality of sampling was assessed by quantifying the number of epithelial cells. Results: Children (2,397 or 98.9% of the predicted number) and women (1,543; 97.0%) were examined. The prevalence of follicular trachoma (TF) in children was 21% (95% CI 17.8–24.5) and of intense inflammatory trachoma (TI) 5.2% (95% CI 3.6–7.3). Among the women, trichiasis (TT) was observed in 3.4% (95% CI 2.4–4.7), corneal opacities (CO) in 1.4% (95% CI 0.8–2.3) and trachoma-related blindness in 0.9% (95% CI 0.4–1.8). Conditions related to income, illiteracy, latrines, water supply and animals wandering close to dwellings were similar in all the villages. PCR was positive in 35% of children with active trachoma and in 6% of adult females presenting TT and/or related corneal opacities. Conclusion: The prevalence of trachoma and the severe trachoma sequelae found during this survey underline the urgent need to implement efficient blindness prevention interventions to improve the visual future of the people in the Sahelian region.
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Affiliation(s)
- Pablo Goldschmidt
- Laboratoire du Centre National d'Ophtalmologie des Quinze-Vingts, Paris, France
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Harkins AL, Munson E. Molecular Diagnosis of Sexually Transmitted Chlamydia trachomatis in the United States. ISRN OBSTETRICS AND GYNECOLOGY 2011; 2011:279149. [PMID: 21822498 PMCID: PMC3148448 DOI: 10.5402/2011/279149] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 04/27/2011] [Indexed: 12/03/2022]
Abstract
Chlamydia, with its Chlamydia trachomatis etiology, is the most common bacterial sexually transmitted infection in the United States and is often transmitted via asymptomatic individuals. This review summarizes traditional and molecular-based diagnostic modalities specific to C. trachomatis. Several commercially available, FDA-approved molecular methods to diagnose urogenital C. trachomatis infection include nucleic acid hybridization, signal amplification, polymerase chain reaction, strand displacement amplification, and transcription-mediated amplification. Molecular-based methods are rapid and reliable genital specimen screening measures, especially when applied to areas of high disease prevalence. However, clinical and analytical sensitivity for some commercial systems decreases dramatically when testing urine samples. In vitro experiments and clinical data suggest that transcription-mediated amplification has greater analytical sensitivity than the other molecular-based methods currently available. This difference may be further exhibited in testing of extragenital specimens from at-risk patient demographics. The development of future molecular testing could address conundrums associated with confirmatory testing, medicolegal testing, and test of cure.
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Affiliation(s)
- April L Harkins
- Department of Clinical Laboratory Science, Marquette University, Milwaukee, WI 53233, USA
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Alexander N, Cundill B, Sabatelli L, Bethony JM, Diemert D, Hotez P, Smith PG, Rodrigues LC, Brooker S. Selection and quantification of infection endpoints for trials of vaccines against intestinal helminths. Vaccine 2011; 29:3686-94. [PMID: 21435404 PMCID: PMC3093614 DOI: 10.1016/j.vaccine.2011.03.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 02/21/2011] [Accepted: 03/02/2011] [Indexed: 12/22/2022]
Abstract
Vaccines against human helminths are being developed but the choice of optimal parasitological endpoints and effect measures to assess their efficacy has received little attention. Assuming negative binomial distributions for the parasite counts, we rank the statistical power of three measures of efficacy: ratio of mean parasite intensity at the end of the trial, the odds ratio of infection at the end of the trial, and the rate ratio of incidence of infection during the trial. We also use a modelling approach to estimate the likely impact of trial interventions on the force of infection, and hence statistical power. We conclude that (1) final mean parasite intensity is a suitable endpoint for later phase vaccine trials, and (2) mass effects of trial interventions are unlikely to appreciably reduce the force of infection in the community - and hence statistical power - unless there is a combination of high vaccine efficacy and a large proportion of the population enrolled.
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Affiliation(s)
- Neal Alexander
- London School of Hygiene and Tropical Medicine, London, UK.
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Burton MJ, Holland MJ, Makalo P, Aryee EAN, Sillah A, Cohuet S, Natividad A, Alexander NDE, Mabey DCW, Bailey RL. Profound and sustained reduction in Chlamydia trachomatis in The Gambia: a five-year longitudinal study of trachoma endemic communities. PLoS Negl Trop Dis 2010; 4. [PMID: 20957147 PMCID: PMC2950148 DOI: 10.1371/journal.pntd.0000835] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 09/01/2010] [Indexed: 11/26/2022] Open
Abstract
Background The elimination of blinding trachoma focuses on controlling Chlamydia trachomatis infection through mass antibiotic treatment and measures to limit transmission. As the prevalence of disease declines, uncertainty increases over the most effective strategy for treatment. There are little long-term data on the effect of treatment on infection, especially in low prevalence settings, on which to base guidelines. Methodology/Principal Findings The population of a cluster of 14 Gambian villages with endemic trachoma was examined on seven occasions over five years (baseline, 2, 6, 12, 17, 30 and 60 months). Mass antibiotic treatment was given at baseline only. All families had accessible clean water all year round. New latrines were installed in each household after 17 months. Conjunctival swab samples were collected and tested for C. trachomatis by PCR. Before treatment the village-level prevalence of follicular trachoma in 1 to 9 year olds (TF%1–9) was 15.4% and C. trachomatis was 9.7%. Antibiotic treatment coverage was 83% of the population. In 12 villages all baseline infection cleared and few sporadic cases were detected during the following five years. In the other two villages treatment was followed by increased infection at two months, which was associated with extensive contact with other untreated communities. The prevalence of infection subsequently dropped to 0% in these 2 villages and 0.6% for the whole population by the end of the study in the absence of any further antibiotic treatment. However, several villages had a TF%1–9 of >10%, the threshold for initiating or continuing mass antibiotic treatment, in the absence of any detectable C. trachomatis. Conclusions/Significance A single round of mass antibiotic treatment may be sufficient in low prevalence settings to control C. trachomatis infection when combined with environmental conditions, which suppress transmission, such as a good water supply and sanitation. Trachoma is the most common infectious cause of blindness worldwide. Mass antibiotic treatment with azithromycin is used to control ocular Chlamydia trachomatis infection. There is uncertainty over how frequently and for how long treatment is needed, particularly in low prevalence settings. This study examines the effect of a single round of treatment on clinical disease and infection in a cluster of trachoma endemic Gambian villages over a five-year period. These villages had good water supplies and sanitation improved part way through the study. We found treatment was followed by a marked decline in infection prevalence (by PCR) to less than 1%. The decline in prevalence of active disease in children was less marked. Several villages had a prevalence of active trachoma in 1 to 9 year old children of greater than 10% during the follow-up period, mostly in the absence of detectable infection. The implication of this study is that a single, high coverage mass treatment may be sufficient to control C. trachomatis infection in a low prevalence setting, particularly when combined with environmental measures to limit transmission. However, relying on clinical signs to guide treatment decisions is likely to lead to significant amounts of over treatment where current guidelines are implemented.
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Affiliation(s)
- Matthew J Burton
- London School of Hygiene and Tropical Medicine, London, United Kingdom.
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12
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Goldschmidt P, Afghani T, Nadeem M, Ali-Khan W, Chaumeil C, de Barbeyrac B. Clinical and microbiological diagnosis of trachoma in children living in rural areas in the district of Attock, Punjab, Pakistan. Ophthalmic Epidemiol 2006; 13:335-42. [PMID: 17060112 DOI: 10.1080/09286580600943796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
BACKGROUND Trachoma is a sight-threatening process triggered by infection of the conjunctiva with Chlamydiae. When this infection becomes chronic and is associated with poverty it triggers trachoma, the prime cause of infectious blindness in the world. Since the 1958 report indicating that the highest incidence of trachoma in Pakistan was found in the province of Punjab, no new trials have been published. In the present study, we assessed the prevalence of trachoma in 3968 children living in 11 rural villages in the district of Attock, Punjab, Pakistan. The children with trachoma were sampled to detect C. trachomatis by PCR. METHODS Children in rural villages in the district of Attock were examined for trachoma in February 2004. Samples were obtained by scraping, and DNA was extracted (MagnaPure-LC Robot) and amplified to detect C. trachomatis (Amplicor-Roche). The quality of sampling was assessed by quantifying the number of cells by real-time PCR. RESULTS The prevalence of trachoma was 3.7% (0 to 6.2%). PCR was positive in 20% of samples from trachomatous children and the number of cells was always > 100/sample. The income levels, illiteracy, use of latrines, water supply, and the presence of animals close to dwellings were similar in all the villages. In Sujjenda, the prevalence was doubled in the warmest season. CONCLUSIONS Trachoma was diagnosed in 3.7% of the children aged < 10 years. The low rates for positive PCR may be due to loss of the plasmid, the involvement of other Chlamydiae, or their absence in chronic infections. The results obtained here underestimate the prevalence of trachoma because most of the mothers (and babies) were not tested in the district of Attock.
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Affiliation(s)
- Pablo Goldschmidt
- Laboratoire du Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris, France.
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13
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Goldschmidt P, Rostane H, Sow M, Goépogui A, Batellier L, Chaumeil C. Detection by broad-range real-time PCR assay of Chlamydia species infecting human and animals. Br J Ophthalmol 2006; 90:1425-9. [PMID: 16899531 PMCID: PMC1857507 DOI: 10.1136/bjo.2006.096420] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Tests available for molecular diagnosis of chlamydial infections detect Chlamydiatrachomatis, but do not find other Chlamydia species associated with genital, ophthalmic, cardiovascular, respiratory or neurological diseases. The routine detection of all Chlamydia species would improve the prognosis of infected people and guide therapeutic choices. AIM To design and validate a sensitive, specific, reproducible, inexpensive and easy-to-perform assay to quantify most Chlamydia species. METHODS Primers and probe were selected using the gene coding for the 16S rRNA. The detection limits were assessed for suspensions of Chlamydia trachomatis, Chlamydia psittaci and Chlamydia pneumoniae. The performance of this test was compared with that of two commercial kits (Amplicor-Roche and Artus) on 100 samples obtained from children with trachoma. RESULTS The detection capacities for Chlamydia trachomatis of the broad-range real-time polymerase chain reaction (PCR) were similar or slightly better than those obtained with commercial kits (0.2 copies of DNA/microl). Only the broad-range PCR identified specimens containing Chlamydia psittaci and Chlamydia pneumoniae. The commercial kits and the broad-range assay detected Chlamydia species in 5% and in 11%, respectively, of samples from children with trachoma. CONCLUSIONS This new real-time PCR offers a sensitive, reproducible assay that produces results in <3 h. With panels of quantified Chlamydia species, this real-time PCR can be run with all real-time PCR equipment. Larger trials are needed to confirm the utility of this test in diagnosis and for therapeutic follow-up.
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Affiliation(s)
- P Goldschmidt
- Laboratoire du Centre Hospitalier National d'Ophtalmologie des Quinze Vingts, 28 rue de Charenton, 75012 Paris, France.
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Singer MS, Dana R. Recent advances in the global effort to eradicate trachoma. Int Ophthalmol Clin 2006; 46:79-90. [PMID: 16770156 DOI: 10.1097/00004397-200604620-00009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Affiliation(s)
- Michael S Singer
- Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA
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