| 1. |
- Hadfield, James, et al.
(författare)
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Comprehensive global genome dynamics of Chlamydia trachomatis show ancient diversification followed by contemporary mixing and recent lineage expansion
- 2017
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory Press. - 1088-9051 .- 1549-5469. ; 27:7, s. 1220-1229
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Tidskriftsartikel (refereegranskat)abstract
- Chlamydia trachomatis is the world's most prevalent bacterial sexually transmitted infection and leading infectious cause of blindness, yet it is one of the least understood human pathogens, in part due to the difficulties of in vitro culturing and the lack of available tools for genetic manipulation. Genome sequencing has reinvigorated this field, shedding light on the contemporary history of this pathogen. Here, we analyze 563 full genomes, 455 of which are novel, to show that the history of the species comprises two phases, and conclude that the currently circulating lineages are the result of evolution in different genomic ecotypes. Temporal analysis indicates these lineages have recently expanded in the space of thousands of years, rather than the millions of years as previously thought, a finding that dramatically changes our understanding of this pathogen's history. Finally, at a time when almost every pathogen is becoming increasingly resistant to antimicrobials, we show that there is no evidence of circulating genomic resistance in C. trachomatis.
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| 2. |
- Harding-Esch, Emma M., et al.
(författare)
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Impact of a single round of mass drug administration with azithromycin on active trachoma and ocular Chlamydia trachomatis prevalence and circulating strains in The Gambia and Senegal
- 2019
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Ingår i: Parasites & Vectors. - : BMC. - 1756-3305. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Mass drug administration (MDA) with azithromycin is a cornerstone of the trachoma elimination strategy. Although the global prevalence of active trachoma has declined considerably, prevalence persists or even increases in some communities and districts. To increase understanding of MDA impact, we investigated the prevalence of active trachoma and ocular C. trachomatis prevalence, organism load, and circulating strains at baseline and one-year post-MDA in The Gambia and Senegal.Methods: Pre- and one-year post-MDA, children aged 0-9 years were examined for clinical signs of trachoma in six Gambian and 12 Senegalese villages. Ocular swabs from each child's right conjunctiva were tested for evidence of ocular C. trachomatis infection and organism load (ompA copy number), and ompA and multi-locus sequence typing (MLST) was performed.Results: A total of 1171 children were examined at baseline and follow-up in The Gambia. Active trachoma prevalence decreased from 23.9% to 17.7%, whereas ocular C. trachomatis prevalence increased from 3.0% to 3.8%. In Senegal, 1613 and 1771 children were examined at baseline and follow-up, respectively. Active trachoma prevalence decreased from 14.9% to 8.0%, whereas ocular C. trachomatis prevalence increased from 1.8% to 3.6%. Higher organism load was associated with having active trachoma and severe inflammation. Sequence typing demonstrated that all Senegalese samples were genovar A, whereas Gambian samples were a mix of genovars A and B. MLST provided evidence of clustering at village and household levels and demonstrated differences of strain variant frequencies in Senegal, indicative of an "outbreak". MLST, including partial ompA typing, provided greater discriminatory power than complete ompA typing.Conclusions: We found that one round of MDA led to an overall decline in active trachoma prevalence but no impact on ocular C. trachomatis infection, with heterogeneity observed between villages studied. This could not be explained by MDA coverage or number of different circulating strains pre- and post-MDA. The poor correlation between active trachoma and infection prevalence supports the need for further work on alternative indicators to clinical signs for diagnosing ocular C. trachomatis infection. MLST typing has potential molecular epidemiology utility, including better understanding of transmission dynamics, although relationship to whole-genome sequence variability requires further exploration.
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| 3. |
- Harris, Simon R., et al.
(författare)
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Whole-genome analysis of diverse Chlamydia trachomatis strains identifies phylogenetic relationships masked by current clinical typing
- 2012
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Ingår i: Nature Genetics. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 44:4, s. 413-419
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Tidskriftsartikel (refereegranskat)abstract
- Chlamydia trachomatis is responsible for both trachoma and sexually transmitted infections, causing substantial morbidity and economic cost globally. Despite this, our knowledge of its population and evolutionary genetics is limited. Here we present a detailed phylogeny based on whole-genome sequencing of representative strains of C. trachomatis from both trachoma and lymphogranuloma venereum (LGV) biovars from temporally and geographically diverse sources. Our analysis shows that predicting phylogenetic structure using ompA, which is traditionally used to classify Chlamydia, is misleading because extensive recombination in this region masks any true relationships present. We show that in many instances, ompA is a chimera that can be exchanged in part or as a whole both within and between biovars. We also provide evidence for exchange of, and recombination within, the cryptic plasmid, which is another key diagnostic target. We used our phylogenetic framework to show how genetic exchange has manifested itself in ocular, urogenital and LGV C. trachomatis strains, including the epidemic LGV serotype L2b.
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| 4. |
- Macleod, Colin, et al.
(författare)
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Eyelash Epilation in the Absence of Trichiasis : Results of a Population-Based Prevalence Survey in the Western Division of Fiji
- 2017
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Ingår i: PLoS Neglected Tropical Diseases. - : PUBLIC LIBRARY SCIENCE. - 1935-2727 .- 1935-2735. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Background The WHO definition of trachomatous trichiasis (TT) is "at least one eyelash touching the globe, or evidence of recent epilation of in-turned eyelashes ", reflecting the fact that epilation is used as a self-management tool for TT. In Fiji's Western Division, a high TT prevalence (8.7% in those aged >= 15 years) was reported in a 2012 survey, yet a 2013 survey found no TT and Fijian ophthalmologists rarely see TT cases. Local anecdote suggests that eyelash epilation is a common behaviour, even in the absence of trichiasis. Epilators may have been identified as TT cases in previous surveys. Methods We used a preliminary focus group to design an interview questionnaire, and subsequently conducted a population-based prevalence survey to estimate the prevalence of epilation in the absence of trichiasis, and factors associated with this behaviour, in the Western Division of Fiji. Results We sampled 695 individuals aged >= 15 years from a total of 457 households in 23 villages. 125 participants (18%) reported epilating their eyelashes at least once within the past year. Photographs were obtained of the eyes of 121/125 (97%) individuals who epilated, and subsequent analysis by an experienced trachoma grader found no cases of trachomatous conjunctival scarring or trichiasis. The age-and sex-adjusted prevalence of epilation in those aged >= 15 years was 8.6% ( 95% Cl 5.7-11.3%). iTaukei ethnicity, female gender, and a higher frequency of drinking kava root were independently associated with epilation. Conclusion Epilation occurs in this population in the absence of trichiasis, with sufficient frequency to have markedly inflated previous estimates of local TT prevalence. Individuals with epilated eyelashes should be confirmed as having epilated in-turned eyelashes in an eye with scarring of the conjunctiva before being counted as cases of TT.
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| 5. |
- Robinson, W. Douglas, et al.
(författare)
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Integrating concepts and technologies to advance the study of bird migration
- 2010
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Ingår i: Frontiers in Ecology and the Environment. - : Wiley. - 1540-9309 .- 1540-9295. ; 8:7, s. 354-361
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Forskningsöversikt (refereegranskat)abstract
- Recent technological innovation has opened new avenues in migration research - for instance, by allowing individual migratory animals to be followed over great distances and long periods of time, as well as by recording physiological information. Here, we focus on how technology - specifically applied to bird migration - has advanced our knowledge of migratory connectivity, and the behavior, demography, ecology, and physiology of migrants. Anticipating the invention of new and smaller tracking devices, in addition to the ways that technologies may be combined to measure and record the behavior of migratory animals, we also summarize major conceptual questions that can only be addressed once innovative, cutting-edge instrumentation becomes available.
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| 6. |
- Unemo, Magnus, 1970-, et al.
(författare)
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Sexually transmitted infections : challenges ahead
- 2017
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Ingår i: The Lancet - Infectious diseases. - 1473-3099 .- 1474-4457. ; 17:8, s. e235-e279
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Forskningsöversikt (refereegranskat)abstract
- WHO estimated that nearly 1 million people become infected every day with any of four curable sexually transmitted infections (STIs): chlamydia, gonorrhoea, syphilis, and trichomoniasis. Despite their high global incidence, STIs remain a neglected area of research. In this Commission, we have prioritised five areas that represent particular challenges in STI treatment and control. Chlamydia remains the most commonly diagnosed bacterial STI in high-income countries despite widespread testing recommendations, sensitive and specific non-invasive testing techniques, and cheap effective therapy. We discuss the challenges for chlamydia control and evidence to support a shift from the current focus on infection-based screening to improved management of diagnosed cases and of chlamydial morbidity, such as pelvic inflammatory disease. The emergence and spread of antimicrobial resistance in Neisseria gonorrhoeae is globally recognised. We review current and potential future control and treatment strategies, with a focus on novel antimicrobials. Bacterial vaginosis is the most common vaginal disorder in women, but current treatments are associated with frequent recurrence. Recurrence after treatment might relate to evidence that suggests sexual transmission is integral to the pathogenesis of bacterial vaginosis, which has substantial implications for the development of effective management approaches. STIs disproportionately affect low-income and middle-income countries. We review strategies for case management, focusing on point-of-care tests that hold considerable potential for improving STI control. Lastly, STIs in men who have sex with men have increased since the late 1990s. We discuss the contribution of new biomedical HIV prevention strategies and risk compensation. Overall, this Commission aims to enhance the understanding of some of the key challenges facing the field of STIs, and outlines new approaches to improve the clinical management of STIs and public health.
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