We searched the University of Melbourne Discovery Library with the subjects Medicine, Dentistry, and Health Science. Databases searched included The University of Melbourne Library Catalogue, Web of Science (ISI), Scopus version 4 (Elsevier), Medline (ISI), CINAHL (EBSCO), and PubMed from Jan 1, 2008, to Dec 31, 2012. We used the search terms “trachoma”, “epidemiology”, or “SAFE strategy” in combination with “trachomatis”. We have included older key and commonly cited publications. Several
SeminarTrachoma
Introduction
Trachoma is a blinding infection caused by an ancient organism. Chlamydia trachomatis evolved with the dinosaurs, and all vertebrates have evolved with their own chlamydial strains.1, 2 Trachoma remains the most common infectious cause of blindness.3 The intense conjunctival inflammation with follicles recognised as active trachoma (TF) is sustained by repeated episodes of reinfection and reflects a sustained immune-mediated response to chlamydial antigens.4 This inflammation causes scarring, distortion of the lid, and inturning of the lid (entropion), with the eyelashes touching the cornea (trichiasis) that leads to blindness (figure 1). The key to trachoma is that repeated episodes of reinfection and inflammation lead to the blinding complications.4
As human beings evolved, occasional chlamydial conjunctivitis did not apparently lead to blindness. However, after the last Ice Age (about 8000 years BCE), when people were crowded in growing communities and hygiene was poor, the frequency of reinfection increased and blinding trachoma resulted.6 Crowding and poor hygiene lead to outbreaks of chlamydial infections in a range of birds, mammals, and marsupials.7 Trachoma rates increased greatly as crowding and poor living standards increased at the end of the Agricultural Revolution and the start of the Industrial Revolution, but waned in the 20th century as living standards improved.6 The disappearance of trachoma from more developed countries was hastened with the introduction of sulpha drugs in the 1930s and antibiotics in the 1940s.
However, trachoma still affects millions of people in the least developed countries. In recognition of the likelihood that spontaneous improvement in living conditions and disappearance of trachoma could take many decades, a specific global commitment has been made to eliminate trachoma. A resolution of the World Health Assembly in 1997 established the Global Alliance for the Elimination of Blinding Trachoma by the year 2020 (GET 2020) and much progress is being made to eliminate the disease. Some successes have led to increased resources and effort as set out here.
Section snippets
Epidemiology
Trachoma is still endemic in many of the poorest and more remote areas of Africa, Asia, Australia, and the Middle East (figure 2). Active trachoma affects an estimated 21 million people with about 2·2 million blind or severely visually impaired. A further 7·3 million have trichiasis3 (table 1). An intensive global trachoma mapping effort is underway at present. WHO classes 53 countries as endemic for trachoma10, 11 and estimates that 229 million people live in endemic areas, with most blinding
The causative organism
Trachoma is caused by the obligate intracellular Gram-negative bacterium C trachomatis, which has a single chromosome of about 1 Mbp and a multicopy plasmid that functions as a virulence factor.2 This unusual organism has a biphasic developmental cycle. Initially the small, hardy, metabolically inactive elementary bodies attach to and enter epithelial cells. Once inside, elementary bodies transform into the larger, metabolically active reticulate bodies within an intracytoplasmic vacuole, the
Overview
Trachoma interventions are planned at the district level, though implemented at the community or household level. They aim to eliminate blinding trachoma, partly by disrupting transmission of infection, and are implemented at the district level to minimise the reintroduction of infection into treated communities. Therefore, the district-level trachoma prevalence is used to identify where programmes are needed (appendix).11
At the start of 2012, trachoma control activities covered about half of
Overview
The GET2020 campaign uses the SAFE strategy, a four-pronged approach to stop the cycle of reinfection within the community and to correct trichiasis.11 WHO and partners aim to scale up SAFE strategy programmes in affected countries in a timely and cost-effective way to eliminate trachoma by 2020.
Surgery
Individuals with trachomatous trichiasis and entropion are at risk of corneal opacification and vision loss. To prevent these features developing, the abrasive action of lashes on the cornea must be
Conclusion
The SAFE strategy provides a targeted way to speed up the process of a general improvement in living conditions and hygiene that is needed to eliminate trachoma in the most disadvantaged areas in the developing world. Countries such as Morocco, Ghana, and Oman have eliminated blinding trachoma by use of the strategy.11 Activities at present cover at least half of the world's endemic districts, and the mapping of the remainder should be completed soon (Figure 2, Figure 4).8 As increasing
Search strategy and selection criteria
References (140)
- et al.
Evaluation of three years of the SAFE strategy (Surgery, Antibiotics, Facial cleanliness and Environmental improvement) for trachoma control in five districts of Ethiopia hyperendemic for trachoma
Trans R Soc Trop Med Hyg
(2009) - et al.
Strategies for control of trachoma: observational study with quantitative PCR
Lancet
(2003) - et al.
Impact of face-washing on trachoma in Kongwa, Tanzania
Lancet
(1995) - et al.
Changing water-use patterns in a water-poor area: lessons for a trachoma intervention project
Soc Sci Med
(1990) - et al.
Transmission ecology of the fly Musca sorbens, a putative vector of trachoma
Trans R Soc Trop Med Hyg
(2000) - et al.
Role of flies and provision of latrines in trachoma control: cluster-randomised controlled trial
Lancet
(2004) - et al.
Constant ocular infection with Chlamydia trachomatis predicts risk of scarring in children in Tanzania
Ophthalmology
(2009) - et al.
Natural history of trachomatous scarring in The Gambia: results of a 12-year longitudinal follow-up
Ophthalmology
(2001) - et al.
In vivo confocal microscopy in scarring trachoma
Ophthalmology
(2011) - et al.
T cells and trachoma: their role in cicatricial disease
Ophthalmology
(1991)
The cellular paradigm of chlamydial pathogenesis
Trends Microbiol
Trachomatous trichiasis and its management in endemic countries
Surv Ophthalmol
Pattern of recurrence of trachomatous trichiasis after surgery surgical technique as an explanation
Ophthalmology
Chlamydial evolution: a billion years and counting
Evolution of Chlamydia trachomatis
Ann N Y Acad Sci
Trachoma: global magnitude of a preventable cause of blindness
Br J Ophthalmol
Pathogenesis of trachoma: the stimulus for inflammation
J Immunol
A simple system for the assessment of trachoma and its complications
Bull World Health Organ
Trachoma: A blinding scourge from the Bronze Age to the twenty-first century
Recent advances in the knowledge of animal chlamydial infections
The end in sight—2020 INSight. International Coalition for Trachoma Control, 2011
Global WHO Alliance for the Elimination of Blinding Trachoma by 2020
Wkly Epidemiol Rec
Trachoma: status of endemicity for blinding trachoma by country 2013
Report of the 3rd global scientific meeting on trachoma elimination (Johns Hopkins University, Baltimore, Maryland; 19–20 July, 2010)
Global atlas of trachoma
Global Alliance for the Elimination of Blinding Trachoma by 2020—progress report on elimination of trachoma, 2012
Wkly Epidemiol Rec
The epidemiology of trachoma in central Tanzania
Int J Epidemiol
The epidemiology of trachoma in Eastern Equatoria and Upper Nile States, southern Sudan
Bull World Health Organ
The natural history of trachoma infection and disease in a Gambian cohort with frequent follow-up
PLoS Negl Trop Dis
Longitudinal study of the microbiology of endemic trachoma
J Clin Microbiol
Trachoma and blindness in the Nile Delta: current patterns and projections for the future in the rural Egyptian population
Br J Ophthalmol
Trachoma in Saudi Arabia
Ophthalmic Epidemiol
The prevalence of trachomatous trichiasis in Oman (Oman eye study 2005)
Ophthalmic Epidemiol
The epidemiology of infection in trachoma
Invest Ophthalmol Vis Sci
How much is not enough? A community randomized trial of a Water and Health Education programme for Trachoma and Ocular C trachomatis infection in Niger
Trop Med Int Health
Estimating household and community transmission of ocular Chlamydia trachomatis
PLoS Negl Trop Dis
Analysis of the household distribution of trachoma in a Gambian village using a Monte Carlo simulation procedure
Int J Epidemiol
Spatial clustering of ocular chlamydial infection over time following treatment, among households in a village in Tanzania
Invest Ophthalmol Vis Sci
Exposure to children and risk of active trachoma in Tanzanian women
Am J Epidemiol
Pesky trachoma suspect finally caught
Br J Ophthalmol
Latrine ownership as a protective factor in inflammatory trachoma in Egypt
Br J Ophthalmol
Comparative genomic analysis of Chlamydia trachomatis oculotropic and genitotropic strains
Infect Immun
Whole-genome analysis of diverse Chlamydia trachomatis strains identifies phylogenetic relationships masked by current clinical typing
Nat Genet
Trachoma: protective and pathogenic ocular immune responses to Chlamydia trachomatis
PLoS Negl Trop Dis
Blinding trachoma in postconflict southern Sudan
PLoS Med
Severe disease in children with trachoma is associated with persistent Chlamydia trachomatis infection
J Infect Dis
Risk factors for constant, severe trachoma among preschool children in Kongwa, Tanzania
Am J Epidemiol
Progression of active trachoma to scarring in a cohort of Tanzanian children
Ophthalmic Epidemiol
Correlation of clinical trachoma and infection in Aboriginal communities
PLoS Negl Trop Dis
Persisting inapparent chlamydial infection in a trachoma endemic community in The Gambia
Scand J Infect Dis Suppl
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