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Bacteria
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
This is a bacterial infection of the mucous membrane lining the eye socket. Bacterial conjunctivitis is caused by a variety of bacteria: Hemophilus, Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Chlamydia sp. are probably the most common. “Pink eye” outbreaks among children are caused by Hemophilus aegypticus. The more serious disease, inclusion conjunctivitis, is caused by Chlamydia trachomatis. This last organism causes trachoma in which there is an invasion of the cornea itself. Trachoma can cause blindness.
Corneal Disorders
Published in Ching-Yu Cheng, Tien Yin Wong, Ophthalmic Epidemiology, 2022
Darren S. J. Ting, Rashmi Deshmukh, Daniel S. W. Ting, Marcus Ang
Trachoma is the most common cause of infectious blindness globally and is responsible for visual impairment in around 1.9 million people across 44 countries.21 Nearly 90% of these individuals live in sub-Saharan Africa. According to a global report published in 2017, the number of people suffering from blindness due to trachoma was 0.4 million.18 Trachoma is caused by Chlamydia trachomatis, which is a Gram-negative, obligate intracellular bacterium. The serotypes of C. trachomatis responsible for endemic trachoma include A, B, Ba, and C.22 Recurrent episodes of infection and inflammation cause ocular surface complications, conjunctival scarring, and consequent lid abnormalities like entropion, trichiasis, and corneal scarring, eventually leading to blindness. A 4-year cohort study from Tanzania reported the progression of trachoma-related conjunctival scarring in 23% of affected children.23 The scarring progression was strongly associated with papillary conjunctival inflammation. Another study from Ethiopia stressed the effects of trichiasis on the quality of life for adults suffering from trachomatous trichiasis.24 This study concluded that scarring and trichiasis had a profound effect on vision-related as well as health-related quality of life, even in individuals having normal vision.24
Chlamydial infection
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Joyce A. Ibana, Danny J. Schust
In addition to its role in genital diseases, C. trachomatis infection of the eye (trachoma) is one of the world’s leading causes of preventable blindness. In 2002, the WHO reported that this infection accounts for about 3.6% (1.3 million) of total blindness worldwide. This disease is endemic in 56 countries including many in Africa, the Middle East and some parts of Asia, Latin America, and the Western Pacific. Trachoma is transmitted through contact with eye droplets from contaminated hands, clothing, and eye-seeking flies. The most affected populations are those living in poverty where resources are limited, hygiene is poor, and conditions permit facile transmission of the infection (5). C. trachomatis can also cause a systemic sexually transmitted disease, Lymphogranuloma venereum (LGV), which is characterized by genital ulceration and inguinal lymphadenopathy (buboes). This disease can progress and result in hemorrhagic proctocolitis, rectogenital scarring, and lymphedema. LGV is endemic in some areas of Africa, Asia, South America, and the Caribbean but is uncommon in industrialized countries (6).
Chlamydia trachomatis: quest for an eye-opening vaccine breakthrough
Published in Expert Review of Vaccines, 2022
Vivek P Chavda, Anjali Pandya, Erica Kypreos, Vandana Patravale, Vasso Apostolopoulos
Trachoma symptoms include soreness of the eyes, itchy skin, eye and eyelid irritation, eye weeping, swelling of the eyelids, eye pain, and photophobia. It is critical to ascertain the period of these symptoms and acquire a history of travel to endemic areas (e.g. North Africa, the Middle East, and India). Vaginitis, cervicitis, or urethritis may occur concurrently. Trachoma is diagnosed primarily based on the patient’s history and clinical signs that can be seen on slit-lamp evaluation. While many diagnostic assays have been developed to diagnose the organism, no ‘gold standard’ exploration persists. Trachoma has a favorable prognosis wherein early detection and treatment are critical for preventing irreversible side effects and eye damage. In recent years, community-based SAFE strategy implementation has improved the prognosis for thousands of people at risk. A study conducted in Rural Sudan found that using this stratification resulted in massive declines in the pervasiveness of active disease [91].
Community-level Association between Clinical Trachoma and Ocular Chlamydia Infection after MASS Azithromycin Distribution in a Mesoendemic Region of Niger
Published in Ophthalmic Epidemiology, 2019
Abdou Amza, Boubacar Kadri, Beido Nassirou, Sun Y Cotter, Nicole E. Stoller, Sheila K West, Robin L. Bailey, Travis C. Porco, Jeremy D. Keenan, Thomas M. Lietman, Catherine E. Oldenburg
An annual census was conducted in each community. A random sample of 100 children aged 0–5 years (or all children if the community had fewer than 100 children) was examined biannually over the 36-month course of the study. Clinical examination for clinical signs of trachoma, including TF and TI, was performed according to the WHO simplified grading system by examiners who were trained and certified by experienced graders.4 All graders underwent standardized training and passed an exam with a kappa>0.6 against a gold standard grader to be certified. To measure ocular chlamydia infection, we swabbed the everted right upper tarsal conjunctiva with a Dacron swab, collected without media. Swabs were placed on ice for <8 h while in the field and then stored in a −20°C freezer until being transported at 4°C to the University of California, San Francisco, and then stored at −80°C until they were processed. Swabs were pooled by community into pools of five plus a remainder pool. The pools were processed with Roche Amplicor PCR testing, and prevalence was estimated from the pools as previously described.19 The sensitivity and specificity of the Amplicor assay has been shown to be high versus the quantitative Abbott m2000 assay and the Aptima assay in ocular samples.20,21
Optimising age adjustment of trichiasis prevalence estimates using data from 162 standardised surveys from seven regions of Ethiopia
Published in Ophthalmic Epidemiology, 2019
Colin K. Macleod, Travis C. Porco, Michael Dejene, Oumer Shafi, Biruck Kebede, Nebiyu Negussu, Berhanu Bero, Sadik Taju, Yilikal Adamu, Kassahun Negash, Tesfaye Haileselassie, John Riang, Ahmed Badei, Ana Bakhtiari, Rebecca Willis, Robin L. Bailey, Anthony W. Solomon
Trachoma is an eye disease caused by infection with the bacterium Chlamydia trachomatis. It is thought to account for the blindness or visual impairment of 1.9 million people worldwide.1 Repeated conjunctival infections2 contribute to trichiasis,3 associated with chronic, painful irritation of the cornea leading to permanent opacification, visual impairment, and blindness.4 Surgery to correct trichiasis is the recommended means by which further vision loss can be minimised, and in many countries, ophthalmic nurses are trained to carry out these corrective surgeries. However, training trichiasis surgeons is costly, and the numbers required are largely informed by the estimated number of eyes requiring surgery in a given area. Accurate population-level estimates of the trichiasis prevalence help guide planning for recruitment and training and enable confident assessment of whether or not districts have reached the World Health Organization (WHO) elimination prevalence threshold.