There are two phases during the development of trachoma, the active phase and a scarring (or cicatricial) phase, which do not necessarily follow a linear pathway, but might be seen coexisting simultaneously in the same patient.

The main feature of active trachoma is mucopurulent keratoconjunctivitis, usually associated with the presence of follicular and inflammatory response on the inflamed surface of the upper eyelid. Superior neovascularization (pannus), punctate keratitis, and at least 5 limbal follicles can be observed on the cornea. The limbal follicles are at least 0.5 mm in diameter and represent major germinal centers at the limbus. This intense inflammatory state might cause pronounced inflammatory thickening of the upper tarsal conjunctiva that is usually followed by scarring.

The scarring phase begins with the appearance of visible scars on the tarsal conjunctiva. If these are severe enough, they can be followed by trichiasis, the lids begin to grow back towards the eye, touching the cornea or conjunctiva and causing a continuous rubbing over the surface of these structures. Trichiasis might lead to corneal opacification and eventually to vision loss.

There might be additional symptoms which include eye discharge (due to secondary infections), swollen eyelids, and sensitivity to bright lights. Additional symptoms might also involve other parts of the body, like swelling of lymph nodes in the ears and increased heart rate.

• Malnutrition

  […] conditions; through change in fauna and flora and the impact this might have on the ecosystem, agriculture and hence food security and the economy; increases in extreme weather events are likely to increase diarrhoeal disease, vector-borne diseases and malnutrition [iceh.lshtm.ac.uk]

  Trachoma may occur where there are great public health deficiencies such as malnutrition, poor public sanitation, poor insect control, e.g. flies, and housing conditions that lead to overcrowding and filthy conditions. [museumoffamilyhistory.com]

  […] being infected with trachoma: Poor hygiene – Unclean hands and faces increases risk of spread of trachoma Poverty – The disease is endemic in developing countries amongst the very poor due to overcrowded and unhygienic living conditions, not to mention malnutrition [medindia.net]

  Their original goal was to promote birth control, but the women proved so effective and popular that they are now trained for many health tasks, like giving out vitamin A and polio vaccine, testing newborns for pneumonia and malnutrition — and diagnosing [nytimes.com]

  A woman's blindness can have a dreadful impact on her family, putting her children at greater risk of other health problems, including malnutrition. [web.worldbank.org]

• Pneumonia

  Of the 14 C. trachomatis-negative samples, one was positive for adenoviral infection (serotype D) and 13 were positive for bacterial infections (H. influenzae, M. catarrhalis, S. pneumoniae, S. aureus, streptococci other than S. pneumoniae, Staphylococcus [ncbi.nlm.nih.gov]

  Surprisingly, all three species— C. trachomatis, Chlamydophila psittaci, and Chlamydophila pneumoniae —were detected in eight (89%) study households; one household had no members infected with C. pneumoniae. [doi.org]

  The genus Chlamydia is comprised of four known species: C. trachomatis, C. psittaci, C. pneumoniae, and Chlamydia pecorum. [intechopen.com]

• Corneal Opacity

  Another common finding is a diffused corneal opacity that is the end stage of peripheral and central corneal infiltrates. [ncbi.nlm.nih.gov]

  opacity Eyelashes have abraded and damaged cornea, causing corneal opacity and visual loss Clinical images Images hosted on other servers: WHO grading Presence of five or more follicles Thickening of the tarsal conjunctiva Scarring in the tarsal conjunctiva [pathologyoutlines.com]

  opacity (CO): Characterized by easily visible corneal opacity over the pupil Rarely, corneal neovascularization regresses completely without treatment, and corneal transparency is restored. [merckmanuals.com]

  Corneal opacities from previous trachoma cause visual loss Presence of corneal opacity over the pupil 12. [slideshare.net]

• Photophobia

  It is characterized initially by inflammation, pain, photophobia, and lacrimation. If untreated, follicles form on the upper eyelids, forming scarring that causes trichiasis and corneal sequelae, eventually causing blindness. [medical-dictionary.thefreedictionary.com]

   Foreign body sensation or grittiness  Itching  Watering, photophobia and redness  Discharge is usually scanty, but may be more due to secondary infections  Acute Trachoma- Secondary infection superimposed on a relatively mild trachoma 6.  Bulbar [slideshare.net]

  Initial symptoms are conjunctival hyperemia, eyelid edema, photophobia, and lacrimation. Later, corneal neovascularization and scarring of the conjunctiva, cornea, and eyelids occur. Diagnosis is usually clinical. [msdmanuals.com]

• Lacrimation

  It is characterized initially by inflammation, pain, photophobia, and lacrimation. If untreated, follicles form on the upper eyelids, forming scarring that causes trichiasis and corneal sequelae, eventually causing blindness. [medical-dictionary.thefreedictionary.com]

  Lacrimal sac ◦ Chronic dacryocystitis 15. 1. [slideshare.net]

  Initial symptoms are conjunctival hyperemia, eyelid edema, photophobia, and lacrimation. Later, corneal neovascularization and scarring of the conjunctiva, cornea, and eyelids occur. Diagnosis is usually clinical. [msdmanuals.com]

• Eye Pain

  Individual may complain about sticky eyes or itchy, painful eyes. [nigeriagalleria.com]

  Sensitivity to light Red lumps in the eyelid Eventual eye pain, corneal scarring and visual impairment Irreversible blindness if left untreated Transmission Trachoma is caused by the bacterium Chlamydia trachomatis and is passed through close contact [web.archive.org]

  As the infection progresses, it causes eye pain and blurred vision. If the infection is untreated, scarring occurs inside the eyelid. This leads to the eyelashes turning inward toward the eye, a condition called trichiasis. [aao.org]

  The most common symptoms of Trachoma, which usually affects both eyes, are mild itching and irritation in the eyes, discharge from eyes, swelling, eye pain and light sensitivity. [food.ndtv.com]

• Foreign Body Sensation

   Foreign body sensation or grittiness  Itching  Watering, photophobia and redness  Discharge is usually scanty, but may be more due to secondary infections  Acute Trachoma- Secondary infection superimposed on a relatively mild trachoma 6.  Bulbar [slideshare.net]

  Clinical features Symptoms include: Foreign body sensation. Mild photophobia and Mucopurulent discharges from the eyes. Signs are: Conjunctival hyperaemia more marked in the fornices. [intechopen.com]

  Symptoms include itchiness, lacrimation, photophobia, foreign body sensation and burning. [health.gov.au]

The diagnosis is firstly made through physical examination. The major signs of active infection include subtarsal and limbal follicels, subtarsal inflammation and pannus (vessels growing over the clear cornea). Scarring can be observed over the superior tarsal conjunctiva, possibly with a superior transverse condensation called Arlt line. Small pits can be observed around the margin of the cornea, called Herbet pits, which are the final result of the limbal follicles. Trichiasis can be usually identified by observing one or more lashes rubbing over the surface of cornea and conjunctiva, which might subsequently lead to corneal opacities or vision loss. Blindness is irreversible, and patients with serious level of trichiasis can be in need of lid surgery to prevent it.

Laboratory tests usually confirm the initial diagnosis reached through physical examination. The most frequently and effective laboratory techniques used are the nucleic acid amplification tests (NAATs), of which polymerase chain reaction (PCR) is perhaps the most famous example. Frequently used are also direct fluorescein-labeled monoclonal antibody assay and enzyme immunoassay of conjunctival smears, even though they are less sensitive and specific than NAATs. Other possible tests include cell culture and Giemsa cytology, with a high level of specificity but technically demanding and economically expensive.

• Chlamydia Trachomatis

  Trachoma is an infection of the eye caused by bacteria called chlamydia. Trachoma is caused by infection with the bacteria Chlamydia trachomatis. The condition occurs around the world. It is most often seen in rural areas of developing countries. [nlm.nih.gov]

  Trachoma is a prolonged infection of the conjunctiva caused by the bacterium Chlamydia trachomatis. Chlamydia trachomatis can infect the eye, usually in children who live in lesser-developed, hot, dry countries. [msdmanuals.com]

  Keywords : Azithromycin; Blindness; Chlamydia Trachomatis; Neglected Diseases; Trachoma. [scielo.org.co]

  See Chlamydia trachomatis. tra·cho·ma ( tră-kō'mă ) Chronic inflammation and hypertrophy of the conjunctiva, marked by the formation of minute grayish or yellowish translucent granules, caused by Chlamydia trachomatis. [medical-dictionary.thefreedictionary.com]

The treatment of the disorder is mainly based on antibiotics, especially azithromycin and topical tetracycline. Between these two azithromycin is preferred, because it can be taken in a single dose and is very easily administered [11]. Although more expensive than topical tetracycline, azithromycin also has a high efficacy and a low incidence of mild adverse effects. No development of significant resistance has been observed for both antibiotics.

Many epidemiological studies and community-randomized trials have shown that facial cleanliness can markedly decrease the risk and spreading [12]. Therefore, while implementing the treatment, facial cleanliness is highly recommended. This especially applies to all those subjects living in countries with poor hygienic conditions such as Africa and Asia, where environmental improvement activities should be promoted, especially in terms of building new water supplies and improvement of household sanitation.

Surgery is recommended for all those subjects showing clear signs of trichiasis. Bilamellar tarsal rotation is the preferred procedure to push the bent lashes away from the eye [13]. Early intervention is highly advised, as it can decrease the risk of recurrence [14].

The prognosis depends on the initial conditions of the patient and might vary very much according to three important factors:

1. The time of the treatment: If treatment is started very early major complications like scarring can be prevented.
2. The treatment itself: It is important to choose the appropriate antibiotics to treat trachoma.
3. Risk of reinfection: This factor is strictly linked to the social and economical conditions of the patient. Usually poverty and poor hygiene conditions can foster the spreading of infections, increasingly the risk of developing trachoma.

In general, if the patient is promptly and appropriately treated, prognosis is good and his/her conditions can improve fast. In any case, if corneal scarring has begun to develop, the vision of the patient might not improve.

As previously indicated, the etiological factor of trachoma is the bacterium Chlamydia trachomatis, spread both directly, by direct contact with the secretions of eye and nose, or indirectly by contact with the objects touched by affected subjects (the so called fomites) [5]. The condition mainly affects children because of their tendency to get dirty while playing with their friends and toys, and might frequently result in entropion, a painful medical condition in which the eyelid folds inward causing the eyelashes to constantly rub against the cornea. As a result, the cornea gets irritated and a permanent blindness might occur.

In USA no case of trachoma is currently reported. The disease was eradicated at the beginning of the 20th century, due to improved hygienic conditions fostered by the US booming economy. However, cases of trachoma could still be seen in the Native American reservations until 1960s, when it was completely eradicated after the launch of large-scale antibiotic treatment programs based on the oral sulfonamide drugs by the US government.

The condition remains an endemic disease in 54 countries of the world, especially in poor regions such as Africa, Asia, Middle East, Latin America, and the Pacific Islands. Cases of have even been observed in certain aboriginal communities in Australia. In total, trachoma currently affects approximately 84 million people around the world, 1.3 million of which are blind [6] [7].

Chlamydia trachomatis is an obligate intracellular gram-negative of the genus Chlamydia [8]. In particular, trachoma is caused by the serotypes A, B, and C of this bacterium, which provokes a self-limited acute conjunctivitis. The pathogen is easily spread through contact with ocular secretions or through the help of typical vectors such as flies. Children usually develop a characteristic follicular inflammatory response of the tarsal conjunctiva, a response which frequently leads to pathologic scarring. The spreading of trachoma appears to be predicted by repeated and frequent episodes of acute conjunctival inflammation [9].

The characteristic pathological change is the progressive scarring of the conjunctiva which is caused by the constant abrasive effect of the lashes rubbing against the corneal surface underneath, as a consequence of the eyelid margins pulled inward. If left untreated, scarring might cause corneal opacification and irreversible vision loss. Trichiasis and corneal visual impairment are frequently observed in patients affected by the condition [10].

The World Health Organization (WHO) has organized a plan to eliminate trachoma as global health concern by the year 2020, based on the so called SAFE strategy [7]. SAFE is an acronym that stands for surgery (S), antibiotics (A), facial cleanliness (F) and environmental improvement (E), in other words the major points of prevention. At a personal level, patients are especially advised to maintain personal hygiene at acceptable levels, avoid the presence of flies, which can act as very effective biological vector, and stay away from crowded places, which might foster the spreading of the infection.

Trachoma is also known as granular conjunctivitis, Egyptian ophthalmia [2], or blinding trachoma. This infection is a form of keratoconjunctivitis predominantly occurring in children, and since it can cause pain, cornea breakdown, eyelid scarring and blindness [1], it might be very dangerous and sometime requires surgery to avoid severe complications. Trachoma can be transmitted both directly, through direct contact with the eyes and nose of the subject infected, or indirectly, by touching other body’s parts, objects and cloths. As many other infections, trachoma too is fostered by poor sanitation, especially poor facial cleanliness, and crowded environments. Factors which markedly favor the spread of the disorder include lack of water, absence of sanitary services, the presence of flies or the close proximity to cattle [3] [4].

Trachoma, also known as as granular conjunctivitis, Egyptian ophthalmia [2], or blinding trachoma, is an infection provoked by the bacterium Chlamydia trachomatis causing a characteristic roughening of the eyelid's inner surface. This infection is a form of keratoconjunctivitis predominantly occurring in children, and since it can cause pain, cornea breakdown, eyelid scarring and blindness, it might be very dangerous and sometime requires surgery to avoid severe complications. Trachoma can be transmitted both directly, through direct contact with the eyes and nose of the subject infected, or indirectly, by touching other body’s parts, objects and cloths. As many other infections, trachoma too is fostered by poor sanitation, especially poor facial cleanliness, and crowded environments. Factors which markedly favor the spread include lack of water, absence of sanitary services, the presence of flies or the close proximity to cattle.

Symptoms of trachoma may include:

• Cloudy cornea
• Eye discharge 
• Swelling of lymph nodes in front of the ears
• Swollen eyelids
• Sensitivity to light
• Turned-in eyelashes (trichiasis)
• The final results of trichiasis might be corneal opacification and eventually vision loss.

Antibiotics, facial cleanliness and surgery are common treatment options. The World Health Organization (WHO) has organized a plan to eliminate trachoma as global health concern by the year 2020, based on the so called SAFE strategy. SAFE is an acronym standing for surgery (S), antibiotics (A), facial cleanliness (F) and environmental improvement (E), in other words the major points of prevention. 

1. Blinding Trachoma Fact sheet N°382. World Health Organization. November 2013.
2. Meunier YA. Tropical diseases : a practical guide for medical practitioners and students. Oxford: Oxford University Press 2014, USA. p. 199. 
3. Taylor H. Trachoma: A Blinding Scourge from the Bronze Age to the Twenty-first Century. Centre for Eye Research Australia. 2008
4. Wright HR, Turner A, Taylor HR. Trachoma. Lancet 2008 371 (9628): 1945–54. 
5. Goldman L. Goldman's Cecil Medicine (24th ed.). 2011 Philadelphia: Elsevier Saunders. pp. e326–2. 
6. Polack S, Brooker S, Kuper H, et al. Mapping the global distribution of trachoma. Bull World Health Organ. 2005;83:913-919. 
7. World Health Organization. Report of the 2nd global scientific meeting on trachoma. Geneva, Switzerland: WHO; 2003:WHO/PBD/GET 03.1. 
8. Ryan KJ, Ray CG. Sherris Medical Microbiology (4th ed.). 2004 McGraw Hill. pp. 463–70. 
9. West SK, Munoz B, Mkocha H, et al. Progression of active trachoma to scarring in a cohort of Tanzanian children. Ophthalmic Epidemiol. 2001;8:137-144. 
10. Bowman RJ, Jatta B, Cham B, et al. Natural history of trachomatous scarring in the Gambia: results of a 12-year longitudinal follow-up. Ophthalmology. 2001;108:2219-2224. 
11. Evans JR, Solomon AW. Antibiotics for trachoma. Cochrane Database Syst Rev. Mar 16 2011;CD001860. 
12. West S, Munoz B, Lynch M, et al. Impact of face-washing on trachoma in Kongwa, Tanzania. Lancet. Jan 21 1995;345(8943):155-8. 
13. Reacher M, Foster A, Huber J. Trichiasis Surgery for Trachoma. The Bilamellar Tarsal Rotation Procedure. 1993; World Health Organization, Geneva: WHO/PBL/93.29 
14. Burton MJ, Kinteh F, Jallow O et al. A randomised controlled trial of azithromycin following surgery for trachomatous trichiasis in the Gambia. Br J Ophthalmol 2005 89 (10): 1282–8.