Trachoma

Trachoma
Name	Trachoma
Field	Ophthalmology, Infectious disease, Public health
Symptoms	Eyelid scarring, Conjunctival inflammation, Corneal opacity
Complications	Blindness, Visual impairment
Onset	Gradual
Duration	Chronic, recurrent
Causes	Chlamydia trachomatis serovars A–C
Diagnosis	Clinical examination, Polymerase chain reaction, Direct immunofluorescence
Prevention	Facial cleanliness, Environmental improvement, Azithromycin mass drug administration
Treatment	Antibiotics, Eyelid surgery
Frequency	Endemic in parts of Sub-Saharan Africa, Middle East, Southeast Asia

Trachoma is a chronic infectious disease of the conjunctiva caused by specific serovars of Chlamydia trachomatis that leads to progressive eyelid scarring and potentially irreversible blindness. Historically associated with overcrowding and poor sanitation, trachoma remains a major neglected tropical disease targeted by global initiatives led by organizations such as the World Health Organization, International Agency for the Prevention of Blindness, and nongovernmental implementers like The Carter Center. Clinical management, public health control, and elimination programs involve coordinated efforts spanning antimicrobial chemotherapy, eyelid surgery, and water, sanitation, and hygiene interventions.

Signs and symptoms

Early inflammatory stages present with follicles and papillae on the upper tarsal conjunctiva accompanied by mucopurulent discharge, conjunctival hyperemia, and photophobia in children. Recurrent infection and chronic inflammation produce conjunctival scarring, entropion, trichiasis with lashes abrading the cornea, and progressive corneal opacity that culminates in visual impairment or blindness in advanced cases. Complications may include secondary bacterial keratitis, corneal ulceration, and symblepharon formation; these ocular sequelae are monitored in surveillance activities by partners such as United Nations agencies and national ministries of health.

Causes and transmission

The etiologic agent is specific serovars (A, B, Ba, C) of Chlamydia trachomatis, an obligate intracellular bacterium transmitted through direct contact with infected ocular and nasal secretions, indirectly via fomites like towels and cloths, and mechanically by eye-seeking flies such as Musca sorbens. Transmission is amplified by overcrowding, limited access to clean water, and poor facial hygiene, factors addressed in interventions supported by organizations such as UNICEF, World Bank, and regional public health institutions.

Pathophysiology

Infection of the conjunctival epithelium by Chlamydia trachomatis triggers a host immune response mediated by infected epithelial cells, antigen-presenting cells, and recruited lymphocytes, including CD4+ T cells and interferon-γ–producing cells. Repeated or persistent infection leads to chronic inflammation and conjunctival fibroblast activation with deposition of extracellular matrix and cicatricial remodeling, culminating in entropion and trichiasis. Host genetic factors, coinfections, and environmental stressors modulate disease progression; immunopathologic mechanisms have been investigated in contexts involving researchers affiliated with institutions such as London School of Hygiene & Tropical Medicine, Centers for Disease Control and Prevention, and university ophthalmology departments.

Diagnosis

Diagnosis is primarily clinical using standardized grading systems developed through collaborative research by groups including the World Health Organization and academic partners; grading assesses follicular inflammation, intense inflammation, scarring, trichiasis, and corneal opacity. Laboratory confirmation can be achieved with nucleic acid amplification tests such as Polymerase chain reaction assays, antigen detection via Direct immunofluorescence, or culture in specialized laboratories at reference centers like national public health laboratories. Population-level surveillance uses cluster sampling methodologies endorsed by agencies including WHO and the London School of Hygiene & Tropical Medicine for mapping endemicity and guiding mass drug administration campaigns.

Prevention and control

The SAFE strategy—Surgery for trichiasis, Antibiotics to clear infection, Facial cleanliness, and Environmental improvement—constitutes the internationally recommended comprehensive approach promoted by the World Health Organization, regional health authorities, and partners such as The Carter Center, Sight Savers International, and national ministries of health. Preventive efforts emphasize mass drug administration with Azithromycin in endemic districts, promotion of facial hygiene among children, provision of clean water and sanitation infrastructure supported by UNICEF and bilateral donors, and vector control targeting Musca sorbens where feasible.

Treatment

Active infection is treated with oral Azithromycin single-dose regimens or topical tetracycline eye ointment in accordance with WHO guidelines; antibiotic distribution is often implemented through mass drug administration campaigns coordinated by public health alliances and nongovernmental organizations. Surgical correction of entropion and trichiasis—procedures refined by surgeons trained via programs at institutions like Brien Holden Vision Institute and university hospitals—reduces the risk of corneal damage. Management of advanced corneal opacity may require corneal transplantation where capacity exists; surgical training, supply chains, and follow-up care are supported by tertiary eye centers and outreach initiatives.

Epidemiology and public health impact

Trachoma remains endemic in parts of Sub-Saharan Africa, areas of the Middle East, Central Asia, and Southeast Asia, disproportionately affecting impoverished and remote communities. Global elimination as a public health problem is targeted by initiatives led by the World Health Organization with support from philanthropic entities such as the Bill & Melinda Gates Foundation and implementation partners including The Carter Center and Sightsavers. Mapping studies and impact assessments conducted by research groups at institutions such as London School of Hygiene & Tropical Medicine and University of California, San Francisco inform resource allocation for mass drug administration, surgery campaigns, and water and sanitation projects. Persistent challenges include conflict-affected settings, migration, and health system constraints that impede surveillance and service delivery, prompting coordination among multilateral agencies, national health ministries, and civil society organizations.

Category:Infectious diseases of the eye