Trachoma

Trachoma is a chronic follicular keratoconjunctivitis caused by Chlamydia trachomatis serovars A, B, Ba and C, and the leading infectious cause of blindness worldwide.

• Endemic in poor, rural, dry communities with limited water and sanitation (sub-Saharan Africa, especially Ethiopia and Sudan, plus parts of Asia, Australia and Latin America).
• Transmission via eye seeking flies (Musca sorbens), fomites, and child-to-child contact; young children are the reservoir; women are affected more than men (3:1) due to childcare exposure.
• Repeated infection over years causes conjunctival scarring, entropion, trichiasis, corneal opacity and blindness.

• Staging by the simplified grading system:
  • TF (trachomatous inflammation, follicular): 5 or more follicles at least 0.5 mm on the upper tarsal conjunctiva.
  • TI (trachomatous inflammation, intense): papillary hypertrophy obscuring over half the deep tarsal vessels.
  • TS (trachomatous conjunctival scarring): fibrous white bands.
  • TT (trachomatous trichiasis): at least one eyelash touching the globe.
  • CO (corneal opacity): corneal opacity over the pupil margin.
• Active disease: itching, discharge, ocular discomfort in children, with Herbert pits (scarred limbal follicles) and superior pannus.
• Late disease: scarring, lid entropion, trichiasis, dry eye, corneal ulceration and opacity, lacrimal obstruction.
• Pain, photophobia and watering from trichiasis.

• Clinical diagnosis by examining the upper tarsal conjunctiva (evert the upper lid) with a 2.5x loupe and torch in field settings.
• Confirmation: nucleic acid amplification test on conjunctival swab; culture not needed.
• Community assessment: prevalence of TF in children aged 1 to 9 years, TT in adults aged 15 or more.
• Exclude other follicular conjunctivitis (viral, adult inclusion conjunctivitis, drug induced).

• SAFE strategy:
  • Surgery for trichiasis.
  • Antibiotics: azithromycin 20 mg/kg (maximum 1 g) orally, single dose, for individuals and mass drug administration of entire communities annually for at least 3 years (when district TF prevalence in children is 10 percent or higher) and until prevalence falls below 5 percent. Alternative: topical tetracycline 1 percent ointment twice daily for 6 weeks. For children under 6 months, tetracycline ointment is preferred. Pregnancy: azithromycin is acceptable.
  • Facial cleanliness: regular face washing to reduce transmission.
  • Environmental improvement: access to water, sanitation, fly control, latrines.
• Trichiasis surgery: bilamellar tarsal rotation for upper lid trichiasis, with recurrence rates about 10 to 20 percent at one year; epilation for minor trichiasis (fewer than 5 lashes, awaiting surgery) with forceps; electrolysis or cryotherapy for isolated lashes; mucous membrane grafting for severe cicatricial entropion.
• Corneal opacity: keratoplasty has a poor prognosis due to dry eye and neovascularisation.
• Treat secondary bacterial infection, lubricate dry eye, and examine family members.