Infectious Eye Diseases: Leprosy, Trachoma and Onchocerciasis

Ridley-Jopling Classification (1965):

1. Tuberculoid (TT): This is the least severe form of leprosy, occurring in people with the strongest immune response. Patients have a few, well-defined skin lesions with loss of sensation and nerve thickening.
2. Borderline Tuberculoid (BT): Intermediate in severity with more skin lesions than TT, and nerve thickening is common.
3. Mid-Borderline (BB): Also intermediate in severity, with features of both TT and LL leprosy.
4. Borderline Lepromatous (BL): Intermediate in severity, with more skin lesions than BT, and nerve thickening is common.
5. Lepromatous (LL): The most severe form, occurring in people with the weakest immune response. Patients typically have many poorly defined skin lesions with loss of sensation and nerve thickening.

World Health Organization (WHO) Classification (1982):

• Multibacillary (MB): - LL, BL, BB (Many bacilli)- This class includes patients with a positive skin smear or more than five skin lesions, requiring longer treatment.
• Paucibacillary (PB): - TT, BT (Few bacilli)- This class includes patients with a negative skin smear and five or fewer skin lesions.

• Leprosy is a significant public health issue worldwide, with a decreasing trend.
• Approximately 75% of WHO reported cases are concentrated in Asia.
• There are 2-4 million individuals affected by leprosy globally, with 1-2 million residing in tropical countries.
• Ocular involvement has been documented in 6-90% of leprosy patients.
• The rate of blindness associated with leprosy is 8.7%.

The ocular manifestations of leprosy depend on the type of interaction between the leprosy bacillus and the host's defense mechanisms:

• If the host's defense is high, resulting in a low bacterial count, it is categorized as Paucibacillary (PB) leprosy.
• If the host's defense is low, leading to a high bacterial count, it is categorized as Multibacillary (MB) leprosy.
• Ocular complications in leprosy primarily occur in multibacillary (MB) patients.

Ocular Features

• Madarosis: Loss of eyelashes and eyebrows.
• Blepharochalasis: Laxity and sagging of the eyelids.
• Lagophthalmos: Inability to close the eyelids completely.
• Dacryocystitis: Inflammation of the tear sac.
• Conjunctivitis: Inflammation of the conjunctiva, the thin membrane that lines the inside of the eyelids and covers the front of the eye.
• Scleritis: Inflammation of the sclera, the white outer layer of the eye.
• Staphyloma: A bulging of the sclera that can occur secondary to scleritis.

Ocular manifestations of leprosy can occur in any form of the disease, but they are more common in lepromatous leprosy. This is because the leprosy bacterium can directly invade the eye and cause inflammation. Ocular complications can also occur secondary to damage to the nerves that control the muscles of the eyelids and eye. Leprosy can affect any part of the eye, but it is most common in the anterior segment (cornea, iris, and lens). Leprosy can also cause damage to the optic nerve, which can lead to vision loss.

Cornea

• Thickening and beading of corneal nerves
• Punctate keratitis
• Interstitial keratitis
• Exposure keratitis
• Corneal hypoesthesia
• Pannus
• Corneal ulceration
• Corneal scarring/opacity

Other Features

• Iris: Iridocyclitis, Iris pearls, Iris atrophy, seclusio pupillae)
• Secondary glaucoma
• Complicated cataract
• Phthisis bulbi
• Blindness

• Primary (1°): Prevent occurrence
• Secondary (2°): Prevent complication
• Tertiary (3°): Reducing disability from diagnosed complications

Primary Prevention

• Good water supplies, sanitation, environmental hygiene.
• Health education, facial hygiene, safety practices.
• BCG immunization coverage.

Secondary Prevention

• Early detection and MDT therapy

Paucibacillary: Single skin lesion

• 600mg rifampicin
• 400mg ofloxacin
• 100mg minocycline
• All single dose

Paucibacillary leprosy (2-5 skin lesions)

• 100mg DDS (dapsone) once daily
• 600mg rifampicin, supervised monthly: 6 doses to be completed

Multibacillary leprosy

• 100mg DDS (dapsone) once daily
• 50mg clofazimine (lamprene) once daily
• 600g rifampicin once per month
• 300mg clofazimine once per month
• Supervised monthly: 12 doses to be completed

Anti-leprosy drugs (MDT) are provided by WHO free of cost and are distributed to the Leprosy Centres through the NGOs.

Tertiary Prevention

• Lagophthalmos and Trichiasis surgery
• Eye brow and nasal reconstruction
• Cataract surgery
• Optical iridectomy
• Corneal grafting
• Low vision services
• Special education
• Rehabilitation

Microfilaria

• Each female can produce around 1600 microfilaria per day.
• Total body load can reach 150 million microfilaria.
• Microfilaria live in sub-epidermal tissue where they die after 6-30 months, unless ingested by a black fly.
• Disease manifestation is predominantly a consequence of the immune response to microfilarial death.

• At least 220 million people required Preventive Chemotherapy.
• 14.6 million of the infected people already had skin disease.
• 20.9 million infected globally (99% of cases in 31 African countries).
• Approximately 1.15 million people have vision loss due to onchocerciasis.
• Ivermectin treatments continued to scale up, reaching 152.9 million people in 2019.

Common Onchocerciasis Symptoms

• Skin disease - unbearable itching, nodules.
• Visual loss and blindness.

Eye Signs of Onchocerciasis

Anterior Segment:

• Punctate keratitis: Small, dot-like lesions on the cornea.
• Sclerosing keratitis: Inflammation of the cornea that can lead to scarring and thickening of the cornea.
• Anterior uveitis: Inflammation of the iris and ciliary body, the two structures that make up the middle layer of the eye.
• Cataract: Clouding of the lens of the eye.
• Glaucoma: A condition that causes damage to the optic nerve due to increased pressure inside the eye.

Posterior Segment:

• Chorioretinal atrophy: Thinning and degeneration of the choroid and retina, the two innermost layers of the eye.
• Optic atrophy: Thinning and degeneration of the optic nerve.

Diagnosis of Leprosy

Clinical Findings:

• Skin Lesions: Hypopigmented or erythematous patches with loss of sensation.
• Nerve Thickening: Thickening of peripheral nerves, especially the ulnar, median, and posterior tibial nerves.

Laboratory Tests:

• Skin Smear: Microscopic examination of a skin smear for acid-fast bacilli (AFB).
• Nerve Biopsy: Microscopic examination of a nerve biopsy for AFB and granulomas.

Histopathological Examination:

• Skin Biopsy: Microscopic examination of a skin biopsy for granulomas and AFB.

The diagnosis of leprosy is confirmed by the presence of AFB in the skin smear or nerve biopsy, or by the presence of granulomas in the skin or nerve biopsy.

Blindness/Skin Disease: The risk of developing blindness or severe skin disease is influenced by the following factors:

• Microfilarial Load: Higher microfilarial load is associated with increased disability.

Microfilarial Load is Determined by:

• Annual Transmission Potential: This is the number of times per year a person is bitten by a fly carrying the infection.

Reduce Black Fly Breeding:

• OCP Programme: The Onchocerciasis Control Programme (OCP) has been highly effective in reducing the breeding of black flies.

Control of Onchocerciasis

• Reduce Black Fly Breeding:
  • OCP Programme: The Onchocerciasis Control Programme (OCP) has been highly effective in reducing black fly breeding.
• Reduce Transmission by Behavioral Change:
  • Effectiveness: Not effective
• Surgical Removal of Adult Worms:
  • Feasibility: Not feasible
• Drugs Which Kill Adult Worms:
  • Being actively researched
• Drugs Which Kill the Microfilaria:
  • Ivermectin has replaced diethylcarbamazine (DEC)

What Is Community-Directed Treatment (ComDT)?

Community decide how to distribute.

Health services give health education and monitor.

Community-Directed Treatment (ComDT) is a public health approach used in the distribution of medications or treatments for various diseases, particularly in resource-limited or remote areas. In ComDT, the community plays a central role in decision-making and the distribution process. Here's how it works:

1. Community Involvement: Local communities are actively engaged in the decision-making process regarding the distribution of medications. This includes selecting community members or volunteers who will be responsible for drug distribution and treatment administration.
2. Decision-Making: Communities are given the autonomy to decide how medications or treatments should be distributed. They may consider factors such as the most effective distribution methods, identifying at-risk populations, and planning for the administration process.
3. Health Education: Health services or trained individuals provide essential health education to community members. This education typically covers the importance of the medication, proper administration, potential side effects, and the need for compliance with the treatment plan.
4. Monitoring and Evaluation: Health services or local health workers monitor the distribution process, ensuring that the medications are being administered correctly and that any potential side effects are addressed promptly. They also evaluate the overall impact of the treatment.

ComDT is often used in the distribution of medications for diseases like onchocerciasis (river blindness), lymphatic filariasis (elephantiasis), and other neglected tropical diseases. It leverages community involvement and local knowledge to improve the success of treatment programs, especially in areas with limited access to healthcare services.

The involvement of communities in the decision-making process helps ensure that treatment programs are culturally sensitive, that community members are more likely to adhere to the treatment plan, and that the medications are distributed effectively and safely.

Important Things to Know:

• Community involvement is a key element of ComDT.
• Communities make decisions about drug distribution.
• Health education is provided to community members.
• Health services monitor the distribution process.
• ComDT is used for diseases like onchocerciasis and lymphatic filariasis.

Trachoma is a chronic follicular keratoconjunctivitis caused by the bacterium Chlamydia trachomatis. It is characterized by a cycle of repeated infections, often resulting from poor hygiene conditions. Over time, these infections can lead to conjunctival scarring, entropion (inward turning of the eyelid), and corneal scarring. Trachoma is a major cause of preventable blindness in many parts of the world and primarily affects communities with limited access to clean water and sanitation.

Trachoma is a significant global health concern:

• 46 countries have trachoma.
• 150 million children have active disease (TF or TI).
• 300 million people have scarring (TS).
• 10-30 million people have potentially blinding trichiasis (TT).
• 3-5 million are blind (CO).
• 5-7 million have low vision.

Trachoma is influenced by several risk factors:

• Severity of inflammation plays a role in disease progression.
• Frequency of re-infection can worsen the condition.
• Factors promoting transmission contribute to its spread.
• Community environment, often dry, dusty, and dirty/dung, can facilitate trachoma transmission.
• Family environment with discharges and overcrowding can also contribute to transmission.
• Transmission commonly occurs through flies, fingers, and fomites, and there can be clusters within households.

• Trachoma follicular (TF)
• Trachomatous inflammation, intense (TI)
• Trachomatous conjunctival scarring (TS)
• Trachomatous trichiasis (TT)
• Corneal opacity

• Proportion of TF in children <10 years (how widespread)
• Proportion of TI in children <10 years (severity of disease in the community)

SAFE strategy (WHO)

• Surgery for trichiasis (tarsal rotation; community-based)
• Antibiotics: Tetracycline ointment 1% twice daily for 6 weeks or Azithromycin 1 stat (Azithromycin 250mg/kg stat)
• Face washing for facial cleanliness
• Environmental improvement with water and sanitation