Leprosy is a **neglected tropical disease** (NTD) that has existed for thousands of years. Today, it is curable with multidrug therapy (MDT), but early detection remains essential to prevent disability and stigma.

Who It Affects

• Geography: Endemic in parts of South‑East Asia, Brazil, sub‑Saharan Africa and the Caribbean. In 2022, the World Health Organization (WHO) reported 127,558 new cases worldwide, a 12 % drop from 2019.
• Age: Most cases are diagnosed in adults aged 15‑45, though children can be affected, indicating recent transmission.
• Gender: Slight male predominance (male : female ratio ≈ 1.5 : 1), likely reflecting occupational exposure and health‑seeking behavior.
• Socio‑economic status: Poverty, overcrowding, and limited access to health care increase risk.

Prevalence

According to the WHO leprosy database (2023), the highest burden countries are India (≈ 114,000 cases), Brazil (≈ 27,000) and Indonesia (≈ 15,000). In the United States, the disease is rare, with < 150 cases reported annually, mostly among immigrants or travelers from endemic regions.

Symptoms

Leprosy has a broad clinical spectrum ranging from mild (paucibacillary) to severe (multibacillary) forms. Symptoms may develop slowly over months to years.

Skin Manifestations

• Hypopigmented or reddish patches: Usually flat, with loss of sensation (numbness) to light touch, temperature, or pain.
• Thickened skin lesions: May become raised, nodular, or ulcerated in multibacillary disease.
• Hair loss (alopecia) within patches due to nerve damage.
• Loss of sweating (anhidrosis) over lesions, making skin dry.

Neurological Signs

• Peripheral nerve thickening: Palpable enlargements of nerves at the elbow, wrist, knee, or behind the ear.
• Numbness or tingling: Often begins in the hands and feet, leading to a "glove‑and‑stocking" distribution.
• Muscle weakness: Especially of the intrinsic hand muscles, leading to claw‑hand deformities.

Eye Involvement

• Dry eye (keratoconjunctivitis sicca) caused by reduced corneal sensation.
• Corneal ulcers, cataracts, or glaucoma may develop if ocular nerves are damaged.
• Vision loss is a late complication.

Upper Respiratory Tract

• Nasal congestion or obstruction due to mucosal infiltration.
• Epistaxis (nosebleeds) and crusting.
• Loss of sense of smell (anosmia).

Systemic Symptoms (Rare)

• Fever, malaise, weight loss – typically in the lepromatous (multibacillary) form.

Causes and Risk Factors

Etiology

Leprosy is caused exclusively by Mycobacterium leprae, an intracellular, acid‑fast bacillus that preferentially infects cool‑temperature tissues (skin, peripheral nerves, superficial mucosa). The organism cannot be cultured on artificial media, which historically made diagnosis challenging.

Transmission

• Respiratory droplets: Prolonged close contact with an untreated, multibacillary patient is the most accepted route.
• Skin‑to‑skin contact: Possible but less efficient.
• Zoonotic reservoirs: Armadillos in the southern United States harbor viable M. leprae and can transmit infection to humans (CDC, 2023).

Risk Factors

• Living in or traveling to endemic areas.
• Close, prolonged exposure to an untreated patient (e.g., household members, caregivers).
• Genetic susceptibility: Certain HLA types (e.g., HLA‑DRB1*15) are linked to higher risk.
• Immunosuppression (e.g., HIV, diabetes, long‑term steroids) can increase disease severity.
• Poor socioeconomic conditions, malnutrition, and lack of access to preventive health services.

Diagnosis

Because early clinical signs are subtle, a combination of clinical assessment, laboratory tests, and sometimes imaging is required.

Clinical Examination

• Detailed skin inspection for lesions and sensory testing (light touch, pinprick, temperature).
• Palpation of peripheral nerves for thickening and tenderness.
• Assessment of eye function (visual acuity, corneal reflexes).

Laboratory Tests

1. Skin slit‑smear microscopy: A sample from the edge of a lesion is stained (Ziehl‑Neelsen or Fite‑Faraco) to detect acid‑fast bacilli. Positivity indicates multibacillary disease.
2. Skin biopsy: Histopathology shows granulomas, nerve involvement, and can differentiate paucibacillary vs. multibacillary forms.
3. Polymerase‑chain reaction (PCR): Molecular detection of M. leprae DNA improves sensitivity, especially in paucibacillary cases (Cleveland Clinic, 2022).
4. Serology: Antibodies against phenolic glycolipid‑1 (PGL‑1) are supportive but not definitive.

Additional Tests

• Electroneurography or nerve conduction studies – to gauge the extent of peripheral nerve damage.
• Radiography of hands/feet – may reveal osteolysis in advanced cases.

Treatment Options

Since 1982, the WHO‑recommended multidrug therapy (MDT) has made leprosy a curable disease. Treatment is individualized based on disease classification.

Multibacillary (MB) Leprosy

• Rifampicin 600 mg monthly (supervised) – bactericidal.
• Dapsone 100 mg daily (self‑administered) – bacteriostatic.
• Clofazimine 300 mg monthly (supervised) + 50 mg daily – anti‑inflammatory and bactericidal.
• Duration: **12 months** (WHO standard) or 24 months for severe cases.

Paucibacillary (PB) Leprosy

• Rifampicin 600 mg monthly + Dapsone 100 mg daily.
• Duration: **6 months**.

Management of Reactions

Leprosy reactions (type 1 reversal reactions and type 2 erythema nodosum leprosum) can cause acute inflammation and nerve damage. They are treated with:

• Corticosteroids (prednisone 40‑60 mg/day) for type 1 reactions.
• Thalidomide (highly effective for ENL) – used with strict pregnancy precautions.
• Adjunctive NSAIDs, antihistamines, or low‑dose methotrexate in refractory cases.

Lifestyle & Supportive Care

• Wound care for ulcerated lesions to prevent secondary infection.
• Physiotherapy & orthotic devices to preserve muscle strength and prevent contractures.
• Regular ophthalmology reviews; lubricating eye drops for dry eye.
• Nutrition optimization – adequate protein, vitamins A, C, D, and zinc support immune recovery.

Living with Jerusalem Disease (Leprosy)

Successful treatment does not automatically eliminate the risk of disability. The following daily‑management tips help maintain function and quality of life.

Self‑Care Practices

• Skin protection: Keep lesions clean, apply antibiotic ointment if crusted, and cover with sterile dressings.
• Temperature sensation testing: Daily check for loss of heat/cold perception in hands/feet; use gentle warm/cold objects.
• Foot care: Inspect feet each morning for cuts, blisters, or calluses; use soft, well‑fitting shoes; consider custom orthotics.
• Eye hygiene: Use preservative‑free artificial tears 2‑4 times daily; avoid rubbing eyes; seek prompt ophthalmology review if redness or vision changes occur.
• Exercise: Gentle range‑of‑motion stretches and low‑impact activities (e.g., swimming, walking) maintain muscle tone.

Psychosocial Support

• Connect with local leprosy support groups – sharing experiences reduces stigma.
• Access counseling services if anxiety or depression develops (common in chronic disease).
• Inform family members about the low infectivity after 6 months of effective therapy to reduce fear.

Follow‑up Schedule

1. Monthly visits during MDT to monitor drug adherence and side effects.
2. Quarterly neurologic assessment for the first year after treatment.
3. Annual skin and eye exams lifelong, as late complications can appear years later.

Prevention

• Early case detection: Active surveillance in endemic communities reduces transmission.
• Prompt MDT: Patients become non‑infectious within days of the first rifampicin dose.
• Contact prophylaxis: A single dose of rifampicin (SDR) given to close contacts lowers risk by ~57 % (WHO, 2020).
• Vaccination research: The BCG vaccine offers modest protection; ongoing trials of a specific leprosy vaccine (MIP) show promise.
• Improved living conditions: Reducing crowding, ensuring adequate nutrition, and providing clean water diminish overall susceptibility.

Complications

If left untreated or inadequately managed, leprosy can cause irreversible damage.

• Peripheral neuropathy: Sensory loss leading to repeated injuries, ulcerations, and eventually foot amputations.
• Motor weakness: Claw hand, foot drop, and facial palsy.
• Eye complications: Corneal ulcers, cataracts, and blindness.
• Skin ulceration & secondary infection: May progress to osteomyelitis.
• Social stigma & mental health issues: Discrimination can lead to isolation, unemployment, and depression.

When to Seek Emergency Care

References

• World Health Organization. Leprosy Fact Sheet. Updated 2023.
• Mayo Clinic. Leprosy (Hansen Disease) – Symptoms and Causes. Accessed April 2026.
• Cleveland Clinic. Leprosy (Hansen Disease) Overview. 2022.
• Centers for Disease Control and Prevention. Leprosy (Hansen Disease) – CDC. 2023.
• National Institute of Health (NIH). Current concepts in the diagnosis and management of leprosy. *Lancet Infectious Diseases*. 2021.
• World Health Organization. Guidelines for the treatment of leprosy, 2020.