Annotations only — chart still shows the full chemistry of each drug.
1. Clinical Syndrome
Chronic granulomatous infection by Mycobacterium leprae affecting skin + peripheral nerves + (with bacillary load) anterior eye, upper airway, testes, bone. Spectrum from tuberculoid (TT, paucibacillary, strong CMI) → lepromatous (LL, multibacillary, weak CMI).
WHO simplified PB vs MB classification drives treatment:
- PB (paucibacillary): ≤5 skin lesions + negative slit-skin smear
- MB (multibacillary): ≥6 lesions OR positive smear
Excludes: other mycobacteria, sarcoidosis (granulomas without AFB), leishmaniasis (cutaneous lesions in endemic regions).
2. Pathogens
Consider the patient: Endemic region origin (India, Brazil, Indonesia), armadillo exposure (southern US — major reservoir), nerve symptoms (numbness, weakness, claw hand, foot drop, anesthesia), eye involvement (lagophthalmos, corneal anesthesia → keratitis), family history.
Consider the case: PB vs MB classification, lepra reaction (Type 1 reversal or Type 2 ENL) — can occur before, during, or after MDT; ulceration / disability prevention.
Common
- Mycobacterium leprae
Uncultivable in vitro. Diagnosis: clinical + skin biopsy with Fite stain + slit-skin smear bacterial index.
- Mycobacterium leprae
3. Empiric Therapy
| Tier | First choice | Alternatives | Duration | Comments |
|---|---|---|---|---|
| Outpatient |
| — | **WHO MDT**: PB = rifampin monthly + dapsone daily × 6 months. MB = rifampin monthly + dapsone daily + clofazimine (monthly 300 + daily 50) × 12 months. | **WHO MDT (multidrug therapy)** is the standard worldwide. **Check G6PD** before starting dapsone. **Monthly rifampin dose is supervised** in many programs (DOT). Counsel re: clofazimine skin discoloration (reversible over months–years after stopping). **Routine eye + peripheral nerve exam** at each visit — disability prevention is the main long-term goal. |
4. Directed Therapy
WHO MDT is the cornerstone — PB 6 months, MB 12 months.
Lepra reactions (immune-mediated, NOT progression of infection):
- Type 1 (Reversal Reaction, RR): upgrading immune response → worsening lesion erythema + tenderness + nerve pain / functional loss. Treat with corticosteroids (prednisone 1 mg/kg taper over 12–20 weeks). Continue MDT throughout.
- Type 2 (Erythema Nodosum Leprosum, ENL): tender red nodules + systemic symptoms (fever, arthralgia, lymphadenopathy, iritis, orchitis) in lepromatous disease. Treat with corticosteroids ± thalidomide ± high-dose clofazimine (anti-inflammatory). Thalidomide highly effective for ENL — Category X teratogen (REMS program in US). Continue MDT.
Adjunctive:
- Eye care: artificial tears, eyelid taping at night for lagophthalmos, ophthalmology for corneal disease
- Peripheral nerve protection: avoid trauma, daily inspection of insensate skin, protective footwear, hand therapy
- Disability prevention — long-term focus once microbiologic cure achieved
Notifiable disease in US — report to National Hansen's Disease Program (LA) — provides free medications + specialist consultation.
5. Monitoring
Monthly clinical assessment during MDT — lesion evolution, nerve function, eye exam, dapsone-related hemolysis (Hgb), rifampin LFT check.
Bacterial Index (BI) decline on slit-skin smears (MB cases) — typically falls 1 log per year.
Long-term: peripheral nerve function + eye status for years after microbiologic cure — disability prevention. Relapse rare with adherent MDT (<1% over 10 years).
Pearls
WHO MDT regimens: PB = R-monthly + D-daily × 6 mo; MB = R-monthly + D-daily + C-monthly+daily × 12 mo. Check G6PD before dapsone. Lepra reactions (Type 1 reversal + Type 2 ENL) — don't stop MDT, add steroids ± thalidomide. Thalidomide for ENL — highly effective, REMS program (Category X). Hansen's Disease Program (Baton Rouge) provides free meds + consultation for US cases. Notifiable. Armadillo exposure in southern US is the classic non-travel exposure. Disability prevention is the long-term goal — eyes, hands, feet.