Leprosy/Hansen's disease

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. It primarily affects the skin, peripheral nerves, and mucosal surfaces of the upper respiratory tract.

• Neurological Symptoms: Patients often report localized areas of numbness or tingling (paresthesia). A classic history involves a patient burning or injuring themselves without feeling pain.

• Skin Changes: They may notice skin patches that are "different"—either lighter in color or reddish—that do not itch or hurt.

• Motor Weakness: Some may report gradual weakness in the hands or feet, leading to difficulty with fine motor tasks or frequent tripping (foot drop).

• Exposure History: A history of prolonged, close contact with someone with untreated leprosy or travel/residency in endemic areas (e.g., parts of Southeast Asia, Africa, or Brazil) is a major clue.

• Timeline: Symptoms develop very slowly, often appearing 5 to 20 years after the initial exposure.

Diagnosis relies on the "Cardinal Signs" established by the WHO.

1. Skin Patches:

   • Appearance: Single or multiple hypopigmented (light) or reddish (erythematous) patches.

   • Sensation: Pathognomonic sign: The patches show a definite loss of sensation (anesthesia) to light touch, pain, or temperature.

2. Nerve Involvement:

   • Palpation: Look for thickened, enlarged, or tender peripheral nerves (e.g., ulnar, common peroneal, or posterior tibial nerves).

   • Deformities: Advanced nerve damage can lead to "Claw hand" (ulnar/median nerve), "Foot drop" (peroneal nerve), or Lagophthalmos (inability to close the eye due to facial nerve damage).

3. Facies Leonina (Lion-like face): In lepromatous (multibacillary) leprosy, there is diffuse skin thickening, loss of eyebrows/eyelashes (madarosis), and enlargement of the earlobes.

In 1982, the World Health Organization published a recommendation to use dapsone and rifampin for tuberculoid leprosy and in combination with clofazimine for managing the lepromatous disease. 2018 WHO guidelines now advise for uniform MDT with the recommendations for treatment from 1998 still maintained.  MDT typically extends from 6-12 months based on severity.

This entails administering three drugs: rifampin, dapsone, and clofazimine, to individuals despite the classified type.

• Tuberculoid disease: dapsone (100 mg daily) with rifampicin (600 mg daily) for 12 months

• Lepromatous disease: dapsone, rifampicin, and clofazimine (50 mg daily) for 24 months

Managing "Reactions":

• Patients may experience sudden inflammation (Type 1 or Type 2 Reactions). This does not mean the treatment is failing; it is an immune response. These often require corticosteroids to prevent rapid nerve damage

Disability Prevention:

• Education on "Self-Care": Because of the loss of sensation, patients must be taught to inspect their hands and feet daily for injuries they cannot feel.

 It's essential to educate patients on adherence to prevent relapses and monitor for side effects such as anemia or gastrointestinal discomfort. For nerve pain or inflammation, corticosteroids can provide relief, but monitoring for adverse effects is crucial. Surgical intervention might be necessary in cases of deformities or nerve compression.

Leprosy is treatable, but delayed care can result in irreversible nerve damage, leading to disability or deformity. Early MDT can prevent progression and complications, ensuring a positive prognosis. 

Darker Skin Tones – Specific Treatment Risks:

• Clofazimine Pigmentation: A common side effect of Clofazimine is a reddish-black discoloration of the skin. In darker skin tones, this can be very pronounced and cosmetically distressing. Counsel the patient that this is temporary and will fade after the medication is stopped.

• Dapsone Hypersensitivity: Be alert for "Dapsone Syndrome" (fever, rash, and jaundice), which can be life-threatening and may be mistaken for other tropical fevers.

• World Health Organization (WHO) – Leprosy Fact Sheet: https://www.who.int/news-room/fact-sheets/detail/leprosy

• DermNet NZ – Leprosy: https://dermnetnz.org/topics/leprosy

• StatPearls – Leprosy (2024 update): https://www.ncbi.nlm.nih.gov/books/NBK559307/