Leprosy – Scaly Skin Disease

Leprosy – Scaly Skin Disease

Have you ever noticed the appearance of leprosy patients in old movies? They are usually represented wearing filthy clothes indicating a low socioeconomic status. Apart from that, they are portrayed with multiple wounds over the body with deformed limbs and faces.

Due to late diagnosis and lack of treatment options, patients often present with late stages of the disease with high morbidity in the older days. However, with recent advances in antimicrobial therapy for leprosy and better awareness and availability of medications, the morbidity of the disease has been minimized to a great extent!

History

The origin of the term leprosy was from the Latin word lepra, which means scaly. People once considered a disease as the curse of God. Olden time’s leprosy patients were treated as sinners. Leprosy patients were treated in leprosy colonies, isolated from society. In fact, the cover image of this article shows a part of one such leprosy colony on the island of Spinalonga, Greece. There was a time when these diseased people were asked to carry a bell to identify their presence. They used arsenic, creosote, and mercury to treat leprosy. How ridiculous, isn’t it? 

Causative Agent

Leprosy is a granulomatous bacterial disease caused by Mycobacterium leprae and Mycobacterium lepromatosis.

In 1873 G H Armauer Hansen discovered Mycobacterium leprae. As an honor to the scientist, leprosy is also called Hansen’s disease (HD).

Mode Of Transmission

The exact mechanism of transmission is still hidden. Even though classically we explain the transmission by,

  • Droplet Infection: The presence of bacteria is more on the nasal mucosa. Because of this, the nasal discharge may also contain plenty of causative organisms. When the diseased person sneezes, the aerosols become contaminated, and by inhaling this, a healthy person may get leprosy.
  • Contact Transmission: Close contact with the diseased person either by direct or indirect (e.g., contact with soil and fomites such as contaminated clothes and linen) method can lead to lepra infection.
  • Other Routes: Infection can also spread by insect vectors, by contaminated needles, etc.

Risk Factors

  • Low socioeconomic status(people living in areas with polluted water)
  • Poor diet
  • Immunity compromised persons (HIV, organ transplanted persons, etc.)

A Patient with Leprosy

It is a skin disease. So by appearance itself, it is easy to guess the disease clinically. 

  • Hypopigmented patches, skin lesions
  • Partial or complete loss of cutaneous sensation
  • Presence of thickened nerves

These are the clinical features of a leprosy patient. Other than this, you may also hear something like, in leprosy persons, the body parts will fall off. It’s nothing but another misconception about leprosy.  

Other than these clinical symptoms, leprosy patients also show deformities. It can also be considered as a symptom of leprosy.

Face: Mask face, leonine facies, sagging face, lagophthalmos, loss of eyebrows (superciliary madarosis) and eyelashes (ciliary madarosis), corneal ulcers, and opacities, perforated nose, depressed nose, ear deformities, e.g., nodules on the ear and elongated lobules.

Hands: Claw hand, wrist-drop, ulcers, absorption of digits, thumb-web contracture, hollowing of the interosseous spaces, and swollen hand.

Feet: Plantar ulcers, foot-drop, inversion of the foot, clawing of the toes, absorption of the toes, collapsed foot, swollen foot, and callosities.

Types

Based on the appearance of the skin lesions, leprosy is classified into three.

  1. Tuberculoid leprosy: one or two well-defined lesions which may be flat or raised, hypopigmented, or erythematous, and these are painless lesions.
  2. Borderline leprosy: more lesions which may be flat or raised well or ill-defined, hypopigmented or erythematous, and show sensory impairment or loss.
  3. Lepromatous leprosy: diffuse infiltration or numerous flat or raised, poorly defined, shiny, smooth, symmetrically distributed lesions.

For easy assessment, and treatment leprosy is broadly classified into two.

  1. Paucibacillary leprosy (1 - 5 skin lesions)
  2. Multibacillary leprosy (more than six skin lesions)

Confirming Your Suspicion

We can only guess by seeing the lesions that it can be leprosy. But the skin lesions may also mimic psoriasis, syphilis lesions. To confirm whether it is leprosy or not, we will do certain lab investigations.

Bacteriological Examination: We will collect skin smears, nasal smears/ swabs, and nasal scrapings. And by the acid fasting method, we will try to detect the presence of acid-fast bacilli (M. Leprae).

Foot Pad Culture: This is done to distinguish between M. leprae and other acid-fast bacilli. We will inoculate the collected samples and see the colony formation of bacteria.

Histamine Test: For detecting early-stage peripheral nerve damage.

Immunological Tests
These are done to distinguish immunological effects towards lepra infection:

  1. Lepromin test: inject 0.1 ml of lepromin intradermally into the inner aspect of the forearm of the individual. And the reactions are noted. It is not a diagnostic test. In the first six months of life, most children are lepromin negative.
  2. FLA-ABS test (Fluorescent Leprosy Antibody Absorption Test): widely used for identification of subclinical infection
  3. Detection of monoclonal antibodies against M.leprae

Differential diagnosis

  • Sarcoidosis
  • Leishmaniasis
  • Lupus vulgaris
  • Dermatofibroma,
  • Histiocytoma,
  • Lymphoma
  • Syphilis
  • Yaws
  • Granuloma annulare,

Treatment

Early detection and treatment are important to prevent the progression of the disease. We will use antileprotic drugs for the treatment of leprosy. It can be used individually or in a combined form. To prevent the development of antibiotic-resistant bacteria and to prevent the adverse effect, multi-drug therapy is more preferred over individual use of drugs.

For multibacillary leprosy we use,

  • Rifampicin: 600 mg, once monthly, given under the supervision
  • Dapsone: 100 mg daily, self-administered
  • Clofazimine: 300 mg once monthly supervised; and 50 mg daily, self-administered

For treating paucibacillary, we can use,

  • Rifampicin: 600 mg once a month, supervised
  • Dapsone: 100 mg (1-2 mg/kg of bodyweight) daily, self-administered

 Rehabilitation is also an integral part of leprosy control.

Prevention

To prevent and control the disease, health programs (The National Leprosy Eradication Programme) play an important role. BCG vaccination at birth is effective in preventing leprosy. Chemoprophylaxis with dapsone reduces the incidence of tuberculoid leprosy.

Reference:

  1. Harrison’s Principles of Internal Medicine 20th edition; Page no:1259 - 1266
  2. Park’s Textbook of Preventive and Social Medicine 23rd edition; Page no: 314 - 329
  3. K D Tripathi essentials of medical pharmacology 7th edition; Page no: 780 - 786
  4. Ananthanarayan & Paniker’s microbiology Textbook 7th edition; page no; 370-376

Author’s Footnotes

Feel free to click on the references for a more in-depth reading if you so desire.

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