[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Leprosy (Hansen disease)

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# Leprosy (Hansen disease)

Leprosy is a curable bacterial infection of skin and nerves; early treatment prevents numb hands and feet, injuries and disability.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Ulnar nerve](https://durgical.com/en/anatomy/ulnar-nerve/)
- [Common fibular nerve](https://durgical.com/en/anatomy/common-fibular-nerve/)
- [Skin](https://durgical.com/en/anatomy/skin/)
- [Median nerve](https://durgical.com/en/anatomy/median-nerve/)
- [Radial nerve](https://durgical.com/en/anatomy/radial-nerve/)
- [Digital nerves](https://durgical.com/en/anatomy/palmar-digital-nerves/)
- [Tibial nerve](https://durgical.com/en/anatomy/tibial-nerve/)
- [Superficial fibular nerve](https://durgical.com/en/anatomy/superficial-fibular-nerve/)
- [Deep fibular nerve](https://durgical.com/en/anatomy/deep-fibular-nerve/)

## Microorganisms that cause it

- [Mycobacterium leprae](https://durgical.com/en/microbiology/mycobacterium-leprae/)

## Why it happens

- [Granulomatous inflammation: caseating vs non-caseating, the causes to know](https://durgical.com/en/general-pathology/granulomatous-inflammation-caseating-vs-non-caseating-the-causes-to-know/)
- [Special stains in diagnosis: Congo red, Prussian blue, PAS, Ziehl–Neelsen, Gram](https://durgical.com/en/general-pathology/special-stains-in-diagnosis-congo-red-prussian-blue-pas-ziehl-neelsen-gram/)
- [Innate and adaptive immunity: overview](https://durgical.com/en/physiology/innate-and-adaptive-immunity-overview/)
- [Peripheral nerve: endoneurium, perineurium, epineurium; myelin](https://durgical.com/en/histology/peripheral-nerve-endoneurium-perineurium-epineurium-myelin/)
- [Glial cells: astrocytes, oligodendrocytes, microglia, Schwann cells](https://durgical.com/en/histology/glial-cells-astrocytes-oligodendrocytes-microglia-schwann-cells/)

## What it is

A chronic infection by Mycobacterium leprae (and M. lepromatosis) that targets the skin and peripheral nerves. Its form depends on the host's cellular immunity, ranging from few, well-defined anaesthetic patches to widespread nodules. It is curable with multidrug therapy.

## Who gets it

The Americas report over a tenth of new cases worldwide, more than 90% of them in Brazil. Colombia still notifies a few hundred new cases a year, many with disability at diagnosis, and leprosy is a mandatory notifiable disease under national surveillance.

## Causes

- Mycobacterium leprae, an acid-fast bacillus that cannot be cultured and grows best in cooler body parts
- Spread by respiratory droplets from untreated patients during prolonged close contact
- Armadillos are a natural reservoir in the Americas

## Risk factors

- Household contact with an untreated multibacillary patient
- Living in endemic areas with poverty and crowding
- Genetic susceptibility
- Contact with armadillos

## Pathophysiology

The bacillus multiplies very slowly (incubation of years) and invades Schwann cells of peripheral nerves, especially where nerves lie superficially and are cool. In tuberculoid disease a strong Th1 response forms granulomas, with few bacilli but early nerve damage. In lepromatous disease a weak cellular response allows huge numbers of bacilli in skin, nasal mucosa and nerves. Immune reactions (type 1 reversal reaction, type 2 erythema nodosum leprosum) can occur before, during or after treatment and rapidly damage nerves. Loss of sensation leads to unnoticed injuries, ulcers and deformity.

## Classification

- Ridley-Jopling spectrum: tuberculoid, borderline (BT, BB, BL), lepromatous
- WHO treatment classification: paucibacillary (1–5 skin lesions) or multibacillary (more than 5 lesions, nerve involvement or positive smear)
- Leprosy reactions: type 1 (reversal) and type 2 (erythema nodosum leprosum)

## Symptoms and signs

- Hypopigmented or reddish skin patches with loss of sensation to touch, pain and temperature
- Thickened, sometimes tender peripheral nerves (ulnar, common fibular, great auricular)
- Numbness and weakness of hands and feet: claw hand, foot drop
- Nodules, thickened skin of the face ("leonine facies"), loss of eyebrows, nasal congestion in lepromatous disease
- Painless injuries, burns and plantar ulcers
- Eye dryness and inability to close the [eyelids](https://durgical.com/en/anatomy/superior-tarsus/)

## Red flags

- Painful nerves, new weakness or new loss of sensation (reaction with acute neuritis)
- Painful red nodules with fever (erythema nodosum leprosum)
- Red, painful eye or loss of vision
- Infected plantar ulcer

## Diagnosis

**Clinical**
WHO cardinal signs: a [skin](https://durgical.com/en/anatomy/skin/) patch with definite loss of sensation, a thickened peripheral nerve with loss of sensation or weakness, or acid-fast bacilli in a slit-skin smear. A careful sensory and motor exam of the hands, feet and eyes grades disability.

**Tests**
Slit-skin smear for acid-fast bacilli (bacterial index); skin biopsy with histopathology; PCR in difficult cases. Lepromin test is not diagnostic. Screen household contacts.

**Imaging**
Not routine; nerve ultrasound can show thickening; X-rays of hands and feet for bone resorption and osteomyelitis.

## Differential diagnosis

- Vitiligo and pityriasis versicolor (no loss of sensation)
- Cutaneous leishmaniasis
- Diabetic and other peripheral neuropathies
- Cubital tunnel syndrome and other entrapment neuropathies
- Sarcoidosis, cutaneous tuberculosis and fungal infections

## Goal of treatment

Cure the infection and stop transmission early, prevent and treat reactions to save nerve function, and prevent disability through self-care and rehabilitation.

## Treatment

**Medical**
WHO multidrug therapy free of charge: rifampicin, dapsone and clofazimine for 6 months (paucibacillary) or 12 months (multibacillary).

**Medical**
Leprosy reactions: corticosteroids for neuritis and reversal reactions; clofazimine or thalidomide (strictly avoided in pregnancy) for erythema nodosum leprosum.

**Follow-up**
Regular nerve function tests to detect silent neuritis; contact examination and single-dose rifampicin prophylaxis for contacts; notification to public health.

**Rehabilitation**
Daily self-care of insensitive hands, feet and eyes, protective footwear, physiotherapy and occupational therapy; stigma-reduction counselling.

**Surgical**
Reconstructive tendon transfers, ulcer care and, in selected cases, nerve decompression.

## Drugs for this condition

- [Rifampicin](https://durgical.com/en/pharmacology/rifampicin/)
- [Dapsone](https://durgical.com/en/pharmacology/dapsone/)
- [Clofazimine](https://durgical.com/en/pharmacology/clofazimine/)

## Complications

- Permanent nerve damage with claw hand, foot drop and lagophthalmos
- Plantar ulcers, infections, bone loss and resorption of fingers and toes
- Blindness from corneal exposure or uveitis
- Nasal collapse and testicular atrophy in lepromatous disease
- Stigma, social exclusion and loss of work

## Prognosis

Multidrug therapy cures the infection and patients stop being infectious soon after starting it; nerve damage already present is often permanent, so early diagnosis is what prevents disability.

## Prevention

- Early diagnosis and complete treatment of cases
- Contact tracing with single-dose rifampicin prophylaxis
- BCG vaccination gives some protection

## Test yourself

Think of the answer, then tap the question to see it.

## What are the WHO cardinal signs of leprosy?

A skin patch with loss of sensation, a thickened peripheral nerve with sensory or motor loss, or acid-fast bacilli on slit-skin smear.

## Which cells does M. leprae invade in nerves?

Schwann cells.

## Which drugs make up WHO multidrug therapy?

Rifampicin, dapsone and clofazimine.

## What distinguishes paucibacillary from multibacillary leprosy for treatment?

Paucibacillary has 1–5 skin lesions without nerve involvement and negative smears; more lesions, nerve involvement or a positive smear means multibacillary.

## What is the nursing priority for insensitive hands and feet?

Daily inspection and protection (self-care, proper footwear) to prevent unnoticed injuries and ulcers.

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## Related conditions

- [Peripheral neuropathy (diabetic and other)](https://durgical.com/en/conditions/peripheral-neuropathy/)
- [Cubital tunnel syndrome (ulnar neuropathy at the elbow)](https://durgical.com/en/conditions/cubital-tunnel-syndrome/)
- [Diabetic foot](https://durgical.com/en/conditions/diabetic-foot/)
- [Leishmaniasis](https://durgical.com/en/conditions/leishmaniasis/)
- [Vitiligo](https://durgical.com/en/conditions/vitiligo/)
- [Erythema nodosum](https://durgical.com/en/conditions/erythema-nodosum/)
- [Uveitis](https://durgical.com/en/conditions/uveitis/)
- [Tuberculosis](https://durgical.com/en/conditions/tuberculosis/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Leprosy](https://www.who.int/news-room/fact-sheets/detail/leprosy) (World Health Organization, 2025); [Leprosy (Hansen disease) - PAHO/WHO | Pan American Health Organization](https://www.paho.org/en/topics/leprosy) (Pan American Health Organization, 2025); [Leprosy: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/001347.htm) (MedlinePlus (U.S. National Library of Medicine), 2024).

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Source: https://durgical.com/en/conditions/leprosy/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/leprosy/