DR9.1-6 | Leprosy — Glossary

A bacillus whose mycolic-acid-rich cell wall retains carbol fuchsin and resists acid-alcohol decolourisation, appearing red on Ziehl-Neelsen staining; M. leprae is acid-fast but less strongly so than M. tuberculosis.

Programmatic searching for hidden leprosy cases (e.g., through campaigns and surveys) so that treatment can begin before disability develops.

Sudden painful inflammation of a peripheral nerve during a lepra reaction, with rapid loss of sensory or motor function; a medical emergency requiring urgent corticosteroids to recover nerve function.

A 0-6 logarithmic (Ridley) scale quantifying the density of acid-fast bacilli in slit-skin smears; high at the lepromatous pole, zero at the tuberculoid pole.

The highest Bacteriological Index step: more than 1000 bacilli per oil-immersion field, often in clumps called globi; characteristic of lepromatous leprosy.

The immunologically unstable middle of the spectrum (BT, BB, BL); most prone to Type 1 (reversal) lepra reactions; BB is the least stable point.

The three WHO diagnostic signs, any ONE of which establishes leprosy: a hypopigmented/reddish anaesthetic skin patch, a thickened peripheral nerve, or a positive slit-skin smear.

Hyperextension at the metacarpophalangeal joints with flexion at the interphalangeal joints from intrinsic muscle paralysis; ulnar nerve damage claws the ring and little fingers.

A bacteriostatic and anti-inflammatory antileprosy drug; deposits in skin causing reversible reddish-brown to black pigmentation; given at 50 mg/day plus 300 mg monthly in MB-MDT.

Used at 300 mg/day for the anti-inflammatory treatment of ENL (distinct from the 50 mg/day multidrug-therapy dose), usually for one to three months then tapered; long-term low doses reduce recurrent ENL.

Palpated at the neck of the fibula; its damage causes foot drop (loss of dorsiflexion) and a high-stepping gait.

Identifying and examining household and close contacts of a leprosy patient to detect early disease and offer prophylaxis.

The rule that multidrug therapy is never stopped during a lepra reaction, because the reaction is an immunological event and not a sign of antibiotic failure.

A bacteriostatic antileprosy drug (folate-pathway antagonist) taken daily; can cause haemolysis (especially in G6PD deficiency), methaemoglobinaemia, and the dapsone hypersensitivity syndrome.

A potentially fatal drug reaction usually appearing 4-6 weeks into treatment with fever, exfoliative/morbilliform rash, lymphadenopathy, and hepatitis; requires immediate cessation of dapsone.

Tissue fluid and cells scraped from the dermis during a slit-skin smear; the target specimen, deliberately kept free of blood, where intracellular M. leprae reside in macrophages.

Disability Prevention and Medical Rehabilitation — the NLEP component providing protective footwear, self-care training, physiotherapy, and reconstructive surgery for patients with nerve damage.

The WHO operational target of a registered prevalence below 1 case per 10,000 population; achieved by India nationally in 2005 but not at every sub-district level.

The cutaneous hallmark of a Type 2 reaction: crops of tender erythematous subcutaneous nodules, typically with fever and multi-organ involvement, in lepromatous-end patients.

A modified acid-fast stain with gentler decolourisation, preferred for tissue (biopsy) sections in leprosy because M. leprae is weakly acid-fast and can be lost with standard ZN decolourisation.

Inability to dorsiflex the foot due to common peroneal nerve damage, producing a high-stepping (steppage) gait and predisposing to injury.

Clumps of acid-fast bacilli packed within foamy macrophages, seen in heavily bacillated (lepromatous) smears and corresponding to a high Bacteriological Index.

Visible deformity or damage (lagophthalmos/corneal damage, claw hand, trophic ulcer, digit resorption, foot drop); its frequency at diagnosis is an NLEP indicator of delayed detection.

Visible deformity or damage at diagnosis; the proportion of new patients with Grade 2 disability is an NLEP indicator of how early cases are being detected.

A superficial nerve crossing the sternocleidomastoid in the posterior triangle of the neck; frequently visibly or palpably enlarged in leprosy.

An early, not-yet-classifiable lesion — a single ill-defined hypopigmented macule with minimal sensory change and nonspecific histology — that may heal or evolve to a determinate type; stands apart from the Ridley-Jopling spectrum.

Inability to fully close the eye due to facial (zygomatic branch) nerve involvement, risking corneal exposure; counts as Grade 2 disability for the eye.

The lion-like facial appearance of advanced lepromatous leprosy caused by diffuse infiltration, nodules, and thickened skin.

An acute immunological episode interrupting the chronic course of leprosy; the main cause of nerve damage and disability; classed as Type 1 (reversal) or Type 2 (erythema nodosum leprosum).

The low/absent-immunity, multibacillary pole of the spectrum: numerous symmetrical infiltrated lesions, very high bacillary load, negative lepromin test, foamy (Virchow) macrophages on histology.

A skin test measuring cell-mediated immunity to M. leprae; strongly positive at the tuberculoid pole and negative at the lepromatous pole; a classification/prognostic aid, NOT a diagnostic test.

Loss of the eyebrows (and sometimes eyelashes), seen in advanced lepromatous leprosy due to dermal infiltration.

The multibacillary regimen: rifampicin 600 mg monthly (supervised) + clofazimine 300 mg monthly (supervised) and 50 mg daily + dapsone 100 mg daily, for 12 months.

Custom protective footwear with a soft, pressure-redistributing sole prescribed for the insensate or deformed leprosy foot to prevent and heal plantar ulcers.

The percentage of solid-staining (uniformly stained, intact) bacilli out of the total counted, estimating the proportion of viable organisms; falls early with effective treatment; technically demanding and now used less than the BI.

The 0-5 motor scale: 0 = no contraction, 1 = flicker, 2 = movement with gravity eliminated, 3 = movement against gravity, 4 = movement against some resistance, 5 = normal.

WHO operational class defined by more than 5 lesions OR a positive slit-skin smear at any site; treated with rifampicin + dapsone + clofazimine for 12 months.

WHO operational class defined as more than 5 skin lesions OR a positive slit-skin smear at any site; treated with rifampicin + dapsone + clofazimine for 12 months.

The standard combination treatment for leprosy using rifampicin, dapsone, and (in multibacillary disease) clofazimine; combining drugs prevents resistance and cures the infection.

The obligate intracellular acid-fast bacillus that causes leprosy; cannot be cultured on artificial media, multiplies slowly, prefers cooler tissues, and has a tropism for Schwann cells of peripheral nerves.

Surgical release of an entrapped or swollen nerve, considered in selected cases of severe reaction neuritis that does not respond to corticosteroids.

New loss of sensory or motor function in the territory of a named peripheral nerve, occurring during treatment or within a defined period after release from treatment; recent-onset NFI is an indication for urgent corticosteroids.

Rolling each cardinal peripheral nerve against underlying bone to assess thickening, consistency, and tenderness, always comparing with the opposite side.

National Leprosy Eradication Programme — India's integrated national programme providing free multidrug therapy and pursuing elimination, defined as a prevalence of fewer than 1 case per 10,000 population.

Removing mechanical pressure from a plantar ulcer (by rest, total-contact casting, or protective footwear) to allow it to heal; the cornerstone of plantar ulcer management.

High-magnification (100x objective with immersion oil) light microscopy required to visualise and count acid-fast bacilli on stained slit-skin smears.

WHO operational class defined by 5 or fewer lesions AND a negative smear; expected to remain smear-negative; treated with rifampicin + dapsone for 6 months.

WHO operational class defined as 5 or fewer skin lesions AND a negative slit-skin smear; treated with rifampicin + dapsone for 6 months.

The paucibacillary regimen: rifampicin 600 mg once monthly (supervised) plus dapsone 100 mg daily, for 6 months; contains no clofazimine.

A painless ulcer on the anaesthetic sole resulting from posterior tibial nerve damage and unfelt repetitive pressure or injury; the commonest disabling foot complication of leprosy.

Palpated behind the medial malleolus; its damage causes loss of protective sensation on the sole (predisposing to plantar ulcers) and clawing of the toes.

The corticosteroid mainstay for both reaction types and the urgent treatment for acute neuritis; for Type 1 typically started at ~40 mg/day and tapered over roughly 12 weeks.

A sensory nerve palpated over the lateral aspect of the wrist; supplies sensation to the dorsal web space of the thumb.

Precipitants of lepra reactions including initiation of multidrug therapy, pregnancy and the puerperium, intercurrent infection, stress, surgery, and vaccination.

Repeated episodes of erythema nodosum leprosum over months to years, often requiring long-term low-dose clofazimine (or steroid-sparing strategies) to reduce frequency.

Return of active disease after completion of and release from treatment; on smears it is signalled by a rising Bacteriological Index on serial examination.

Discharge of a patient on completion of the prescribed multidrug-therapy course; subsequent surveillance smears watch for a rising BI that would indicate relapse.

Another name for the Type 1 reaction, reflecting an upgrading shift of cell-mediated immunity toward the tuberculoid pole that drives acute inflammation of lesions and nerves.

An immunological and histological spectrum grading leprosy by cell-mediated immunity: TT → BT → BB → BL → LL, with Indeterminate as an early off-spectrum lesion.

The key bactericidal antileprosy drug; inhibits bacterial RNA polymerase, killing >99.9% of bacilli in a few doses; a hepatic enzyme inducer causing orange secretions and drug interactions; given monthly under supervision.

A depressed nasal bridge caused by destruction of the nasal cartilage and septum from mucosal infiltration in advanced lepromatous leprosy.

The daily routine by which patients inspect, protect, and care for insensate hands, feet, and eyes to prevent injuries and ulcers they can no longer feel forming.

A calibrated nylon filament used to test protective sensation; the 10 g (and 2 g) monofilaments are standard for assessing the leprosy patient's sole and hand.

Mapping skin lesions and nerve territories using graded stimuli in the order temperature, light touch (cotton/monofilament), then pinprick, with the patient's eyes closed.

Nerve function loss during a reaction without overt pain or visible inflammation; still requires corticosteroid treatment and is detected only by routine nerve-function testing.

Nerve function impairment occurring without pain or visible skin inflammation, common in borderline leprosy; detectable only by routine active testing of sensation and power against a documented baseline.

A single dose of rifampicin offered to eligible contacts of a leprosy patient to reduce their risk of developing the disease.

A bedside test that samples dermal pulp from standard sites to demonstrate Mycobacterium leprae by acid-fast staining; used to classify leprosy, set a baseline bacterial load, monitor treatment, and detect relapse.

Uniformly and intactly stained bacilli taken to be viable; in contrast, dead bacilli stain irregularly, fragmented, or beaded — the basis of the Morphological Index.

The conventional sampling sites for a slit-skin smear: both ear lobes (almost always involved in multibacillary disease) plus at least one active skin lesion, for a minimum of about three sites.

The social rejection, discrimination, and internalised shame attached to leprosy, driven by myths of curse, contagion, and heredity; a major cause of late presentation, isolation, and treatment default that counselling must address directly.

The monthly component of MDT (rifampicin, and clofazimine 300 mg in MB) taken in front of a health worker to ensure adherence, as distinct from the daily self-administered doses.

A surgical procedure partially joining the eyelids to protect the cornea in lagophthalmos when conservative measures are insufficient.

Reconstructive surgery that re-routes a functioning tendon to restore movement lost to nerve damage, used to correct established claw hand or foot drop.

The most effective drug for severe or recurrent ENL (~100-300 mg/day), but an ABSOLUTE teratogen contraindicated in all women of childbearing potential; reserved for men and post-menopausal women.

The absolute prohibition of thalidomide in any woman who could become pregnant, because it causes severe limb-reduction birth defects (phocomelia).

The high-immunity, paucibacillary pole of the Ridley-Jopling spectrum: few well-defined anaesthetic lesions, negative smear, strongly positive lepromin test, epithelioid granulomas on histology.

A T-cell-mediated (Type IV, delayed) hypersensitivity reaction in borderline leprosy (BT, BB, BL), causing inflammation of existing lesions and acute neuritis; treated with corticosteroids.

An immune-complex-mediated (Type III) reaction in lepromatous leprosy (BL, LL), causing crops of new tender nodules with systemic features; treated with corticosteroids plus clofazimine or thalidomide.

Immune-complex-mediated hypersensitivity in which antigen-antibody complexes deposit in tissues, activate complement, and recruit neutrophils; the mechanism of Type 2 (ENL) reactions.

Delayed-type, T-cell-mediated hypersensitivity in which sensitised T cells drive macrophage activation and granulomatous inflammation over days; the mechanism of the Type 1 reversal reaction.

The most commonly affected nerve in leprosy; palpated behind the medial epicondyle of the elbow; its damage causes clawing of the ring and little fingers and wasting of the intrinsic hand muscles.

Grading the power of key muscles supplied by affected nerves on the Medical Research Council 0-5 scale to detect and monitor motor nerve function impairment.

A 0-1-2 scale applied separately to each eye, hand, and foot: Grade 0 = no anaesthesia or deformity; Grade 1 = anaesthesia only; Grade 2 = visible deformity or damage.

A practical two-group system used only to choose the MDT regimen: paucibacillary (PB) vs multibacillary (MB); separate from the Ridley-Jopling spectrum.

The standard acid-fast staining method for slit-skin smears: carbol fuchsin, acid-alcohol decolouriser, methylene blue counterstain; bacilli appear red against a blue background.