Leprosy in United States: Symptoms, Causes & Treatment

Leprosy in United States: Symptoms, Causes & Treatment | aihealz

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How you might notice it

01Hypopigmented or reddish skin patches with sensory loss — the patient cannot feel light touch or pinprick over the lesion, a finding present in over 90% of paucibacillary cases.

02Thickened peripheral nerves palpable as firm cords, most often the ulnar nerve at the elbow, the common peroneal nerve at the fibular head, and the greater auricular nerve in the neck.

03Numbness and tingling in hands and feet, often in a glove-and-stocking distribution in advanced multibacillary disease.

04Loss of eyebrows and eyelashes (madarosis) and diffuse infiltration of facial skin (leonine facies) in lepromatous disease.

05Painless ulcers, burns, or injuries on hands and feet from undetected trauma due to sensory neuropathy.

06Foot drop, claw hand, or wrist drop from motor nerve involvement — late signs of established nerve damage.

07Nasal stuffiness, nosebleeds, and eventual collapse of the nasal bridge in lepromatous disease with mucosal involvement.

08Painful red tender skin nodules with fever, joint pain, and malaise — erythema nodosum leprosum (Type 2 reaction).

09Sudden swelling and tenderness of pre-existing skin lesions plus acute nerve pain — Type 1 reversal reaction, a neurologic emergency.

10Reduced corneal sensation and lagophthalmos (inability to fully close the eye) from facial and trigeminal nerve involvement, risking corneal ulceration.

early warning signs

•A new patch on the skin that is paler than surrounding skin and feels different to touch — typically reduced or absent sensation
•Numbness in fingers, toes, or feet without obvious cause in someone living in or from an endemic region
•A painless small burn, cut, or ulcer on the hand or foot the patient cannot remember sustaining
•Family member or close household contact with diagnosed leprosy in the past 5-10 years
•Persistent nasal stuffiness, frequent nosebleeds, or hoarseness in an adult from an endemic area

● emergency signs

•Sudden severe pain along a peripheral nerve with new motor weakness — Type 1 reaction with acute neuritis requires urgent high-dose corticosteroids to prevent permanent nerve damage
•Erythema nodosum leprosum with high fever, severe joint pain, and systemic illness — Type 2 reaction may require corticosteroids, thalidomide, or hospital admission
•Acute eye redness, pain, or visual loss in a leprosy patient — possible iritis or corneal ulcer needing urgent ophthalmology
•Severe infected ulcer or necrotic wound on an anesthetic foot — risk of osteomyelitis and amputation
•Stevens-Johnson syndrome or severe hepatitis after starting dapsone — life-threatening and requires immediate medication review

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How it’s diagnosed

diagnosis

Diagnosis is primarily clinical, anchored on the WHO three-sign rule: a definite diagnosis requires one or more of (1) a hypopigmented or reddish skin lesion with definite loss of sensation, (2) thickening or enlargement of one or more peripheral nerves with associated motor or sensory deficit, or (3) demonstration of acid-fast bacilli on slit-skin smear. Any of these signs alone is sufficient in an endemic context. Slit-skin smear is performed at 4-6 sites (earlobes, forehead, suspect lesions) by making a small superficial incision and scraping dermal tissue for Ziehl-Neelsen staining. Positive smears confirm multibacillary disease; negative smears do not exclude paucibacillary leprosy. Skin biopsy with histopathology is the reference standard, showing the characteristic perineural infiltrate, granulomas in tuberculoid forms, or foamy macrophages (Virchow cells) packed with acid-fast bacilli in lepromatous forms. PCR for M. leprae DNA has 80-95% sensitivity and is increasingly available in reference labs; it is particularly useful in pure neural leprosy where biopsy is challenging. Nerve function assessment — including monofilament testing of hands and feet, voluntary muscle testing of the small muscles of the hand and foot, and palpation of named peripheral nerves — is essential at diagnosis and serially through treatment. The Ridley-Jopling spectrum is determined by clinical features plus histology; for treatment, the WHO paucibacillary/multibacillary classification suffices. Distinguish leprosy from vitiligo (no sensory loss), tinea versicolor (positive KOH preparation), sarcoidosis (no nerve thickening), and post-inflammatory hypopigmentation (history of prior dermatitis).

Key tests

Slit-skin smear with Ziehl-Neelsen stainingDemonstrates acid-fast bacilli from dermal sites. Positive smear confirms multibacillary disease and quantifies bacillary index. Negative smear does not exclude paucibacillary leprosy.

Skin biopsy with histopathologyReference-standard test. Identifies perineural infiltration (characteristic of leprosy), granulomas in tuberculoid forms, and foamy macrophages packed with bacilli in lepromatous forms. Classifies along the Ridley-Jopling spectrum.

PCR for M. leprae DNASensitive and specific molecular confirmation, particularly valuable in pure neural leprosy without skin lesions and in paucibacillary cases with negative smears. Can also detect drug-resistance mutations.

Peripheral nerve examination with monofilament testingQuantifies sensory loss on hands and feet using Semmes-Weinstein monofilaments. Identifies subclinical nerve damage that should be monitored to prevent ulcers and disability.

Voluntary muscle testing (VMT)Grades strength of small muscles of the hand (abductor pollicis brevis, first dorsal interosseous) and foot (tibialis anterior, extensor hallucis longus). Detects early motor nerve damage that often precedes deformity.

Ophthalmologic assessmentIdentifies lagophthalmos, reduced corneal sensation, iritis, and other ocular complications. Recommended at diagnosis and annually thereafter for multibacillary disease.

Outlook

Prognosis is excellent with timely MDT. Cure rates exceed 98% in completed paucibacillary and multibacillary courses, and patients become non-infectious within days of starting rifampicin. Relapse occurs in under 1% of cases over 10 years post-treatment. Nerve damage is the major source of long-term disability; damage present at diagnosis often does not fully reverse, but early MDT and timely management of reactions prevent most new damage. WHO data show approximately 6% of patients globally present with Grade 2 (visible) disability at diagnosis — the operational marker of delayed detection. Leprosy reactions remain a challenge: Type 1 reversal reactions occur in 20-30% of multibacillary patients, often during the first year of MDT, and Type 2 ENL occurs in 20-50% of lepromatous patients, sometimes recurrently for years. Mortality directly from leprosy is rare in modern practice. Quality of life is heavily influenced by stigma, particularly in cultures with strong historical association; community-based rehabilitation programs and inclusion in mainstream healthcare have substantially reduced this over the past two decades. With sustained access to MDT and early diagnosis, WHO maintains the goal of zero new pediatric Grade 2 disability cases by 2030 as part of its global leprosy strategy.

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Causes & risk factors

known causes

Infection with Mycobacterium leprae: An acid-fast intracellular bacterium discovered by Gerhard Hansen in 1873. It has the longest doubling time of any known bacterium (12-14 days), cannot be cultured in artificial media, and grows preferentially at 30-33°C — explaining its predilection for the cooler skin, peripheral nerves, eyes, and testes.
Infection with Mycobacterium lepromatosis: A second species identified in 2008 in patients with diffuse lepromatous leprosy in Mexico and the Caribbean. Genetically distinct from M. leprae but produces an indistinguishable clinical syndrome. Responds to the same multidrug therapy.
Prolonged close contact with an untreated multibacillary case: Household contacts of a multibacillary index case have 5-10 times higher risk than the general population. Transmission is most likely via nasal mucosal shedding of the bacterium during years before treatment. Patients become non-infectious within days of starting MDT.
Genetic susceptibility (HLA-DR variants, PARK2/PACRG): Over 95% of exposed individuals never develop disease. Susceptibility is partly heritable: HLA-DR2 and HLA-DR3 variants predispose to tuberculoid forms; HLA-DQ1 to lepromatous forms. PARK2 polymorphisms also confer susceptibility, particularly in South Asian populations.
Armadillo zoonotic reservoir (US south-central states): Nine-banded armadillos are a confirmed natural reservoir of M. leprae in the southern US. About 30% of new US cases occur in patients with no foreign travel and documented armadillo exposure, particularly in Louisiana, Texas, Florida, and Mississippi.
Immune compromise and poverty: HIV co-infection, malnutrition, and overcrowding can accelerate progression to symptomatic disease. Diabetes also increases risk. Poverty is the strongest macro-level driver of incidence, primarily through density of contact and delayed diagnosis.

risk factors

Living in or originating from an endemic countryenvironmental: India, Brazil, and Indonesia together carry roughly 80% of global cases. Sub-Saharan Africa, Bangladesh, Nepal, Myanmar, and parts of the Philippines also have meaningful transmission.
Household contact with an untreated multibacillary casemodifiable: Household contacts have 5-10 times higher risk than the general population. WHO recommends single-dose rifampicin chemoprophylaxis for contacts after thorough screening.
Male sexnon-modifiable: Men have approximately twice the incidence in most endemic regions; reasons include both biological and exposure-related factors (occupation, migration patterns).
Age 5-50 yearsnon-modifiable: Most new cases present in this age range; rare under 2 years (the long incubation period accounts for this). Childhood cases indicate ongoing transmission.
Armadillo exposure (US south-central states)environmental: Nine-banded armadillos are a natural reservoir in the southern US. About 30% of US cases have no foreign travel and traceable armadillo exposure (handling, hunting, eating).
Genetic susceptibility (HLA variants)genetic: Over 95% of exposed individuals are naturally immune. Susceptibility is partly heritable: HLA-DR2, HLA-DR3, HLA-DQ1, and PARK2 polymorphisms have replicated associations.

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When to seek help

why see an infectious disease

All suspected leprosy should be evaluated by an infectious disease specialist, dermatologist, or designated leprosy clinic. In endemic countries, national leprosy programs provide free MDT and management. Pure neural leprosy, leprosy reactions, drug resistance, and ocular involvement require specialist input. Disability-prevention programs benefit from physiotherapist and ophthalmologist involvement throughout treatment and the first 2 years afterward.

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01Permanent peripheral nerve damage with sensory loss, motor weakness, and deformity — preventable with early MDT and prompt reaction management

02Plantar ulcers, osteomyelitis, and progressive foot deformity from undetected trauma on anesthetic feet

03Lagophthalmos, corneal ulceration, iritis, and blindness from facial and trigeminal nerve involvement

04Type 1 reversal reactions with acute neuritis — a neurologic emergency requiring corticosteroids

05Type 2 erythema nodosum leprosum with recurrent fever, joint pain, and systemic illness

06Renal involvement (secondary amyloidosis) in long-standing untreated lepromatous disease

07Stigma-related social isolation, unemployment, and depression — well-documented in endemic regions

choosing the right hospital

01Access to slit-skin smear and skin biopsy with experienced cytopathology
02WHO MDT blister-pack supply and prescribing protocols
03Trained physiotherapist or specialist nurse for nerve function assessment
04Ophthalmology referral for ocular complication management
05Linkage to national leprosy program for case reporting and contact tracing

Essential facilities

National Hansen's Disease (Leprosy) Program — Baton Rouge, Louisiana (US federal referral center)Schieffelin Institute of Health-Research and Leprosy Centre, Karigiri (India)Anandaban Leprosy Hospital, Kathmandu (Nepal) — INF-supported tertiary referralTLM (The Leprosy Mission) global network across India, Bangladesh, Nigeria, and other endemic countriesHospital for Tropical Diseases (London) for returning travelers and immigrant cases

Living with Leprosy

Timeline

Skin lesions begin to fade within 4-8 weeks of starting MDT and continue to improve over 6-12 months. Nerve function in untreated cases often improves modestly with MDT alone, but established damage may persist. Patients are no longer infectious within days of the first rifampicin dose. Type 1 reactions resolve over 12-24 weeks with prednisolone tapers; Type 2 ENL may persist or recur for years and requires individualized long-term management. Clofazimine pigmentation fades 6-12 months after stopping treatment. Disability that remains 2 years after completing MDT is typically permanent and is addressed through rehabilitation and reconstructive surgery.

Lifestyle

01Inspect hands and feet daily for cuts, blisters, and ulcers that may not be felt due to neuropathy
02Wear well-fitting protective footwear at all times; avoid walking barefoot, especially on hot surfaces
03Use heat-protective gloves and adequate cooking utensils to prevent burns to insensate hands
04Protect eyes with sunglasses and lubricating drops if corneal sensation is reduced or lagophthalmos is present
05Maintain regular physiotherapy contact during and after MDT for strength, joint range, and ulcer prevention
06Inform employers, family, and clinicians about your diagnosis and complete the full MDT course without interruption

Daily management

01Take dapsone and clofazimine daily at the same time without interruption until the full MDT course is complete
02Attend monthly clinic visits for supervised rifampicin and clofazimine doses
03Inspect anesthetic hands and feet daily; clean and dress any wound promptly even if painless
04Report any new skin lesion, nerve pain, sudden weakness, or fever during or after treatment
05Continue nerve function monitoring every 3 months during MDT and every 6 months for at least 2 years afterward

Exercise

Regular exercise is encouraged with attention to protecting insensate limbs. Swimming, cycling, and walking in protective footwear are excellent. Avoid bare-foot activities, high-impact exercises that could cause unnoticed foot injury, and prolonged gripping that may damage insensate hands. Physiotherapist-guided range-of-motion exercises preserve joint function and prevent contractures.

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Frequently asked

Is leprosy curable?

Yes. WHO multidrug therapy (MDT) cures leprosy completely — 6 months for paucibacillary and 12 months for multibacillary disease. Cure rates exceed 98% in completed courses, and patients become non-infectious within days of the first rifampicin dose. MDT is supplied free of charge by WHO globally.

Is leprosy contagious?

Leprosy is far less contagious than commonly believed. Over 95% of people are naturally immune. Transmission requires prolonged close contact (usually household-level) with an untreated multibacillary case, most likely via nasal mucosal shedding.

How is leprosy spread?

Leprosy spreads through prolonged close contact with an untreated multibacillary case, primarily via nasal droplets shed in the months to years before diagnosis. Household contacts have 5-10 times higher risk than the general population.

What does leprosy look like?

Early leprosy typically presents as one or a few pale or reddish patches on the skin with reduced or absent sensation when tested with light touch. Advanced multibacillary leprosy may show numerous symmetric lesions, eyebrow loss, nasal congestion, and thickened palpable peripheral nerves.

How is leprosy diagnosed?

Diagnosis is clinical, based on WHO criteria: a hypopigmented skin lesion with sensory loss, a thickened peripheral nerve with deficit, or acid-fast bacilli on slit-skin smear. Skin biopsy and PCR confirm the diagnosis. In endemic regions, trained leprosy workers can often diagnose at first visit.

What is multidrug therapy (MDT)?

Multidrug therapy is the WHO standard regimen for leprosy: rifampicin once monthly, clofazimine daily plus a monthly larger dose, and dapsone daily. Paucibacillary leprosy is treated for 6 months; multibacillary leprosy for 12 months.

How long does leprosy treatment take?

Paucibacillary leprosy (1-5 lesions, smear-negative) is treated for 6 months. Multibacillary leprosy (6 or more lesions or smear-positive) is treated for 12 months.

Does leprosy cause deformity?

Untreated leprosy can damage peripheral nerves, leading to sensory loss, muscle weakness, and deformity (claw hand, foot drop, facial paralysis). With early MDT, most cases avoid permanent deformity.

Where is leprosy most common?

WHO documented approximately 180,000 new cases globally in 2023. India, Brazil, and Indonesia together account for roughly 80% of new cases. Other notable endemic countries include Bangladesh, Nepal, Myanmar, the Philippines, Ethiopia, the Democratic Republic of the Congo, and Madagascar.

Can leprosy occur in the United States?

Yes. About 150-200 new cases are reported annually in the US, roughly 30% in patients with no foreign travel — most often linked to armadillo exposure in Louisiana, Texas, Florida, and Mississippi. The National Hansen's Disease Program in Baton Rouge provides free treatment and consultation.

What are leprosy reactions?

Leprosy reactions are sudden inflammatory episodes during or after MDT, caused by immune response to the bacteria. Type 1 (reversal) reactions inflame existing skin lesions and nerves, risking permanent damage; Type 2 (erythema nodosum leprosum) causes painful tender nodules with fever.

Can children get leprosy?

Yes. Approximately 7% of new cases globally in 2023 were in children under 15 — an indicator of ongoing community transmission. Children typically present with paucibacillary disease. WHO weight-adjusts MDT doses for pediatric patients.

Is BCG vaccine effective against leprosy?

BCG vaccination provides partial protection against leprosy — roughly 50-60% efficacy in pooled studies, though it varies by region. BCG is routinely given to infants in most endemic countries primarily for tuberculosis protection. Boosting BCG in adolescence may extend leprosy protection.

What is single-dose rifampicin prophylaxis?

Single-dose rifampicin (SDR-PEP) is WHO-recommended chemoprophylaxis for household and close contacts of newly diagnosed cases. A single 600 mg dose (weight-adjusted in children) reduces contact leprosy incidence by approximately 60% over 2 years.

Why does leprosy affect cooler body parts?

Mycobacterium leprae grows preferentially at 30-33°C, well below body core temperature. It therefore localizes in the cooler skin, peripheral nerves, eyes, upper airway, and testes. The face, hands, and feet — typically a few degrees cooler than the core — are the most commonly affected sites.

Can leprosy be passed from mother to baby?

Vertical transmission is rare. Most children born to mothers with leprosy are healthy, especially when the mother is on MDT during pregnancy. MDT (rifampicin, clofazimine, dapsone) is considered safe in pregnancy.

Why does my skin turn red on clofazimine?

Clofazimine, a component of MDT, accumulates in skin and causes reddish-brown pigmentation, particularly in lesional skin. This is harmless and reversible — the pigmentation fades over 6-12 months after completing treatment.

Will I always be at risk of relapse?

Relapse after completed MDT is rare — under 1% over 10 years in WHO surveillance. Nerve function should be monitored every 6 months for at least 2 years after treatment because delayed reactions can occur. Any new skin lesion, sensory change, or nerve thickening should be reported promptly.

Is leprosy mentioned in religious texts the same as Hansen disease?

Biblical 'leprosy' (Hebrew tzaraat, Greek lepra) referred to a range of skin conditions, most of which were not actual Hansen disease. Modern Hansen disease is a specific bacterial infection identified by Gerhard Hansen in 1873.

How much does leprosy treatment cost?

MDT is provided free of charge by WHO worldwide through national leprosy programs. In the US, the National Hansen's Disease Program treats patients without cost regardless of insurance status.

Leprosy.Care & specialists in United States

What it is

How you might notice it

How it’s diagnosed

Treatment & cost

Causes & risk factors

Living with it

When to seek help

Related conditions

Easily confused with

Often appears alongside

Types and stages

Living with Leprosy

Patient support resources

Frequently asked

Sources & references

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