Leprosy

Dr. Gerrard Uy

Leprosy

• A.k.a. Hansen’s Disease• nonfatal, chronic infectious disease caused by

Mycobacterium leprae• clinical manifestations are largely confined to

the skin, peripheral nervous system, upper respiratory tract, eyes, and testes

Etiology

• Mycobacterium leprae– obligate intracellular bacillus– confined to humans, armadillos in certain locales,

and sphagnum moss– Acid fast; ideally detected in tissue sections by a

modified Fite stain– No known toxins and is well adapted to penetrate

macrophages– Known to bind to the basal lamina of Schwann

cells

Etiology

• Mycobacterium leprae– can be cultivated in mouse footpads– Grows best in cooler tissues (skin, peripheral

nerves nerves, anterior chamber of the eye, upper respiratory tract and testes)

– almost exclusively a disease of the developing world

– associated with poverty and rural residence

Transmission

• Remains uncertain• Nasal droplet infection, contact with infected

soil, and even insect vectors have been considered the prime candidates

• bedbugs and mosquitoes • Skin to skin contact is generally not considered

an important route of transmission• ~50% of leprosy patients have a history of

intimate contact with an infected person

Disease Spectrum

• Incubation period: between 2 and 40 years, although it is generally 5–7 years

• polar tuberculoid (TT) • borderline tuberculoid (BT) • mid-borderline (BB, which is rarely

encountered) • borderline lepromatous (BL) • polar lepromatous (LL)

• Tuberculoid Leprosy• symptoms confined to the

skin and peripheral nerves• consist of one or a few

hypopigmented macules or plaques • sharply demarcated and

hypesthetic, often have erythematous or raised borders, • devoid of the normal skin

organs (sweat glands and hair follicles) • dry, scaly, and anhidrotic.

• Tuberculoid Leprosy• asymmetric enlargement of

one or a few peripheral nerves• most commonly affected are

the ulnar, posterior auricular, peroneal, and posterior tibial nerves, with associated hypesthesia and myopathy• Positive Lepromin skin test

• Lepromatous Leprosy• symmetrically distributed

skin nodules , raised plaques, or diffuse dermal infiltration, which, when on the face, results in leonine facies• loss of eyebrows and

eyelashes, pendulous earlobes, and dry scaling skin, particularly on the feet• acral, distal, symmetric

peripheral neuropathy and a tendency toward symmetric nerve-trunk enlargement

• Lepromatous Leprosy• bacilli are numerous in the

skin (as many as 109/g), where they are often found in large clumps (globi), and in peripheral nerves• bacilli are plentiful in

circulating blood and in all organ systems except the lungs and the central nervous system• nerve enlargement and

damage tend to be symmetric• Negative Lepromin skin test

Complications• Extremities– primarily a consequence of neuropathy leading to

insensitivity and myopathy– affects fine touch, pain, and heat receptors but

generally spares position and vibration appreciation– ulnar nerve

• clawing of the fourth and fifth fingers• loss of sensation

– Median Nerve impair thumb opposition and grasp– loss of distal digits in leprosy is a consequence of

insensitivity, trauma, secondary infection– Plantar ulceration – most frquent complication of

leprous neuropathy

Complications • Nose– chronic nasal congestion and

epistaxis– destruction of the nasal cartilage,

with consequent saddle-nose deformity or anosmia

• Eye– lagophthalmos and corneal

insensitivity– uveitis, with consequent cataracts

and glaucoma

Complications

• Testes– mild to severe testicular dysfunction– decreased testosterone, and aspermia or

hypospermia – impotent and infertile

• Amyloidosis– Occurs as a complication of LL leprosy

• Nerve Abscesses– cellulitic appearance of the skin– affected nerve is swollen and exquisitely tender

Diagnosis

– characteristic skin lesions and skin histopathology– associated with diffuse hyperglobulinemia, which

may result in false-positive serologic tests (e.g., VDRL, RA, ANA)

Treatment

• dapsone (50–100 mg/d), clofazimine (50–100 mg/d, 100 mg three times weekly, or 300 mg monthly), and rifampin (600 mg daily or monthly)

Prevention and Control

• Vaccination at birth with bacille Calmette-Guérin (BCG) has proved variably effective in preventing leprosy