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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