CHAPTER 8

Leprosy is a chronic systemic bacterial infection caused by mycobacterium leprae .

Predisposing factors

• Children are highly susceptible to infection .

• Malnutrition

• Poor hygiene

• Inadequate housing

• Low standard of living and education .

Modes of Infections

1. Direct contact with the infected individuals.

2. Person to person infection.

3. Contact with infected ulcerating lesions .

4. Secretions of infected mucous membranes.

5. Insects such as cockroaches , bed bugs and skin parasites .

Clinical types

• Lepromatous leprosy

• Tuberculoid leprosy

• Borderline leprosy

LEPROMATOUS LEPROSY

The diagnosis of leprosy is vague until the diagnostic skin lesions begin to appear or after the characteristic features become manifested .

Prodromal manifestations

The secondary lesion begins by non-specific manifestations such as fever , muscle pain and numbness .

Skin manifestations:

Skin lesions are macules followed later by anesthesia , paralysis and trophic changes . This type is contagious where the bacilli are abundant in the nodules and secretions of the infected mucous membranes .

The early skin manifestation is usually a solitary hypo-pigmented macule that enlarges gradually mainly on the cheeks , upper arms , buttocks and thighs.

Sensory manifestations

The earliest manifestations are sensory manifestations. Numbness and inability to differentiate cold and heat sensations .

The lepromin test is negative .

Clinical types of lepromatous leprosy

1. Macular type :
   The lesions are:

• Diffuse, ill-defined, shiny, greasy macules .

• Symmetrically distributed.

• Sensory sensations are not changed .

• Skin over the macules is almost normal .

• Hair changes: progressive hair fall of the eyebrows, or eyelashes. Scalp hair is not affected .

2. Lepromatous infiltration
   The skin lesions may be diffuse, plaque or nodular.

3. Diffuse type
   Diffuse lepromas are shiny, waxy infiltrating nodules with an erythematous, cyanotic surface due to fusion of the macules. The main areas involved are the face, mainly the forehead. The infiltrate is ill-defined nodules slightly anesthetic and devoid of hair mainly on the supra-orbital area, forehead, face, ears, hands and buttocks.
   Hair changes are loss of the eyebrow hair.
   Disfiguration giving the leonine appearance (lion faces ).

   Course of the infiltrate:

   May involute spontaneously.
   Increases in size forming large plaques .
   Diffuse leprosy of Lucio : is uncommon type of the diffuse leprosy . The lesions show multiple necrosis and ulceration that heal by extensive scarring.

4. Ulcerating type :
   The ulcer is indolent, covered by seropurulent exudate and characteristically heals with scarring, causing destruction and deformities of the affected areas.

5. Lichen leprosus
   This type has a very chronic course. The lesions become stable without changes for a long time .
   Skin lesion is yellowish, small, follicular hard papules with sharp boundaries giving the "goose skin" appearance .

6. Neural involvement
   All patients with lepromatous leprosy manifest with varying degree of nerve involvement such as anesthesia, nerve enlargement, trophic changes muscular atrophy, paralysis and wasting .

Sensory changes

• Inability to differentiate heat from cold sensations . These may be the first signs of the lepromatous leprosy .

• Touch sensation impairment .

• Anesthesia .

• Loss of pain sensation.

• Numbness, burning and tingling sensation of the affected parts of the feet, hands, legs and the back .

• Trophic ulcers of the feet .

7. Eye manifestations of lepromatous leprosy

• Corneal erosions

• Keratitis

• Ulcerations

• Corneal opacity forming white flecks ‘pearls‘.

• ritis and iridocyclitis .

8. Mucous membrane manifestations
   Nose : nodules and infiltration with ulceration of the nasal septum leading to saddle nose shape
   Vocal cord : hoarseness of the voice .

9. Teeth - loss of the upper incisor teeth.

10. Internal organs manifestations

Liver , spleen , bone marrow, testicles, lymph nodes and reticulo-endothelial system may be involved .

TUBERCULOID LEPROSY

This is less serious type where lepra bacilli are few or even absent in the lesions. Lepromin test is positive.

Nerve involvement is more than skin involvement causing anesthesia and thickened nerves.

Tuberculoid leprosy has usually good prognosis .

Clinical features

Childhood leprosy

The lesions appear as solitary , raised erythematous macule or a group of tiny papule surrounded by hypopigmented halo mainly on the exposed skin surface . The lesion usually passes without notice and disappears after one or two years-leaving hypopigmented thin scar .

Adulthood Leprosy

Infection erupts later on, after a very long period of quiescence until puberty.

Skin manifestations:

Skin lesion appears as large , erythematous plaque , with sharp , ill-defined and elevated border and atrophic center forming arciform , annular and circinate plaques on healing. The bacilli are less abundant than that of the lepromatous type .

The area above the skin lesions is dry ,scaly, thick , rough and has the appearance of pigskin.

Anesthesia of the lesions which are accompanied by hypopigmented, hypohidrotic maculo-anaesthetic manifestations mainly on the face and limbs.

Healing of the lesions leave scarring and pigmentary changes .

Neural manifestations:

Nerve involvement may lead to:

Nerve enlargement and thickening.

Anesthesia

Muscular paralysis , wasting and atrophy .

BORDERLINE TUBERCULOID

The lesions are the same as tuberculoid but smaller and more numerous. Lepra bacilli do not exist in this type or may be very rare. This type is usually non-contagious .

Systemic manifestations such as neural and hair involvement are minimal.

BORDERLINE LEPROSY

The lesions are few, asymmetrical and consist of vague irregular shaped plaques with ill-defined borders. Small satellite lesions may develop.

In this type the skin and nerves are the only affected . Anesthesia is usually moderate .

Clinical features

The lesions of borderline lepromatous type are sparse , which may be macular, papular, or plaques .

Absence of lepromatous features such as keratitis, ulceration and disfiguration.

Nerve involvement may occur later .

INDETERMINATE LEPROSY

Skin manifestations are macules followed later by anesthetic and trophic lesions. Plaques and nodules do not occur in this type .

Histopathology of leprosy

The infected tissues show chronic inflammatory infiltrate in a banal shape around the blood vessels, nerves, and glands of the skin with small round cells and occasionally histiocytes and fibroblasts. The histopathological changes depend on the type of leprosy.

1. Lepromatous type
   The granulomatous lesions are composed chiefly of bacillus-laden histiocytes (foam cells).
   Atrophy of the epidermis and sweat glands .
   Acid-fast bacilli are profuse in the section .
    

2. Tuberculoid leprosy
   This type shows high degree of resistence

• The follicular type: shows tuberculoid granuloma in the epidermis composed of epitheloid cells and some giant cells .

• The sarcoid variety : presents with granuloma, which is formed of epitheloid cells and lymphocytes.

3. Borderline tuberculoid
   The histological picture is mainly histiocytes with few epitheloid cells and dense lymphocytes infiltration.
   Few bacilli and some vacuolated cells may be seen in the field.
    

4. Borderline lepromatous leprosy
   Diffuse spread of epitheloid cells through the granuloma.
   Abundant lepra bacilli.
   Lymphocytes are not aggregated in zones .
   Absent giant cells .

Differential Diagnosis of Leprosy

Some authors describe leprosy as "the great imitators" that can give clinical picture simulating different skin diseases .

1. Lepromatous type:

• Lupus vulgaris

• Leishmaniasis

• Urticaria

• Mycoses fungoides

• Cystic acne

• Erythema chronicum peristans

2. Tuberculoid type

• Drug eruption

• Erythema multiforme

• Erythema nodosum

• Erythema induratum

• Tinea corporis

• Lichen planus

• Discoid lupus erythematosus

3. Borderline tuberculoid

• Pityriasis alba

• Tinea versicolor

• Seborrheic dermatitis

• Berloque dermatitis

• Pellagra

Lepromin test (Mistuda reaction )

This is an immunologic test indicating the host resistance to M. leprae .

Lepra reaction

During treatment of leprosy two reactions may occur. The cause of these reactions is related to bacterial products released by disintegration of the bacilli as a result of the bactericidal action of the sulphones or due to development of immunity.

The reaction may be :

1. Acute exacerbation of the lesions - occurs usually during the first four months of treatment showing swelling and erythema of the existing lesions.

2. Erythema nodosum leprosum - this is considered an allergic vasculitis that appears later usually after six months of beginning the treatment .

Clinical features of Erythema Nodosum

Skin Manifestations

Small , erythematous nodules appear in crops, which may be accompanied by systemic manifestations.

General Manifestations

Fever, chills, malaise, muscle pain and arthralgia .

Visceral manifestations:

Nephritis , orchitis and hepatosplenomegaly

Treatment of leprosy

1. Dapsone or DDS (diaminodiphenyl sulphones) is the drug of choice for treatment of all forms of leprosy.

   DOSE :
   First 2 weeks :	25mg twice a week
   Second 2 weeks:	50mg twice a week
   Third 2 weeks:	75mg twice a week
   Fourth 2 weeks:	100 mg twice a week.

2. Ciba SU-1906 (Diphenyl thiourea) : Adult dose is two-grams daily for two years. This drug may be useful for cases resistant to sulphones .

3. Madribon (Sulfadimethoxine): is effective for treatment of tuberculoid leprosy.

4. Lamprene (Geigy) is useful in treating cases of reactive leprosy. There is less lepra reaction with this medication and is also used for sulphones-resistant cases.

Treatment of Lepra Reaction

Mild cases:

1. Reduce the dose to half .

2. Antihistamines

3. Antimalarial drugs

4. If the reaction persists after all these measures , stop Dapsone.

Moderate or severe lepra reaction :

1. Stop the medication .

2. Sedatives

3. Antimalarial

4. Antihistamines

5. Steroids

REFERENCES

1. Lara CB. Leprosy in children: general considerations; initial and early stages. WPR/LEP/24 Geneva: WHO, 1961.

2. Kaplan G, Cohn ZA. Regulation of cell mediated immunity in lepromatous leprosy. Lepr Rev 1986; 57: 199-207.

3. Neill MA, Hightower AW, Broome CV. Leprosy in the United States. J Inf Dis 1985; 152: 1064-9.

4. McDougall AC, Archibald GC. Lepromatous leprosy presenting with swelling of the legs. Br Med J 1977; i: 23-4.

5. Duncan ME, Melsom R, Pearson JMH et al. A clinical and immunological Study of four babies of mothers with lepromatous leprosy, two of whom developed leprosy in infancy. Int J Lepr 1983; 51: 7-17.

6. Drutz DJ, Chen TSN, Lu W-H. The continuous bacteraemia of lepromatous leprosy. New Engl J Med 1972; 287: 159-64.

7. Dabholkar VR, Gaitonde BB. A study of autonomic functions in leprosy. Leprosy in India 1982; 54: 303-17.

8. Bryceson ADM, Pfaltzgraff RF. Leprosy 3rd edn. Edinburgh: Churchill Livingstone, 1990.

9. Pearson JMH. Dapsone resistant leprosy. Lepr Rev 1983; (Special Issue): 85S-89S.

10. Pedley JC, Harman DJ, Waudby H et al. Leprosy in peripheral nerves: histopathological findings in 119 untreated patients in Nepal. J Neurol Neurosurg Psych 1980; 43: 198-204.

11. Ridley DS. Reactions in leprosy. Lepr Rev 1969; 40: 77-81.

12. Ridley DS, Jopling WH. Classification of leprosy according to immunity, a five-group system. Int J Lepr 1966; 34: 255-73.

13. Ellard GA. Rationale of multidrug regimens recommended by a WHO Study Group on chemotherapy of leprosy for control programmes. Int J Lepr 1984; 52:394-401.

14. Duncan ME, Melsom R, Pearson JMH et al. A clinical and immunological Study of four babies of mothers with lepromatous leprosy, two of whom developed leprosy in infancy. Int J Lepr 1983; 51: 7-17.

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