Leprosy, called Hansen’s disease in publications of the United States Public Health Service, is rare in this country, but a small number of cases, both imported and domestically acquired, are reported each year. Worldwide, it is a much larger problem, with an estimated 10 to 12 million cases. Dozens of cases in the United States have been linked to contact with or ingestion of armadillos, a known reservoir of the pathogen.

1. Pathogenicity: Mycobacterium leprae is transmitted from human to human through prolonged contact, for example, between exudates of a leprosy patient’s skin lesions and the abraded skin of another individual. The infectivity of M. leprae is low, and the incubation period protracted, so that clinical disease may develop years or even decades after initial contact with the organism.

2. Clinical significance: Leprosy is a chronic granulomatous condition of peripheral nerves and mucocutaneous tissues, particularly the nasal mucosa. It occurs as a continuum between two clinical extremes: tuberculoid and lepromatous leprosy (Figure.1). In tuberculoid leprosy, the lesions occur as large maculae (spots) in cooler body tissues, such as skin (especially the nose, outer ears, and testicles), and in superficial nerve endings. Neuritis leads to patches of anesthesia in the skin. The lesions are heavily infiltrated by lymphocytes and giant and epithelioid cells, but caseation does not occur. The patient mounts a strong cell-mediated immune response and develops delayed hypersensitivity, which can be shown by a skin test with lepromin, a tuberculin-like extract of lepromatous tissue. There are few bacteria in the lesions (paucibacillary). The course of lepromatous leprosy is slow but progressive (Figure 2). Large numbers of organisms are present in the lesions and reticuloendothelial system (multi bacillary), the results of a severely depressed immune system. No well-formed granulomas emerge.

Fig1. Classification of leprosy.

Fig2. A. Leprosy in a 13-year-old Hawaiian boy in 1931. B. Same boy 2 years later. [Note: This patient had the misfortune of contracting leprosy before the era of effective antibiotics.]

3. Laboratory identification: M. leprae is an acid-fast bacillus. It has not been successfully maintained in artificial culture but can be grown in the footpads of mice and in the armadillo, which is a natural host and reservoir of the pathogen. Laboratory diagnosis of lepromatous leprosy, in which organisms are numerous, involves acid-fast stains of specimens from nasal mucosa or other infected areas. In tuberculoid leprosy, organisms are extremely rare, and diagnosis depends on clinical findings and the histology of biopsy material.

4. Treatment and prevention: Several drugs are effective in the treatment of leprosy, including sulfones such as dapsone, rifampin, and clofazamine. Treatment is prolonged, and combined therapy is necessary to ensure the suppression of resistant mutants. The fact that vaccination with BCG has shown some protective effect in leprosy has encouraged further interest in vaccine development. Thalidomide, an inhibitor of tumor necrosis factor-α, is being distributed under tight restrictions for use as a treatment for erythema nodosum leprosum, a serious and severe skin complication of leprosy.

اخر الاخبار

اخبار العتبة العباسية المقدسة

العتبة العباسية المقدسة تنشر لافتات الحزن والعزاء بذكرى شهادة الإمام الحسن المجتبى (عليه السلام)

كلية التمريض في جامعة العميد تحصل على الاعتماد البرامجي الكامل من وزارة التعليم

العتبة العباسية المقدسة تعلن تهيئة مساحات جديدة قرب الحرم الطاهر استعدادًا لزيارة الأربعين

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Antimicrobial Susceptibility Testing and Therapy of Rhizobium, Ochrobactrum, and Similar Organisms

Laboratory Diagnosis of Rhizobium, Ochrobactrum, and Similar Organisms

Antimicrobial Susceptibility Testing and Therapy of Pseudomonas, Burkholderia, and Similar Organisms

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