Leprosy overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Leprosy is a chronic infectious disease caused by the bacterium Mycobacterium leprae.[1] Leprosy is primarily a granulomatous disease of the peripheral nerves and mucosa of the upper respiratory tract; skin lesions are the primary external symptom. Left untreated, leprosy can be progressive, causing permanent damage to the skin, nerves, limbs, and eyes.
Historical Perspective
Mycobacterium leprae, the causative agent of leprosy, was discovered by G. H. Armauer Hansen in Norway in 1873, making it the first bacterium to be identified as causing disease in man.[2][3] The importance of the nasal mucosa was recognized as early as 1898 by Schäffer, particularly that of the ulcerated mucosa. Historically, individuals with Hansen's disease have been known as lepers, however, this term is falling into disuse as a result of the diminishing number of leprosy patients and the pejorative connotations of the term. The term most widely accepted among people and agencies working in the field of Hansen's disease is 'people affected by Hansen's disease'.
Classification
The Ridley Jopling classification and the WHO classification are the two most widely used systems to classify Leprosy. These classification systems are based on clinical, microbiological and histopathological features, and are used to determine the patient's prognosis and the treatment regimen.[4][5][6]
Pathophysiology
Worldwide, 1-2 million persons are permanently disabled as a result of Hansen's disease. However, persons receiving antibiotic treatment or having completed treatment are considered free of active infection. Although the mode of transmission of Hansen's disease remains uncertain, most investigators think that M. leprae is usually spread from person to person in respiratory droplets.
Causes
Mycobacterium leprae is a gram-positive obligate intracellular, acid-fast bacillus, responsible for the development of leprosy, or Hansen's disease. This organism has a very slow growth and affects particularly colder parts of the body, such as the skin, superficial nerves and upper respiratory mucous membranes. Although a route of transmission has not been absolutely defined yet, studies are pointing to a colonization of the dermis and respiratory mucosa of the infected patients, with the respiratory system also as the entry port. It is an uncommon bacteria, since it has only been noticed to infect and grown in some species of primates and in the nine-banded armadillo.[6]
Differential Diagnosis
Leprosy is has a very important skin component, with manifestations such as skin lesions, nodules, plaques and thickened dermis, Thise manifestations may be present in other conditions, from which leprosy should then be distinguished. These may include autoimmune diseases, such as vitiligo and SLE, parasitic infections, such as dermatophyte or more generalized infections, such as cutaneous tuberculosis.
Epidemiology and Demographics
In 1990, the WHO defined a goal of eliminating leprosy as a public health issue within 10 years. Between the years of 1985 and 2010, the number of registered cases of leprosy fell from 5.4 million to 244,796, with prevalence rate per 10,000 falling from 21,1 to 0.37. However this prevalence is very variable according to the region, since most reported cases come from developing countries, such as India, Brazil and Indonesia. Efforts have been made to decrease the number of cases in endemic areas and to avoid transmission of the disease to other parts of the world, since international travel represents an important vehicle of the bacteria into other parts of the globe. This transmission has such impact that among the cases reported annually in the United States, 75% occur in emigrants.[7]
Risk Factors
Close contacts of patients with untreated, active multibacillary disease are at highest risk of acquiring leprosy. Children are more susceptible than adults to contracting the disease.
Diagnosis
Leprosy is a disease with very different clinical presentations, depending on the immune response provided by the host. Therefore it is important to consider the different conditions that may mimic leprosy's presentation, particularly since the diagnosis of leprosy has a very serious psychological and social impact in someone's life. To minimize the risk of reaching an erroneous diagnosis and inflicting stress and concern in the patient, criteria were developed to guide the diagnosis, which should only be communicated to the patient when a reasonable degree of certainty is present.
History and Symptoms
This chronic infectious disease usually affects the skin and peripheral nerves but has a wide range of possible clinical manifestations. Patients are classified as having paucibacillary or multibacillary Hansen's disease. Paucibacillary Hansen's disease is milder and characterized by one or more hypopigmented skin macules. Multibacillary Hansen's disease is associated with symmetric skin lesions, nodules, plaques, thickened dermis, and frequent involvement of the nasal mucosa resulting in nasal congestion and epistaxis.
Physical Examination
Paucibacillary Hansen's disease is milder and characterized by one or more hypopigmented skin macules. Multibacillary Hansen's disease is associated with symmetric skin lesions, nodules, plaques, thickened dermis, and frequent involvement of the nasal mucosa resulting in nasal congestion and epistaxis.
Laboratory Findings
Lepromin skin test can be used to distinguish lepromatous from tuberculoid leprosy, but is not used for diagnosis. Other tests include skin lesion biopsy and skin scraping examination for acid fast bacteria.
Treatment
Medical Therapy
The age-old social stigma associated with the advanced form of leprosy lingers in many areas, and remains a major obstacle to self-reporting and early treatment. Effective treatment for leprosy appeared in the late 1940s with the introduction of dapsone and its derivatives. However, leprosy bacilli resistant to dapsone gradually evolved and became widespread, and it was not until the introduction of multidrug therapy (MDT) in the early 1980s that the disease could be diagnosed and treated successfully within the community.
Secondary Prevention
Prevention consists of avoiding close physical contact with untreated people. People on long-term medication become noninfectious (they do not transmit the organism that causes the disease).
References
- ↑ Sasaki S, Takeshita F, Okuda K, Ishii N (2001). "Mycobacterium leprae and leprosy: a compendium". Microbiol Immunol. 45 (11): 729–36. PMID 11791665.
- ↑ Hansen GHA (1874). "Undersøgelser Angående Spedalskhedens Årsager (Investigations concerning the etiology of leprosy)". Norsk Mag. Laegervidenskaben (in Norwegian). 4: pp. 1–88.
- ↑ Irgens L (2002). "The discovery of the leprosy bacillus". Tidsskr Nor Laegeforen. 122 (7): 708–9. PMID 11998735.
- ↑ Walker, Stephen L.; Lockwood, Dina N.J. (2007). "Leprosy". Clinics in Dermatology. 25 (2): 165–172. doi:10.1016/j.clindermatol.2006.05.012. ISSN 0738-081X.
- ↑ Eichelmann, K.; González González, S.E.; Salas-Alanis, J.C.; Ocampo-Candiani, J. (2013). "Leprosy. An Update: Definition, Pathogenesis, Classification, Diagnosis, and Treatment". Actas Dermo-Sifiliográficas (English Edition). 104 (7): 554–563. doi:10.1016/j.adengl.2012.03.028. ISSN 1578-2190.
- ↑ 6.0 6.1 Bhat, Ramesh Marne; Prakash, Chaitra (2012). "Leprosy: An Overview of Pathophysiology". Interdisciplinary Perspectives on Infectious Diseases. 2012: 1–6. doi:10.1155/2012/181089. ISSN 1687-708X.
- ↑ "Leprosy: global situation".