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Article Excerpt
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Infection a Mycobacterium ulcerans
L'infection a Mycobacterium ulcerans (ulcere de Buruli) constitue un important probleme sanitaire dans plusieurs pays d'Afrique de l'Ouest. Elle est prevalente sous forme de foyers disperses a travers le monde, principalement dans les zones fluviales soumises a un climat humide et chaud. L'article examine l'epidemiologie, la bacteriologie, la transmission, l'immunologie, la pathologie, le diagnostic et le traitement de cette infection. M. ulcerans est un microorganisme omnipresent. Il est heberge par des poissons, des escargots et des insectes d'eau. Le mode de transmission n'est pas connu. Les lesions touchent le plus souvent les parties exposees du corps, en particulier les membres. Une guerison spontanee est possible. Dans les zones endemiques, de nombreux malades se presentent tardivement, avec des lesions a un stade avance et grave. La vaccination par le BCG apporte une protection immunitaire limitee, de duree relativement courte. Le traitement recommande consiste en un debridage chirurgical des lesions, suivi si necessaire, d'une greffe de peau. De nombreux malades souffrent de limitations fonctionnelles une fois gueris. Pour combattre et prevenir plus efficacement l'ulcere de Buruli, il convient de mieux comprendre la transmission de cette maladie et sa pathogenese.
Resumen
Enfermedad pot Mycobacterium ulcerans
La enfermedad causada por Mycobacterium ulcerans (ulcera de Buruli) constituye un grave problema de salud en varios paises de Africa occidental, pero es frecuente en focos dispersos en todo el mundo, predominantemente en zonas fluviales con clima calido y humedo. Examinamos aqui la epidemiologia, bacteriologia, transmision, inmunologia, histopatologia, diagnostico y tratamiento de este tipo de infection. M. ulcerans es un microorganismo ubicuo que se alberga en peces, caracoles e insectos acuaticos. Se desconoce el modo de transmision. Las lesiones aparecen sobre todo en las partes expuestas del cuerpo, en particular en los miembros. A veces se produce una curacion espontanea. Muchos de los pacientes de las zonas endemicas acuden al medico cuando presentan ya lesiones muy avanzadas y graves. La vacunacion con BCG confiere una proteccion inmunitaria limitada y relativamente breve. El tratamiento recomendado consiste en et desbridamiento quirurgico, seguido de injerto cutaneo si es necesario. Muchos pacientes sufren limitaciones funcionales aun despues de curados. Es preciso comprender mejor la transmision y la patogenesis de la enfermedad para poder prevenir y controlar mas satisfactoriamente la ulcera de Buruli.
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Introduction
Mycobacterium ulcerans disease, or Buruli ulcer, occurs in scattered foci around the world in riverine areas with a humid, hot climate (1-3). However, the disease may also occur in temperate climates, such as in coastal southeastern Australia (2). Although originally regarded as an unusuat form of tropical skin ulcer, Buruli ulcer is now recognized as a distinct disease that places a major burden on affected populations and health facilities in endemic regions, particularly in West Africa. The typical presentation with indolent, painless, undermined ulcers is easily diagnosed, but atypical forms can be confounded with other causes of skin ulcers.
Unless super-infection has occurred, patients usually do not show signs of systemic inflammatory response. Early, pre-ulcerative lesions, usually in the form of nodules, may be easily managed by simple surgical excision and suturing (4). Surgical management is more complicated when the disease has advanced, and many patients in endemic regions present late because they live in rural areas and their families cannot afford the time to attend hospital, and also because they fear surgery (5, 6). Treatment of advanced disease is often difficult, and complicated by persistence and relapse (7). Surgery is still considered the main treatment option despite its poor acceptability, high costs, and failure to prevent recurrence. Over hall of the people who have Buruli ulcers have functional limitations after treatment (8, 9), and surfer from social stigmatization (5), and loss of livelihoods (10). In 1998, WHO established the Global Buruli ulcer Initiative, and the importance of Buruli ulcer disease was again recognized by the 57th World Health Assembly in 2004 (11). The Assembly called for increased surveillance and control of Buruli ulcer and intensified research to develop tools to diagnose, treat and prevent the disease, thereby reducing the burden in poverty-stricken communities affected by this disease.
We review the current understanding of the epidemiology and transmission of M. ulcerans. We summarize new developments in diagnostic tests, and describe what is known about the pathology and immunology of this infection and how these characteristics relate to current and potential treatments. We discuss pathogenesis, mediated by a toxin produced by M. ulcerans, which causes the extensive necrosis characteristic of the disease.
Search strategy: We extracted information from peer-reviewed publications retrieved from a MEDLINE search (English and French) with the search terms {Buruli OR (Mycobacterium AND ulcerans)} accessed on March 20, 2005, together with other published and unpublished data, presented at annual meetings of the Buruli ulcer ad hoc advisory group in Geneva.
Epidemiology and Transmission
Although the first report of Buruli ulcer from Africa dates back to 1897, when Sir Albert Cook described cases of chronic ulceration in Uganda, the first definitive description of Mycobacterium ulcerans was published in 1948 (12). The report describes lesions in different stages of Buruli ulcer disease in two Australian children and four adults in a riverine area in Bairnsdale, Victoria. Buruli ulcer has since been reported from several different regions. Most of these reports are of infections that occur in people living in riverine areas, in humid, hot climates. The area around Melbourne, Australia appears to be one of the few foci of disease in a temperate climate (13). Disease foci have been reported from tropical areas in Asia (Malaysia, Papua New Guinea, and Sri Lanka) and Latin America (Guyana, Mexico, Peru), but the largest numbers of patients with Buruli ulcer disease have been detected in sub-Saharan Africa (14,...
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