Assessing Water-Related Risk Factors for Buruli Ulcer: A Case-Control Study in Ghana

Aiga, Hirotsugu; Amano, Takayuki; Cairncross, Sandy; Domako, Joseph A.; Nanas, Ofosu-Kwabi; Coleman, Susan

doi:10.4269/ajtmh.2004.71.387

Cited by 83 publications

(102 citation statements)

References 26 publications

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“…Although several water-related risk factors have been recognized, none has been consistently reported, making it diffi cult to identify specifi c water-related risk activities (6)(7)(8). Most studies suggest that infection occurs through inoculation of M. ulcerans into skin lesions or insect bites (2,4,9-11).…”

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confidence: 99%

Aquatic Invertebrates as Unlikely Vectors of Buruli Ulcer Disease

Benbow

Williamson

Kimbirauskas

et al. 2008

Emerg. Infect. Dis.

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Buruli ulcer is a necrotizing skin disease caused by Mycobacterium ulcerans and associated with exposure to aquatic habitats. To assess possible transmission of M. ulcerans by aquatic biting insects, we conducted a fi eld examination of biting water bugs (Hemiptera: Naucoridae, Belostomatidae, Nepidae) in 15 disease-endemic and 12 non-disease-endemic areas of Ghana, Africa. From collections of 22,832 invertebrates, we compared composition, abundance, and associated M. ulcerans positivity among sites. Biting hemipterans were rare and represented a small percentage (usually <2%) of invertebrate communities. No signifi cant differences were found in hemipteran abundance or pathogen positivity between disease-endemic and nondisease-endemic sites, and between abundance of biting hemipterans and M. ulcerans positivity. Therefore, although infection through insect bites is possible, little fi eld evidence supports the assumption that biting hemipterans are primary vectors of M. ulcerans. M ycobacterium ulcerans infection is an emerging skin disease often called Buruli ulcer (BU). Infection results in illness and lasting negative socioeconomic effects in rural areas of the tropics and subtropics (1). The pathologic changes, clinical signs and symptoms, and treatment have been reviewed elsewhere (2-5). In this article we evaluate fi eld evidence for the potential of aquatic invertebrates to be vectors of M. ulcerans.The exact mode of BU transmission remains unknown; however, past epidemiologic studies have associated BU with human activity near, or within, slow-fl owing or standing water bodies that have been created or disturbed by humans (2-4). Although several water-related risk factors have been recognized, none has been consistently reported, making it diffi cult to identify specifi c water-related risk activities (6-8). Most studies suggest that infection occurs through inoculation of M. ulcerans into skin lesions or insect bites (2,4,9-11). Portaels et al. (11) were the fi rst to propose that aquatic insects might serve as vectors of M. ulcerans. This hypothesis maintains that M. ulcerans is found in biofi lms of aquatic habitats and concentrated by grazing or fi lter-feeding invertebrates that are then consumed by predators known to bite humans (11). Initial evidence for this hypothesis used PCR detection of the insertion sequence IS2404 to document M. ulcerans' association with biting water bugs (Hemiptera), fi ltered concentrates of water, detritus, and aquatic plants (4,(12)(13)(14). These studies were important for understanding the possible environmental reservoirs of M. ulcerans. However, IS2404 is now understood to be not specifi c for M. ulcerans because this insertion sequence has been found in a number of other aquatic mycobacterial species, including M. marinum (15)(16)(17). When more discriminatory methods based on detection of variable number tandem repeats were used, many IS2404-positive environmental samples were reported to lack M. ulcerans (18). In light of these recent fi ndings, the relative fr...

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confidence: 99%

Aquatic Invertebrates as Unlikely Vectors of Buruli Ulcer Disease

Benbow

Williamson

Kimbirauskas

et al. 2008

Emerg. Infect. Dis.

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“…Previous studies have demonstrated that populations that use unprotected sources of water for domestic purposes have prevalence rates of BU higher than those who use protected sources (1,21,30,54). The preferable habitat of M. ulcerans is probably unprotected waters, since the presumed reservoir and/or vector(s) of M. ulcerans probably occurs more frequently in unprotected waters (39).…”

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confidence: 99%

Occurrence of Free-Living Amoebae in Communities of Low and High Endemicity for Buruli Ulcer in Southern Benin

Eddyani

Jonckheere

Durnez

et al. 2008

Appl Environ Microbiol

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Buruli ulcer or Mycobacterium ulcerans disease occurs mainly in areas in proximity to standing or slowly running freshwater, habitats in which free-living amoebae occur. For this reason, a possible link between the habitat of M. ulcerans and free-living amoebae was investigated. Free-living amoebae and mycobacteria were isolated from water and biofilm specimens taken from protected and unprotected sources of water in villages known to have either high or low endemicity for Buruli ulcer in Benin. Amoebae were isolated from 78.8% of samples. A greater proportion of water bodies in areas of high endemicity had amoebae than in areas of low endemicity (83.3% versus 66.7%). Protected sources of water were significantly more likely to contain amoebae in areas of high endemicity than in areas of low endemicity (88.0% versus 11.1%). Several pathogenic free-living amoebae and mycobacteria were isolated. However, no M. ulcerans was isolated and no specimen was positive for IS2404 PCR. Our results show that the study area has a water hygiene problem, which is greater in areas of high Buruli ulcer endemicity than in areas of low endemicity. Our observations indicate that additional studies are required to explore the possible link between free-living amoebae and mycobacteria.

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“…La démonstration, chez des souris infectées par M. ulcerans, de l'efficacité de l'association de deux antibiotiques, la rifampicine et l'amikacine, a contribué à la réalisation de deux études thérapeutiques pilotes qui ont confirmé l'intérêt de cette antibiothé-rapie puisque la moitié des patients a été guérie sans avoir recours à la chirurgie [2]. À l'heure actuelle, il n'existe pas de vaccin spécifique dirigé contre M. ulcerans et l'efficacité de la vaccination BCG est, pour les formes cutanées, fort controversée [3,4]. [5].…”

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