Associations Between Mycobacterium ulcerans and Aquatic Plant Communities of West Africa: Implications for Buruli Ulcer Disease

Abstract

Numerous studies have associated Buruli ulcer (BU) disease with disturbed aquatic habitats; however, the natural reservoir, distribution, and transmission of the pathogen, Mycobacterium ulcerans, remain unknown. To better understand the role of aquatic plants in the ecology of this disease, a large-scale survey was conducted in waterbodies of variable flow throughout three regions of Ghana, Africa. Our objectives were to characterize plant communities and identify potential relationships with M. ulcerans and other mycolactone-producing mycobacteria (MPM). Waterbodies with M. ulcerans had significantly different aquatic plant communities, with submerged terrestrial plants identified as indicators of M. ulcerans presence. Mycobacterium ulcerans and MPM were detected on 14 plant taxa in emergent zones from both lotic and lentic waterbodies in endemic regions; however, M. ulcerans was not detected in the non-endemic Volta region. These findings support the hypothesis that plants provide substrate for M. ulcerans colonization and could act as potential indicators for disease risk. These findings also suggest that M. ulcerans is a widespread environmental bacteria species, but that it is absent or reduced in regions of low disease incidence. A better understanding is needed regarding the mechanistic associations among aquatic plants and M. ulcerans for identifying the mode of transmission of BU disease.

Topography and Land Cover of Watersheds Predicts the Distribution of the Environmental Pathogen Mycobacterium ulcerans in Aquatic Insects

“…These 5 Orders may not be the primary habitat of M. ulcerans in the wild, as the full biotic extent of M. ulcerans distribution is still unknown, but they are commonly found to be persistently infected and appear to be important hosts [32]. Previous work has found that M. ulcerans abundance does respond to water body type, being more commonly detected in swamps (still lentic systems) than rivers (flowing lotic systems) in Ghana [33], [34]. The pathogen is associated with lowland, flat, swampy areas in contact with stagnant water [35], is known to have complex seasonal dynamics [32], and appears to be present at low levels throughout the entire local biotic community along the year [29].…”

Landscape and environmental influences on Mycobacterium ulcerans distribution among aquatic sites in Ghana

“…PCR was carried out using methods described by McIntosh et al (2014) [26], Williamson et al (2008) [19], and Williamson et al (2014) [39] where all samples were initially subjected to amplification of IS 2404 . Positive samples were further assayed for the presence of the enoyl reductase (ER) domain encoded on the plasmid responsible for mycolactone production, as previously described [19, 26, 39–41]. Samples found to be ER positive were profiled when possible using variable number tandem repeat profile targeting a number of loci [19, 26, 39].…”

“…Positive samples were further assayed for the presence of the enoyl reductase (ER) domain encoded on the plasmid responsible for mycolactone production, as previously described [19, 26, 39–41]. Samples found to be ER positive were profiled when possible using variable number tandem repeat profile targeting a number of loci [19, 26, 39]. Standard operating procedures for quality assurance of molecular analyses were strictly followed according to the Quality Assurance/Quality Control Guidance for Laboratories performing PCR analyses on Environmental Samples and microbial source tracking by the Environmental Protection Agency, USA [42].…”

Chemistry of natural waters and its relation to Buruli ulcer in Ghana

“…Still others have found that direct contact with aquatic environments is a major risk factor (Aiga et al, 2004;Raghunathan et al, 2005;Debacker et al, 2006;Sopoh et al, 2010), and M. ulcerans has been detected in fish (Eddyani et al, 2004), aquatic snails (Marsollier et al, 2004), aquatic insects (Portaels et al, 1999), and submerged terrestrial plants (McIntosh et al, 2014). While the culturing of M. ulcerans from an aquatic invertebrate (Portaels et al, 2008) suggested a potential reservoir or vector for BU (e.g., Merritt et al, 2010), Benbow et al (2008) discounted predatory aquatic insects as a potential vector because the number of insects and presence of M. ulcerans in these insects are similar at BU-endemic and non-endemic sites.…”