rapidly growing photochromogenic Mycobacterium.

References 1. Falkinham JO III. Epidemiology of infection by nontuberculous mycobacteria.bacterium novocastrense sp. nov., a rapidly growing photochromogenic Myco-bacterium. Development of a single-tube, cell lysis-based, genus-specifi c PCR method for rapid identifi cation of mycobacteria: optimization of cell lysis, PCR primers and conditions, and restriction pattern analysis. rpoB-based identifi cation of nonpigmented and late-pigmenting rapidly growing mycobacteria. To the Editor: Buruli ulcer disease (BU) is a necrotizing skin disease caused by Mycobacterium ulcerans that affects mostly children in humid, tropical areas (1). The exact mode of M. ulcerans transmission remains unclear, although the role of water bugs has been supported by various observations and experimental studies (2,3). We report the identifi cation of a new BU-endemic area in Cameroon, the Bankim district, and specify ecologic and clinical characteristics of M. ulcerans infection in this area. These characteristics hint at the possible role of environmental changes (building of a dam several years ago) in the expansion of BU in this area. Since 1969, only 1 BU-endemic area in Cameroon has been described: the Nyong River basin, where equatorial forest predominates (4). In 2004, clinically suspected cases of BU in the district of Bankim have been reported (5). This region differs from the fi rst BU-endemic area by geography and climate. Representing a transition between forested south and savanna north, this area has benefi ted from the building of a dam on the Mape River in 1989, which created an artifi cial lake of 3.2 billion m 3 capacity. all cases of skin lesions evocative of active BU were recorded as BU probable cases according to World Health Organization guidelines (6). During this period, 195 clinically suspected cases were reported from the Bankim health district (Figure).


Geographic Expansion of Buruli Ulcer Disease, Cameroon
To the Editor: Buruli ulcer disease (BU) is a necrotizing skin disease caused by Mycobacterium ulcerans that affects mostly children in humid, tropical areas (1). The exact mode of M. ulcerans transmission remains unclear, although the role of water bugs has been supported by various observations and experimental studies (2,3). We report the identifi cation of a new BU-endemic area in Cameroon, the Bankim district, and specify ecologic and clinical characteristics of M. ulcerans infection in this area. These characteristics hint at the possible role of environmental changes (building of a dam several years ago) in the expansion of BU in this area.
Since 1969, only 1 BU-endemic area in Cameroon has been described: the Nyong River basin, where equatorial forest predominates (4). In 2004, clinically suspected cases of BU in the district of Bankim have been reported (5). This region differs from the fi rst BU-endemic area by geography and climate. Representing a transition between forested south and savanna north, this area has benefi ted from the building of a dam on the Mape River in 1989, which created an artifi cial lake of 3.2 billion m 3 capacity.
From January 2007 through June 2009, all cases of skin lesions evocative of active BU were recorded as BU probable cases according to World Health Organization guidelines (6). During this period, 195 clinically suspected cases were reported from the Bankim health district (Figure). The overall median age for these 195 patients was 19.5 years (interquartile range 10-37 years). No signifi cant difference in age was found according to gender, but a signifi cant trend of decreasing overall median age was found (20 years in 2007 to 12 years in 2009. The most frequent type of lesion was ulcer. Since March 2009, the Centre Pasteur of Cameroon has performed laboratory confi rmation for suspected BU cases: microscopic examination for acid-fast bacilli, culture, and M. ulcerans DNA detection by PCR (6). From April through June 2009, of 34 consecutive samples tested in the reference laboratory, 10 were positive for M. ulcerans by at least microscopy and PCR.
Whether BU is emerging in Bankim or is just a newly recognized preexisting disease is diffi cult to establish. However, that the incidence of BU in the region is increasing is unquestionable. The decreasing median age of patients since 2007 might be consistent with emergence of BU as a new disease in Bankim. This observation could suggest either an increasing level of acquired immunity in the population, leading to protection correlated with age, or the expansion of risky sites for human infection with M. ulcerans.
During 1 week in January 2008, water bugs were collected from the artifi cial lake and water bodies located within or close to each community. A previously described sampling method was used (2). To detect M. The emergence of BU may be a consequence of the marked changes in the environment caused by the building of the dam. Elsewhere, human environmental modifi cations such as construction of dams have been linked with increased incidence of BU (1). The main visible environmental effect is the large amount of fl ooded farmland. According to the seasons, the reservoir margins change the milieu of swamps and meadows. All these modifi cations affect plant and animal resources in the reservoir area by favoring rapid growth of aquatic macrophyte populations during reservoir fi lling, thus providing breeding sites for insects and leading to the extinction of area-endemic species and creation of new niches (7). These changes might favor development of M. ulcerans in biofi lms on aquatic plants, which are then ingested by herbivorous animals, which are further prey for water bug predators, hosts, and possible vectors of M. ulcerans (8,9). The water bugs that were most frequently trapped and colonized by M. ulcerans (families Belostomatidae, Naucoridae, Nepidae, Notonectidae) are carnivorous and able to bite humans (10