Buruli ulcer distribution in Benin

Evaluation of Buruli Ulcer Disease Surveillance System in the Ga West Municipality, Ghana, 2011-2015

Background

Buruli ulcer (BU) is one of the most neglected tropical diseases caused by Mycobacterium ulcerans. M. ulcerans infection may manifest initially as a pre-ulcerative nodule, a plaque, or oedema which breaks down to form characteristic ulcers with undermined edges. The Ga West Municipality is an endemic area for Buruli ulcer, and we evaluated the BU surveillance system to determine whether the system is meeting its objectives and to assess its attributes.

Materials and Methods

We used a checklist based on Centers for Disease Control and Prevention (CDC) updated surveillance evaluation guidelines, 2006. We reviewed records and dataset on Buruli ulcer for the period 2011–2015. The evaluation was carried out at the national, regional, district, and community levels using the Ga West Municipality of the Greater Accra Region as a study site. Interviews with key stakeholders at the various levels were done using an interview guide, and observations were done with a checklist. Data were entered and analyzed using Epi info 7.

Results

A total of 594 cases of Buruli ulcer were reported from 2011 to 2015 in Ga West. The number of confirmed cases decreased from 109 in 2011 to 17 in 2015. The system was useful, fairly simple, flexible, representative, and fairly acceptable. The system was sensitive with a PVP of 45.3%. Although the data quality was good with 85% of case report forms completed, there was under-reporting (3.6%), some discrepancies of data at the district, regional, and national levels. The system was moderately stable, and timeliness of reporting was 30.7%.

Conclusion

The Buruli ulcer surveillance system is meeting its set objectives, and the data generated are used to reliably describe the epidemiologic situation and evaluate the results for actions and plan future interventions. There is a need for timely submission of data. We recommend that the National Buruli Ulcer Control Program (NBUCP) provides logistical support to treatment centres.

Effect of well drilling on Buruli ulcer incidence in Benin: a case-control, quantitative survey

BACKGROUND

Buruli ulcer is the third most common mycobacterial disease worldwide. The public health burden of this neglected tropical disease is large, particularly in poor areas of west and central Africa. The development of appropriate preventive strategies is hampered by an incomplete understanding of the epidemiology and transmission of the disease. We investigated the effect of the drilling of wells on Buruli ulcer incidence.

METHODS

In this case-control, quantitative survey, we obtained field data for Buruli ulcer incidence over a 10-year period from a specialised centre that collected data for the Ouémé and Plateau departments in Benin, and data for well drilling from the Ministry of Energy, Water and Mines in Benin. The coordinates of the wells drilled were obtained during site visits. A case-control study was then done to investigate the role of well water use in protecting against Buruli ulcer.

FINDINGS

We found a strong inverse correlation between the incidence of Buruli ulcer and the number of new wells drilled in the Bonou municipality (r²=0·8818). A case-control study (106 cases and 212 controls) showed that regular use of the water from the wells for washing, bathing, drinking, or cooking was protective against Buruli ulcer (adjusted odds ratio 0·1, 95% CI 0·04-0·44; p=0·0012).

INTERPRETATION

This study opens up new possibilities for developing an effective yet affordable policy to fight the disease on a substantial geographical scale. Our study shows that providing access to protected water is an efficient and feasable way to reduce the incidence of Buruli ulcer.

FUNDING

Fondation Francaise Raoul Follereau, French National Institute of Health and Medical Research, and Région Pays de Loire.

Decrease in Mycobacterium ulcerans disease (Buruli ulcer) in the Lalo District of Bénin (West Africa)

BACKGROUND

Buruli ulcer (BU) is a chronic, necrotizing infectious skin disease caused by Mycobacterium ulcerans. In recent years, there has been a decrease in the number of new cases detected. This study aimed to show the evolution of its distribution in the Lalo District in Bénin from 2006 to 2017.

METHODS

The database of the BU Detection and Treatment Center of Lalo allowed us to identify 1017 new cases in the Lalo District from 2006 to 2017. The annual prevalence was calculated with subdistricts and villages. The trends of the demographic variables and those related to the clinical and treatment features were analysed using Microsoft Excel® 2007 and Epi Info® 7. Arc View version® 3.4 was used for mapping.

RESULTS

From 2006 to 2017, the case prevalence of BU in the Lalo District decreased by 95%. The spatial distribution of BU cases confirmed the foci of the distribution, as described in the literature. The most endemic subdistricts were Ahomadégbé, Adoukandji, Gnizounmè and Tchito, with a cumulative prevalence of 315, 225, 215 and 213 cases per 10,000 inhabitants, respectively. The least endemic subdistricts were Zalli, Banigbé, Lalo-Centre and Lokogba, with 16, 16, 10, and 5 cases per 10,000 inhabitants, respectively. A significant decrease in the number of patients with ulcerative lesions (p = 0.002), as well as those with category 3 lesions (p < 0.001) and those treated surgically (p < 0.001), was observed. The patients confirmed by PCR increased (from 40.42% in 2006 to 84.62% in 2017), and joint limitation decreased (from 13.41% in 2006 to 0.0% in 2017).

CONCLUSION

This study confirmed the general decrease in BU prevalence rates in Lalo District at the subdistrict and village levels, as also observed at the country level. This decrease is a result of the success of the BU control strategies implemented in Bénin, especially in the Lalo District.

Buruli Ulcer, a Prototype for Ecosystem-Related Infection, Caused by Mycobacterium ulcerans

Buruli ulcer is a noncontagious disabling cutaneous and subcutaneous mycobacteriosis reported by 33 countries in Africa, Asia, Oceania, and South America. The causative agent, Mycobacterium ulcerans, derives from Mycobacterium marinum by genomic reduction and acquisition of a plasmid-borne, nonribosomal cytotoxin mycolactone, the major virulence factor. M. ulcerans-specific sequences have been readily detected in aquatic environments in food chains involving small mammals. Skin contamination combined with any type of puncture, including insect bites, is the most plausible route of transmission, and skin temperature of <30°C significantly correlates with the topography of lesions. After 30 years of emergence and increasing prevalence between 1970 and 2010, mainly in Africa, factors related to ongoing decreasing prevalence in the same countries remain unexplained. Rapid diagnosis, including laboratory confirmation at the point of care, is mandatory in order to reduce delays in effective treatment. Parenteral and potentially toxic streptomycin-rifampin is to be replaced by oral clarithromycin or fluoroquinolone combined with rifampin. In the absence of proven effective primary prevention, avoiding skin contamination by means of clothing can be implemented in areas of endemicity. Buruli ulcer is a prototype of ecosystem pathology, illustrating the impact of human activities on the environment as a source for emerging tropical infectious diseases.

High-Throughput Carbon Substrate Profiling of Mycobacterium ulcerans Suggests Potential Environmental Reservoirs

BACKGROUND

Mycobacterium ulcerans is a close derivative of Mycobacterium marinum and the agent of Buruli ulcer in some tropical countries. Epidemiological and environmental studies pointed towards stagnant water ecosystems as potential sources of M. ulcerans, yet the ultimate reservoirs remain elusive. We hypothesized that carbon substrate determination may help elucidating the spectrum of potential reservoirs.

METHODOLOGY/PRINCIPAL FINDINGS

In a first step, high-throughput phenotype microarray Biolog was used to profile carbon substrates in one M. marinum and five M. ulcerans strains. A total of 131/190 (69%) carbon substrates were metabolized by at least one M. ulcerans strain, including 28/190 (15%) carbon substrates metabolized by all five M. ulcerans strains of which 21 substrates were also metabolized by M. marinum. In a second step, 131 carbon substrates were investigated, through a bibliographical search, for their known environmental sources including plants, fruits and vegetables, bacteria, algae, fungi, nematodes, mollusks, mammals, insects and the inanimate environment. This analysis yielded significant association of M. ulcerans with bacteria (p = 0.000), fungi (p = 0.001), algae (p = 0.003) and mollusks (p = 0.007). In a third step, the Medline database was cross-searched for bacteria, fungi, mollusks and algae as potential sources of carbon substrates metabolized by all tested M. ulcerans; it indicated that 57% of M. ulcerans substrates were associated with bacteria, 18% with alga, 11% with mollusks and 7% with fungi.

CONCLUSIONS

This first report of high-throughput carbon substrate utilization by M. ulcerans would help designing media to isolate and grow this pathogen. Furthermore, the presented data suggest that potential M. ulcerans environmental reservoirs might be related to micro-habitats where bacteria, fungi, algae and mollusks are abundant. This should be followed by targeted investigations in Buruli ulcer endemic regions.

Spatial Analysis of Anthropogenic Landscape Disturbance and Buruli Ulcer Disease in Benin

BACKGROUND

Land use and land cover (LULC) change is one anthropogenic disturbance linked to infectious disease emergence. Current research has focused largely on wildlife and vector-borne zoonotic diseases, neglecting to investigate landscape disturbance and environmental bacterial infections. One example is Buruli ulcer (BU) disease, a necrotizing skin disease caused by the environmental pathogen Mycobacterium ulcerans (MU). Empirical and anecdotal observations have linked BU incidence to landscape disturbance, but potential relationships have not been quantified as they relate to land cover configurations.

METHODOLOGY/PRINCIPAL FINDINGS

A landscape ecological approach utilizing Bayesian hierarchical models with spatial random effects was used to test study hypotheses that land cover configurations indicative of anthropogenic disturbance were related to Buruli ulcer (BU) disease in southern Benin, and that a spatial structure existed for drivers of BU case distribution in the region. A final objective was to generate a continuous, risk map across the study region. Results suggested that villages surrounded by naturally shaped, or undisturbed rather than disturbed, wetland patches at a distance within 1200 m were at a higher risk for BU, and study outcomes supported the hypothesis that a spatial structure exists for the drivers behind BU risk in the region. The risk surface corresponded to known BU endemicity in Benin and identified moderate risk areas within the boundary of Togo.

CONCLUSIONS/SIGNIFICANCE

This study was a first attempt to link land cover configurations representative of anthropogenic disturbances to BU prevalence. Study results identified several significant variables, including the presence of natural wetland areas, warranting future investigations into these factors at additional spatial and temporal scales. A major contribution of this study included the incorporation of a spatial modeling component that predicted BU rates to new locations without strong knowledge of environmental factors contributing to disease distribution.

A Field Study in Benin to Investigate the Role of Mosquitoes and Other Flying Insects in the Ecology of Mycobacterium ulcerans

Background

Buruli ulcer, the third mycobacterial disease after tuberculosis and leprosy, is caused by the environmental mycobacterium M. ulcerans. There is at present no clear understanding of the exact mode(s) of transmission of M. ulcerans. Populations affected by Buruli ulcer are those living close to humid and swampy zones. The disease is associated with the creation or the extension of swampy areas, such as construction of dams or lakes for the development of agriculture. Currently, it is supposed that insects (water bugs and mosquitoes) are host and vector of M. ulcerans. The role of water bugs was clearly demonstrated by several experimental and environmental studies. However, no definitive conclusion can yet be drawn concerning the precise importance of this route of transmission. Concerning the mosquitoes, DNA was detected only in mosquitoes collected in Australia, and their role as host/vector was never studied by experimental approaches. Surprisingly, no specific study was conducted in Africa. In this context, the objective of this study was to investigate the role of mosquitoes (larvae and adults) and other flying insects in ecology of M. ulcerans. This study was conducted in a highly endemic area of Benin.

Methodology/Principal Findings

Mosquitoes (adults and larvae) were collected over one year, in Buruli ulcer endemic in Benin. In parallel, to monitor the presence of M. ulcerans in environment, aquatic insects were sampled. QPCR was used to detected M. ulcerans DNA. DNA of M. ulcerans was detected in around 8.7% of aquatic insects but never in mosquitoes (larvae or adults) or in other flying insects.

Conclusion/Significance

This study suggested that the mosquitoes don't play a pivotal role in the ecology and transmission of M. ulcerans in the studied endemic areas. However, the role of mosquitoes cannot be excluded and, we can reasonably suppose that several routes of transmission of M. ulcerans are possible through the world.

Buruli ulcer is a neglected tropical disease due to M. ulcerans, an environmental mycobacteria. Modes of transmission to human remain unclear and water bugs and mosquitoes had been incriminated with more or less experimental laboratory evidences and filed studies. In this context, we have investigated the presence of M. ulcerans DNA in mosquitoes and other flying insect in a highly endemic area of Buruli ulcer in Benin. No trace of the bacteria was found in mosquitoes and other flying insects, while 8,7% of aquatic insects, including water bugs, caught in the same area and in the same period were found positive to M. ulcerans DNA. Our results support the hypothesis that mosquitoes don’t play a major role in ecology of M. ulcerans in our research area and is in favor of a transmission from the aquatic environment.

Whole genome comparisons suggest random distribution of Mycobacterium ulcerans genotypes in a Buruli ulcer endemic region of Ghana

Efforts to control the spread of Buruli ulcer – an emerging ulcerative skin infection caused by Mycobacterium ulcerans - have been hampered by our poor understanding of reservoirs and transmission. To help address this issue, we compared whole genomes from 18 clinical M. ulcerans isolates from a 30km² region within the Asante Akim North District, Ashanti region, Ghana, with 15 other M. ulcerans isolates from elsewhere in Ghana and the surrounding countries of Ivory Coast, Togo, Benin and Nigeria. Contrary to our expectations of finding minor DNA sequence variations among isolates representing a single M. ulcerans circulating genotype, we found instead two distinct genotypes. One genotype was closely related to isolates from neighbouring regions of Amansie West and Densu, consistent with the predicted local endemic clone, but the second genotype (separated by 138 single nucleotide polymorphisms [SNPs] from other Ghanaian strains) most closely matched M. ulcerans from Nigeria, suggesting another introduction of M. ulcerans to Ghana, perhaps from that country. Both the exotic genotype and the local Ghanaian genotype displayed highly restricted intra-strain genetic variation, with less than 50 SNP differences across a 5.2Mbp core genome within each genotype. Interestingly, there was no discernible spatial clustering of genotypes at the local village scale. Interviews revealed no obvious epidemiological links among BU patients who had been infected with identical M. ulcerans genotypes but lived in geographically separate villages. We conclude that M. ulcerans is spread widely across the region, with multiple genotypes present in any one area. These data give us new perspectives on the behaviour of possible reservoirs and subsequent transmission mechanisms of M. ulcerans. These observations also show for the first time that M. ulcerans can be mobilized, introduced to a new area and then spread within a population. Potential reservoirs of M. ulcerans thus might include humans, or perhaps M. ulcerans-infected animals such as livestock that move regularly between countries.

In this study we use the power of whole genome sequence comparisons to track the spread of Mycobacterium ulcerans, the causative agent of Buruli ulcer, through several villages in the Ashanti region of Ghana, providing new insights on the behaviour of this enigmatic and emerging pathogen.

Buruli ulcer in South Western Nigeria: a retrospective cohort study of patients treated in Benin

Nigeria is known to be endemic to Buruli ulcer, but epidemiological data are remarkably rare. Here, we present a large cohort of 127 PCR-confirmed M. ulcerans infection patients coming from Nigeria and treated in a neighbouring country, Benin. Severe lesions and delay of consultation are factors that should encourage establishment of a treatment centre in South Western Nigeria.

Buruli ulcer is known to be endemic to Nigeria since at least 1967, however epidemiological data are rare and incomplete. In total, only 51 Buruli ulcer patients were described in 45 years, all found in Southern Nigeria. This is likely a result of the lack of adequate public health structures dedicated to the diagnosis and treatment of Buruli ulcer in the region. Here, we report a large cohort of 127 PCR-confirmed Nigerian patients treated in neighbouring Benin. Nigerian patients presented mainly severe lesions of Buruli ulcer, and this is linked by the fact that period prior consultation is delayed (24% of the patients waited more than one year between the beginning of the lesion and the consultation in the Buruli ulcer treatment centre in Pobè). We identify South Western Nigeria as an important endemic area for Buruli ulcer, and believe our results will be of importance to Nigerian health authorities, the World Health Organisation and NGO's involved in management of Buruli ulcer.

Findings in patients from Benin with osteomyelitis and polymerase chain reaction-confirmed Mycobacterium ulcerans infection

BACKGROUND

Mycobacterium ulcerans is known to cause Buruli ulcer (BU), a necrotizing skin disease leading to extensive cutaneous and subcutaneous destruction and functional limitations. However, M. ulcerans infections are not limited to skin, and osteomyelitis, still poorly described in the literature, occurs in numerous young patients in Africa.

METHODS

In a retrospective matched case-control study conducted in a highly endemic area in Benin, we analyzed demographic, clinical, biological, and radiological features in all patients with M. ulcerans infections with bone involvement, identified from a cohort of 1257 patients with polymerase chain reaction-proved M. ulcerans infections.

RESULTS

The 81 patients studied had a median age of 11 years (interquartile range, 7-16 years) and were predominantly male (male-female ratio, 2:1). Osteomyelitis was observed beneath active BU lesions (60.5%) or at a distance from active or apparently healed BU lesions (14.8%) but also in patients without a history of BU skin lesions (24.7%). These lesions had an insidious course, with nonspecific clinical findings leading to delayed diagnosis. A comparison with findings in 243 age- and sex-matched patients with BU without osteomyelitis showed that case patients were less likely to have received BCG immunization than controls (33.3% vs 52.7%; P = .01). They were also at higher risk of longer hospital stay (118 vs 69 days; P = .001), surgery (92.6% vs 63.0%; P = .001), and long-term crippling sequelae (55.6% vs 15.2%; P < .001).

CONCLUSIONS

This study highlighted the difficulties associated with diagnosis of M. ulcerans osteomyelitis, with one-fourth of patients having no apparent history of BU skin lesions, including during the current course of illness. Delays in treatment contributed to the high proportion (55.6%) of patients with crippling sequelae.

Mycobacterium ulcerans ecological dynamics and its association with freshwater ecosystems and aquatic communities: results from a 12-month environmental survey in Cameroon

BACKGROUND

Mycobacterium ulcerans (MU) is the agent responsible for Buruli Ulcer (BU), an emerging skin disease with dramatic socioeconomic and health outcomes, especially in rural settings. BU emergence and distribution is linked to aquatic ecosystems in tropical and subtropical countries, especially to swampy and flooded areas. Aquatic animal organisms are likely to play a role either as host reservoirs or vectors of the bacilli. However, information on MU ecological dynamics, both in space and time, is dramatically lacking. As a result, the ecology of the disease agent, and consequently its mode of transmission, remains largely unknown, which jeopardizes public health attempts for its control. The objective of this study was to gain insight on MU environmental distribution and colonization of aquatic organisms through time.

METHODOLOGY/PRINCIPAL FINDINGS

Longitudinal sampling of 32 communities of aquatic macro-invertebrates and vertebrates was conducted from different environments in two BU endemic regions in Cameroon during 12 months. As a result, 238,496 individuals were classified and MU presence was assessed by qPCR in 3,084 sample-pools containing these aquatic organisms. Our study showed a broad distribution of MU in all ecosystems and taxonomic groups, with important regional differences in its occurrence. Colonization dynamics fluctuated along the year, with the highest peaks in August and October. The large variations observed in the colonization dynamics of different taxonomic groups and aquatic ecosystems suggest that the trends shown here are the result of complex ecological processes that need further investigation.

CONCLUSION/PERSPECTIVES

This is the largest field study on MU ecology to date, providing the first detailed description of its spatio-temporal dynamics in different aquatic ecosystems within BU endemic regions. We argue that coupling this data with fine-scale epidemiological data through statistical and mathematical models will provide a major step forward in the understanding of MU ecology and mode of transmission.

Insertion sequence element single nucleotide polymorphism typing provides insights into the population structure and evolution of Mycobacterium ulcerans across Africa

Buruli ulcer is an indolent, slowly progressing necrotizing disease of the skin caused by infection with Mycobacterium ulcerans. In the present study, we applied a redesigned technique to a vast panel of M. ulcerans disease isolates and clinical samples originating from multiple African disease foci in order to (i) gain fundamental insights into the population structure and evolutionary history of the pathogen and (ii) disentangle the phylogeographic relationships within the genetically conserved cluster of African M. ulcerans. Our analyses identified 23 different African insertion sequence element single nucleotide polymorphism (ISE-SNP) types that dominate in different areas where Buruli ulcer is endemic. These ISE-SNP types appear to be the initial stages of clonal diversification from a common, possibly ancestral ISE-SNP type. ISE-SNP types were found unevenly distributed over the greater West African hydrological drainage basins. Our findings suggest that geographical barriers bordering the basins to some extent prevented bacterial gene flow between basins and that this resulted in independent focal transmission clusters associated with the hydrological drainage areas. Different phylogenetic methods yielded two well-supported sister clades within the African ISE-SNP types. The ISE-SNP types from the "pan-African clade" were found to be widespread throughout Africa, while the ISE-SNP types of the "Gabonese/Cameroonian clade" were much rarer and found in a more restricted area, which suggested that the latter clade evolved more recently. Additionally, the Gabonese/Cameroonian clade was found to form a strongly supported monophyletic group with Papua New Guinean ISE-SNP type 8, which is unrelated to other Southeast Asian ISE-SNP types.

Illness meanings and experiences for pre-ulcer and ulcer conditions of Buruli ulcer in the Ga-West and Ga-South Municipalities of Ghana

BACKGROUND

Ghana is a Buruli ulcer (BU) endemic country yet there is paucity of socio-cultural research on BU. Examining distinctive experiences and meanings for pre-ulcers and ulcers of BU may clarify the disease burden, illness experience and local perceptions of causes and spread, and environmental features of BU, which are useful to guide public health programmes and future research. This study aimed to explain local meanings and experiences of BU for persons with pre-ulcers and ulcers in the Ga-West and Ga-South municipalities in Accra.

METHODS

Semi-structured interviews based on the Explanatory Model Interview Catalogue framework were administered to 181 respondents comprising 15 respondents with pre-ulcers and 166 respondents with ulcers. The Wilcoxon rank-sum test was used to compare categories of illness experiences (PD) and perceived causes (PC) among respondents with pre-ulcer and ulcer conditions. The Fisher's exact test was used to compare the most troubling PD and the most important PC variables. Qualitative phenomenological analysis of respondents' narratives clarified illness experiences and meanings with reference to PC and PD variables.

RESULTS

Families of respondents with pre-ulcers and the respondents themselves were often anxious about disease progression, while families of respondents with ulcers, who had to give care, worried about income loss and disruption of school attendance. Respondents with pre-ulcers frequently reported swimming in ponds and rivers as a perceived cause and considered it as the most important PC (53.3%). Respondents with ulcers frequently attributed their BU illness to witchcraft (64.5%) and respondents who claimed they had no water contact, questioned the credibility of health messages

CONCLUSIONS

Affected persons with pre-ulcers are likely to delay treatment because of social and financial constraints and the absence of pain. Scepticism on the role of water in disease contagion and prolonged healing is perceived to make ideas of witchcraft as a PC more credible, among respondents with ulcers. Health messages should address issues of locally perceived risk and vulnerability. Guided by study findings, further research on the role of environmental, socio-cultural and genetic factors in BU contagion, is also needed to clarify and formulate health messages and strengthen public health initiatives.

Ecology and transmission of Buruli ulcer disease: a systematic review

Buruli ulcer is a neglected emerging disease that has recently been reported in some countries as the second most frequent mycobacterial disease in humans after tuberculosis. Cases have been reported from at least 32 countries in Africa (mainly west), Australia, Southeast Asia, China, Central and South America, and the Western Pacific. Large lesions often result in scarring, contractual deformities, amputations, and disabilities, and in Africa, most cases of the disease occur in children between the ages of 4-15 years. This environmental mycobacterium, Mycobacterium ulcerans, is found in communities associated with rivers, swamps, wetlands, and human-linked changes in the aquatic environment, particularly those created as a result of environmental disturbance such as deforestation, dam construction, and agriculture. Buruli ulcer disease is often referred to as the "mysterious disease" because the mode of transmission remains unclear, although several hypotheses have been proposed. The above review reveals that various routes of transmission may occur, varying amongst epidemiological setting and geographic region, and that there may be some role for living agents as reservoirs and as vectors of M. ulcerans, in particular aquatic insects, adult mosquitoes or other biting arthropods. We discuss traditional and non-traditional methods for indicting the roles of living agents as biologically significant reservoirs and/or vectors of pathogens, and suggest an intellectual framework for establishing criteria for transmission. The application of these criteria to the transmission of M. ulcerans presents a significant challenge.

Family relationship, water contact and occurrence of Buruli ulcer in Benin

BACKGROUND

Mycobacterium ulcerans disease (Buruli ulcer) is the most widespread mycobacterial disease in the world after leprosy and tuberculosis. How M. ulcerans is introduced into the skin of humans remains unclear, but it appears that individuals living in the same environment may have different susceptibilities.

OBJECTIVES

This study aims to determine whether frequent contacts with natural water sources, family relationship or the practice of consanguineous marriages are associated with the occurrence of Buruli ulcer (BU).

DESIGN

Case control study.

SETTING

Department of Atlantique, Benin.

SUBJECTS

BU-confirmed cases that were diagnosed and followed up at the BU detection and treatment center (CDTUB) of Allada (Department of the Atlantique, Benin) during the period from January 1st, 2006, to June 30th, 2008, with three matched controls (persons who had no signs or symptoms of active or inactive BU) for age, gender and village of residence per case.

MAIN OUTCOMES MEASURED

Contact with natural water sources, BU history in the family and the practice of consanguineous marriages.

RESULTS

A total of 416 participants were included in this study, including 104 cases and 312 controls. BU history in the family (p<0.001), adjusted by daily contact with a natural water source (p = 0.007), was significantly associated with higher odds of having BU (OR; 95% CI = 5.5; 3.0-10.0). The practice of consanguineous marriage was not associated with the occurrence of BU (p = 0.40). Mendelian disorders could explain this finding, which may influence individual susceptibility by impairing immunity.

CONCLUSION

This study suggests that a combination of genetic factors and behavioral risk factors may increase the susceptibility for developing BU.

Seasonal and regional dynamics of M. ulcerans transmission in environmental context: deciphering the role of water bugs as hosts and vectors

BACKGROUND

Buruli ulcer, the third mycobacterial disease after tuberculosis and leprosy, is caused by the environmental mycobacterium M. ulcerans. Various modes of transmission have been suspected for this disease, with no general consensus acceptance for any of them up to now. Since laboratory models demonstrated the ability of water bugs to transmit M. ulcerans, a particular attention is focused on the transmission of the bacilli by water bugs as hosts and vectors. However, it is only through detailed knowledge of the biodiversity and ecology of water bugs that the importance of this mode of transmission can be fully assessed. It is the objective of the work here to decipher the role of water bugs in M. ulcerans ecology and transmission, based on large-scale field studies.

METHODOLOGY/PRINCIPAL FINDINGS

The distribution of M. ulcerans-hosting water bugs was monitored on previously unprecedented time and space scales: a total of 7,407 water bugs, belonging to large number of different families, were collected over one year, in Buruli ulcer endemic and non endemic areas in central Cameroon. This study demonstrated the presence of M. ulcerans in insect saliva. In addition, the field results provided a full picture of the ecology of transmission in terms of biodiversity and detailed specification of seasonal and regional dynamics, with large temporal heterogeneity in the insect tissue colonization rate and detection of M. ulcerans only in water bug tissues collected in Buruli ulcer endemic areas.

CONCLUSION/SIGNIFICANCE

The large-scale detection of bacilli in saliva of biting water bugs gives enhanced weight to their role in M. ulcerans transmission. On practical grounds, beyond the ecological interest, the results concerning seasonal and regional dynamics can provide an efficient tool in the hands of sanitary authorities to monitor environmental risks associated with Buruli ulcer.

Terrestrial small mammals as reservoirs of Mycobacterium ulcerans in benin

Mycobacterium ulcerans, the causative agent of Buruli ulcer (BU), is considered an environmental pathogen. Different mycobacteria were detected in 68 (12%) out of 565 small mammals collected in areas in Benin where BU is endemic. Although M. ulcerans was not found, we suggest that more research on M. ulcerans in African (small) mammals is needed.

Buruli ulcer

Buruli ulcer is an indolent necrotizing disease of the skin, subcutaneous tissue, and bone that is caused by Mycobacterium ulcerans. Buruli ulcer is presently the third most common mycobacterial disease of humans, after tuberculosis and leprosy, and the least understood of the three. The disease remained largely ignored by many national public health programs, but more recently, it has been recognized as an emerging health problem, primarily due to its frequent disabling and stigmatizing complications. The contribution discusses various aspects of Buruli ulcer, including its geographic distribution, incidence, and prevalence; mode of transmission, pathogenesis, and immunity; clinical manifestations; laboratory diagnosis; differential clinical diagnosis; and treatment.

New foci of Buruli ulcer, Angola and Democratic Republic of Congo

We report 3 patients with laboratory-confirmed Buruli ulcer in Kafufu/Luremo, Angola, and Kasongo-Lunda, Democratic Republic of Congo. These villages are near the Kwango/Cuango River, which flows through both countries. Further investigation of artisanal alluvial mining as a risk factor for Buruli ulcer is recommended.

Occurrence of free-living amoebae in communities of low and high endemicity for Buruli ulcer in southern Benin

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.

Setting up a national reference laboratory for Buruli ulcer: the case of Benin

OBJECTIVE

To report the experience of Benin, where Buruli ulcer (BU) is endemic, in the implementation of diagnostic laboratory services.

METHODS AND RESULTS

There has been a gradual introduction of biologic diagnostic activities for BU comprising (1) training of a laboratory technician in a highly experienced reference laboratory; (2) acquiring indispensable laboratory start-up materials; (3) progressive development of diagnostic laboratory activities; (4) regular external quality assessment with an experienced reference laboratory and (5) decentralization of activities to various clinical diagnostic and treatment centres for BU in Benin.

CONCLUSION

Setting up a reference laboratory for BU is a continuous process, which necessitates motivated personnel and the cooperation of an experienced external reference laboratory.

A Landscape-based model for predicting Mycobacterium ulcerans infection (Buruli Ulcer disease) presence in Benin, West Africa

Mycobacterium ulcerans infection (Buruli ulcer [BU] disease) is an emerging tropical disease that causes severe morbidity in many communities, especially those in close proximity to aquatic environments. Research and control efforts are severely hampered by the paucity of data regarding the ecology of this disease; for example, the vectors and modes of transmission remain unknown. It is hypothesized that BU presence is associated with altered landscapes that perturb aquatic ecosystems; however, this has yet to be quantified over large spatial scales. We quantified relationships between land use/land cover (LULC) characteristics surrounding individual villages and BU presence in Benin, West Africa. We also examined the effects of other village-level characteristics which we hypothesized to affect BU presence, such as village distance to the nearest river. We found that as the percent urban land use in a 50-km buffer surrounding a village increased, the probability of BU presence decreased. Conversely, as the percent agricultural land use in a 20-km buffer surrounding a village increased, the probability of BU presence increased. Landscape-based models had predictive ability when predicting BU presence using validation data sets from Benin and Ghana, West Africa. Our analyses suggest that relatively small amounts of urbanization are associated with a decrease in the probability of BU presence, and we hypothesize that this is due to the increased availability of pumped water in urban environments. Our models provide an initial approach to predicting the probability of BU presence over large spatial scales in Benin and Ghana, using readily available land use data.

Buruli ulcer surveillance, Benin, 2003-2005

We reviewed Buruli ulcer (BU) surveillance in Benin, using the World Health Organization BU02 form. We report results of reliable routine data collected on 2,598 new and recurrent cases from 2003 through 2005.

Association between haemoglobin variants S and C and Mycobacterium ulcerans disease (Buruli ulcer): a case-control study in Benin

Risk factors for Buruli ulcer (BU) are poorly understood. We conducted a case-control study in southern Benin to investigate the association between haemoglobin variants S or C and BU, and particularly the association between haemoglobinopathies HbSS/SC and BU osteomyelitis. We compared the haemoglobin genotype of 179 patients with BU and 44 with BU osteomyelitis to that of 242 community controls. We found no evidence of an increased risk of BU according to the presence of haemoglobin variants S and/or C [odds ratio adjusted for sex, age, region of residence and ethnicity: 1.24 (95% CI: 0.80-1.93), P = 0.34]. Haemoglobin variants S and C are unlikely to play a role in the BU burden. However, haemoglobinopathies HbSS/SC were more frequent among BU osteomyelitis patients than among controls (6.8% vs. 1.0%, Fisher's exact P-value = 0.045), which may suggest that those disorders facilitate growth of Mycobacterium ulcerans in the bone matrix.

Risk factors for Buruli ulcer, Benin

We identified risk factors for Buruli ulcer (BU) in Benin in an unmatched case-control study at the Centre Sanitaire et Nutritionnel Gbemoten in southern Benin. A total of 2,399 persons admitted from 1997 through 2003 and 1,444 unmatched patients with other conditions in 2002 were recruited. Adjusted odds ratios were determined for age, sex, place of residence, Mycobacterium bovis BCG vaccination at birth, type of water for domestic use, and occupation. Children <15 years of age and adults >49 years of age had a higher risk for BU. Use of unprotected water from swamps was associated with increased risk for BU; this association was strongest in adults >49 years of age. Sex was not a risk factor for BU. Our data showed that BU was mainly associated with age, place of residence, and water sources in all age groups. Risk for BU was higher in BCG-vaccinated patients > or =5 years of age.

[Distribution of Mycobacterium ulcerans (Buruli ulcer) in the district of Lalo in Benin]

This study aimed to determine the distribution of Buruli ulcer (BU) in Lalo, one of the endemic districts of the Couffo department in Bénin. A total of 752 BU patients were detected in this district with 160 active and 592 inactive cases. The overall prevalence of BU in this district is 86.6 per 10,000 inhabitants, varying from 0 to 249/10,000 between sub-districts. At village level the prevalence varies between 0 and 561 cases per 10,000 inhabitants. Our findings confirm the large variation of distribution of the disease at the village level in endemic area. Children under 15 years are frequently affected. We also found a significant association between age and location of Buruli lesions. Further epidemiological and environmental studies are needed to identify the reasons for the extraordinary variation in BU distribution between villages from the same sub-district, and to confirm if it is associated with temporal variations.

Buruli ulcer recurrence, Benin

Access to high-quality treatment prevents Buruli ulcer recurrence.

Buruli ulcer is a recognized public health problem in West Africa. In Benin, from 1989 to 2001, the Centre Sanitaire et Nutritionnel Gbemoten (CSNG) treated >2,500 Buruli ulcer patients. From March 2000 to February 2001, field trips were conducted in the Zou and Atlantique regions. The choice of the 2 regions was based on the distance from CSNG and on villages with the highest number of patients treated at CSNG. A total of 66 (44.0%) of 150 former patients treated at CSNG were located in the visited villages. The recurrence rate of CSNG-treated patients after a follow-up period of up to 7 years was low (6.1%, 95% confidence interval [CI] 2.0–15.6). We attribute this low rate to the high quality of Buruli ulcer treatment at an accessible regional center (CSNG). The World Health Organization definition of a Buruli ulcer recurrent case should be revised to include a follow-up period >1 year.