Report on laboratory confirmation of Buruli ulcer cases in Congo-Brazzaville

In 2009, 87 diagnostic samples (corresponding to 78 patients suspected of M. ulcerans infection) from Congo Brazzaville were subjected to IS2404 PCR at the Centre Hospitalier Universitaire of Angers. 38 samples (corresponding to 32 patients) were confirmed positive to M. ulcerans infection by PCR

First Detection of Mycobacterium ulcerans DNA in Environmental Samples from South America

The occurrences of many environmentally-persistent and zoonotic infections are driven by ecosystem changes, which in turn are underpinned by land-use modifications that alter the governance of pathogen, biodiversity and human interactions. Our current understanding of these ecological changes on disease emergence however remains limited. Buruli ulcer is an emerging human skin disease caused by the mycobacterium, Mycobacterium ulcerans, for which the exact route of infection remains unclear. It can have a devastating impact on its human host, causing extensive necrosis of the skin and underlying tissue, often leading to permanent disability. The mycobacterium is associated with tropical aquatic environments and incidences of the disease are significantly higher on floodplains and where there is an increase of human aquatic activities. Although the disease has been previously diagnosed in South America, until now the presence of M. ulcerans DNA in the wild has only been identified in Australia where there have been significant outbreaks and in western and central regions of Africa where the disease is persistent. Here for the first time, we have identified the presence of the aetiological agent's DNA in environmental samples from South America. The DNA was positively identified using Real-time Polymerase Chain Reaction (PCR) on 163 environmental samples, taken from 23 freshwater bodies in French Guiana (Southern America), using primers for both IS2404 and for the ketoreductase-B domain of the M. ulcerans mycolactone polyketide synthase genes (KR). Five samples out of 163 were positive for both primers from three different water bodies. A further nine sites had low levels of IS2404 close to a standard CT of 35 and could potentially harbour M. ulcerans. The majority of our positive samples (8/14) came from filtered water. These results also reveal the Sinnamary River as a potential source of infection to humans. © 2014 Morris et al

Mycobacterium ulcerans disease (Buruli ulcer) in Mali, a new potential African endemic country

International audienc

Survey of aquatic bugs' species in Bankim, a new endemic area in Cameroon

Bankim district located in the Northern part of Cameroon (Adamaoua region: N 06°04\u2705" E 10°27\u2737"), has been recently described as a new endemic site in Cameroon. This region benefited from the construction of a dam which considerably modified the environment. Previous collections of some aquatic bugs in this region were shown positive for M. ulcerans. But aquatic bugs’ biodiversity and biology still poorly documented. In the afore-mentioned context the present study was carried out to identify the commonly occurring medium and large size aquatic bugs fauna and workout their relative abundance, diversity  according to type of water bodies and comparing with those trap in the night by light trap.  Insects were collected daily from June 1st to June 30 2010 in ponds formed around dam flooded area, in streams and a river. Light traps made up of a 250 W bulb connected to an electrical generator put in front of a white sheet, were installed from 6 PM to 11PM during one lunar cycle, in 3 sites (near the dam, near habitations and in the forest) in the same month.  We collected 338 aquatic bugs in different water bodies belonging to 6 families. Belostomatidae was numerically the most abundant group constituting of 33.13 % of the total aquatic insects followed by Naucoridae, Ranatridae (27.81%, 18.63%).  The other families identified were Nepidae, Notonectidae, and of Gerridae representing respectively 9.46%, 5.91% and 5.02%. All families identified were present in streams and ponds but only two families (Ranatridae and Nepidae) were collected in the river;  Among these 338 aquatic bugs, 59.17% (200) were collected in the streams, 38.16% (129) in the ponds and only 9 (2.66%) in the river. Through the light trap only 2 families were identified among a total of 390 aquatic bugs caught. Belostomatidae , predominant with 80.51% and Notonectidae 19.49%. Notonectidae were caught all along the month and during the full moon, but Belostomatidae were absent during full moon. According to the site of collection, we obtained 25.64% (100) of Belostomatidae and 11.94% (46) of Notonectidae near the dam; near habitations 21.53% (84) of Belostomatidae and 2.56% (10) of Notonectidae and in the forest, 33.33% (130) of Belostomatidae and 5.12% (20) of Notonectidae. This preliminary entomological survey shows the variation of aquatic bugs\u27 diversity according to the types of water bodies in the same endemic region and according to light attraction and the moon phases.

Troisième cours international portant sur la microbiologie de M. ulcerans (M2U) à Yaoundé

International audienc

M. ulcerans infection diagnosis by fine needle aspiration

Date du colloque&nbsp;: 04/2009</p

Seasonal and Regional Dynamics of M. ulcerans Transmission in Environmental Context: Deciphering the Role of Water Bugs as Hosts and Vectors

Buruli ulcer, caused by Mycobacterium ulcerans, is a devastating skin disease. Most cases of Buruli ulcer occur in poor rural communities. As a result, treatment is frequently sought too late and about 25% of those infected—particularly children—become permanently disabled. Outbreaks of Buruli ulcer have always been associated with swampy areas. However, the route(s) of bacillus transmission is (are) still unclear. This Mycobacterium species resides in water where it colonizes many ecological niches such as aquatic plants, herbivorous animals and predatory/carnivorous insects. For several years the role of water bugs as hosts and vectors of M. ulcerans was suspected and was demonstrated under laboratory conditions. The aim of this work was to further assess the role of water bugs as hosts and vectors of M. ulcerans in environmental context. This work identifies several water bug families as hosts of M. ulcerans in Buruli ulcer endemic area. The detection of bacilli in saliva of human biting insects provides further evidence for their role in M. ulcerans transmission. Interestingly, three of these insects are good flyers, and as such could participate in M. ulcerans dissemination

Report of the laboratory confirmation of cases from the CDTUB Pobé, Benin

In 2009, 420 diagnostic samples (corresponding to 301 patients suspected of M. ulcerans infection) from the Centre de Dépistage et de Traitement de l’Ulcère de Buruli of Benin were subjected to IS2404 PCR at the Centre Hospitalier Universitaire of Angers. 180 samples (corresponding to 141 patients) were confirmed positive to M. ulcerans infection by PCR

High throughput screening for identification of mycolactone targets : Relations between M. ulcerans and nervous system

Buruli ulcer is an infectious disease transmitted by arthropod vectors harboring Mycobacterium ulcerans, a mycobacterium which belong to the same family of bacteria causing tuberculosis and leprosy. The infection causes painless swelling and severe skin lesions. One key feature of M. ulcerans bacterium is its ability to secrete a necrotic toxin, the mycolactone within small lipophilic vesicles, which are critical for the bacterial induced cytotoxicity. The biological knowledge as well as the preventive and therapeutic means for this invalidating disease is still very limited.   Our first approach was to investigate whether the mycolactone toxin could be involved in the neutralization of pain by acting directly on the peripheral nervous system without causing destruction of nervous fibers. By use of live time fluorescence microscopy and appropriate markers, we showed that the addition of toxin at sub-toxic dose provokes modification of ionic currents of neuron cells. Based on this ability of the toxin, a molecular high throughput methodology was developed for the screening of a genome wide siRNA library and small molecules inhibitors to enable the search of the cellular targets for the toxin. The cell-based assay relies on automated confocal microscopy on macrophages coupled with dedicated image analysis. These two screening allowed us to identify a putative toxin target, and a toxin inhibitor. A binding assay confirmed that the putative target is a receptor of the toxin. Together these results allowed us to build a potential signaling pathway activated by the mycolactone and implicated in ionic channel activities.   The second approach was to confirm this model in the mouse model of M. ulcerans infection and its role in the hypoesthesia of the lesions. Toxin inhibitor, daily administered to mice, which were experimentally infected by M. ulcerans, conducted to the absence of the hypoesthesia of the lesions. Furthermore, a histological study of neuronal fibers did not show a destruction of neuronal cells. Moreover, in vitro studies have showed that M. ulcerans are able to colonize neuronal cells. Then, these results suggested that the hypoesthesia of the M. ulcerans lesions could be caused by a non-destructive process of nervous cells.

Deforestation-driven food-web collapse linked to emerging tropical infectious disease, Mycobacterium ulcerans.

Generalist microorganisms are the agents of many emerging infectious diseases (EIDs), but their natural life cycles are difficult to predict due to the multiplicity of potential hosts and environmental reservoirs. Among 250 known human EIDs, many have been traced to tropical rain forests and specifically freshwater aquatic systems, which act as an interface between microbe-rich sediments or substrates and terrestrial habitats. Along with the rapid urbanization of developing countries, population encroachment, deforestation, and land-use modifications are expected to increase the risk of EID outbreaks. We show that the freshwater food-web collapse driven by land-use change has a nonlinear effect on the abundance of preferential hosts of a generalist bacterial pathogen, Mycobacterium ulcerans. This leads to an increase of the pathogen within systems at certain levels of environmental disturbance. The complex link between aquatic, terrestrial, and EID processes highlights the potential importance of species community composition and structure and species life history traits in disease risk estimation and mapping. Mechanisms such as the one shown here are also central in predicting how human-induced environmental change, for example, deforestation and changes in land use, may drive emergence