Entomological investigations carried out from 2002 to 2010 into the involvement of water bugs (Heteroptera - Hemiptera) in transmission of Mycobacterium ulcerans to humans in Côte d’Ivoire (West Africa)

Ulcer is a disease caused by a mycobacterium present in the environment: Mycobacterium ulcerans.This communicable disease occurs essentially in wet tropical regions, and in particular in west Africa where it is endemic. It is the third most common mycobacterial disease affecting humans after leprosy and tuberculosis, although it is more prevalent than either leprosy or tuberculosis in some rural areas of several countries (Benin, Côte d’Ivoire and Ghana). This has led WHO to act, and in 1998 to declare Buruli ulcer an « emerging disease » and to recognize it as a neglected tropical disease. Its development is a source of concern in Côte d’Ivoire, the country most affected in the world, with an aggregate number of 30 000 cases and more than 2000 cases detected each year. It particularly affects children living in isolated rural areas around bodies of stagnant or slowly flowing water.  In order to control the disease, it is essential fully to understand its epidemiology. In this connection, there are several hypotheses on the mode of transmission of M. ulcerans to humans. Since 1999, the involvement of water bugs belonging to the order of the hemiptera has been invoked by Portaels. In 2002, this hypothesis was confirmed by Marsollier et al. for water bugs of the genus Naucoris taken from the region of Daloa in Côte d’Ivoire, where the disease is endemic. In 2008, Portaels also found M. ulcerans in samples taken from the environment (Gerridae) in Ghana. In 2007, studies began in Côte d’Ivoire into the specific diversity, biology, ecology, ethology and role of aquatic heteroptera in the transmission of M. ulcerans to humans. Samples of aquatic heteroptera were collected each month from different aquatic environments in endemic areas of Côte d’Ivoire. The insects were identified by family, genus and occasionally species. Their distribution, population dynamics and ecological distribution in the water points investigated were correlated with human activities. Monospecific batches of water bugs were regularly composed in order to identify the molecular signatures of M. ulcerans using PCR at the bacteriology laboratory of the Institut Pasteur in Côte d’Ivoire and at the bacteriology laboratory of the Groupe d’Etudes des Interactions Hôtes-Pathogènes (Host-Pathogen Study Group) at the University Teaching hospital in Angers, France. Eighteen (18) species belonging to 8 families were identified. After the aquatic insects collected had been identified, 283 monospecific batches were composed and sent to the Institut Pasteur in Côte d’Ivoire (IPCI) for PCR. Twenty four (24) of the 283 batches i.e. 8,5% containing the following, 14 Diplonychus sp, 2 Naucoris sp, 3 Micronecta sp, 2 Ranatra fusca, 2 Anisops sp and 1 Laccotrephes ater, respectively belonging to the families Belostomatidae, Naucoridae, Corixidae, Ranatridae and Nepidae tested positive under PCR. Thirty five (35) samples of saliva were collected from specimens of the genus Diplonychus. Six of the samples (i.e. 17%) tested positive under PCR. Out of 109 other monospecific batches sent to the laboratory in Angers, France, 33 (i.e. 30%) tested positive under PCR. They comprised 11 batches of Diplonychus sp (Belostomatidae), 8 batches of Micronecta sp (Corixidae), 2 batches of Laccocoris sp (Naucoridae), 4 batches of Ranatra fusca (Ranatridae), 3 batches of Anisops sp, 1 lot de Anisops sardea et 1 lot de Enithares sp (Notonectidae), 2 batches of Plea pullula (Pleidae) and 1 batch of de Laccotrephes sp (Nepidae). Clearly, not only is Diplonychus sp the genus most commonly found, it is also that most affected by M. ulcerans. This justifies the decision to breed this genus in the laboratory since 2008, in order to improve our understanding of its biology and ethology and to standardize physical and chemical parameters so as to determine the best conditions for breeding the insect which would provide an animal model for experimental infections. We have now bred six successive generations in the laboratory. To conclude, although some aquatic heteroptera that host M. ulcerans are strictly phytophagous, (e.g. the Corixidae), the great majority of water bugs are carnivorous predators that are hosts and vectors of M. ulcerans. The absence of a reliable key for determining the family, genus and species in central and west Africa has led us to draw up an iconographic catalogue to determine the taxonomy of these insects

Biodiversity and implication of waters bugs in transmission of Mycobacterium ulcerans, etiological agent of Buruli ulcer in Côte d’Ivoire (West Africa)

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

Differential Expression of Iron Acquisition Genes by Brucella melitensis and Brucella canis during Macrophage Infection

Brucella spp. cause chronic zoonotic disease often affecting individuals and animals in impoverished economic or public health conditions; however, these bacteria do not have obvious virulence factors. Restriction of iron availability to pathogens is an effective strategy of host defense. For brucellae, virulence depends on the ability to survive and replicate within the host cell where iron is an essential nutrient for the growth and survival of both mammalian and bacterial cells. Iron is a particularly scarce nutrient for bacteria with an intracellular lifestyle. Brucella melitensis and Brucella canis share ∼99% of their genomes but differ in intracellular lifestyles. To identify differences, gene transcription of these two pathogens was examined during infection of murine macrophages and compared to broth grown bacteria. Transcriptome analysis of B. melitensis and B. canis revealed differences of genes involved in iron transport. Gene transcription of the TonB, enterobactin, and ferric anguibactin transport systems was increased in B. canis but not B. melitensis during infection of macrophages. The data suggest differences in iron requirements that may contribute to differences observed in the lifestyles of these closely related pathogens. The initial importance of iron for B. canis but not for B. melitensis helps elucidate differing intracellular survival strategies for two closely related bacteria and provides insight for controlling these pathogens

Gene Expression in Skeletal Muscle Biopsies from People with Type 2 Diabetes and Relatives: Differential Regulation of Insulin Signaling Pathways

BACKGROUND:Gene expression alterations have previously been associated with type 2 diabetes, however whether these changes are primary causes or secondary effects of type 2 diabetes is not known. As healthy first degree relatives of people with type 2 diabetes have an increased risk of developing type 2 diabetes, they provide a good model in the search for primary causes of the disease. METHODS/PRINCIPAL FINDINGS:We determined gene expression profiles in skeletal muscle biopsies from Caucasian males with type 2 diabetes, healthy first degree relatives, and healthy controls. Gene expression was measured using Affymetrix Human Genome U133 Plus 2.0 Arrays covering the entire human genome. These arrays have not previously been used for this type of study. We show for the first time that genes involved in insulin signaling are significantly upregulated in first degree relatives and significantly downregulated in people with type 2 diabetes. On the individual gene level, 11 genes showed altered expression levels in first degree relatives compared to controls, among others KIF1B and GDF8 (myostatin). LDHB was found to have a decreased expression in both groups compared to controls. CONCLUSIONS/SIGNIFICANCE:We hypothesize that increased expression of insulin signaling molecules in first degree relatives of people with type 2 diabetes, work in concert with increased levels of insulin as a compensatory mechanism, counter-acting otherwise reduced insulin signaling activity, protecting these individuals from severe insulin resistance. This compensation is lost in people with type 2 diabetes where expression of insulin signaling molecules is reduced

Risk factors for Buruli ulcer in Côte d’Ivoire: Results of a case-control study, August 2001

A case-control study was carried out in 3 highly endemic regions of Côte d’Ivoire to study risk factors for Buruli ulcer. A case was defined as a Buruli ulcer occurring less than one year before the date ofsurvey, resident in one of the regions investigated and there was no history of Buruli ulcer illness. Controls were selected from the general population by a two stage cluster sampling method. A total of116 cases and 116 controls were included. For the cases, the male/female sex ratio was 0.84, the median age was 19.5 years and 40.5% were children 15 years. Biological results were obtained for 86 (74%) cases using skin exudate samples. Positive rates were 22.0, 22.1 and 27.9% respectively for smear examination, culture and PCR IS2404, respectively. After adjusting for possible confounders, nohistory of BCG vaccination (ORa = 5.0, CI 1.7 - 14.3), presence of a case 15 years (ORa = 8.3, CI 2.8 -24.1), having a river/lake/dam near the housing (ORa = 4.4, CI 1.6 - 12.2) and the type of place for fishing (p = 0.001) were associated with illness. Young children and women having daily water related activities were most at risk. Swab samples were not sensitive enough for Buruli ulcer diagnosis. There is an urgent need for a rapid field test to diagnosis Buruli Ulcer as PCR IS2404 remains expensive for most of the endemic countries

[Qnr-type quinolone resistance in extended-spectrum beta-lactamase producing enterobacteria in Abidjan, Ivory Coast].

International audienceThe aim of the study was to show the emergence of the qnr genes in extended spectrum beta-lactamases producing enterobacteria in Abidjan between 2005 and 2006. The whole of 151 strains of extended spectrum beta-lactamases producing enterobacteria were studied: 64 Escherichia coli, 66 Klebsiella pneumoniae, seven Klebsiella oxytoca and 14 Enterobacter spp. isolated from various biological products and from in- and out-patients. The techniques of disks diffusion, double-disk synergy, E-test were respectively used for the antimicrobial susceptibility test, the detection of extended spectrum beta-lactamases and the minimal inhibiting concentration. The bla genes(SHV, TEM, CTXM groups 1, 2, 8, 9), and AmpC were determined by PCR and characterized by sequencing. A global prevalence of 27,2 % (41/151) and rates of 9,9, 14,6, 2,7 % for the qnr genes A, B, A and S were observed. The distribution was 42,9 % for Enterobacter spp, 31,2 % for Escherichia coli, 20,5 % for Klebsiella; 30 strains expressed at least two bla genes; four strains were associated with AmpC. The strains were resistant to the cotrimoxazole (97,6 %), to the céfépime (73,2 %), to the céfoxitine (56,1 %), to the imipénème (0 %) and 43,9 % to all the aminosides. This high qnr gene prevalence associated with several types of bla genes in epidemic matter, the high level of resistance to antibiotics make fear a high risk of the transmission of multi-resistants bacteria and challenge the authorities for a resistance monitoring policy