Center International Of Recherches Medicales Of Franceville

Franceville, Gabon

Center International Of Recherches Medicales Of Franceville

Franceville, Gabon
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Rougeron V.,Center International Of Recherches Medicales Of Franceville | Rougeron V.,IRD Montpellier | Sam I.-C.,University of Malaya | Caron M.,Center International Of Recherches Medicales Of Franceville | And 5 more authors.
Journal of Clinical Virology | Year: 2015

Chikungunya virus (CHIKV) is an alphavirus of the Togaviridae family that causes chronic and incapacitating arthralgia in human populations. Since its discovery in 1952, CHIKV was responsible for sporadic and infrequent outbreaks. However, since 2005, global Chikungunya outbreaks have occurred, inducing some fatalities and associated with severe and chronic morbidity. Chikungunya is thus considered as an important re-emerging public health problem in both tropical and temperate countries, where the distribution of the Aedes mosquito vectors continues to expand. This review highlights the most recent advances in our knowledge and understanding of the epidemiology, biology, treatment and vaccination strategies of CHIKV. © 2014 Elsevier B.V.

Kamgang B.,Institute Pasteur Of Bangui | Ngoagouni C.,Institute Pasteur Of Bangui | Manirakiza A.,Institute Pasteur Of Bangui | Nakoune E.,Institute Pasteur Of Bangui | And 3 more authors.
PLoS Neglected Tropical Diseases | Year: 2013

The invasive Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) was first reported in central Africa in 2000, in Cameroon, with the indigenous mosquito species Ae. aegypti (Diptera: Culicidae). Today, this invasive species is present in almost all countries of the region, including the Central African Republic (CAR), where it was first recorded in 2009. As invasive species of mosquitoes can affect the distribution of native species, resulting in new patterns of vectors and concomitant risk for disease, we undertook a comparative study early and late in the wet season in the capital and the main cities of CAR to document infestation and the ecological preferences of the two species. In addition, we determined the probable geographical origin of invasive populations of Ae. albopictus with two mitochondrial DNA genes, COI and ND5. Analysis revealed that Ae. aegypti was more abundant earlier in the wet season and Ae. albopictus in the late wet season. Used tyres were the most heavily colonized productive larval habitats for both species in both seasons. The invasive species Ae. albopictus predominated over the resident species at all sites in which the two species were sympatric. Mitochondrial DNA analysis revealed broad low genetic diversity, confirming recent introduction of Ae. albopictus in CAR. Phylogeographical analysis based on COI polymorphism indicated that the Ae. albopictus haplotype in the CAR population segregated into two lineages, suggesting multiple sources of Ae. albopictus. These data may have important implications for vector control strategies in central Africa. © 2013 Kamgang et al.

Ayala D.,IRD Montpellier | Ayala D.,Center International Of Recherches Medicales Of Franceville | Ullastres A.,University Pompeu Fabra | Gonzalez J.,University Pompeu Fabra
Frontiers in Genetics | Year: 2014

Chromosomal inversions have been repeatedly involved in local adaptation in a large number of animals and plants. The ecological and behavioral plasticity of Anopheles species-human malaria vectors-is mirrored by high amounts of polymorphic inversions. The adaptive significance of chromosomal inversions has been consistently attested by strong and significant correlations between their frequencies and a number of phenotypic traits. Here, we provide an extensive literature review of the different adaptive traits associated with chromosomal inversions in the genus Anopheles. Traits having important consequences for the success of present and future vector control measures, such as insecticide resistance and behavioral changes, are discussed. © 2014 Ayala, Ullastres and González.

Grard G.,Center International Of Recherches Medicales Of Franceville | Caron M.,Center International Of Recherches Medicales Of Franceville | Caron M.,IRD Montpellier | Mombo I.M.,Center International Of Recherches Medicales Of Franceville | And 8 more authors.
PLoS Neglected Tropical Diseases | Year: 2014

Background:Chikungunya and dengue viruses emerged in Gabon in 2007, with large outbreaks primarily affecting the capital Libreville and several northern towns. Both viruses subsequently spread to the south-east of the country, with new outbreaks occurring in 2010. The mosquito species Aedes albopictus, that was known as a secondary vector for both viruses, recently invaded the country and was the primary vector involved in the Gabonese outbreaks. We conducted a retrospective study of human sera and mosquitoes collected in Gabon from 2007 to 2010, in order to identify other circulating arboviruses.Methodology/Principal Findings:Sample collections, including 4312 sera from patients presenting with painful febrile disease, and 4665 mosquitoes belonging to 9 species, split into 247 pools (including 137 pools of Aedes albopictus), were screened with molecular biology methods. Five human sera and two Aedes albopictus pools, all sampled in an urban setting during the 2007 outbreak, were positive for the flavivirus Zika (ZIKV). The ratio of Aedes albopictus pools positive for ZIKV was similar to that positive for dengue virus during the concomitant dengue outbreak suggesting similar mosquito infection rates and, presumably, underlying a human ZIKV outbreak. ZIKV sequences from the envelope and NS3 genes were amplified from a human serum sample. Phylogenetic analysis placed the Gabonese ZIKV at a basal position in the African lineage, pointing to ancestral genetic diversification and spread.Conclusions/Significance:We provide the first direct evidence of human ZIKV infections in Gabon, and its first occurrence in the Asian tiger mosquito, Aedes albopictus. These data reveal an unusual natural life cycle for this virus, occurring in an urban environment, and potentially representing a new emerging threat due to this novel association with a highly invasive vector whose geographic range is still expanding across the globe. © 2014 Grard et al.

Becquart P.,IRD Montpellier | Becquart P.,Center International Of Recherches Medicales Of Franceville | Mahlakoiv T.,Center International Of Recherches Medicales Of Franceville | Nkoghe D.,Center International Of Recherches Medicales Of Franceville | And 2 more authors.
PLoS ONE | Year: 2014

Ebola virus (EBOV) is a highly virulent human pathogen. Recovery of infected patients is associated with efficient EBOV-specific immunoglobulin G (IgG) responses, whereas fatal outcome is associated with defective humoral immunity. As B-cell epitopes on EBOV are poorly defined, we sought to identify specific epitopes in four EBOV proteins (Glycoprotein (GP), Nucleoprotein (NP), and matrix Viral Protein (VP)40 and VP35). For the first time, we tested EBOV IgG+ sera from asymptomatic individuals and symptomatic Gabonese survivors, collected during the early humoral response (seven days after the end of symptoms) and the late memory phase (7-12 years post-infection). We also tested sera from EBOV-seropositive patients who had never had clinical signs of hemorrhagic fever or who lived in non-epidemic areas (asymptomatic subjects). We found that serum from asymptomatic individuals was more strongly reactive to VP40 peptides than to GP, NP or VP35. Interestingly, anti-EBOV IgG from asymptomatic patients targeted three immunodominant regions of VP40 reported to play a crucial role in virus assembly and budding. In contrast, serum from most survivors of the three outbreaks, collected a few days after the end of symptoms, reacted mainly with GP peptides. However, in asymptomatic subjects the longest immunodominant domains were identified in GP, and analysis of the GP crystal structure revealed that these domains covered a larger surface area of the chalice bowl formed by three GP1 subunits. The B-cell epitopes we identified in the EBOV VP35, VP40, NP and GP proteins may represent important tools for understanding the humoral response to this virus and for developing new antibody-based therapeutics or detection methods. © 2014 Becquart et al.

Rougeron V.,French National Center for Scientific Research | Rougeron V.,Center International Of Recherches Medicales Of Franceville | De MeeUs T.,CIRDES Center International Of Recherche Développement Sur L'elevage En Zone Sub Humide | Banuls A.-L.,French National Center for Scientific Research
Trends in Parasitology | Year: 2015

Leishmaniases remain a major public health problem. Despite the development of elaborate experimental techniques and sophisticated statistical tools, how these parasites evolve, adapt themselves to new environmental compartments and hosts, and develop resistance to new drugs remains unclear. Leishmania parasites constitute a complex model from a biological, ecological, and epidemiological point of view but also with respect to their genetics and phylogenetics. With this in view, we seek to outline the criteria, caveats, and confounding factors to be considered for Leishmania population genetic studies. We examine how the taxonomic complexity, heterozygosity, intraspecific and interspecific recombination, aneuploidy, and ameiotic recombination of Leishmania intersect with population genetic studies of this parasite. © 2014 Elsevier Ltd.

Despite progress in the control of malaria, it remains a serious public health problem. Substantial declines in malaria transmission, morbidity and mortality have nonetheless been reported in several countries where new malaria control strategies have been implemented. We conducted this molecular and epidemiological analysis of malaria in the pediatric department of the Chinese-Gabon Friendship Hospital (HCGC) in Franceville in 2010. Franceville is the third largest town in Gabon, and malaria transmission is high year-round. We included 945 children, 756 of them febrile. Malaria was diagnosed based on the detection of P. falciparum in thick blood films, with Lambarene's method. Malaria prevalence among the febrile children included in this study was 17.9% (n=135). The burden of malaria is thus lower than in the past; it is now the second leading cause of pediatric hospital visits, rather than the leading cause as it was in 2004. The children's mean age was 48.5 ± 3.9 months, older than in 2004 (p<0.05). We also analysed the molecular drug resistance marker, Pfmdr1. The prevalence of the wild-type genotype N86 of Pfmdr1 was 47.4% (n=64), higher than in 2004 (p<0.001). The increased prevalence of codon 1246 was not significant. Socio-economic factors and known malaria risk factors were analysed. We found that the use of Insecticide-treated mosquito nets and the provision of information (education or communication) to parents and guardians about malaria were protective factors against the disease. In conclusion, a larger study of the entire region over a longer period is necessary to characterise malaria in Franceville today. Transmission factors must also be studied.

Le Flohic G.,Center International Of Recherches Medicales Of Franceville | Porphyre V.,CIRAD - Agricultural Research for Development | Barbazan P.,Institute Of Recherche Pour Le Developpement | Gonzalez J.-P.,Center International Of Recherches Medicales Of Franceville | And 2 more authors.
PLoS Neglected Tropical Diseases | Year: 2013

The Japanese encephalitis virus (JEV), an arthropod-born Flavivirus, is the major cause of viral encephalitis, responsible for 10,000-15,000 deaths each year, yet is a neglected tropical disease. Since the JEV distribution area has been large and continuously extending toward new Asian and Australasian regions, it is considered an emerging and reemerging pathogen. Despite large effective immunization campaigns, Japanese encephalitis remains a disease of global health concern. JEV zoonotic transmission cycles may be either wild or domestic: the first involves wading birds as wild amplifying hosts; the second involves pigs as the main domestic amplifying hosts. Culex mosquito species, especially Cx. tritaeniorhynchus, are the main competent vectors. Although five JEV genotypes circulate, neither clear-cut genotype-phenotype relationship nor clear variations in genotype fitness to hosts or vectors have been identified. Instead, the molecular epidemiology appears highly dependent on vectors, hosts' biology, and on a set of environmental factors. At global scale, climate, land cover, and land use, otherwise strongly dependent on human activities, affect the abundance of JEV vectors, and of wild and domestic hosts. Chiefly, the increase of rice-cultivated surface, intensively used by wading birds, and of pig production in Asia has provided a high availability of resources to mosquito vectors, enhancing the JEV maintenance, amplification, and transmission. At fine scale, the characteristics (density, size, spatial arrangement) of three landscape elements (paddy fields, pig farms, human habitations) facilitate or impede movement of vectors, then determine how the JEV interacts with hosts and vectors and ultimately the infection risk to humans. If the JEV is introduced in a favorable landscape, either by live infected animals or by vectors, then the virus can emerge and become a major threat for human health. Multidisciplinary research is essential to shed light on the biological mechanisms involved in the emergence, spread, reemergence, and genotypic changes of JEV. © 2013 Le Flohic et al.

Wauquier N.,Center International Of Recherches Medicales Of Franceville | Becquart P.,Center International Of Recherches Medicales Of Franceville | Becquart P.,Aix - Marseille University | Padilla C.,Center International Of Recherches Medicales Of Franceville | And 3 more authors.
PLoS Neglected Tropical Diseases | Year: 2010

Background: Ebolavirus species Zaire (ZEBOV) causes highly lethal hemorrhagic fever, resulting in the death of 90% of patients within days. Most information on immune responses to ZEBOV comes from in vitro studies and animal models. The paucity of data on human immune responses to this virus is mainly due to the fact that most outbreaks occur in remote areas. Published studies in this setting, based on small numbers of samples and limited panels of immunological markers, have given somewhat different results. Methodology/Principal Findings: Here, we studied a unique collection of 56 blood samples from 42 nonsurvivors and 14 survivors, obtained during the five outbreaks that occurred between 1996 and 2003 in Gabon and Republic of Congo. Using Luminex technology, we assayed 50 cytokines in all 56 samples and performed phenotypic analyses by flow cytometry. We found that fatal outcome was associated with hypersecretion of numerous proinflammatory cytokines (IL-1β, IL-1RA, IL-6, IL-8, IL-15 and IL-16), chemokines and growth factors (MIP-1α, MIP-1β, MCP-1, M-CSF, MIF, IP-10, GRO-α and eotaxin). Interestingly, no increase of IFNa2 was detected in patients. Furthermore, nonsurvivors were also characterized by very low levels of circulating cytokines produced by T lymphocytes (IL-2, IL-3, IL-4, IL-5, IL-9, IL-13) and by a significant drop of CD3+CD4+ and CD3+CD8+ peripheral cells as well as a high increase in CD95 expression on T lymphocytes. Conclusions/Significance: This work, the largest study to be conducted to date in humans, showed that fatal outcome is associated with aberrant innate immune responses and with global suppression of adaptive immunity. The innate immune reaction was characterized by a "cytokine storm," with hypersecretion of numerous proinflammatory cytokines, chemokines and growth factors, and by the noteworthy absence of antiviral IFNα2. Immunosuppression was characterized by very low levels of circulating cytokines produced by T lymphocytes and by massive loss of peripheral CD4 and CD8 lymphocytes, probably through Fas/FasL-mediated apoptosis. © 2010 Wauquier et al.

Leroy E.M.,Center International Of Recherches Medicales Of Franceville | Leroy E.M.,Montpellier University | Gonzalez J.-P.,Center International Of Recherches Medicales Of Franceville | Baize S.,Institute Pasteur Paris
Clinical Microbiology and Infection | Year: 2011

Ebola and Marburg viruses are the only members of the Filoviridae family (order Mononegavirales), a group of viruses characterized by a linear, non-segmented, single-strand negative RNA genome. They are among the most virulent pathogens for humans and great apes, causing acute haemorrhagic fever and death within a matter of days. Since their discovery 50years ago, filoviruses have caused only a few outbreaks, with 2317 clinical cases and 1671 confirmed deaths, which is negligible compared with the devastation caused by malnutrition and other infectious diseases prevalent in Africa (malaria, cholera, AIDS, dengue, tuberculosis ...). Yet considerable human and financial resourses have been devoted to research on these viruses during the past two decades, partly because of their potential use as bioweapons. As a result, our understanding of the ecology, host interactions, and control of these viruses has improved considerably. © 2011 The Authors. Clinical Microbiology and Infection © 2011 European Society of Clinical Microbiology and Infectious Diseases.

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