Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Plasmodium vivax malaria is an important public health issue in the Amazon region, and it accounts for approximately 84 % of cases of the disease. Migration across the border between Brazil and French Guiana contributes to the maintenance of the disease. The aim of this study was to evaluate the therapeutic and parasitological responses of patients with P. vivax malaria treated with chloroquine and primaquine in the socio-environmental context of cross-border interactions between Brazil and French Guiana. The factors controlled were diagnostic agreement, adherence, adjustment of primaquine doses for patient weight, and quality of the drugs used. A prospective study was conducted in 2011 with 103 individuals aged 10-60 years with a positive diagnosis of P. vivax treated with chloroquine (10 mg base/kg on the first day, followed by 7.5 mg/kg on the second and third days) and primaquine for 7 days, who were followed for 28 days. The primaquine doses were adjusted for the patients' weight. A number of factors were determined: epidemiological characteristics, origin of patients, signs and symptoms, initial parasitaemia and parasitaemia clearance time, blood concentrations of chloroquine and primaquine, quality of anti-malarial drugs and diagnostic agreement. Ninety-five patients were followed for 28 days. There was a 100 % agreement in microscopic diagnosis between field laboratory and reference centre. The adhesion to the treatment was 100 %. Of these patients, 32.6 % received a weight-adjusted dose of primaquine. The chloroquine and primaquine tablets were consistent with the optimal quality limits for human consumption. The investigated patients achieved optimal blood exposure to anti-malarial drugs. The parasitological and therapeutic response was adequate in 99.0 % of cases. In the municipality of Oiapoque, the therapeutic regime used for the treatment of P. vivax malaria using chloroquine combined with primaquine remains effective, when external factors are controlled, such as the quality of anti-malarial drugs, the adhesion to the treatment prescribed, the correct diagnostic and the adjustment of primaquine dose for patient body weight.
ISSN: 1475-2875

Droits : http://creativecommons.org/licenses/by/
pasteur-01229355
https://hal-pasteur.archives-ouvertes.fr/pasteur-01229355
https://hal-pasteur.archives-ouvertes.fr/pasteur-01229355/document
https://hal-pasteur.archives-ouvertes.fr/pasteur-01229355/file/s12936-015-0925-7.pdf
PUBMEDCENTRAL : PMC4600333

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
BACKGROUND: Dengue and malaria are two major public health concerns in tropical settings. Although the pathogeneses of these two arthropod-borne diseases differ, their clinical and biological presentations are unspecific. During dengue epidemics, several hundred patients with fever and diffuse pain are weekly admitted at the emergency room. It is difficult to discriminate them from patients presenting malaria attacks. Furthermore, it may be impossible to provide a parasitological microscopic examination for all patients. This study aimed to establish a diagnostic algorithm for communities where dengue fever and malaria occur at some frequency in adults. METHODOLOGY/PRINCIPAL FINDINGS: A sub-study using the control groups of a case-control study in French Guiana - originally designed to compare dengue and malaria co-infected cases to single infected cases - was performed between 2004 and 2010. In brief, 208 patients with malaria matched to 208 patients with dengue fever were compared in the present study. A predictive score of malaria versus dengue was established using .632 bootstrap procedures. Multivariate analysis showed that male gender, age, tachycardia, anemia, thrombocytopenia, and CRP>5 mg/l were independently associated with malaria. The predictive score using those variables had an AUC of 0.86 (95%CI: 0.82-0.89), and the CRP was the preponderant predictive factor. The sensitivity and specificity of CRP>5 mg/L to discriminate malaria from dengue were of 0.995 (95%CI: 0.991-1) and 0.35 (95%CI 0.32-0.39), respectively. CONCLUSIONS/SIGNIFICANCE: The clinical and biological score performed relatively well for discriminating cases of dengue versus malaria. Moreover, using only the CRP level turned to be a useful biomarker to discriminate feverish patients at low risk of malaria in an area where both infections exist. It would avoid more than 33% of unnecessary parasitological examinations with a very low risk of missing a malaria attack.
ISSN: 1935-2727

inserm-00872353
http://www.hal.inserm.fr/inserm-00872353
http://www.hal.inserm.fr/inserm-00872353/document
http://www.hal.inserm.fr/inserm-00872353/file/journal.pntd.0002420.pdf
DOI : 10.1371/journal.pntd.0002420

Éditeur(s) : HAL CCSD Frontiers Media
Résumé : International audience
The Anopheles midgut hosts diverse bacterial communities and represents a complex ecosystem. Several evidences indicate that mosquito midgut microbiota interferes with malaria parasite transmission. However, the bacterial composition of salivary glands and ovaries, two other biologically important tissues, has not been described so far. In this study, we investigated the dynamics of the bacterial communities in the mosquito tissues from emerging mosquitoes until 8 days after a blood meal containing Plasmodium falciparum gametocytes and described the temporal colonization of the mosquito epithelia. Bacterial communities were identified in the midgut, ovaries, and salivary glands of individual mosquitoes using pyrosequencing of the 16S rRNA gene. We found that the mosquito epithelia share a core microbiota, but some bacteria taxa were more associated with one or another tissue at a particular time point. The bacterial composition in the tissues of emerging mosquitoes varied according to the breeding site, indicating that some bacteria are acquired from the environment. Our results revealed temporal variations in the bacterial community structure, possibly as a result of the mosquito physiological changes. The abundance of Serratia significantly correlated with P. falciparum infection both in the midgut and salivary glands of malaria challenged mosquitoes, which suggests that interactions occur between microbes and parasites. These bacteria may represent promising targets for vector control strategies. Overall, this study points out the importance of characterizing bacterial communities in malaria mosquito vectors.
ISSN: 1664-302X

hal-01546162
https://hal.archives-ouvertes.fr/hal-01546162
DOI : 10.3389/fmicb.2015.01500

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
BACKGROUND:In French Guiana, a French overseas territory in South America, 6 to 10 thousands undocumented persons work illegally in gold mining sites in the Amazonian forest. Precarious life conditions lead to poor health but few data exist on the health status of illegal gold miners in French Guiana. The objective of this article was to describe the sociodemographic and health status of this vulnerable population.METHOD:A prospective cross-sectional survey was conducted in 2015 on gold mine supply sites at the border between French Guiana and Suriname. Health status was assessed through medical examination, past medical history, haemoglobin concentration, and HIV and malaria testing. A questionnaire was used to collect data about the migration itinerary and life conditions on mining sites.RESULTS:Among the 421 adults included in the study, 93.8% (395/421) were Brazilian, mainly from Maranhão (55.7%, 220/395), the poorest Brazilian state. The sex ratio was 2.4. Overall, 48% of persons never went to school or beyond the primary level. The median time spent in gold mining was quite long (10 years), with a high turn-over. One third of the surveyed population (37.1%, 156/421) had high blood pressure, and only two had a medical follow-up. Most persons had experienced malaria (89.3%, 376/421). They declared frequent arboviroses and digestive disorders. Active leishmaniasis was observed in 8.3% of gold miners. Among women, 28.5% were anemic. Concerning HIV, 36.6% (154/421) of persons, mainly men, never got tested before and 6 were tested positive, which represented an HIV prevalence of 1.43% (95%CI =0.29-2.5).CONCLUSION:These findings support the hypothesis that mining in remote areas is linked to several specific illnesses. Theoretically, gold miners would be presumed to start their economical migration to French Guiana as a healthy group. However, their strenuous working and living conditions there lead to poor health caused by infectious and non infectious diseases. This description of their health status is precious for health policy planners in French Guiana given the importance of controlling communicable disease, and the severity and range of specific illnesses acquired by this neglected population.TRIAL REGISTRATION:Clinical trial registration PRS N° NCT02903706 . Retrospectively registered 09/13/2016.
ISSN: 1471-2458

inserm-01566314
http://www.hal.inserm.fr/inserm-01566314
http://www.hal.inserm.fr/inserm-01566314/document
http://www.hal.inserm.fr/inserm-01566314/file/2017%2C%20Douine%20-%20Illegal%20gold%20miners%20in%20French%20Guiana.pdf
DOI : 10.1016/S0140-6736(10)62169-1

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
: Malaria is a public health problem in French Guiana. Plasmodium vivax is the most frequent parasite. The objective of this analysis was to estimate the proportion of relapses in the burden of vivax malaria using the statistical rule stating that any case of vivax malaria occurring less than 90 days following a first episode is a relapse.A total of 622 subjects were followed for 2,9 years with 336 first single episodes of P. vivax malaria, and a total of 1,226 episodes of vivax malaria among which 559 were relapses (45.5%). For 194 patients having had falciparum malaria followed by vivax malaria it was estimated that 19% of the vivax episodes occurred less than 90 days following the falciparum episode and thus were possibly relapses due to the activation of latent hypnozoites. Despite the number of vivax cases and the number of relapses, there were only 28 recorded primaquine prescriptions (3.4% of vivax episodes, 4.5% of subjects).The present study points out that despite the fact that nearly half of the P. vivax cases, many of which in children, are caused by latent hypnozoites, only a minority of them benefit from primaquine radical cure. The obstacles to this are discussed and suggestions are made to reduce the burden of vivax malaria in Camopi and other remote health centres in French Guiana.
ISSN: 1475-2875

inserm-00903890
http://www.hal.inserm.fr/inserm-00903890
http://www.hal.inserm.fr/inserm-00903890/document
http://www.hal.inserm.fr/inserm-00903890/file/1475-2875-12-367.pdf
DOI : 10.1186/1475-2875-12-367

Résumé : Notre étude s’est proposée d’analyser l’incidence du paludisme et son évolution dans le temps et dans l’espace, ainsi que de rechercher les facteurs de risque d’accès palustres chez les enfants d’un village du Moyen-Oyapock (Camopi), peuplé d’Amérindiens wayampi et émerillon, d’une part, et d’un village du Haut-Maroni (Antecume Pata), peuplé d’Amérindiens wayana, d’autre part. L’approche a été multiple avec, pour chacun des deux sites d’étude :- Une analyse de survie (modèle de Cox) à partir des accès palustres confirmés biologiquement dans une cohorte d’enfants de moins de sept ans régulièrement suivis, ainsi qu’un questionnaire de type Connaissances, Attitudes et Pratiques (CAP), puis les caractéristiques des habitats et la description de leur environnement immédiat.- Une analyse spatiale avec une classification de l’occupation du sol à partir d’images satellites SPOT 5, l’extraction de variables environnementales d’intérêt, l’étude de leur effet sur la transmission du paludisme et la mise au point d’une méthode objective de sélection d’un rayon d’observation autour des habitations pour la caractérisation de l’environnement.- Une étude de séries temporelles (ARIMA) afin de déterminer l’effet des évènements climatiques et hydrologiques sur le paludisme, aux niveaux local et plus global (El Niño).Les taux d’incidence d’accès palustres sur la période 2001-2009 se sont révélés particulièrement élevés chez les jeunes enfants, notamment à Camopi avec une moyenne de 773‰ par année. Une diminution brutale de l’incidence a eue lieu en 2007 sur le Haut-Maroni et ce phénomène est observé à Camopi depuis 2010. Une prémunition se développe assez rapidement au cours de la vie (2-3 ans), surtout contre les reviviscences à Plasmodium vivax. Les facteurs environnementaux se sont avérés être les plus nombreux et les plus fortement liés à l’incidence palustre. En effet, le dégagement des alentours du carbet de toute végétation et une certaine distance de celui-ci à la forêt sont des facteurs protecteurs. La composante géographique est également apparue essentielle à Camopi avec une incidence qui variait selon le fleuve d’habitation et en fonction de la distance au hameau principal. Les facteurs météorologiques locaux (température et niveau du fleuve) se sont également révélés être liés à l’incidence du paludisme à court terme (0-3 mois). Par ailleurs, nos résultats ont permis d’émettre un certain nombre d’hypothèses quant à la transmission et au(x) vecteur(s) local(ux), et notamment de suggérer la participation d’un vecteur autre qu’An. darlingi dans la transmission du paludisme à Camopi. Nous avons également prouvé par ce travail que la télédétection et les systèmes d’information géographique sont très prometteurs pour la prise en compte de la dimension spatiale et environnementale dans l’étude des maladies transmissibles, notamment dans les zones d’accès difficile de Guyane.
The aim of our study was to analyze the incidence of malaria in children and its evolution through time and space, as well as to search for risk factors in a village in Mid-Oyapock (Camopi), populated by Amerindians Wayampi and Emerillon, on the one hand, and a village in Upper-Maroni (Antecume Pata), populated by Amerindians Wayana, on the other hand. The approach was multiple with, for both study sites:- A survival analysis (Cox modelling) completed out of biologically confirmed malaria attacks in a cohort of children under seven, as well as a Knowledge, Attitudes, Practices and Behavior (KAPB) questionnaire, and also the characteristics of the houses and the description of their immediate environment.- A spatial analysis with a land cover classification from SPOT 5 satellite images, the extraction of environmental variables, the study of their effect on malaria transmission and the development of an objective method for picking the proper observation horizon around houses in order to characterize the environment.- A time series study (ARIMA) to determine the effect of climatic and hydrological events on malaria at local and global (El Niño) scales.The incidence rates of malaria attacks during the period 2001-2009 were particularly high among young children, especially in Camopi with an average of 773‰ by year. A sharp decline in incidence occurred in 2007 on the Upper Maroni and this phenomenon has been observed in Camopi since 2010. An acquired immunity develops quite rapidly during the life (2-3 years old), especially against P. vivax relapses. Environmental factors were found to be the most strongly associated with malaria incidence. Indeed, living in a hut cleared from the surrounding vegetation and at a larger distance from the forest are protective factors. The geographic component also appeared essential in Camopi with an incidence which varied with the river of living and with the distance from the main hamlet. The local meteorological factors (temperature and river level) also proved to be linked to malaria incidence in the short term (0-3 months). Moreover, our results have allowed issuing a number of assumptions about the transmission and the local vector(s), in particular to suggest the involvement of another vector than An. darlingi in the malaria transmission in Camopi. We also proved by this work that remote sensing and geographic information systems hold great promise for the inclusion of the spatial and environmental dimensions in the study of transmitted diseases, especially in areas of difficult access in French Guiana.

http://www.theses.fr/2011AGUY0448/document

Éditeur(s) : HAL CCSD Lippincott, Williams & Wilkins
Résumé : PURPOSE OF REVIEW: Malaria represents one of the most important selective factors affecting human populations. Several inherited diseases of red blood cells lead to resistance at the erythrocytic stage. Among patients who experience hereditary elliptocytosis related to mutations of erythrocyte membrane proteins, molecular studies have shown the prevalence of particular spectrin mutations in patients from black ethnic extraction, leading one to question the selection of new malaria-resistant genes. RECENT FINDINGS: Prospective epidemiological and molecular studies in West Africa have confirmed the prevalence (between 0.6 and 1.6%) of particular spectrin mutations related to hereditary elliptocytosis. These studies have also revealed the frequency of alpha-spectrin chain polymorphisms, associated in cis with elliptocytogenic spectrin mutations and defining particular spectrin allele haplotypes. Culture studies of Plasmodium falciparum in elliptocytes bearing such elliptocytogenic alleles of spectrin showed that these alleles are supplementary genetic factors of malaria resistance in vitro. SUMMARY: Certain instances of spectrin mutations or polymorphisms have not yet been shown to constitute new factors of innate resistance to malaria in vivo. Epidemiological surveys of hereditary elliptocytosis and parasite culture studies, however, have argued that the relationships between parasite and spectrin-based skeleton should be examined more closely and the molecular interactions between parasite ligands and particular spectrin chain domains should be characterized.
ISSN: 1065-6251

inserm-00128119
http://www.hal.inserm.fr/inserm-00128119
http://www.hal.inserm.fr/inserm-00128119/document
http://www.hal.inserm.fr/inserm-00128119/file/Dhermy_et_al_figures.pdf
DOI : 10.1097/MOH.0b013e3280d21afd

Éditeur(s) : HAL CCSD
Résumé : International audience
The Duffy Antigen/Receptor for Chemokine (DARC) is a seven segment transmembrane protein. It was firstly discovered as a blood group antigen and was the first specific gene locus assigned to a specific autosome in man. It became more famous as an erythrocyte receptor for malaria parasites (Plasmodium vivax and Plasmodium knowlesi), and finally for chemokines. DARC is an unorthodox chemokine receptor as (i) it binds chemokines of both CC and CXC classes and (ii) it lacks the Asp-Arg-Tyr consensus motif in its second cytoplasmic loop hence cannot couple to G proteins and activate their signaling pathways. DARC had also been associated to cancer progression, numerous inflammatory diseases, and possibly to AIDS. In this review, we will summarize important biological data on DARC. Then we shall focus on recent development of the elaboration and analyzes of structural models of DARC. We underline the difficulty to propose pertinent structural models of transmembrane protein using comparative modeling process, and other dedicated approaches as the Protein Blocks. The chosen structural models encompass most of the biochemical data known to date. Finally, we present recent development of protein - protein docking between DARC structural models and CXCL-8 structures. We propose a hierarchal search based on separated rigid and flexible docking.
Infectious disorders drug targets

Droits : info:eu-repo/semantics/OpenAccess
inserm-00366309
http://www.hal.inserm.fr/inserm-00366309
http://www.hal.inserm.fr/inserm-00366309/document
http://www.hal.inserm.fr/inserm-00366309/file/de_Brevern_Autin_Bertrand_Colin_Etchebest.pdf
http://www.hal.inserm.fr/inserm-00366309/file/inserm-00366309_edited.pdf

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
BACKGROUND: Malaria is a major public health problem in French Guiana, where Plasmodium vivax has become the dominant malaria species since 2000. As in others endemic areas, it is important to specify the pattern of vivax malaria relapses and to try to discriminate efficiently re-infections from relapses. METHODS: This study was conducted in children born between January 1, 2001 and December 31, 2008 in Camopi, an Amerindian village located in the Amazon forest (n = 325), using an open cohort design. Primary and secondary attack rates of P. vivax were calculated using survival analysis. With the difference between the primary and secondary rates, this study aimed to estimate indirectly P. vivax relapse rate and evaluate its time evolution. RESULTS: Of the 1042 malaria attacks recorded, 689 (66%) were due to P. vivax (without mixed infection). One hundred and fifty one children had their primary attack with P. vivax and 106 had their two first attacks with P. vivax. In the absence of primaquine treatment, it was shown that P. vivax relapses mainly occurred during the first three months after the first attack. Thirty percent of children never had a relapse, 42% had a relapse before the first month after primary attack, 59% before the second month and 63% before the third month. CONCLUSION: This study confirmed that the relapse pattern in Camopi was compatible with the pattern described for the P. vivax Chesson (tropical) strain. In addition, due to the relapse rate time evolution, a simple arbitrary classification rule could be constructed: before 90 days after the primary attack, the secondary attack is a relapse; after 90 days, it is a re-infection. Adapted management of malaria cases based on these results could be devised.
ISSN: 1475-2875

inserm-00663913
http://www.hal.inserm.fr/inserm-00663913
http://www.hal.inserm.fr/inserm-00663913/document
http://www.hal.inserm.fr/inserm-00663913/file/1475-2875-8-278.pdf
DOI : 10.1186/1475-2875-8-278

Éditeur(s) : HAL CCSD
Résumé : International audience
Some of the immunologic mechanisms involved in malaria physiopathology remain unclear. In animals, the spleen seems to play a key role in protecting the host against malaria. However, little is known about the effect of spleen dysfunction on human malaria. We report two severe cases of Plasmodium falciparum infection with unusual clinical and parasitologic features in two splenectomized men living in French Guiana. The peripheral blood of these cases showed hyperparasitemia, with a high proportion of mature parasites and leukocytes with malaria pigment. Despite appropriate treatment and adequate absorption, hyperparasitemia persisted. Parasite clearance was delayed and one patient died. Only the patient who died had the merozoite surface protein 1 allele B-K1 and the varD gene genotype, which is considered to be a probable parasite virulence factor. These uncommon cases differ from most of those described in the literature, illustrating the complexity of the mechanisms underlying the protective function of the spleen in human malaria.
The American journal of tropical medicine and hygiene

pasteur-00590993
https://hal-riip.archives-ouvertes.fr/pasteur-00590993
PUBMED : 15381808

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
BACKGROUND: The genetic diversity of Plasmodium falciparum has been extensively studied in various parts of the world. However, limited data are available from Mauritania. The present study examined and compared the genetic diversity of P. falciparum isolates in Mauritania. METHODS: Plasmodium falciparum isolates blood samples were collected from 113 patients attending health facilities in Nouakchott and Hodh El Gharbi regions. K1, Mad20 and RO33 allelic family of msp-1 gene were determined by nested PCR amplification. RESULTS: K1 family was the predominant allelic type carried alone or in association with Ro33 and Mad20 types (90%; 102/113). Out of the 113 P. falciparum samples, 93(82.3%) harboured more than one parasite genotype. The overall multiplicity of infection was 3.2 genotypes per infection. There was no significant correlation between multiplicity of infection and age of patients. A significant increase of multiplicity of infection was correlated with parasite densities. CONCLUSIONS: The polymorphism of P. falciparum populations from Mauritania was high. Infection with multiple P. falciparum clones was observed, as well as a high multiplicity of infection reflecting both the high endemicity level and malaria transmission in Mauritania.
ISSN: 1475-2875

inserm-00936407
http://www.hal.inserm.fr/inserm-00936407
http://www.hal.inserm.fr/inserm-00936407/document
http://www.hal.inserm.fr/inserm-00936407/file/1475-2875-13-26.pdf
DOI : 10.1186/1475-2875-13-26

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Local variation in the density of Anopheles mosquitoes and the risk of exposure to bites are essential to explain the spatial and temporal heterogeneities in the transmission of malaria. Vector distribution is driven by environmental factors. Based on variables derived from satellite imagery and meteorological observations, this study aimed to dynamically model and map the densities of Anopheles darlingi in the municipality of Saint-Georges de l’Oyapock (French Guiana). Longitudinal sampling sessions of An. darlingi densities were conducted between September 2012 and October 2014. Landscape and meteorological data were collected and processed to extract a panel of variables that were potentially related to An. darlingi ecology. Based on these data, a robust methodology was formed to estimate a statistical predictive model of the spatial-temporal variations in the densities of An. darlingi in Saint-Georges de l’Oyapock. The final cross-validated model integrated two landscape variables—dense forest surface and built surface—together with four meteorological variables related to rainfall, evapotranspiration, and the minimal and maximal temperatures. Extrapolation of the model allowed the generation of predictive weekly maps of An. darlingi densities at a resolution of 10-m. Our results supported the use of satellite imagery and meteorological data to predict malaria vector densities. Such fine-scale modeling approach might be a useful tool for health authorities to plan control strategies and social communication in a cost-effective, targeted, and timely manner.
ISSN: 1932-6203

hal-01383486
https://hal.archives-ouvertes.fr/hal-01383486
https://hal.archives-ouvertes.fr/hal-01383486/document
https://hal.archives-ouvertes.fr/hal-01383486/file/Adde_et_al_PlosONE_2016.pdf
DOI : 10.1371/journal.pone.0164685

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The susceptibility of Anopheles mosquitoes to Plasmodium infections relies on complex interactions between the insect vector and the malaria parasite. A number of studies have shown that the mosquito innate immune responses play an important role in controlling the malaria infection and that the strength of parasite clearance is under genetic control, but little is known about the influence of environmental factors on the transmission success. We present here evidence that the composition of the vector gut microbiota is one of the major components that determine the outcome of mosquito infections. A. gambiae mosquitoes collected in natural breeding sites from Cameroon were experimentally challenged with a wild P. falciparum isolate, and their gut bacterial content was submitted for pyrosequencing analysis. The meta-taxogenomic approach revealed a broader richness of the midgut bacterial flora than previously described. Unexpectedly, the majority of bacterial species were found in only a small proportion of mosquitoes, and only 20 genera were shared by 80% of individuals. We show that observed differences in gut bacterial flora of adult mosquitoes is a result of breeding in distinct sites, suggesting that the native aquatic source where larvae were grown determines the composition of the midgut microbiota. Importantly, the abundance of Enterobacteriaceae in the mosquito midgut correlates significantly with the Plasmodium infection status. This striking relationship highlights the role of natural gut environment in parasite transmission. Deciphering microbe-pathogen interactions offers new perspectives to control disease transmission.
ISSN: 1553-7366

hal-01546176
https://hal.archives-ouvertes.fr/hal-01546176
DOI : 10.1371/journal.ppat.1002742

Éditeur(s) : HAL CCSD
Résumé : International audience
The search for safe antimalarial compounds acting against asexual symptom-responsible stages and sexual transmission-responsible forms of Plasmodium species is one of the major challenges in malaria elimination programs. So far, among current drugs approved for human use, only primaquine has transmission-blocking activity. The discovery of small molecules targeting different Plasmodium falcip-arum life stages remains a priority in antimalarial drug research. In this context, several independent studies have recently reported antiplasmodial and transmission-blocking activities of commonly used stains, dyes and fluorescent probes against P. falciparum including chloroquine-resistant isolates. Herein we have studied the antimalarial activities of dyes with different scaffold and we report that the triar-ylmethane dye (TRAM) Brilliant green inhibits the growth of asexual stages (IC 50 2 mM) and has exflagellation-blocking activity (IC 50 800 nM) against P. falciparum reference strains (3D7, 7G8) and chloroquine-resistant clinical isolate (Q206). In a second step we have investigated the antiplasmodial activities of two polysulfonated triarylmethane food dyes. Green S (E142) is weakly active against P. falciparum asexual stage (IC 50 x 17 mM) whereas Patent Blue V (E131) is inactive in both antimalarial assays. By applying liquid chromatography techniques for the culture supernatant analysis after cell washings and lysis, we report the detection of Brilliant green in erythrocytes, the selective uptake of Green S (E142) by infected erythrocytes, whereas Patent Blue V (E131) could not be detected within non-infected and 3D7-infected erythrocytes. Overall, our results suggest that two polysulfonated food dyes might display different affinity with transporters or channels on infected RBC membrane.
International journal for parasitology. Drugs and drug resistance

Droits : http://creativecommons.org/licenses/by-nc-sa/
pasteur-01614675
https://hal-pasteur.archives-ouvertes.fr/pasteur-01614675
https://hal-pasteur.archives-ouvertes.fr/pasteur-01614675/document
https://hal-pasteur.archives-ouvertes.fr/pasteur-01614675/file/Leba%20LJ-article%20colorant-version%20publiee.pdf
DOI : 10.1016/j.ijpddr.2017.07.002

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
During their immature life stages, malaria mosquitoes are exposed to a wide array of microbes and contaminants from the aquatic habitats. Although prior studies have suggested that environmental exposure shapes the microbial community structure in the adult mosquito, most reports have focused on laboratory-based experiments and on a single mosquito epithelium, the gut. In this study, we investigated the influence of the breeding site on the development of the Anopheles coluzzii and Anopheles gambiae microbiota in natural conditions. We characterized bacterial communities from aquatic habitats, at surface microlayer and subsurface water levels, to freshly emerge adult mosquitoes using multiplexed 16S rRNA gene pyrosequencing and we separately analyzed the microbiota associated with the different epithelia of adult individual, midguts, ovaries and salivary glands. We found that the distribution of bacterial communities in the aquatic habitats differed according to the depth of water collections. Inter-individual variation of bacterial composition was large in larvae guts but adult mosquitoes from a same breeding site shared quite similar microbiota. Although some differences in bacterial abundances were highlighted between the different epithelia of freshly emerged An. coluzzii and An. gambiae, an intriguing feature from our study is the particular similarity of the overall bacterial communities. Our results call for further investigations on the bacterial population dynamics in the different tissues to determine the distinctive characteristics of each microbiota during the mosquito lifespan and to identify specific interactions between certain key phyla or species and the insect life history traits.
ISSN: 1567-1348

hal-01546167
https://hal.archives-ouvertes.fr/hal-01546167
DOI : 10.1016/j.meegid.2014.09.029

Éditeur(s) : HAL CCSD
Résumé : International audience
—Managing spatial reservoirs of malaria infection plays a crucial role in effective disease control. In this paper, a reservoir of infection refers to one or more interconnected subpopulations that sustain the epidemic at the level of the metapopulation to which applying a (linear) control strategy suffices to eradicate the disease in the whole system. We propose a numerical method to explain the steps for identifying reservoirs of malaria infection within n connected regions with the explicit movement of human population from the previous theoretical results in order to design an efficient computational tool. Furthermore, we determine the minimal percentage (critical vaccination fraction) of susceptible individuals in the reservoirs that should be protected to eliminate malaria. The costs and cost-effectiveness of malaria control interventions were analysed considering two strategies of control. (i) protecting the minimal fraction of susceptible individual; (ii) protecting any fraction greater than the minimal fraction. Cost-effectiveness analysis shows that the less cost and more effective strategy is to vaccinate (or protect) the minimal fraction of susceptible human in the reservoir of infection to halt outbreak. A numerical example provides insight into the efficiency of this approach.
IAENG International Journal of Applied Mathematics

Droits : info:eu-repo/semantics/OpenAccess
hal-01683800
https://hal.univ-antilles.fr/hal-01683800
https://hal.univ-antilles.fr/hal-01683800/document
https://hal.univ-antilles.fr/hal-01683800/file/ZongoDorvilleGouba28Janvier2017.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : The Duffy antigen/receptor for chemokine (DARC) is an erythrocyte receptor for malaria parasites (Plasmodium vivax and Plasmodium knowlesi) and for chemokines. In contrast to other chemokine receptors, DARC is a promiscuous receptor that binds chemokines of both CC and CXC classes. The four extracellular domains (ECDs) of DARC are essential for its interaction with chemokines, whilst the first (ECD1) is sufficient for the interaction with malaria erythrocyte-binding protein. In this study, we elaborate and analyze structural models of the DARC. The construction of the 3D models is based on a comparative modeling process and on the use of many procedures to predict transmembrane segments and to detect far homologous proteins with known structures. Threading, ab initio, secondary structure and Protein Blocks approaches are used to build a very large number of models. The conformational exploration of the ECDs is performed with simulated annealing. The second and fourth ECDs are strongly constrained. On the contrary, the ECD1 is highly flexible, but seems composed of three consecutive regions: a small beta-sheet, a linker region and a structured loop. The chosen structural models encompass most of the biochemical features and reflect the known experimental data. They may be used to analyze functional interaction properties.
ISSN: 0006-3002

inserm-00143373
http://www.hal.inserm.fr/inserm-00143373
http://www.hal.inserm.fr/inserm-00143373/document
http://www.hal.inserm.fr/inserm-00143373/file/de_Brevern_BBA_2005.pdf
DOI : 10.1016/j.bbagen.2005.05.016

Éditeur(s) : HAL CCSD Centers for Disease Control and Prevention
Résumé : International audience
To assess the prevalence of malaria among illegal gold miners in the ă French Guiana rainforest, we screened 205 miners during May-June 2014. ă Malaria prevalence was 48.3%; 48.5% of cases were asymptomatic. ă Patients reported self-medication with artemisinin-based combination ă therapy. Risk for emergence and spread of artemisinin resistance among ă gold miners in the rainforest is high.
ISSN: 1080-6040

hal-01467560
https://hal.archives-ouvertes.fr/hal-01467560
DOI : 10.3201/eid2205.151957

Éditeur(s) : HAL CCSD
Résumé : Anopheles darlingi, one of the main malaria vectors in the Neotropics, is widely distributed in French Guiana, where malaria remains a major public-health problem. Elucidation of the relationships between the population dynamics of An. darlingi and local environmental factors would appear to be an essential factor in the epidemiology of human malaria in French Guiana and the design of effective vector-control strategies. In a recent investigation, longitudinal entomological surveys were carried out for 2-4 years in one village in each of three distinct endemic areas of French Guiana. Anopheles darlingi was always the anopheline mosquito that was most frequently caught on human bait, although its relative abundance (as a proportion of all the anophelines collected) and human biting rate (in bites/person-year) differed with the study site. Seasonality in the abundance of human-landing An. darlingi (with peaks at the end of the rainy season) was observed in only two of the three study sites. Just three An. darlingi were found positive for Plasmodium (either P. falciparum or P. vivax) circumsporozoite protein, giving entomological inoculation rates of 0*0-8*7 infectious bites/person-year. Curiously, no infected An. darlingi were collected in the village with the highest incidence of human malaria. Relationships between malaria incidence, An. darlingi densities, rainfall and water levels in the nearest rivers were found to be variable and apparently dependent on land-cover specificities that reflected the diversity and availability of habitats suitable for the development and reproduction of An. darlingi.
Annals of Tropical Medicine and Parasitology / Annals of Tropical Medicine & Parasitology

pasteur-00583507
https://hal-riip.archives-ouvertes.fr/pasteur-00583507
DOI : 10.1179/136485911X12899838683322
PUBMED : 21396247

Éditeur(s) : HAL CCSD Centers for Disease Control and Prevention
Résumé : Dengue-malaria co-infection reports are scarce. Of 1,723 consecutive febrile patients in Cayenne Hospital, 238 had dengue (174 early dengue fever cases) and 393 had malaria (371 acute malaria); 17 had both. Diagnosis of 1 of these 2 infections should not rule out testing for the other infection.
ISSN: 1080-6040

pasteur-00583875
https://hal-riip.archives-ouvertes.fr/pasteur-00583875
https://hal-riip.archives-ouvertes.fr/pasteur-00583875/document
https://hal-riip.archives-ouvertes.fr/pasteur-00583875/file/Carme.EID.2009.pdf
PUBMED : 19331769