Temporal and structural relations within bark and trunk in Hevea brasiliensis Muell. Arg. (Euphorbiaceae): Physiological maturity index of bark and latex vessels

In Africa and particularly in Côte d'Ivoire, the exploitation of Hevea brasiliensis clones having strong vegetative growth based on the criterion of vigour adopted so far has raised physiological and physical problems characterized by a high rate of tapping panel dryness and wind damage. A study was conducted on three clones of Hevea brasiliensis (PB 235, GT 1 and PR 107) belonging respectively to classes of fast, moderate and slow vegetative growth, in order to determine the right moment for an exploitation which would minimize those drawbacks. Trunk measurements, bark collecting and histological sections followed by laticifers counting made on rubber trees aged from one to fifteen years, have enabled to describe the process of establishment of bark and laticifers. The intensity of development and thickening of the bark and the rate of laticifer emission are described respectively by distinct hyperbolic and logistic sigmoid functions. However, their temporal evolution is strongly marked by an irreversible decrease of the whole process of formation, whatever the clone, from six years after planting. Furthermore, the density of laticifers per mm2 switches, whatever the clone studied, from a number greater than 5, the first six years (5-8 < ?lv <2) to 0.35 the next 25 years (2 < ?lv < 0.4). This evolution which is very significant the first six years varies relatively little the rest of time. These results show six years after planting a major phenologic phenomenon, like a physiological maturity, which occurs within the tree. This study has allowed identifying good indicators for determining the age and/or the time when plantations should be tapped in Hevea brasiliensis. These relationships have certain and practical interests insofar as they will allow to determine the maturity of exploitation for plantations which age is unknown by using only a bark gauge to measure bark thickness and a measuring tape to measure the girth. (Résumé d'auteur

Candidate genes-based investigation of susceptibility to Human African Trypanosomiasis in Cote d'Ivoire

Human African Trypanosomiasis (HAT) or sleeping sickness is a Neglected Tropical Disease. Long regarded as an invariably fatal disease, there is increasing evidence that infection by T. b. gambiense can result in a wide range of clinical outcomes, including latent infections, which are long lasting infections with no parasites detectable by microscopy. The determinants of this clinical diversity are not well understood but could be due in part to parasite or host genetic diversity in multiple genes, or their interactions. A candidate gene association study was conducted in Côte d’Ivoire using a case-control design which included a total of 233 subjects (100 active HAT cases, 100 controls and 33 latent infections). All three possible pairwise comparisons between the three phenotypes were tested using 96 SNPs in16 candidate genes (IL1, IL4, IL4R, IL6, IL8, IL10, IL12, IL12R, TNFA, INFG, MIF, APOL1, HPR, CFH, HLA-A and HLA-G). Data from 77 SNPs passed quality control. There were suggestive associations at three loci in IL6 and TNFA in the comparison between active cases and controls, one SNP in each of APOL1, MIF and IL6 in the comparison between latent infections and active cases and seven SNP in IL4, HLA-G and TNFA between latent infections and controls. No associations remained significant after Bonferroni correction, but the Benjamini Hochberg false discovery rate test indicated that there were strong probabilities that at least some of the associations were genuine. The excess of associations with latent infections despite the small number of samples available suggests that these subjects form a distinct genetic cluster different from active HAT cases and controls, although no clustering by phenotype was observed by principle component analysis. This underlines the complexity of the interactions existing between host genetic polymorphisms and parasite diversity

Candidate gene polymorphisms study between human African trypanosomiasis clinical phenotypes in Guinea

Human African trypanosomiasis (HAT), a lethal disease induced by Trypanosoma brucei gambiense, has a range of clinical outcomes in its human host in West Africa: an acute form progressing rapidly to second stage, spontaneous self-cure and individuals able to regulate parasitaemia at very low levels, have all been reported from endemic foci. In order to test if this clinical diversity is influenced by host genetic determinants, the association between candidate gene polymorphisms and HAT outcome was investigated in populations from HAT active foci in Guinea.Samples were collected from 425 individuals; comprising of 232 HAT cases, 79 subjects with long lasting positive and specific serology but negative parasitology and 114 endemic controls. Genotypes of 28 SNPs in eight genes passed quality control and were used for an association analysis. IL6 rs1818879 allele A (p = 0.0001, OR = 0.39, CI95 = [0.24-0.63], BONF = 0.0034) was associated with a lower risk of progressing from latent infection to active disease. MIF rs36086171 allele G seemed to be associated with an increased risk (p = 0.0239, OR = 1.65, CI95 = [1.07-2.53], BONF = 0.6697) but did not remain significant after Bonferroni correction. Similarly MIF rs12483859 C allele seems be associated with latent infections (p = 0.0077, OR = 1.86, CI95 = [1.18-2.95], BONF = 0.2157). We confirmed earlier observations that APOL1 G2 allele (DEL) (p = 0.0011, OR = 2.70, CI95 = [1.49-4.91], BONF = 0.0301) is associated with a higher risk and APOL1 G1 polymorphism (p = 0.0005, OR = 0.45, CI95 = [0.29-0.70], BONF = 0.0129) with a lower risk of developing HAT. No associations were found with other candidate genes.Our data show that host genes are involved in modulating Trypanosoma brucei gambiense infection outcome in infected individuals from Guinea with IL6 rs1818879 being associated with a lower risk of progressing to active HAT. These results enhance our understanding of host-parasite interactions and, ultimately, may lead to the development of new control tools

Genetic Diversity of Simulium damnosum complex Onchocerciasis Vector and its Influence on Entomological Monitoring in the West of Côte d'Ivoire

In West Africa, Onchocerca volvulus, the causative pathogen of human onchocerciasis, is transmitted by sibling species of the Simulium damnosum complex. Little is known about blackfly intraspecific variability and its consequences on vectorial capacity in Côte d’Ivoire. This study reports the use of microsatellite markers to study the genetic profile and evaluate the gene flow between populations of S. damnosum s.l from three (3) different epidemiological facies in western Côte d’Ivoire, fifteen years after the end of onchocerciasis control program. Adult flies were collected on human attractants from 07 : 00 to 18 : 00 hours for three consecutive days by site, from December 2016 to October 2017. Four (4) microsatellite loci were used to characterize individuals from these populations. The four (4) loci were polymorphic with 13.25 alleles per locus. Two (2) specific alleles (190 bp and 290 bp), were reveal abundant with respective frequencies of 0.46 % and 0.58 %. Asignificant heterozygosity deficiency and low genetic differentiation (FST = 0.046, P = 0.024) have been observed for all the populations. The genetic analysis showed significant deviation from Hardy-Weinberg and significant heterozygosity deficiencies. Then, the great interspecific variability would be a general characteristic in S. damnosum s.l. At last, a probable evolution of the invasive strains of S. damnosum would have occurred in these localities. This study has shown significant deviation from Hardy-Weinberg and significant heterozygosity deficiencies in the populations of the three localities. The loci give independent estimate genetic parameters. The H3-4 locus to a low genetic differentiation between the populations. &nbsp

Évaluation de la diversité et de la charge parasitaire des lacs de la ville de Yamoussoukro en Côte d’Ivoire

Objectif: Cette étude vise à caractériser les parasites des eaux des lacs de Yamoussoukro et d’étudier les risques sanitaires dans la réutilisation de ces eaux usées afin d'en tirer les conséquences épidémiologiques.Méthodologie et résultats : Vingt-huit échantillons d’eaux résiduaires ont été collectés dans huit lacs de Yamoussoukro à partir de récipients stériles. La méthode de Bailenger a été utilisée pour la mise en évidence des parasites. La reconnaissance spécifique et le dénombrement des parasites ont été faits à l’aide d’un microscope optique. Les prévalences observées ont été comparées entre lacs et par espèce de parasite.Au total, 13 espèces de parasites: Ankylostoma sp., Strongyloïde sp., Ascaris sp., Nematodirus sp., Trichuris sp., Toxocara sp., Capillaria sp., Ascaridia galli, Enterobius vermicularis, Taenia sp., Hymenolepis diminuta., Entamoeba coli., Entamoeba histolytica et les larves de Strongles ont été détectées dans les eaux des huit lacs investigués à Yamoussoukro. Les oeufs d’helminthes sont quasi-présents dans tous les lacs investigués avec des charges parasitaires variables. Trois espèces ont donné des charges parasitaires très élevées : L’espèce Ankylostoma sp a été retrouvée dans tous les lacs. Les Strongyloïdes et les Ascaris sp présentaient des prévalences de 100 % et 87,5 % respectivement. Au niveau des lacs investigués, lacs, le lac N° 5 était le plus parasité avec une prévalence de 100 % sur l’ensemble des parasites, ensuite viennent les lacs N°1, 6 et 8 (69,2 %) puis les lacs G0, 9 et 10 (53,8 %).Conclusion et application des résultats: Les analyses parasitologiques montrent que les lacs de Yamoussoukro sont contaminés par des parasites d’importances médicales. L’infestation de ces eaux en agents pathogènes interdit leur usage en agriculture ce qui n’est pas couramment observé sur le terrain.Mots clés: Parasites, lacs, eaux résiduaires, Yamoussoukro, Côte d’IvoireEnglish AbstractObjectives: Water, source of life is essential for all living beings. After its use, the water is loaded in various elements modifying its physical, chemical and biological characteristics. One of the most serious environmental problems is the problem of sanitation. Indeed, human activity leads to the production of wastewater discharged daily into the wild.Methodology and results: Twenty-eight waste water samples were collected from eight Yamoussoukro lakes from sterile containers. The method of Bailenger was used for the detection of parasites. The specific recognition and enumeration of the parasites was done using an optical microscope Prevalences observed were compared between lakes and by parasite species. A total of 13 species of parasites: Ankylostoma sp., Strongyloïd sp., Ascaris sp., Nematodirus sp., Trichuris sp., Toxocara sp., Capillaria sp., Ascaridia galli, Enterobius vermicularis, Taenia sp., Hymenolepis diminuta., Entamoeba coli., Entamoeba histolytica et les larves de Strongles were detected in the waters of Yamoussoukro lakes. Helminth eggs are almost present in all investigated lakes with variable parasite loads. Three species gave very high parasite loads: The species Ankylostoma sp was found in all lakes. Strongyloids and Ascaris sp had prevalence rates of 100 % and 87.5 %, respectively. At the level of the parasite load of the lakes, Lake N ° 5 was the most parasitized with a prevalence of 100 % on all the parasites, then the lakes N ° 1, 6 and 8 (69,2 %) then the Lakes G0, 9 and 10 (53.8 %).Conclusion and application of results: Parasitological analysis show that Yamoussoukro lakes are contaminated by parasites of medical importance. The infestation of these waters with pathogens prohibits their use in agriculture, which is not commonly observed in the field.Keywords: Parasites, lakes, wastewater, Yamoussoukro, Côte d’Ivoir

Microbiological and physico-chemical characterisation of well water in the town of Korhogo, Côte d’Ivoire

Water is essential to the life of every living organism. The water used by the consumer must be safe for the preservation of his health. The objective of this study was to assess the quality of well water used in households in the city of Korhogo. To do this, water samples were taken from the wells of different households. Parameters such as pH, temperature, electrical conductivity and total dissolved solids were measured at the sampling sites. Nitrates and ammonium were determined by spectrophotometric methods using sodium salicylate and indophenol blue, respectively. The membrane filtration technique has been used for the enumeration of total coliforms, Escherichia coli, fecal enterococci, sulfite-reducing anaerobic bacteria, yeasts and moulds. The agar incorporation method was used for the enumeration of mesophilic aerobic germs. The non-conformity relative to pH was 73%. All wells were contaminated with nitrates and ammonium. Non-compliance rates of 80% and 53% were obtained for nitrates and ammonium respectively. Non-compliance with mesophilic aerobic germs, total coliforms, E. coli and fecal enterococci was 100% for each indicator. No spore of sulphite-reducing clostridia has been identified. Contamination rates of 80% (mould) and 67% (yeast) were recorded. The moulds isolated from the various water samples belong to the genus Aspergillus. The quality of well water in households is not suitable for human consumption. These waters require treatment or household residents must switch to other safe sources of drinking water

Prevalence of Virulence Genes Associated with Diarrheagenic Pathotypes of Escherichia coli

This study was conducted to characterize virulence genes of Escherichia coli isolates from water, sediment, fish, and crab in Aby Lagoon. Serogrouping was performed by EPEC antisera in 113 E. coli strains. The presence of diarrhea-associated genes (eae, stx, AggR, elt, and est) was assessed by multiplex PCR using specific primers. Based on the multiplex PCR, sixty-two isolates (42 from water, 19 from sediment, and 1 from crab) were positive for virulence genes, including 34 positive for elt (ETEC), 46 positive for est (ETEC), 24 positive for both elt and est, 6 positive for stx (EHEC), 1 positive for both stx + est, and 1 positive for both stx + elt. Genes eae (EPEC) and AggR (EAEC) were not detected. Nine serogroups (O114, O127, O55, O111, O86, O119, O126, O128, and O142) were identified. This study revealed the presence of diarrheagenic and nondiarrheagenic E. coli and potential public health risks if fishery products are not appropriately cooked

Prevalence and Intensity of Intestinal Parasites and Malaria in Pregnant Women at Abobo District in Abidjan, Côte d’Ivoire

A prospective study was carried out from 2010 to 2012 at the Hôpital Général d’Abobo (HGA) in Abidjan, in order to determine the impact of infectious and parasitic diseases on child cognitive development. Blood samples were examined by means of drop thick and blood smear, as for stool by direct examination and concentration by formalin-ether method. We evaluated the prevalence and the parasite load of malaria and gastrointestinal parasites and then investigated the risk factors for these disorders. Overall, 331 pregnant women in the last trimester of their pregnancy were enrolled. The plasmodic index was 3.9% with an infestation specific rate for P. falciparum of 100%. Concerning digestive protozoa, it has been observed 71.3% of nonpathogenic, against 9.7% of pathogens, either an overall prevalence of 51.4% of digestive parasites. The calculated average parasitic loads revealed 3089.2 tpz/μl of blood (95% CI, 591.1–5587.3) for malaria, 6.5 eggs per gram of stool (95% CI, 0.4–13.4) for intestinal helminths, and one (1) parasite by microscopic field for protozoa (common infestation). It has been shown that the occurrence of malaria has been linked to the nonuse of impregnated mosquito nets (χ2 = 0.012, p = 0.018) to age. No link could be established between the presence of digestive parasites and the age of pregnant women or socioeconomic conditions (level of education, profession, type of toilet). Malaria is less common in pregnant women, while the rate of digestive parasites remains high