Contribution à l’évaluation de la contamination par les métaux lourds de trois espèces de poissons, des sédiments et des eaux du Lac Tchad

Les fleuves Logone et Chari qui se jettent dans le Lac Tchad, sont exposés à toute forme de pollution. Le but de ce travail est d’évaluer la  contamination par les métaux lourds des eaux, des sédiments et des poissons du Lac Tchad. Trois espèces de poissons: Tilapia nilotica, Lates niloticus et Arius latiscutatus ont été obtenues au Lac Tchad et  transportées sous glace au laboratoire. Le Cd, le Pb et le Cr ont été dosés dans la tête, le foie, la chair et les os de ces poissons, dans les sédiments et l’eau au spectrophotomètre d’absorption atomique. Le Cd et le Pb n’étaient pas détectés dans les eaux et les sédiments. En comparant nos résultats obtenus dans la chair des poissons, à la grille de qualité de Mersch, la pollution des eaux du Lac Tchad va d’une situation intermédiaire (Cd) à une pollution importante (Cr). Les sédiments étaient plus  contaminés que les eaux. Toutes ces valeurs sont au-delà des normes existantes. L’analyse des variances (ANOVA) inter espèces, au seuil de 95% entre les organes, montre qu’il y a une corrélation positive (r = 0,74) et très significative (p = 0,02) entre la chair et les os des différentes espèces.Mots clés : Lac Tchad, métaux lourds, poissons, bioaccumulation

Triacilgliceroles y composición de ácidos grasos del aceite de semilla de egusi (Cucumeropsis Mannii Naudin)

Triacylglycerols were determined from a Cameroonian (African) white egusi seed oil (Cucumeropsis Mannii Naudin) using reversed phase high performance liquid chromatography. The fatty acid composition of two types of seed (red and white) is obtained by capillary gas chromatography. The study of the triacyiglycerol composition obtained in white egusi seed oil revealed that only nine triacylglycerols were present in amounts above 1% (area). The first five triglycerides represent more than 80% of the total triacylglycerols, and the major triacyiglycerol was palmitoyldilinoleoylglycerol, accounting for 23.6% of the oil. This oil contains a high proportion of linoleic acid (60% wt/wt).Se determinó la composición en triacilgliceroles del aceite de semilla de egusi del Camerún (Cucumeropsis Mannii Naudin) utilizando cromatografía líquida de alta eficacia en fase inversa. La composición en ácidos grasos de dos tipos de semillas de egusi (roja y blanca) fue obtenida por cromatografía de gases en columna capilar. El estudio de la composición en triacilgliceroles del aceite obtenido de semilla blanca de egusi reveló que sólo nueve de ellos se encontraban en proporción superior al 1% (en área). Cinco triacilgliceroles representaron más del 80% del total y el mayoritario fue el palmitoildilinoleoilglicerol (23,6%). Este aceite contiene una alta proporción de ácido linoleico (60%)

Triacylglycerols and fatty acids composition of egusi seed oil (<i>Cucumeropsis Mannii Naudin</i>)

Triacylglycerols were determined from a Cameroonian (African) white egusi seed oil (Cucumeropsis Mannii Naudin) using reversed phase high performance liquid chromatography. The fatty acid composition of two types of seed (red and white) is obtained by capillary gas chromatography. The study of the triacyiglycerol composition obtained in white egusi seed oil revealed that only nine triacylglycerols were present in amounts above 1% (area). The first five triglycerides represent more than 80% of the total triacylglycerols, and the major triacyiglycerol was palmitoyldilinoleoylglycerol, accounting for 23.6% of the oil. This oil contains a high proportion of linoleic acid (60% wt/wt).Se determinó la composición en triacilgliceroles del aceite de semilla de egusi del Camerún (Cucumeropsis Mannii Naudin) utilizando cromatografía líquida de alta eficacia en fase inversa. La composición en ácidos grasos de dos tipos de semillas de egusi (roja y blanca) fue obtenida por cromatografía de gases en columna capilar. El estudio de la composición en triacilgliceroles del aceite obtenido de semilla blanca de egusi reveló que sólo nueve de ellos se encontraban en proporción superior al 1% (en área). Cinco triacilgliceroles representaron más del 80% del total y el mayoritario fue el palmitoildilinoleoilglicerol (23,6%). Este aceite contiene una alta proporción de ácido linoleico (60%)

Traditional Techniques of oil extraction from Kapok (Ceiba pentandra Gaertn.), Mahogany (Khaya senegalensis) and Neem (Azadirach indica A. Juss.) Seeds from the Far-North Region of cameroon

An investigation was carried out in four localities of the Far-North of Cameroon (Maroua, Mokolo, Kaele and Yagoua in order to improve endogenous methods of oil extraction from kapok (Ceiba pentandra Gaertn.), mahogany (Hhaya Senegalensis) and neem (Azadirachta indica A. Juss.) seed. The questionnaire administered to 75 traditional producers permitted us to note that extraction of oil from kapok is scarce. The traditional extraction processes from these oilseeds vary. But two principal techniques are predominant: the kneading process and the heated paste process. Husking, pounding and extraction make up the bottleneck. The yields are low, averagely six pans (of 1L capacity) are used to obtain one litre of oil. Amelioration of these methods through the introduction of grinders and pressers will not only help reduce strenuousness, but also increase the capacity to treat the yields and oil quality

Hepatotoxicity and effectiveness of a Nevirapine-based antiretroviral therapy in HIV-infected patients with or without viral hepatitis B or C infection in Cameroon

Background: Coinfection with hepatitis B virus (HBV) or hepatitis C virus (HCV) in HIV-infected patients receiving a commonly used nevirapine-based antiretroviral therapy is a major concern for African clinicians owing to its high prevalence, the infrequent testing and treatment of viral hepatitis, and the impact of liver disease on the tolerability and effectiveness of anti-HIV treatment. We compared the hepatotoxicity and the immunological, virological and clinical effectiveness of a nevirapine-based antiretroviral therapy between patients infected with HIV only and patients coinfected with hepatitis B or C virus in Cameroon. Methods: A retrospective cohort study was conducted among HIV-1-infected patients. Plasma HBV DNA and HCV RNA were tested in positive or indeterminate samples for HBsAg or HCV antibodies, respectively. All patients received nevirapine and lamivudine plus stavudine or zidovudine. Results: Of 169 HIV-1-infected patients with a median baseline CD4 count of 135 cells/mm(3) (interquartile range [IQR] 67 218), 21% were coinfected with HBV or HCV. In coinfected patients, the median viral load was 2.47 x 107 IU/mL for HBV (IQR 3680-1.59 x 10(8)) and 928 000 IU/mL for HCV (IQR 178 400-2.06 x 10(6)). Multivariate analyses showed that the risk of hepatotoxicity was 2-fold higher in coinfected patients (p < 0.01). The response to antiretroviral therapy was however comparable between monoinfected and coinfected patients in terms of CD4 cell count increase (p = 0.8), HIV-1 viral load below 400 copies/mL (p = 0.9), death (p = 0.3) and death or new AIDS-defining event (p = 0.1). Nevirapine was replaced by a protease inhibitor in 4 patients owing to hepatotoxicity. Conclusion: This study suggests that the nevirapine-based antiretroviral therapy could be used safely as first-line treatment in patients with low CD4 cell count in Africa despite frequent coinfections with HBV or HCV and infrequent testing of these infections. Although testing for HBV and HCV should be systematically performed before initiating antiretroviral therapy, transaminases elevations at baseline or during treatment should be a decisive argument for testing when hepatitis status is unknown

Heavy metals in five leafy vegetables from urban and periurban sites in Ngaoundere, Cameroon

Heavy metal concentrations were estimated in five leafy vegetables (Solanum nigrum, Brassica oleraceae, Lactuca sativa, Amaranthus hybridus and Corchorus olitorius) from urban and periurban sites in Ngaoundere (Cameroon) using an Atomic Absorption Spectrophotometer (AAS). Vegetable samples were collected at the two stages of maturity: stage I (60 days) and stage II (90 days) for analysis. The results showed that the concentrations of heavy metals in all vegetables were greater in urban site than in periurban site. The highest concentrations of Fe (673.92 mg/kg DW), Cu (10.42 mg/kg), Cd (1.70 mg/kg DW), and Pb (31.75 mg/kg DW) were recorded in Lactuca sativa, Zn (94.60 mg/kg DW) in Solanum nigrum, and Ni (16.91 mg/kg DW) in Corchorus olitorius. The concentrations of Cu, and Pb were greater in roots than in aerial parts, while Fe, Cd, Ni and Zn concentrations were greater in aerial parts than in roots. Some of the concentrations of Ni, Zn and Pb in crops reached the critical level for plant growth. In general, the results indicated that the consumption of leafy vegetables harvested at the stage II potentially provides the greatest amount of heavy metals. The transportation index (Ti) decreased in vegetables harvested at the stage II for Fe, Cu, Cd and Zn but slightly increased for Ni and Pb, suggesting that heavy metal transportation from roots to aerial parts depends on the plant phenology and metal species. In all farms and at the two stages of maturity, the lead concentrations in all vegetables were more than the FAO/WHO maximum recommended level in leafy vegetable for human consumption. Moreover, all vegetables had some Cd concentrations that were higher than limits set by FAO/WHO. So, they are not suitable for human consumption

Impact of repeated ivermectin treatments against onchocerciasis on the transmission of loiasis : an entomologic evaluation in central Cameroon

Background: Annual community-directed treatment with ivermectin (CDTI) have been carried out since 1999 in the Lekie division (central region of Cameroon where most cases of Loa-related post ivermectin severe adverse events were reported) as part of the joined activities of the African Programme for Onchocerciasis Control (APOC) and Mectizan (R) Donation Program (MDP). As large-scale administration of ivermetine was demonstrated to be an efficient means to control loiasis transmission, it was hypothesized that CDTI would have lowered or halted the transmission of Loa loa in the Lekie division after 13 years of annual drug administration, indicating a possible reduction in the occurrence of Loa-related post-ivermectin severe adverse events. Methods: A 4-month entomologic study was carried out from March to June 2012 in the Lekie division to evaluate the impact of 13 years of CDTI on the transmission of L. loa whose baseline data were recorded in 1999-2000. Results: There was a significant reduction in the infection rate for Chrysops silacea and C. dimidiata from 6.8 and 9% in 1999-2000 to 3 and 3.6% in 2012, respectively. The differences in the infective rate (IR) (percentage of flies harboring head L3 larvae), potential infective rate (PIR) (percentage of flies bearing L3 larvae), mean head L3 larvae load (MHL3) (average L3 per infective fly) and mean fly L3 larvae load (MFL3) (average L3 per potentially infective fly) for both C. silacea and C. dimidiata were not significantly different between the two investigation periods. The biting density (BD) was almost three-fold higher in 2012 for C. silacea but not for C. dimidiata. The transmission potential (TP) which is a function of the BD, was higher in the present study than in the baseline investigation for each species. Conclusion: The infection rate remaining high, the high TP and the stability observed in the IR, PIR, MHL3 and MFL3 after 13 years of CDTI suggest that transmission of L. loa is still active. This is an indication that the risk of occurrence of severe adverse events such as fatal encephalopathies is still present, especially for heavily microfilaria-loaded people taken ivermectin for the first time

Determining the optimum Fe-o ratio for sustainable granular Fe-o/sand water filters

International audiencePacked beds of metallic iron (Fe0) and sand are tested for their efficiency at discolouring an aqueous methylene blue (MB) solution (2.0 mg L-1) in gravity driven systems for up to 95 days. The aim was to determine the optimal Fe0/sand ration for sustainable filters. Six different Fe0/sand volumetric ratios were explored: 0/100, 20/80, 30/70, 40/60, 60/40 and 100/0. The columns were characterized by (i) the time-dependant extent of MB discoloration and (ii) the evolution of the hydraulic conductivity (permeability). Results clearly showed increased permeability loss with increasing Fe0 ratio. The Fe0/sand ratio dependent extent of MB discoloration was not monotone. These observations corroborated the working hypothesis that properly designing a Fe0/sand filters is finding a compromise between: (i) increased sustainability by lowering Fe0 ratios and (ii) decreased efficiency by lowering Fe0 ratios. This work provided the first experimental evidence for an optimal Fe0/sand volumetric ratio of 25/75. This result will accelerate efforts for non site-specific system design

Effect of a single standard dose (150-200 mu g/kg) of ivermectin on Loa loa microfilaremia : systematic review and meta-analysis

Background. In central Africa, millions of individuals infected with Loa loa have received the anthelminthic drug ivermectin (IVM) as part of mass drug administration (MDA) campaigns targeting onchocerciasis control or elimination. Nonetheless, the parasitological surveys that are occasionally conducted to evaluate the impact of IVM treatments on Onchocerca volvulus do not include an assessment of the extra benefits of those MDA campaigns on L. loa. Methods. We conducted a systematic review of trials on the effect of a single standard (150-200 mu g/kg) dose of IVM on L. loa microfilarial density (MFD). The dynamics of MFD over 365 days of treatment were described using multilevel regression and latent class modeling. Results. IVM brings about a rapid, dramatic, and sustained decrease, with reduction rates of 60%, 75%, 85%, and 90% on day 1 (D1), D2, D7, and D365, respectively. At D365, no participants (0/238) with an initial MFD of = 20 000 mf/mL presented with an MFD above this value. The main predictor of post-treatment MFD was the pretreatment value, but this post-treatment value varied little between D8 and D365 regardless of the pretreatment level. Conclusions. A single dose of IVM is very effective at substantially reducing L. loa MFD for at least a year, irrespective of the initial level of parasitemia. Individuals treated with IVM are probably not any more at risk of severe adverse events when retreated 1 year later

A test-and-not-treat strategy for onchocerciasis in loa loa-endemic areas

BACKGROUND Implementation of an ivermectin-based community treatment strategy for the elimination of onchocerciasis or lymphatic filariasis has been delayed in Central Africa because of the occurrence of serious adverse events, including death, in persons with high levels of circulating Loa loa microfilariae. The LoaScope, a field-friendly diagnostic tool to quantify L. loa microfilariae in peripheral blood, enables rapid, point-of-care identification of persons at risk for serious adverse events. METHODS A test-and-not-treat strategy was used in the approach to ivermectin treatment in the Okola health district in Cameroon, where the distribution of ivermectin was halted in 1999 after the occurrence of fatal events related to L. loa infection. The LoaScope was used to identify persons with an L. loa microfilarial density greater than 20,000 microfilariae per milliliter of blood, who were considered to be at risk for serious adverse events, and exclude them from ivermectin distribution. Active surveillance for posttreatment adverse events was performed daily for 6 days. RESULTS From August through October 2015, a total of 16,259 of 22,842 persons 5 years of age or older (71.2% of the target population) were tested for L. loa microfilaremia. Among the participants who underwent testing, a total of 15,522 (95.5%) received ivermectin, 340 (2.1%) were excluded from ivermectin distribution because of an L. loa microfilarial density above the risk threshold, and 397 (2.4%) were excluded because of pregnancy or illness. No serious adverse events were observed. Nonserious adverse events were recorded in 934 participants, most of whom (67.5%) had no detectable L. loa microfilariae. CONCLUSIONS The LoaScope-based test-and-not-treat strategy enabled the reimplementation of community-wide ivermectin distribution in a heretofore "off limits" health district in Cameroon and is a potentially practical approach to larger-scale ivermectin treatment for lymphatic filariasis and onchocerciasis in areas where L. loa infection is endemic