Caractérisation hydrologique, morpho-métrique et physicochimique d’un hydrosystème urbain : le lac municipal d’Ebolowa (Sud-Cameroun)

La dégradation de la qualité des eaux de surface, constitue l’un des problèmes environnementaux majeurs auquel l’humanité est confrontée. Elle se caractérise par l'asphyxie des écosystèmes aquatiques, conséquence de la prolifération anarchique des algues qui consomment tout l'oxygène nécessaire à la vie de ces écosystèmes. Au Cameroun, de nombreuses sources de pollution des eaux ont été identifiées, mais l'absence d’une véritable stratégie de gestion des déchets est à l’origine de la dégradation de la qualité des eaux de surface. Dans l’optique d’évaluer le Lac Municipal d’Ebolowa (LME) sur les plans hydrologique, morphométrique et physicochimique, une étude a été menée de février à juillet 2012. L’échantillonnage s’est fait à une fréquence bimensuelle, entre la surface et 0.5 m de profondeur au niveau de trois points: S1 situé à quelques mètres de l’entrée des eaux de la rivière Mfoumou dans le LME, S2 situé au centre du LME à quelques mètres de son exutoire et S3 situé à quelques mètres de l’entrée des eaux de la rivière Bengo’o. Ces échantillons prélevés dans des bouteilles en plastique, sont transportés au laboratoire et analysés suivant des techniques appropriées. Les résultats obtenus mettent en évidence une diminution de la profondeur et de la superficie du LME, un débit spécifique moyen de 0,28 m3/s, une transparence n’excédant pas les 50 cm et un temps de renouvellement des eaux largement inférieur à une année. Ces résultats montrent que le LME se dégrade au fil des années, et se trouve au stade actuel d’hypereutrophie, conséquence de l’absence d’une politique de restauration développée et mise en œuvre par les autorités de la ville. En effet, aucune disposition particulière n’a été prise par les autorités en charge de la gestion du LME, pour y empêcher le déversement des déchets provenant à la fois du Marché Central, et des différentes structures qui le jouxtent. Au contraire, on assiste à Ebolowa à une augmentation des activités génératrices de déchets contribuant à aggraver la dégradation de ce lac. Cette situation laisse présager qu’à terme, on pourrait assister à une disparition totale de ce lac, ce qui ne serait pas nouveau car, des lacs de ce type ont déjà connu le même sort dans d’autres villes camerounaises (Bertoua et Yaoundé).Mots-clés : pollution, qualité des eaux, hypereutrophe, lac municipal d’Ebolowa.Hydrological, morphometrical and hydrochemical characterization of an urban hydrosystem: the Ebolowa municipal lake (South-Cameroon)Humanity is facing an important environmental problem, the degradation of surface waters quality, characterized by the asphyxia of aquatic ecosystems, as a result of the uncontrolled proliferation of algae that consume all oxygen necessary for the life of these ecosystems. In Cameroon many sources of water pollution have been identified but, the lack of a clearly defined wastes management strategy is the major reason of surface waters quality degradation. In order to evaluate the Ebolowa Municipal Lake (EML), hydrological, morphometrical and physicochemical parameters were studied from February to July 2012. Samples was collected twice a month, between the surface and 0.5 m depth at three sampling points : S1 located at few meters of the entrance of Mfoumou river waters; S2 located in the center of EML a few meters from its outlet and S3 located at few meters of the entrance of Bengo'o river waters in EML. Those samples were collected in plastic bottles, transported to the laboratory and analyzed with appropriate techniques. It appears from the results that the EML depth and area are continuously decreasing. The average specific flow is 0.28 m3/s, transparency is not exceeding 50 cm and the waters renewal time is below one year. According to these results, the quality of EML water is getting more and more degraded, and is currently in a hyper-eutrophic stage as a result of the absence of a restoration policy developed and implemented by Ebolowa city authorities. Unfortunately, No specific decisions have been taken by those authorities in order to prevent the discharge of wastes coming both from the Central Market and different structures situated around the lake. Instead, increase of waste generating activities in Ebolowa is contributing to the degradation of the lake. This suggests that there could be a total disappearance of the lake in the future, a situation which has been noticed in others lakes located in Cameroonian cities (Bertoua and Yaounde).Keywords : pollution, water quality, hyper-eutrophic, Ebolowa municipal lake

Gender impacts on rural cycling decisions : a case study of Bugesera district, Rwanda

Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2034In recent years, cycling mobility has attracted increasing interest from researchers. However, most available data on bicycling has focused on transport planning and policy development to address urban-related issues related. Only some studies have sought to understand rural cyclists' daily mobility decisions. The Global Positioning System (GPS) is an innovative tool that addresses spatial differences, even from a gender perspective. The study, therefore, assesses the impact of men's and women's cycling decisions in rural communities of low-income countries. The study targeted bike taxi customers and owners. Fifty participants of different gender, social background and occupation were recruited and handed a GPS device to collect their travel tracks in Nyamata and Mayange, Bugesera, Rwanda. Tracks collected contained road network data, distance (Origin-Destination), Elevation and Speed. Additional information was obtained through a survey, Focus Group Discussions and mapping of participants' daily activities. Limited gender inequality between male and female cyclists confirms that travelling speed has no impact on cycling decisions, reinforcing the notion that cultural norms and the lack of bicycle education, among many others, are the main barriers to more female cycling in Sub-Saharan Africa. Creating policies that encourage bicycle education at the school level, and teaching the value of cycling use for health and the environment, will help destigmatize cycling and remove cultural norms and restrictions

Integrating pediatric TB services into child healthcare services in Africa: study protocol for the INPUT cluster-randomized stepped wedge trial

Background Tuberculosis is among the top-10 causes of mortality in children with more than 1 million children suffering from TB disease annually worldwide. The main challenge in young children is the difficulty in establishing an accurate diagnosis of active TB. The INPUT study is a stepped-wedge cluster-randomized intervention study aiming to assess the effectiveness of integrating TB services into child healthcare services on TB diagnosis capacities in children under 5 years of age. Methods Two strategies will be compared: i) The standard of care, offering pediatric TB services based on national standard of care; ii) The intervention, with pediatric TB services integrated into child healthcare services: it consists of a package of training, supportive supervision, job aids, and logistical support to the integration of TB screening and diagnosis activities into pediatric services. The design is a cluster-randomized stepped-wedge of 12 study clusters in Cameroon and Kenya. The sites start enrolling participants under standard-of-care and will transition to the intervention at randomly assigned time points. We enroll children aged less than 5 years with a presumptive diagnosis of TB after obtaining caregiver written informed consent. The participants are followed through TB diagnosis and treatment, with clinical information prospectively abstracted from their medical records. The primary outcome is the proportion of TB cases diagnosed among children < 5 years old attending the child healthcare services. Secondary outcomes include: number of children screened for presumptive active TB; diagnosed; initiated on TB treatment; and completing treatment. We will also assess the cost-effectiveness of the intervention, its acceptability among health care providers and users, and fidelity of implementation. Discussion Study enrolments started in May 2019, enrolments will be completed in October 2020 and follow up will be completed by June 2021. The study findings will be disseminated to national, regional and international audiences and will inform innovative approaches to integration of TB screening, diagnosis, and treatment initiation into child health care services. Trial resistration NCT03862261, initial release 12 February 2019

Plasmodium falciparum population dynamics in a cohort of pregnant women in Senegal

<p>Abstract</p> <p>Background</p> <p>Pregnant women acquire protective antibodies that cross-react with geographically diverse placental <it>Plasmodium falciparum </it>isolates, suggesting that surface molecules expressed on infected erythrocytes by pregnancy-associated malaria (PAM) parasites have conserved epitopes and, that designing a PAM vaccine may be envisaged. VAR2CSA is the main candidate for a pregnancy malaria vaccine, but vaccine development may be complicated by its sequence polymorphism.</p> <p>Methods</p> <p>The dynamics of <it>P. falciparum </it>genotypes during pregnancy in 32 women in relation to VAR2CSA polymorphism and immunity was determined. The polymorphism of the <it>msp2 </it>gene and five microsatellites was analysed in consecutive parasite isolates, and the <it>DBL5ε + Interdomain 5 </it>(<it>Id5</it>) part of the <it>var2csa </it>gene of the corresponding samples was cloned and sequenced to measure variation.</p> <p>Results</p> <p>In primigravidae, the multiplicity of infection in the placenta was associated with occurrence of low birth weight babies. Some parasite genotypes were able to persist over several weeks and, still be present in the placenta at delivery particularly when the host anti-VAR2CSA antibody level was low. Comparison of diversity among genotyping markers confirmed that some PAM parasites may harbour more than one <it>var2csa </it>gene copy in their genome.</p> <p>Conclusions</p> <p>Host immunity to VAR2CSA influences the parasite dynamics during pregnancy, suggesting that the acquisition of protective immunity requires pre-exposure to a limited number of parasite variants. Presence of highly conserved residues in surface-exposed areas of the VAR2CSA immunodominant DBL5ε domain, suggest its potential in inducing antibodies with broad reactivity.</p

Task shifting to non-physician clinicians for integrated management of hypertension and diabetes in rural Cameroon: a programme assessment at two years

<p>Abstract</p> <p>Background</p> <p>The burden of non-communicable chronic diseases, such as hypertension and diabetes, increases in sub-Saharan Africa. However, the majority of the rural population does still not have access to adequate care. The objective of this study is to examine the effectiveness of integrating care for hypertension and type 2 diabetes by task shifting to non-physician clinician (NPC) facilities in eight rural health districts in Cameroon.</p> <p>Methods</p> <p>Of the 75 NPC facilities in the area, 69 (87%) received basic equipment and training in hypertension and diabetes care. Effectiveness was assessed after two years on status of equipment, knowledge among trained NPCs, number of newly detected patients, retention of patients under care, treatment cost to patients and changes in blood pressure (BP) and fasting plasma glucose (FPG) among treated patients.</p> <p>Results</p> <p>Two years into the programme, of 54 facilities (78%) available for re-assessment, all possessed a functional sphygmomanometer and stethoscope (65% at baseline); 96% stocked antihypertensive drugs (27% at baseline); 70% possessed a functional glucose meter and 72% stocked oral anti-diabetics (15% and 12% at baseline). NPCs' performance on multiple-choice questions of the knowledge-test was significantly improved. During a period of two years, trained NPCs initiated treatment for 796 patients with hypertension and/or diabetes. The retention of treated patients at one year was 18.1%. Hypertensive and diabetic patients paid a median monthly amount of 1.4 and 0.7 Euro respectively for their medication. Among hypertensive patients with ≥ 2 documented visits (n = 493), systolic BP decreased by 22.8 mmHg (95% CI: -20.6 to -24.9; p < 0.0001) and diastolic BP by 12.4 mmHg (-10.9 to -13.9; p < 0.0001). Among diabetic patients (n = 79) FPG decreased by 3.4 mmol/l (-2.3 to -4.5; p < 0.001).</p> <p>Conclusions</p> <p>The integration of hypertension and diabetes into primary health care of NPC facilities in rural Cameroon was feasible in terms of equipment and training, accessible in terms of treatment cost and showed promising BP- and FPG-trends. However, low case-detection rates per NPC and a very high attrition among patients enrolled into care, limited the effectiveness of the programme.</p

Is chloroquine chemoprophylaxis still effective to prevent low birth weight? Results of a study in Benin

BACKGROUND: In areas of stable transmission, malaria during pregnancy is associated with severe maternal and foetal outcomes, especially low birth weight (LBW). To prevent these complications, weekly chloroquine (CQ) chemoprophylaxis is now being replaced by intermittent preventive treatment with sulfadoxine-pyrimethamine in West Africa. The prevalence of placental malaria and its burden on LBW were assessed in Benin to evaluate the efficacy of weekly CQ chemoprophylaxis, prior to its replacement by intermittent preventive treatment. METHODS: In two maternity clinics in Ouidah, an observational study was conducted between April 2004 and April 2005. At each delivery, placental blood smears were examined for malaria infection and women were interviewed on their pregnancy history including CQ intake and dosage. CQ was measured in the urine of a sub-sample (n = 166). Multiple logistic and linear regression were used to assess factors associated with LBW and placental malaria. RESULTS: Among 1090 singleton live births, prevalence of placental malaria and LBW were 16% and 17% respectively. After adjustment, there was a non-significant association between placental malaria and LBW (adjusted OR = 1.43; P = 0.10). Multiple linear regression showed a positive association between placental malaria and decreased birth weight in primigravidae. More than 98% of the women reported regular chemoprophylaxis and CQ was detectable in 99% of urine samples. Protection from LBW was high in women reporting regular CQ prophylaxis, with a strong duration-effect relationship (test for linear trend: P < 0,001). CONCLUSION: Despite high parasite resistance and limited effect on placental malaria, a CQ chemoprophylaxis taken at adequate doses showed to be still effective in reducing LBW in Benin

Early biting and insecticide resistance in the malaria vector Anopheles might compromise the effectiveness of vector control intervention in Southwestern Uganda.

BACKGROUND: Southwestern Uganda has high malaria heterogeneity despite moderate vector control and other interventions. Moreover, the early biting transmission and increased resistance to insecticides might compromise strategies relying on vector control. Consequently, monitoring of vector behaviour and insecticide efficacy is needed to assess the effectiveness of strategies aiming at malaria control. This eventually led to an entomological survey in two villages with high malaria prevalence in this region. METHODS: During rainy, 2011 and dry season 2012, mosquitoes were collected in Engari and Kigorogoro, Kazo subcounty, using human landing collection, morning indoor resting collection, pyrethrum spray collection and larval collection. Circumsporozoite protein of Plasmodium falciparum sporozoites in female Anopheles mosquitoes was detected using ELISA assay. Bioassays to monitor Anopheles resistance to insecticides were performed. RESULTS: Of the 1,021 female Anopheles species captured, 62% (632) were Anopheles funestus and 36% (371) were Anopheles gambiae s.l. The most common species were Anopheles gambiae s.l. in Engari (75%) and A. funestus in Kigorogoro (83%). Overall, P. falciparum prevalence was 2.9% by ELISA. The daily entomological inoculation rates were estimated at 0.17 and 0.58 infected bites/person/night during rainy and dry season respectively in Engari, and 0.81 infected bites/person/night in Kigorogoro during dry season. In both areas and seasons, an unusually early evening biting peak was observed between 6 - 8 p.m. In Engari, insecticide bioassays showed 85%, 34% and 12% resistance to DDT during the rainy season, dry season and to deltamethrin during the dry season, respectively. In Kigorogoro, 13% resistance to DDT and to deltamethrin was recorded. There was no resistance observed to bendiocarb and pirimiphos methyl. CONCLUSIONS: The heterogeneity of mosquito distribution, entomological indicators and resistance to insecticides in villages with high malaria prevalence highlight the need for a long-term vector control programme and monitoring of insecticide resistance in Uganda. The early evening biting habits of Anopheles combined with resistance to DDT and deltamethrin observed in this study suggest that use of impregnated bed nets alone is insufficient as a malaria control strategy, urging the need for additional interventions in this area of high transmission

Pregnancy Outcome and Placenta Pathology in Plasmodium berghei ANKA Infected Mice Reproduce the Pathogenesis of Severe Malaria in Pregnant Women

Pregnancy-associated malaria (PAM) is expressed in a range of clinical complications that include increased disease severity in pregnant women, decreased fetal viability, intra-uterine growth retardation, low birth weight and infant mortality. The physiopathology of malaria in pregnancy is difficult to scrutinize and attempts were made in the past to use animal models for pregnancy malaria studies. Here, we describe a comprehensive mouse experimental model that recapitulates many of the pathological and clinical features typical of human severe malaria in pregnancy. We used P. berghei ANKA-GFP infection during pregnancy to evoke a prominent inflammatory response in the placenta that entails CD11b mononuclear infiltration, up-regulation of MIP-1 alpha chemokine and is associated with marked reduction of placental vascular spaces. Placenta pathology was associated with decreased fetal viability, intra-uterine growth retardation, gross post-natal growth impairment and increased disease severity in pregnant females. Moreover, we provide evidence that CSA and HA, known to mediate P. falciparum adhesion to human placenta, are also involved in mouse placental malaria infection. We propose that reduction of maternal blood flow in the placenta is a key pathogenic factor in murine pregnancy malaria and we hypothesize that exacerbated innate inflammatory responses to Plasmodium infected red blood cells trigger severe placenta pathology. This experimental model provides an opportunity to identify cell and molecular components of severe PAM pathogenesis and to investigate the inflammatory response that leads to the observed fetal and placental blood circulation abnormalities

Comparative Transcriptional and Genomic Analysis of Plasmodium falciparum Field Isolates

Mechanisms for differential regulation of gene expression may underlie much of the phenotypic variation and adaptability of malaria parasites. Here we describe transcriptional variation among culture-adapted field isolates of Plasmodium falciparum, the species responsible for most malarial disease. It was found that genes coding for parasite protein export into the red cell cytosol and onto its surface, and genes coding for sexual stage proteins involved in parasite transmission are up-regulated in field isolates compared with long-term laboratory isolates. Much of this variability was associated with the loss of small or large chromosomal segments, or other forms of gene copy number variation that are prevalent in the P. falciparum genome (copy number variants, CNVs). Expression levels of genes inside these segments were correlated to that of genes outside and adjacent to the segment boundaries, and this association declined with distance from the CNV boundary. This observation could not be explained by copy number variation in these adjacent genes. This suggests a local-acting regulatory role for CNVs in transcription of neighboring genes and helps explain the chromosomal clustering that we observed here. Transcriptional co-regulation of physical clusters of adaptive genes may provide a way for the parasite to readily adapt to its highly heterogeneous and strongly selective environment

Drug Resistance in Eukaryotic Microorganisms

Eukaryotic microbial pathogens are major contributors to illness and death globally. Although much of their impact can be controlled by drug therapy as with prokaryotic microorganisms, the emergence of drug resistance has threatened these treatment efforts. Here, we discuss the challenges posed by eukaryotic microbial pathogens and how these are similar to, or differ from, the challenges of prokaryotic antibiotic resistance. The therapies used for several major eukaryotic microorganisms are then detailed, and the mechanisms that they have evolved to overcome these therapies are described. The rapid emergence of resistance and the restricted pipeline of new drug therapies pose considerable risks to global health and are particularly acute in the developing world. Nonetheless, we detail how the integration of new technology, biological understanding, epidemiology and evolutionary analysis can help sustain existing therapies, anticipate the emergence of resistance or optimize the deployment of new therapies