93 research outputs found
Integrated cost-benefit analysis of tsetse control and herd productivity to inform control programs for animal African trypanosomiasis
Animal African trypanosomiasis (AAT) and its tsetse vector are responsible for annual losses estimated in billions of US dollars ($). Recent years have seen the implementation of a series of multinational interventions. However, actors of AAT control face complex resource allocation decisions due to the geographical range of AAT, diversity of ecological and livestock systems, and range of control methods available. The study presented here integrates an existing tsetse abundance model with a bio-economic herd model that captures local production characteristics as well as heterogeneities in AAT incidence and breed. These models were used to predict the impact of tsetse elimination on the net value of cattle production in the districts of Mambwe, in Zambia, and Faro et Déo in Cameroon. The net value of cattle production under the current situation was used as a baseline, and compared with alternative publicly funded control programmes. In Zambia, the current baseline is AAT control implemented privately by cattle owners (Scenario Z0). In Cameroon, the baseline (Scenario C0) is a small-scale publicly funded tsetse control programme and privately funded control at farm level. The model was run for 10 years, using a discount rate of 5%
Effectiveness of ready-to-use therapeutic food compared to a corn/soy-blend-based pre-mix for the treatment of childhood moderate acute malnutrition in Niger.
Standard nutritional treatment of moderate acute malnutrition (MAM) relies on fortified blended flours though their importance to treat this condition is a matter of discussion. With the newly introduced World Health Organization growth standards, more children at an early stage of malnutrition will be treated following the dietary protocols as for severe acute malnutrition, including ready-to-use therapeutic food (RUTF). We compared the effectiveness of RUTF and a corn/soy-blend (CSB)-based pre-mix for the treatment of MAM in the supplementary feeding programmes (SFPs) supported by Médecins Sans Frontières, located in the Zinder region (south of Niger). Children measuring 65 to <110 cm, newly admitted with MAM [weight-for-height (WHM%) between 70% and <80% of the NCHS median] were randomly allocated to receive either RUTF (Plumpy'Nut®, 1000 kcal day(-1)) or a CSB pre-mix (1231 kcal day(-1)). Other interventions were similar in both groups (e.g. weekly family ration and ration at discharge). Children were followed weekly up to recovery (WHM% ≥ 85% for 2 consecutive weeks). In total, 215 children were recruited in the RUTF group and 236 children in the CSB pre-mix group with an overall recovery rate of 79.1 and 64.4%, respectively (p < 0.001). There was no evidence for a difference between death, defaulter and non-responder rates. More transfers to the inpatient Therapeutic Feeding Centre (I-TFC) were observed in the CSB pre-mix group (19.1%) compared to the RUTF group (9.3%) (p = 0.003). The average weight gain up to discharge was 1.08 g kg(-1) day(-1) higher in the RUTF group [95% confidence interval: 0.46-1.70] and the length of stay was 2 weeks shorter in the RUTF group (p < 0.001). For the treatment of childhood MAM in Niger, RUTF resulted in a higher weight gain, a higher recovery rate, a shorter length of stay and a lower transfer rate to the I-TFC compared to a CSB pre-mix. This might have important implications on the efficacy and the quality of SFPs
The vertebrate fauna of the Upper Permian of Niger—III, morphology and ontogeny of the hindlimb of Moradisaurus grandis (Reptilia, Captorhinidae)
We describe hindlimb elements of the large captorhinid Moradisaurus grandis (Reptilia: Captorhinidae) recently collected from the Upper Permian Moradi Formation of north-central Niger. This description is based primarily on an associated partial skeleton comprising a hemimandible, vertebral column, and partial left and nearly complete right hindlimb. Additionally, we report on a well-preserved, articulated, and essentially complete juvenile pes that provides important information on the ontogeny of the captorhinid tarsus. The hindlimb of Moradisaurus is stout and more massively built than in any other known captorhinid. The femur displays several features interpreted as adaptations to the demands of large body size, and the tibia and fibula have short, wide shafts and hypertrophied condyles and epicondyles. The astragalus is very derived, possessing two accessory ossifications and a relatively horizontal tibial articulation, indicating that the tibia was held more vertically than in other captorhinids. The calcaneum is co-ossified with distal tarsal five. The juvenile pes indicates that the captorhinid centrale arose from the fusion of two ossification centers, and that the captorhinid astragalus arose from the fusion of at least three ossification centers
Synthesis and Evaluation of Highly Tolerant Pd Electrocatalysts as Cathodes in Direct Ethylene Glycol Fuel Cells (DEGFC)
Highly selective Pd electrocatalysts were synthesized by the formic acid (FA) method and evaluated as cathodes for DEGFC applications. In rotating disc measurements in acid medium, the Pd/C cathode showed important catalytic activity for the Oxygen Reduction Reaction (ORR). In the presence of ethylene glycol (EG, C(2)H(6)O(2)), Pd/C exhibited a noteworthy electrochemical behavior and full tolerance to the organic molecule. No current density peaks associated to the EG oxidation reaction emerged and the shift in onset potential for the ORR (E(onset)) toward more negative potentials was negligible on this cathode. As a comparison, commercial Pt/C was tested under the same conditions showing a poor selectivity for the ORR when EG was present. The detrimental effect of EG on the Pt electrocatalysts resulted in high intensity current density peaks due to the oxidation of EG and a significant shift in E(onset). The evaluation of Pd/C in a DEGFC operating at 80 degrees C demonstrated its good performance as cathode material. Given these results, it is expected that highly efficient Pd-based cathodes can find application in DEGFCs
The vertebrate fauna of the Upper Permian of Niger. IV. Nigerpeton ricqlesi (Temnospondyli: Cochleosauridae), and the Edopoid Colonization of Gondwana
We describe the edopoid temnospondyl Nigerpeton ricqlesi from the Upper Permian Moradi Formation of northern Niger on the basis of two partial skulls and tentatively associated postcranial material. This crocodile-like taxon displays several edopoid characters states such as a long prenarial region with enlarged premaxillae, elongated vomers, large, posteriorly tapering choanae, and a jugal that broadens anteriorly. Nigerpeton possesses a unique carnivorous dentition. It is autapomorphic in its possession of an extremely elongate snout bearing a maxillary bulge that accommodates three hypertrophied caniniform teeth, inner premaxillary tusks, and anterior paired fenestrae, which pierce the skull roof. In addition, both the maxilla and dentary tooth rows show the sporadic appearance of ‘doubled’ tooth positions. The lateral-line system is present at the adult stage, which suggests an aquatic habitat for this taxon. A phylogenetic analysis of Edopoidea and its relatives places Nigerpeton as the sister taxon to the Permo-Carboniferous genus Chenoprosopus from the U.S.A. As with other members of the Moradi tetrapod fauna, the discovery of Nigerpeton strengthens support for the hypothesis that West Africa hosted an endemic fauna at the close of the Paleozoic Era. Biogeographically, we propose that Late Carboniferous and Permian edopoids were geographically widespread and that they twice crossed the Central Pangean mountain chain (between Laurussia and Gondwana) during their evolution. This distribution was later fragmented with the onset of Late Permian climatic warming
Genotypic Variation for Root Development, Water Extraction and Yield Components in Groundnut Under Low Phosphorus and Drought Stresses
[Context] Unpredictable water deficit (drought) and low soil phosphorus (LP) are major interacting constraints to
groundnut growth and grain yield in Sahelian zones of West Africa. Combining breeding efforts for drought tolerance and P
efficiency could lead to improve tolerance and grains yield in these zones. [Objectives] This study assessed six groundnut
genotypes under lysimetric system to better understand the relative importance of P deficiency, water stress, and their interaction;
investigate the water extraction pattern of genotypes under these constraints and identify tolerance related traits to
accelerate development of more resilient varieties. [Methods] Thus, in experiment 1 (Exp.1) roots traits were investigated at
50% flowering, pod filling stage (60 days after sowing) and maturity stage (90 days after sowing) under high phosphorus (HP)
and LP treatments. In experiment 2 (Exp.2), two water regimes (WW=well water, and WS = water stress) were imposed to HP
and LP plants and parameters like total transpired water (TTW), transpiration efficiency (TE), water extraction (Wex), pods
and haulm weights were investigated. [Results] Roots traits showed significant decrease due to LP stress, pod and haulm
weights correlated significantly to roots length density (RLD) and roots dry matter (RDM). Genotypes 12CS-116 and ICGV
12991 revealed tolerant to LP stress while RLD and RDM revealed LP tolerance related traits in groundnut. Interacting effect
of LP and drought stress (LPWS) was higher than separate effect of LP and WS. Under LPWS, Wex, TTW, TE, pod and haulm
yields decreased significantly. This study suggests that RLD and RDM contributed to Wex in 12CS-116 and ICG 12991 under
LPWS. 55-437 and JL-24 with highest TTW showed drought tolerance strategy while drought avoidance strategy could
explain 12CS-116, 12CS-79, ICG 12991 and ICGV 97183 response to WS. Pod weight showed tight correlation (R2 =0.7) to
TE only under LPWS suggesting that TE explains a large part of pod yield variation under LPWS conditions. TE revealed WS
and LPWS tolerance related trait. The genotypic variation observed on Wex and TTW under LPWS suggests different patterns
of water extraction and use among the groundnut genotypes
Physiological response of cowpea [Vigna unguiculata (L.) Walp.] genotypes to water deficit under lysimeter conditions and agronomical performance in field conditions
Cowpea is the main food legume grown in Niger. Its low yield is mainly due to drought stress occurring at any stage of plant development. This study aims to (i) assess the intermittent and terminal water deficit effects on agro-physiological parameters and (ii) identify relevant traits useful in breeding programs to select high yielding and drought tolerant genotypes. Field and lysimeter experiments were conducted at ICRISAT Sahelian Centre in Niger. For lysimeter experiment, three water treatments were imposed: well-water (BI), intermittent water deficit (DH1) and terminal water deficit (DH2). The results showed significant negative effects of DH1 and DH2 on investigated parameters. Thus, the seed weight decreases up to 54% and 53% due to DH1 and DH2 respectively. These stress reduced transpiration efficiency (TE) by 15% and 13% respectively, and harvest index (HI) by 38% and 26% respectively. For the genotypic variation, the highest seed weight decrease was observed on Tiligré (85% and 78% under DH1 and DH2 respectively) while IT98K-1111-1 showed the lowest seed weight decrease (28% and 17% under DH1 and DH2 respectively). Our results showed that yield variation is mainly explained by the number of matured pods, TE and HI. IT98K-1111-1 and IT96D-610 with highest TE and HI revealed drought tolerant whereas high transpiration was observed in drought sensitive genotypes. The field trial confirmed agronomical trend observed in lysimeter studies
Genetic Diversity and Population Structure of the Secondary Symbiont of Tsetse Flies, Sodalis glossinidius, in Sleeping Sickness Foci in Cameroon
Human African trypanosomiasis remains a threat to the poorest people in Africa. The trypanosomes causing the disease are transmitted by tsetse flies. The drugs currently used are unsatisfactory: some are toxic and all are difficult to administer. Furthermore, drug resistance is increasing. Therefore, investigations for novel disease control strategies are urgently needed. Previous analyses showed the association between the presence of Glossina symbiont, Sodalis glossinidius, and the fly infection by trypanosomes in a south-western region in Cameroon: flies harbouring symbionts had a threefold higher probability of being infected by trypanosomes than flies devoid of symbionts. But the study also showed substantial differences in S. glossinidius and trypanosome infection rates between Glossina populations from two Cameroonian foci of sleeping sickness. We hypothesized that the geographical isolation of the two foci may have induced the independent evolution of each one, leading to the diversification of symbiont genotypes. Microsatellite markers were used and showed that genetic diversity structuring of S. glossinidius varies at different geographical scales with a low but significant differentiation between the Campo and Bipindi HAT foci. This encourages further work on interactions between S. glossinidius subpopulations and Glossina species that could favor tsetse fly infections by a given trypanosome species
Antibody responses to <i>P. falciparum</i> blood stage antigens and incidence of clinical malaria in children living in endemic area in Burkina Faso
Abstract Background High parasite-specific antibody levels are generally associated with low susceptibility to Plasmodium falciparum malaria. This has been supported by several studies in which clinical malaria cases of P. falciparum malaria were reported to be associated with low antibody avidities. This study was conducted to evaluate the role of age, malaria transmission intensity and incidence of clinical malaria in the induction of protective humoral immune response against P. falciparum malaria in children living in Burkina Faso. Methods We combined levels of IgG and IgG subclasses responses to P. falciparum antigens: Merozoite Surface Protein 3 (MSP3), Merozoite Surface Protein 2a (MSP2a), Merozoite Surface Protein 2b (MSP2b), Glutamate Rich Protein R0 (GLURP R0) and Glutamate Rich Protein R2 (GLURP R2) in plasma samples from 325 children under five (05) years with age, malaria transmission season and malaria incidence. Results We notice higher prevalence of P. falciparum infection in low transmission season compared to high malaria transmission season. While, parasite density was lower in low transmission than high transmission season. IgG against all antigens investigated increased with age. High levels of IgG and IgG subclasses to all tested antigens except for GLURP R2 were associated with the intensity of malaria transmission. IgG to MSP3, MSP2b, GLURP R2 and GLURP R0 were associated with low incidence of malaria. All IgG subclasses were associated with low incidence of P. falciparum malaria, but these associations were stronger for cytophilic IgGs. Conclusions On the basis of the data presented in this study, we conclude that the induction of humoral immune response to tested malaria antigens is related to age, transmission season level and incidence of clinical malaria
Structural Extremes in a Cretaceous Dinosaur
Fossils of the Early Cretaceous dinosaur, Nigersaurus taqueti, document for the first time the cranial anatomy of a rebbachisaurid sauropod. Its extreme adaptations for herbivory at ground-level challenge current hypotheses regarding feeding function and feeding strategy among diplodocoids, the larger clade of sauropods that includes Nigersaurus. We used high resolution computed tomography, stereolithography, and standard molding and casting techniques to reassemble the extremely fragile skull. Computed tomography also allowed us to render the first endocast for a sauropod preserving portions of the olfactory bulbs, cerebrum and inner ear, the latter permitting us to establish habitual head posture. To elucidate evidence of tooth wear and tooth replacement rate, we used photographic-casting techniques and crown thin sections, respectively. To reconstruct its 9-meter postcranial skeleton, we combined and size-adjusted multiple partial skeletons. Finally, we used maximum parsimony algorithms on character data to obtain the best estimate of phylogenetic relationships among diplodocoid sauropods. Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic
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