Typhoid fever in children: Clinical presentation and risk factors

Objective: The diagnosis of typhoid fever based on widal test is on the rise despite its set back. We prospectively reviewed over one year period, cases of typhoid fever admitted in our centre to document the pattern of clinical presentation, risk factors and the reliability of Widal test in its diagnosis.Methods: This was a prospective study carried out in a NigerianTeaching Hospital. All children, whose parents consented, admittedwith a diagnosis of typhoid fever using the Centre for Disease Controland prevention (CDC) case definition for typhoid fever, between 1stJanuary and 31st December 2010, were consecutively reviewed using astructured questionnaire.Results: A total of 42 patients were admitted out of which 35 were analysed, the remaining 7 were excluded because consent was notobtained. The disease was more common in males than females withM: F ratio of 3:2. The study gives the incidence of suspected typhoidof 30.5 per 1000 admission. The age range of the study population was 6months to 15 years with cases being common among the age group fiveto nine years 13(37.1%). It has a bimodal peak of occurrence as itoccurs commonly in April/May and in August/September. The diseasewas common in the low socioeconomic classes. All the 35 patientshad fever (100%), vomiting 25 (71.4%), typhoid psychosis 3 (8.6%) and 4 (11.4%) had intestinal perforation. Culture was positive in 8 (22.9%) of the patients. Widal test were significant in 20 (57.1%) with a sensitivity of 62.5%, specificity 44.4%, positive predictive value 25%, negative predictive value 80% and the efficiency of the test was 48.6%.Conclusion: The incidence of typhoid fever in this study is 30.5 per 1000 admission, it is common during rainy and harmattan period. The use of Widal test is not too helpful in diagnosis of typhoid fever. Therefore, culture samples should be done in all cases of suspected typhoid fever

Quantifying the modern recharge of the "fossil" Sahara aquifers

The North-Western Sahara Aquifer System (NWSAS), one of the world's largest groundwater systems, shows an overall piezometric decline associated with increasing withdrawals. Estimating the recharge rate in such a semiarid system is challenging but crucial for sustainable water development. In this paper, the recharge of the NWSAS is estimated using a regional water budget based on GRACE terrestrial water storage monthly records, soil moisture from the GLDAS (a land data system that assimilates hydrological information), and groundwater pumping rates. A cumulated natural recharge rate of 1.40 +/- 0.90 km(3) yr(-1) is estimated for the two main aquifers. Our results suggest a renewal rate of about 40% which partly contradicts the premise that recharge in this area should be very low or even null. Aquifer depletion inferred from our analysis is consistent with observed piezometric head decline in the two main aquifers in the region. Annual recharge variations were also estimated and vary between 0 and 4.40 km(3) yr(-1) for the period 2003-2010. These values correspond to a recharge between 0 and 6.75 mm yr(-1) on the 650,000 km(2) of outcropping areas of the aquifers, which is consistent with the expected weak and sporadic recharge in this semiarid environment. These variations are also in line with annual rainfall variation with a lag time of about 1 year

QUANTIFICATION DE LA SÉCHERESSE MÉTÉOROLOGIQUE PAR DES INDICES STANDARDISES DE PRÉCIPITATION DANS LA VALLÉE DU FLEUVE SÉNÉGAL DE 1980 À 2017

International audienceLes sécheresses qui ont des répercussions sur la disponibilité de l'eau, la production agricole et les exploitations d'élevage, sont généralement identifiées et caractérisées à l'aide d'indices de sécheresse. La présente étude porte sur le potentiel d'utilisation de l'indice standardisé de précipitation (SPI) et de l’indice standardisé de précipitations-évapotranspiration (SPEI) basé sur les précipitations pour reproduire les sécheresses météorologiques observées dans la vallée du fleuve Sénégal. Les sécheresses historiques survenues de 1980 à 2017 ont été examinées et l'analyse du SPI montre un bon accord avec les épisodes de sécheresse enregistrés. Le SPI a également été utilisé pour étudier l’évolution temporelle de la sécheresse et sa gravité. Les sécheresses les plus graves dans le bassin se sont produites au cours des années 1983, 1984, 1992, 2014. L’intensité des sécheresses s'est avérée légère à modérée, malgré la présence de cas de sécheresse sévère à extrême comme en 1984. Les sécheresses les plus longues dans le bassin ont eu lieu au cours de huit années consécutives, de 1980 à 1987. Les valeurs du SPI étaient parfois inférieures à -1 pour ces années sur des échelles de temps de 1, 3, 6 et 12 mois. Les valeurs du SPI sur 12 mois sur cette période sont de -2,25 pour le pas de 1 mois, -1,7 pour les 3 mois, -1,2 pour les 6 mois et -2,2 pour les 12 mois. Ces valeurs du SPI suggèrent une sécheresse modérée (SPI 6 mois) à extrême (SPI 1 mois et 12 mois)

Modeling Groundwater Flow of the Mio-Pliocene Aquifer in the El-Outaya Plain, Biskra (Algeria)

El Outaya plain is located on the southern flank of the Aures Mountains, as part of ??the Saharan Atlas. It has an arid climate (less than 200 mm of rainfall / year). The Mio-Pliocene aquifer associated with this plain is an important resource for irrigation and drinking water. Achieving the first hydrodynamic model of the Mio-Pliocene ground water in El Outaya plain, with different operating scenarios and using the Visual Mod-flow code, shall contribute to the development of an action plan for a rational management of water resources. In addition, the model was calibrated to steady state conditions and then transient state conditions in order to prepare conductivity and porosity maps that characterize the spatial variability, in relation with the geological heterogeneity of the aquifer. Different operating scenarios indicated that the northern part of the plain is fairly vulnerable to feeding and exploitation conditions

Export of functional Streptomyces coelicolor alditol oxidase to the periplasm or cell surface of Escherichia coli and its application in whole-cell biocatalysis

Streptomyces coelicolor A3(2) alditol oxidase (AldO) is a soluble monomeric flavoprotein in which the flavin cofactor is covalently linked to the polypeptide chain. AldO displays high reactivity towards different polyols such as xylitol and sorbitol. These characteristics make AldO industrially relevant, but full biotechnological exploitation of this enzyme is at present restricted by laborious and costly purification steps. To eliminate the need for enzyme purification, this study describes a whole-cell AldO biocatalyst system. To this end, we have directed AldO to the periplasm or cell surface of Escherichia coli. For periplasmic export, AldO was fused to endogenous E. coli signal sequences known to direct their passenger proteins into the SecB, signal recognition particle (SRP), or Twin-arginine translocation (Tat) pathway. In addition, AldO was fused to an ice nucleation protein (INP)-based anchoring motif for surface display. The results show that Tat-exported AldO and INP-surface-displayed AldO are active. The Tat-based system was successfully employed in converting xylitol by whole cells, whereas the use of the INP-based system was most likely restricted by lipopolysaccharide LPS in wild-type cells. It is anticipated that these whole-cell systems will be a valuable tool for further biological and industrial exploitation of AldO and other cofactor-containing enzymes.

High resolution melting: a useful field-deployable method to measure dhfr and dhps drug resistance in both highly and lowly endemic Plasmodium populations

Background: Emergence and spread of drug resistance to every anti-malarial used to date, creates an urgent need for development of sensitive, specifc and feld-deployable molecular tools for detection and surveillance of validated drug resistance markers. Such tools would allow early detection of mutations in resistance loci. The aim of this study was to compare common population signatures and drug resistance marker frequencies between two populations with diferent levels of malaria endemicity and history of anti-malarial drug use: Tanzania and Sénégal. This was accomplished by implementing a high resolution melting assay to study molecular markers of drug resistance as compared to polymerase chain reaction–restriction fragment length polymorphism (PCR/RFLP) methodology. Methods: Fifty blood samples were collected each from a lowly malaria endemic site (Sénégal), and a highly malaria endemic site (Tanzania) from patients presenting with uncomplicated Plasmodium falciparum malaria at clinic. Data representing the DHFR were derived using both PCR–RFLP and HRM assay; while genotyping data representing the DHPS were evaluated in Senegal and Tanzania using HRM. Msp genotyping analysis was used to characterize the multiplicity of infection in both countries. Results: A high prevalence of samples harbouring mutant DHFR alleles was observed in both population using both genotyping techniques. HRM was better able to detect mixed alleles compared to PCR/RFLP for DHFR codon 51 in Tanzania; and only HRM was able to detect mixed infections from Senegal. A high prevalence of mutant alleles in DHFR (codons 51, 59, 108) and DHPS (codon 437) were found among samples from Sénégal while no mutations were observed at DHPS codons 540 and 581, from both countries. Overall, the frequency of samples harbouring either a single DHFR mutation (S108N) or double mutation in DHFR (C59R/S108N) was greater in Sénégal compared to Tanzania Conclusion: Here the results demonstrate that HRM is a rapid, sensitive, and feld-deployable alternative technique to PCR–RFLP genotyping that is useful in populations harbouring more than one parasite genome (polygenomic infections). In this study, a high levels of resistance polymorphisms was observed in both dhfr and dhps, among samples from Tanzania and Sénégal. A routine monitoring by molecular markers can be a way to detect emergence of resistance involving a change in the treatment policy

Ex vivo susceptibility and genotyping of Plasmodium falciparum isolates from Pikine, Senegal

Background: The monitoring of Plasmodium falciparum sensitivity to anti-malarial drugs is a necessity for effective case management of malaria. This species is characterized by a strong resistance to anti-malarial drugs. In Senegal, the first cases of chloroquine resistance were reported in the Dakar region in 1988 with nearly 7% population prevalence, reaching 47% by 1990. It is in this context that sulfadoxine–pyrimethamine temporarily replaced chloroquine as first line treatment in 2003, pending the introduction of artemisinin-based combination therapy in 2006. The purpose of this study is to assess the ex vivo sensitivity to different anti-malarial drugs of the P. falciparum population from Pikine. Methods: Fifty-four samples were collected from patients with non-complicated malaria and aged between 2 and 20 years in the Deggo health centre in Pikine in 2014. An assay in which parasites are stained with 4′, 6-di-amidino-2-phenylindole (DAPI), was used to study the ex vivo sensitivity of isolates to chloroquine, amodiaquine, piperaquine, pyrimethamine, and dihydroartemisinin. High resolution melting was used for genotyping of pfdhps, pfdhfr, pfmdr1, and pfcrt genes. Results: The mean IC50s of chloroquine, amodiaquine, piperaquine, dihydroartemisinin, and pyrimethamine were, respectively, 39.44, 54.02, 15.28, 2.23, and 64.70 nM. Resistance mutations in pfdhfr gene, in codon 437 of pfdhps gene, and an absence of mutation at position 540 of pfdhps were observed. Mutations in codons K76T of pfcrt and N86Y of pfmdr1 were observed at 51 and 11% population prevalence, respectively. A relationship was found between the K76T and N86Y mutations and ex vivo resistance to chloroquine. Conclusion: An increase in sensitivity of isolates to chloroquine was observed. A high sensitivity to dihydroartemisinin was observed; whereas, a decrease in sensitivity to pyrimethamine was observed in the parasite population from Pikine

West Africa International Centers of Excellence for Malaria Research: Drug Resistance Patterns to Artemether-Lumefantrine in Senegal, Mali, and The Gambia.

In 2006, artemether-lumefantrine (AL) became the first-line treatment of uncomplicated malaria in Senegal, Mali, and the Gambia. To monitor its efficacy, between August 2011 and November 2014, children with uncomplicated Plasmodium falciparum malaria were treated with AL and followed up for 42 days. A total of 463 subjects were enrolled in three sites (246 in Senegal, 97 in Mali, and 120 in Gambia). No early treatment failure was observed and malaria infection cleared in all patients by day 3. Polymerase chain reaction (PCR)-adjusted adequate clinical and parasitological response (ACPR) was 100% in Mali, and the Gambia, and 98.8% in Senegal. However, without PCR adjustment, ACPR was 89.4% overall; 91.5% in Mali, 98.8% in Senegal, and 64.3% in the Gambia (the lower value in the Gambia attributed to poor compliance of the full antimalarial course). However, pfmdr1 mutations were prevalent in Senegal and a decrease in parasite sensitivity to artesunate and lumefantrine (as measured by ex vivo drug assay) was observed at all sites. Recrudescent parasites did not show Kelch 13 (K13) mutations and AL remains highly efficacious in these west African sites